Gene Summary

Gene:FOXO4; forkhead box O4
Aliases: AFX, AFX1, MLLT7
Summary:This gene encodes a member of the O class of winged helix/forkhead transcription factor family. Proteins encoded by this class are regulated by factors involved in growth and differentiation indicating they play a role in these processes. A translocation involving this gene on chromosome X and the homolog of the Drosophila trithorax gene, encoding a DNA binding protein, located on chromosome 11 is associated with leukemia. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jan 2010]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:forkhead box protein O4
Source:NCBIAccessed: 21 August, 2015

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 21 August 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • KMT2A
  • Ewing's Sarcoma
  • TOR Serine-Threonine Kinases
  • DNA-Binding Proteins
  • Signal Transduction
  • Cyclin-Dependent Kinase Inhibitor p27
  • Transcription Factors
  • Base Sequence
  • YY1 Transcription Factor
  • Phosphatidylinositol 3-Kinases
  • Reactive Oxygen Species
  • Neck Muscles
  • Immunohistochemistry
  • Cell Differentiation
  • AKT1
  • X Chromosome
  • Messenger RNA
  • Neoplastic Cell Transformation
  • Cell Proliferation
  • Apoptosis
  • Tumor Markers
  • Transcription
  • Bone Cancer
  • Ubiquitin-Protein Ligases
  • Cancer Gene Expression Regulation
  • Transcriptional Activation
  • Ubiquitin
  • MicroRNAs
  • Western Blotting
  • Infant
  • Translocation
  • Phosphorylation
  • Hep G2 Cells
  • Up-Regulation
  • Forkhead Transcription Factors
  • Prostate Cancer
  • Molecular Sequence Data
  • Transfection
Tag cloud generated 21 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: FOXO4 (cancer-related)

Zhu H
Targeting forkhead box transcription factors FOXM1 and FOXO in leukemia (Review).
Oncol Rep. 2014; 32(4):1327-34 [PubMed] Related Publications
Deregulation of forkhead box (FOX) proteins has been found in many genetic diseases and malignancies including leukemia. Leukemia is a common neoplastic disease of the blood or bone marrow characterized by the presence of immature leukocytes and is one of the leading causes of death due to cancer. Forkhead transcription factors, FOXM1 and FOXO family members (FOXOs), are important mediators in leukemia development. Aberrant expression of FOXM1 and FOXOs results in leukemogenesis. Usually the expression of FOXM1 is upregulated, whereas the expression of FOXOs is downregulated due to phosphorylation, nuclear exclusion and degradation in leukemia. On the one hand, FOXOs are bona fide tumor suppressors, on the other hand, active FOXOs maintain leukemia stem cells and stimulate drug resistance genes, contributing to leukemogenesis. FOXM1 and FOXOs have been proven to be potential targets for the development of leukemia therapeutics. They are also valuable diagnostic and prognostic markers in leukemia for clinical applications. This review summarizes the present knowledge concerning the molecular mechanisms by which FOXM1 and FOXOs modulate leukemogenesis and leukemia development, the clinical relevance of these FOX proteins in leukemia and related areas that warrant further investigation.

Brohl AS, Solomon DA, Chang W, et al.
The genomic landscape of the Ewing Sarcoma family of tumors reveals recurrent STAG2 mutation.
PLoS Genet. 2014; 10(7):e1004475 [PubMed] Free Access to Full Article Related Publications
The Ewing sarcoma family of tumors (EFT) is a group of highly malignant small round blue cell tumors occurring in children and young adults. We report here the largest genomic survey to date of 101 EFT (65 tumors and 36 cell lines). Using a combination of whole genome sequencing and targeted sequencing approaches, we discover that EFT has a very low mutational burden (0.15 mutations/Mb) but frequent deleterious mutations in the cohesin complex subunit STAG2 (21.5% tumors, 44.4% cell lines), homozygous deletion of CDKN2A (13.8% and 50%) and mutations of TP53 (6.2% and 71.9%). We additionally note an increased prevalence of the BRCA2 K3326X polymorphism in EFT patient samples (7.3%) compared to population data (OR 7.1, p = 0.006). Using whole transcriptome sequencing, we find that 11% of tumors pathologically diagnosed as EFT lack a typical EWSR1 fusion oncogene and that these tumors do not have a characteristic Ewing sarcoma gene expression signature. We identify samples harboring novel fusion genes including FUS-NCATc2 and CIC-FOXO4 that may represent distinct small round blue cell tumor variants. In an independent EFT tissue microarray cohort, we show that STAG2 loss as detected by immunohistochemistry may be associated with more advanced disease (p = 0.15) and a modest decrease in overall survival (p = 0.10). These results significantly advance our understanding of the genomic and molecular underpinnings of Ewing sarcoma and provide a foundation towards further efforts to improve diagnosis, prognosis, and precision therapeutics testing.

Sugita S, Arai Y, Tonooka A, et al.
A novel CIC-FOXO4 gene fusion in undifferentiated small round cell sarcoma: a genetically distinct variant of Ewing-like sarcoma.
Am J Surg Pathol. 2014; 38(11):1571-6 [PubMed] Related Publications
Differential diagnosis of small round cell sarcomas (SRCSs) grouped under the Ewing sarcoma family of tumors (ESFT) can be a challenging situation for pathologists. Recent studies have revealed that some groups of Ewing-like sarcoma show typical ESFT morphology but lack any EWSR1-ETS gene fusions. Here we identified a novel gene fusion, CIC-FOXO4, in a case of Ewing-like sarcoma with a t(X;19)(q13;q13.3) translocation. The patient was a 63-year-old man who had an asymptomatic, 30-mm, well-demarcated, intramuscular mass in his right posterior neck, and imaging findings suggested a diagnosis of high-grade sarcoma. He was treated with complete resection and subsequent radiotherapy and chemotherapy. He was alive without local recurrence or distant metastasis 6 months after the operation. Histologic examination revealed SRCS with abundant desmoplastic fibrous stroma suggesting a desmoplastic small round cell tumor. Immunohistochemical analysis showed weak to moderate and partial staining for MIC2 (CD99) and WT1, respectively. High-throughput transcriptome sequencing revealed a gene fusion, and the genomic rearrangement between the CIC and FOXO4 genes was identified by fluorescence in situ hybridization. Aside from the desmoplastic stroma, the CIC-FOXO4 fusion sarcoma showed morphologic and immunohistochemical similarity to ESFT and Ewing-like sarcomas, including the recently described CIC-DUX4 fusion sarcoma. Although clinicopathologic analysis with additional cases is necessary, we conclude that CIC-FOXO4 fusion sarcoma is a new type of Ewing-like sarcoma that has a specific genetic signature. These findings have important implications for the differential diagnosis of SRCS.

Su L, Liu X, Chai N, et al.
The transcription factor FOXO4 is down-regulated and inhibits tumor proliferation and metastasis in gastric cancer.
BMC Cancer. 2014; 14:378 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: FOXO4, a member of the FOXO family of transcription factors, is currently the focus of intense study. Its role and function in gastric cancer have not been fully elucidated. The present study was aimed to investigate the expression profile of FOXO4 in gastric cancer and the effect of FOXO4 on cancer cell growth and metastasis.
METHODS: Immunohistochemistry, Western blotting and qRT-PCR were performed to detect the FOXO4 expression in gastric cancer cells and tissues. Cell biological assays, subcutaneous tumorigenicity and tail vein metastatic assay in combination with lentivirus construction were performed to detect the impact of FOXO4 to gastric cancer in proliferation and metastasis in vitro and in vivo. Confocal and qRT-PCR were performed to explore the mechanisms.
RESULTS: We found that the expression of FOXO4 was decreased significantly in most gastric cancer tissues and in various human gastric cancer cell lines. Up-regulating FOXO4 inhibited the growth and metastasis of gastric cancer cell lines in vitro and led to dramatic attenuation of tumor growth, and liver and lung metastasis in vivo, whereas down-regulating FOXO4 with specific siRNAs promoted the growth and metastasis of gastric cancer cell lines. Furthermore, we found that up-regulating FOXO4 could induce significant G1 arrest and S phase reduction and down-regulation of the expression of vimentin.
CONCLUSION: Our data suggest that loss of FOXO4 expression contributes to gastric cancer growth and metastasis, and it may serve as a potential therapeutic target for gastric cancer.

Zaravinos A, Kanellou P, Lambrou GI, Spandidos DA
Gene set enrichment analysis of the NF-κB/Snail/YY1/RKIP circuitry in multiple myeloma.
Tumour Biol. 2014; 35(5):4987-5005 [PubMed] Related Publications
The presence of a dysregulated NF-κB/Snail/YY1/RKIP loop was recently established in metastatic prostate cancer cells and non-Hodgkin's lymphoma; however, its involvement in multiple myeloma (MM) has yet to be investigated. Aim of the study was to investigate the role of the NF-κB/Snail/YY1/RKIP circuitry in MM and how each gene is correlated with the remaining genes of the loop. Using gene set enrichment analysis and gene neighbours analysis in data received from four datasets included in the Multiple Myeloma Genomics Portal of the Multiple Myeloma Research Consortium, we identified various enriched gene sets associated with each member of the NF-κB/Snail/YY1/RKIP circuitry. In each dataset, the 20 most co-expressed genes with the circuitry genes were isolated subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment. Among many, we highlighted on FNDC3B, TPD52, BBX, MBNL1 and MFAP2. Many co-expressed genes participated in the regulation of metabolic processes and nucleic acid binding, or were transcription factor binding genes and genes with metallopeptidase activity. The transcription factors FOXO4, GATA binding factor, Sp1 and AP4 most likely affect the expression of the NF-κB/Snail/YY1/RKIP circuitry genes. Computational analysis of various GEO datasets revealed elevated YY1 and RKIP levels in MM vs. the normal plasma cells, as well as elevated RKIP levels in MM vs. normal B lymphocytes. The present study highlights the relationships of the NF-κB/Snail/YY1/RKIP circuitry genes with specific cancer-related gene sets in multiple myeloma.

Lv Y, Song S, Zhang K, et al.
CHIP regulates AKT/FoxO/Bim signaling in MCF7 and MCF10A cells.
PLoS One. 2013; 8(12):e83312 [PubMed] Free Access to Full Article Related Publications
A number of studies have shown that apoptosis resistance can be observed in multiple human tumors; however the detailed mechanism remains unclear. In the present study, we demonstrated that the abnormal overexpression of the C terminus of Hsc70-interacting protein (CHIP) induced apoptosis resistance by regulating the AKT/FoxO/Bim signaling pathway in the breast cancer cell MCF7 and the human non-tumorigenic cell MCF10A. We found that CHIP overexpression in MCF7 and MCF10A cells activated AKT and inhibited the Forkhead box O (FoxO) transcription factors FoxO1, FoxO3, and FoxO4, thereby inhibiting transcription of the target genes bim and pten. Inhibition of PI3K by a chemical reagent revealed that these events may be critical for CHIP-induced apoptosis resistance. We also determined that inhibition of FoxO3 by CHIP led to the decrease in PTEN and further activated the AKT survival pathway. We corroborated our findings in breast cancer tissues. In general, the CHIP-modulated AKT/FoxO/Bim signaling pathway was shown to induce apoptosis resistance by decreasing the protein level of the tumor suppressor PTEN in both transcriptional and post-translational regulations.

Lee SM, Zhang W, Fernandez MP
Atypical fibroxanthoma arising in a young patient with Li-Fraumeni syndrome.
J Cutan Pathol. 2014; 41(3):303-7 [PubMed] Related Publications
Patients with Li-Fraumeni syndrome (LFS) have a germ-line mutation of p53 (TP53) and are predisposed to develop a variety of malignancies at an early age. In this report, we describe an 18-year-old woman with LFS who developed an atypical fibroxanthoma (AFX) on her left arm. This tumor was based in the dermis, sparsely cellular and had ill-defined borders. It was composed predominantly of medium-sized spindled-shaped cells, but many large cells with pleomorphic nuclei were also present. Immunohistochemical stains showed that the tumor cells lacked expression of keratin, S-100 protein, desmin and CD34. Array-based comparative genomic hybridization (aCGH) revealed marked genomic instability with multiple whole chromosome losses, including chromosomes 8, 10, 13 and 22, as well as a partial loss of 17p. This represents one of a few reports of a cutaneous tumor in a patient with LFS and a rare example of an AFX occurring at a young age.

Bol GM, Raman V, van der Groep P, et al.
Expression of the RNA helicase DDX3 and the hypoxia response in breast cancer.
PLoS One. 2013; 8(5):e63548 [PubMed] Free Access to Full Article Related Publications
AIMS: DDX3 is an RNA helicase that has antiapoptotic properties, and promotes proliferation and transformation. In addition, DDX3 was shown to be a direct downstream target of HIF-1α (the master regulatory of the hypoxia response) in breast cancer cell lines. However, the relation between DDX3 and hypoxia has not been addressed in human tumors. In this paper, we studied the relation between DDX3 and the hypoxic responsive proteins in human breast cancer.
METHODS AND RESULTS: DDX3 expression was investigated by immunohistochemistry in breast cancer in comparison with hypoxia related proteins HIF-1α, GLUT1, CAIX, EGFR, HER2, Akt1, FOXO4, p53, ERα, COMMD1, FER kinase, PIN1, E-cadherin, p21, p27, Transferrin receptor, FOXO3A, c-Met and Notch1. DDX3 was overexpressed in 127 of 366 breast cancer patients, and was correlated with overexpression of HIF-1α and its downstream genes CAIX and GLUT1. Moreover, DDX3 expression correlated with hypoxia-related proteins EGFR, HER2, FOXO4, ERα and c-Met in a HIF-1α dependent fashion, and with COMMD1, FER kinase, Akt1, E-cadherin, TfR and FOXO3A independent of HIF-1α.
CONCLUSIONS: In invasive breast cancer, expression of DDX3 was correlated with overexpression of HIF-1α and many other hypoxia related proteins, pointing to a distinct role for DDX3 under hypoxic conditions and supporting the oncogenic role of DDX3 which could have clinical implication for current development of DDX3 inhibitors.

Keniry M, Pires MM, Mense S, et al.
Survival factor NFIL3 restricts FOXO-induced gene expression in cancer.
Genes Dev. 2013; 27(8):916-27 [PubMed] Free Access to Full Article Related Publications
Depending on the circumstance, FOXO (Forkhead O) (FOXO1, FOXO3, and FOXO4) transcription factors activate the expression of markedly different sets of genes to produce different phenotypic effects. For example, distinct FOXO-regulated transcriptional programs stimulate cell death or enhance organism life span. To gain insight into how FOXOs select specific genes for regulation, we performed a screen for genes that modify FOXO activation of TRAIL, a death receptor ligand capable of inducing extrinsic apoptosis. We discovered that the bZIP transcriptional repressor NFIL3 (nuclear factor interleukin 3-regulated) hindered FOXO transcription factor access to chromatin at the TRAIL promoter by binding to nearby DNA and recruiting histone deacetylase-2 (HDAC2) to reduce histone acetylation. In the same manner, NFIL3 repressed expression of certain FOXO targets--e.g., FAS, GADD45α (growth arrest and DNA damage-inducible, α), and GADD45β--but not others. NFIL3, which we found to be overexpressed in different cancers, supported tumor cell survival largely through repression of TRAIL and antagonized hydrogen peroxide-induced cell death. Moreover, its expression in cancer was associated with lower patient survival. Therefore, NFIL3 alters cancer cell behavior and FOXO function by acting on chromatin to restrict the menu of FOXO target genes. Targeting of NFIL3 could be of therapeutic benefit for cancer patients.

Xie J, Xiang DB, Wang H, et al.
Inhibition of Tcf-4 induces apoptosis and enhances chemosensitivity of colon cancer cells.
PLoS One. 2012; 7(9):e45617 [PubMed] Free Access to Full Article Related Publications
Aberrant activation of β-catenin/Tcf-4 signaling has been implicated in human carcinogenesis, including colorectal cancer. In this study, we compared the effects of Tcf-4 knockdown with β-catenin knockdown on cell proliferation, apoptosis, and chemosensitivity in SW480 and HCT116 colon cancer cells using adenoviral vector-mediated short hairpin RNA (shRNA). Our results show that, compared to β-catenin knockdown, Tcf-4 knockdown more effectively inhibited colony formation, induced apoptosis, and increased 5-FU and oxaliplatin-mediated cytotoxicity in colon cancer cells. We further investigated the mechanisms involved in the different efficacies observed with β-catenin and Tcf-4 knockdown in colon cancer cells. FOXO4 is a member of the subfamily of mammalian FOXO forkhead transcription factors and plays a major role in controlling cellular proliferation, apoptosis, and DNA repair. Our data showed that the protein level of FOXO4 did not change after treatment with both β-catenin and Tcf-4 shRNA. However, β-catenin shRNA was found to increase the accumulation of phosphorylated FOXO4 S193 and decrease the expression of FOXO target genes p27Kip1 and MnSOD, whereas Tcf-4 shRNA showed the opposite effect. Therefore, compared to β-catenin knockdown, Tcf-4 knockdown shows better efficacy for inhibiting proliferation and inducing apoptosis of colorectal cancer cells, which may be related to increased FOXO4 transcriptional activity. These results suggest that Tcf-4 is an attractive potential therapeutic target for colorectal cancer therapy.

Scola N, Wieland U, Silling S, et al.
Prevalence of human polyomaviruses in common and rare types of non-Merkel cell carcinoma skin cancer.
Br J Dermatol. 2012; 167(6):1315-20 [PubMed] Related Publications
BACKGROUND: Little is known about the association of human polyomaviruses (HPyVs) other than Merkel cell polyomavirus (MCPyV) with nonmelanoma skin cancer.
OBJECTIVES: To evaluate the presence of HPyV6, HPyV7, trichodysplasia spinulosa-associated polyomavirus (TSV), also called HPyV8, and the recently discovered HPyV9 in basal cell carcinoma (BCC), actinic keratosis (AK), squamous cell carcinoma in situ (SCCis), squamous cell carcinoma (SCC), keratoacanthoma (KA), microcystic adnexal carcinoma (MAC) and atypical fibroxanthoma (AFX).
METHODS: Archival paraffin-embedded samples (n = 193: 41 BCC, 31 AK, 8 SCCis, 52 SCC, 42 KA, 5 MAC and 14 AFX) were analysed for the presence of the respective HPyV by polymerase chain reaction (PCR). HPyV DNA loads (HPyV DNA copies per β-globin gene copy) were determined in all HPyV-positive samples by quantitative real-time PCR. Immunohistochemical analysis of MCPyV large T-antigen (LTA) expression was performed using the monoclonal antibody CM2B4.
RESULTS: MCPyV DNA was found in 29% of BCC, 19% of AK, 25% of SCCis, 27% of SCC, 29% of KA, 0% of MAC and 29% of AFX. MCPyV DNA loads never exceeded 0·3 MCPyV DNA copies per β-globin gene copy (median 0·004). In the immunohistochemical analysis of MCPyV LTA expression, all evaluated samples (32 MCPyV DNA-positive samples) were LTA negative. HPyV6 DNA was found in 7% of BCC, 3% of AK, 12% of SCCis, 4% of SCC, 5% of KA, and 0% of MAC and AFX. HPyV6 DNA loads never exceeded 0·7 HPyV6 DNA copies per β-globin gene copy (median 0·015). None of the 193 samples was positive for HPyV7, TSV or HPyV9 DNA.
CONCLUSIONS: Our findings argue against a pathogenic role for MCPyV, HPyV6, HPyV7, TSV and HPyV9 in the analysed types of non-Merkel cell carcinoma skin cancer.

Mei Y, Wang Z, Zhang L, et al.
Regulation of neuroblastoma differentiation by forkhead transcription factors FOXO1/3/4 through the receptor tyrosine kinase PDGFRA.
Proc Natl Acad Sci U S A. 2012; 109(13):4898-903 [PubMed] Free Access to Full Article Related Publications
Neuroblastoma is a common childhood malignant tumor originated from the neural crest-derived sympathetic nervous system. A crucial early event in neuroblastoma pathogenesis is arrested differentiation of neuroblasts at various stages. Treatment of neuroblastoma with TPA and PDGF-BB leads to terminal differentiation of neuroblastoma cells. However, the signaling pathways that are involved in this process remain largely unknown. Here, we report that inhibition of endogenous FOXO proteins attenuated TPA/PDGF-BB mediated differentiation of neuroblastoma cells. Activated FOXO transcription factors acted on PDGFRA promoter to direct its basal mRNA expression as well as its induction upon serum deprivation. Depletion of endogenous PDGFRA in neuroblastoma cells significantly diminished neurite formation and extension under TPA/PDGF-BB treatment. Furthermore, ectopic expression of PDGFRA abolished the blockage of neuroblastoma differentiation by FOXOs inhibition. These findings define the FOXO-PDGFRA axis as crucial mechanistic components that govern TPA-induced neuroblastoma differentiation.

Thum C, Hollowood K, Birch J, et al.
Aberrant Melan-A expression in atypical fibroxanthoma and undifferentiated pleomorphic sarcoma of the skin.
J Cutan Pathol. 2011; 38(12):954-60 [PubMed] Related Publications
BACKGROUND: Atypical fibroxanthoma (AFX) is a distinctive clinicopathologic entity presenting on sun-damaged skin of the elderly. Its behavior is benign if strict diagnostic criteria are applied. Tumors showing invasion of deeper structures or perineural/lymphovascular invasion are best regarded as undifferentiated pleomorphic sarcoma of the skin. The diagnosis requires immunohistochemical studies to exclude melanoma, squamous cell carcinoma, angiosarcoma and leiomyosarcoma.
METHODS: Two AFX and one undifferentiated pleomorphic sarcoma showing aberrant expression of Melan-A were identified. Clinical data were obtained and histopathological features, immunohistochemical profile and electron microscopy were assessed.
RESULTS: All tumors arose on sun-damaged skin of elderly males. Two AFX showed pushing growth into superficial subcutis only. The undifferentiated pleomorphic sarcoma was characterized by infiltrative growth into galea as well as perineural invasion. Multifocal expression of Melan-A and MART-1 was largely limited to tumor giant cells in the absence of S100 or HMB-45 labeling. No melanosomes or premelanosomes were identified by electron microscopy.
CONCLUSIONS: Aberrant expression of Melan-A and MART-1 in AFX and undifferentiated pleomorphic sarcoma of the skin represents an important diagnostic pitfall with potential for misdiagnosis as melanoma.

Sheng Z, Ma L, Sun JE, et al.
BCR-ABL suppresses autophagy through ATF5-mediated regulation of mTOR transcription.
Blood. 2011; 118(10):2840-8 [PubMed] Free Access to Full Article Related Publications
The oncoprotein BCR-ABL transforms myeloid progenitor cells and is responsible for the development of chronic myeloid leukemia (CML). In transformed cells, BCR-ABL suppresses apoptosis as well as autophagy, a catabolic process in which cellular components are degraded by the lysosomal machinery. The mechanism by which BCR-ABL suppresses autophagy is not known. Here we report that in both mouse and human BCR-ABL-transformed cells, activating transcription factor 5 (ATF5), a prosurvival factor, suppresses autophagy but does not affect apoptosis. We find that BCR-ABL, through PI3K/AKT/FOXO4 signaling, transcriptionally up-regulates ATF5 expression and that ATF5, in turn, stimulates transcription of mammalian target of rapamycin (mTOR; also called mechanistic target of rapamycin), a well-established master negative-regulator of autophagy. Previous studies have shown that the BCR-ABL inhibitor imatinib mesylate induces both apoptosis and autophagy, and that the resultant autophagy modulates the efficiency by which imatinib kills BCR-ABL-transformed cells. We demonstrate that imatinib-induced autophagy is because of inhibition of the BCR-ABL/PI3K/AKT/FOXO4/ATF5/mTOR pathway that we have identified in this study.

Risueño RM, Campbell CJ, Dingwall S, et al.
Identification of T-lymphocytic leukemia-initiating stem cells residing in a small subset of patients with acute myeloid leukemic disease.
Blood. 2011; 117(26):7112-20 [PubMed] Related Publications
Xenotransplantation of acute myeloid leukemia (AML) into immunodeficient mice has been critical for understanding leukemogenesis in vivo and defining self-renewing leukemia-initiating cell subfractions (LICs). Although AML-engraftment capacity is considered an inherent property of LICs, substrains of NOD/SCID mice that possess additional deletions such as the IL2Rγc(null) (NSG) have been described as a more sensitive recipient to assay human LIC function. Using 23 AML-patient samples, 39% demonstrated no detectable engraftment in NOD/SCID and were categorized as AMLs devoid of LICs. However, 33% of AML patients lacking AML-LICs were capable of engrafting NSG recipients, but produced a monoclonal T-cell proliferative disorder similar to T-ALL. These grafts demonstrated self-renewal capacity as measured by in vivo serial passage and were restricted to CD34-positive fraction, and were defined as LICs. Molecular analysis for translocations in MLL genes indicated that these AML patient-derived LICs all expressed the MLL-AFX1 fusion product. Our results reveal that the in vivo human versus xenograft host microenvironment dictates the developmental capacity of human LICs residing in a small subset of patients diagnosed with AML harboring MLL mutations. These findings have implications both for the basic biology of CSC function, and for the use of in vivo models of the leukemogenic process in preclinical or diagnostic studies.

Monsalve M, Olmos Y
The complex biology of FOXO.
Curr Drug Targets. 2011; 12(9):1322-50 [PubMed] Related Publications
FOXO transcription factors control proliferation, apoptosis, differentiation and metabolic processes. Loss of FOXO function has been identified in several human cancers, and results in increased cellular survival and a predisposition to neoplasia, especially in epithelial cancer. FOXO factors are therefore bona fide tumor suppressors, and their potential use as therapeutic targets in cancer has been a matter of debate. Importantly, FOXO factors can also positively regulate cell survival through the activation of several detoxification genes, complicating its putative therapeutic potential. Targeting of FOXO factors has also been proposed for the treatment of metabolic dysfunctions such as diabetes mellitus, immunological disorders and neurodegeneration, as well as for the prevention of aging by maintaining the hematopoyetic stem cells niche. But again, data has accumulated that cautions against the potential use of the FOXO activators in these settings. Therefore, greater understanding of the regulation of FOXO target specificity is still needed to boost its use as a therapeutic target. The four members of the FOXO family (FOXO1, FOXO3A, FOXO4 and FOXO6) have distinct but overlapping cellular functions, although they seem to bind a common set of DNA sites. This fact together with the observation that FOXOs are only partially dependent on their DNA binding activity to regulate their target genes highlights the fact that the interaction of the FOXOs with other transcription factors is crucial for the FOXO-mediated transcriptional programs. In this review, we provide an overview of recent progress in the understanding of the modulation of FOXO activity and target specificity by transcription factors and coactivators.

Chen Q, Ganapathy S, Singh KP, et al.
Resveratrol induces growth arrest and apoptosis through activation of FOXO transcription factors in prostate cancer cells.
PLoS One. 2010; 5(12):e15288 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Resveratrol, a naturally occurring phytopolyphenol compound, has attracted extensive interest in recent years because of its diverse pharmacological characteristics. Although resveratrol possesses chemopreventive properties against several cancers, the molecular mechanisms by which it inhibits cell growth and induces apoptosis have not been clearly understood. The present study was carried out to examine whether PI3K/AKT/FOXO pathway mediates the biological effects of resveratrol.
METHODOLOGY/PRINCIPAL FINDINGS: Resveratrol inhibited the phosphorylation of PI3K, AKT and mTOR. Resveratrol, PI3K inhibitors (LY294002 and Wortmannin) and AKT inhibitor alone slightly induced apoptosis in LNCaP cells. These inhibitors further enhanced the apoptosis-inducing potential of resveratrol. Overexpression of wild-type PTEN slightly induced apoptosis. Wild type PTEN and PTEN-G129E enhanced resveratrol-induced apoptosis, whereas PTEN-G129R had no effect on proapoptotic effects of resveratrol. Furthermore, apoptosis-inducing potential of resveratrol was enhanced by dominant negative AKT, and inhibited by wild-type AKT and constitutively active AKT. Resveratrol has no effect on the expression of FKHR, FKHRL1 and AFX genes. The inhibition of FOXO phosphorylation by resveratrol resulted in its nuclear translocation, DNA binding and transcriptional activity. The inhibition of PI3K/AKT pathway induced FOXO transcriptional activity resulting in induction of Bim, TRAIL, p27/KIP1, DR4 and DR5, and inhibition of cyclin D1. Similarly, resveratrol-induced FOXO transcriptional activity was further enhanced when activation of PI3K/AKT pathway was blocked. Over-expression of phosphorylation deficient mutants of FOXO proteins (FOXO1-TM, FOXO3A-TM and FOXO4-TM) induced FOXO transcriptional activity, which was further enhanced by resveratrol. Inhibition of FOXO transcription factors by shRNA blocked resveratrol-induced upregulation of Bim, TRAIL, DR4, DR5, p27/KIP1 and apoptosis, and inhibition of cyclin D1 by resveratrol.
CONCLUSION/SIGNIFICANCE: These data suggest that FOXO transcription factors mediate anti-proliferative and pro-apoptotic effects of resveratrol, in part due to activation of extrinsic apoptosis pathway.

Fang L, Wang H, Zhou L, Yu D
Akt-FOXO3a signaling axis dysregulation in human oral squamous cell carcinoma and potent efficacy of FOXO3a-targeted gene therapy.
Oral Oncol. 2011; 47(1):16-21 [PubMed] Related Publications
Phosphoinositide-3-kinase (PI3K)/Akt pathway has been shown to be activated in oral squamous cell carcinoma (OSCC). Activation of Akt suppresses FOXO transcription factor-mediated growth arrest and apoptosis in various cancers. We investigated FOXO3a and phosphor(p)-Akt expression and potential efficacy of FOXO3a-targeted gene therapy in OSCC. Low expression of FOXO3a was negatively associated with overexpression of p-Akt and histological grade using immunohistochemistry. Akt-FOXO3a axis was also examined by detection of FOXO3a expression after induction or inhibition of Akt activity in Tca8113 OSCC cells. Transfection of a constitutively active form of FOXO3a (FOXO3a(3A)) in OSCC cells induced significant G₁-phase arrest and apoptosis as compared with control and transfection of a wild-type FOXO3a (FOXO3a(WT)). Stable FOXO3a(3A) transfectant OSCC cells also revealed the most potent growth inhibition effect in vivo. Furthermore, the downstream effects of FOXO3a activation were found to be inhibition of CDK4/6 and cyclin D1, and accumulation of p27 and Bim. We also found that transcription of FOXO1 and FOXO4 were stimulated by FOXO3a. Our results suggest that FOXO3a activity may be important in tumorigenesis and development of OSCC. Akt-FOXO3a axis inhibition-mediated constitutively active FOXO3a induces significant growth inhibition and FOXO3a activation may present a potent target-based therapeutic strategy for OSCC therapy.

Zheng R, Ma L, Bichakjian CK, et al.
Atypical fibroxanthoma with lymphomatoid reaction.
J Cutan Pathol. 2011; 38(1):8-13 [PubMed] Related Publications
BACKGROUND: Atypical fibroxanthoma (AFX) represents an uncommon skin tumor typically occurring on sun-damaged skin of the elderly. Histopathologic variants include spindled, clear cell, osteoid, osteoclastic, chondroid, pigmented, granular cell and myxoid lesions. To date, an atypical lymphoid infiltrate, including CD30-positive large cells mimicking lymphomatoid papulosis, has not been described in association with AFX.
METHODS: The clinical and histopathological characteristics of two AFX cases inciting an atypical lymphoid infiltrate, along with immunohistochemical profiles and T-cell receptor gamma (TCRγ) gene rearrangement results, were reviewed.
RESULTS: Lesions in both cases occurred as solitary nodules in elderly patients. Microscopically, both lesions showed a cellular proliferation composed of pleomorphic spindle cells, associated with a prominent intralesional atypical lymphoid infiltrate. The spindle cells expressed CD10 but lacked the expression of S-100, cytokeratins and muscle markers, thereby confirming the diagnosis of AFX. CD30 highlighted a significant subset of large mononuclear cells in the lymphoid infiltrate of one case. TCRγ gene rearrangement analyses were negative for both cases.
CONCLUSION: An atypical lymphoid infiltrate, including the one resembling lymphomatoid papulosis, associated with AFX has not been previously described. It is important to recognize the reactive nature of the infiltrate to avoid a misdiagnosis of lymphoma.

Kohan K, Carvajal R, Gabler F, et al.
Role of the transcriptional factors FOXO1 and PPARG on gene expression of SLC2A4 in endometrial tissue from women with polycystic ovary syndrome.
Reproduction. 2010; 140(1):123-31 [PubMed] Related Publications
Fifty to seventy percent of patients with polycystic ovary syndrome (PCOS) present hyperinsulinemia. On the other hand, reports indicate that forkhead box class O 1 (FOXO1) and peroxisome proliferator-activated receptor-gamma (PPARG) are involved in the insulin signaling pathway, regulating the gene expression of SLC2A4 (GLUT4). The negative effect of FOXO1 over PPARG transcription disappears when FOXO1 is phosphorylated (p-FOXO1) and excluded from the nucleus, whereas PPARG can suppress gene expression of SLC2A4. Scarce knowledge is available in endometrium of women with PCOS and hyperinsulinemia (PCOSE h-Ins) about the role of these factors. We aimed to evaluate whether the endocrine and metabolic status of PCOS modify the levels of gene and protein expression of FOXO1, PPARG, and SLC2A4 in the endometria from hyperinsulinemic PCOS women compared with controls. In endometria from control (CE, n=7) or PCOSE h-Ins (n=7), we determined the subcellular location and protein levels of p-FOXO1Ser319 and FOXO1/FOXO4 by immunohistochemistry and western blot respectively; gene and/or protein levels of PPARG and SLC2A4 were evaluated by RT-PCR and/or western blot. Cytoplasm location for FOXO1 and p-FOXO1Ser319 was immunodetected in both groups of endometria, showing significantly higher staining in PCOSE h-Ins for these proteins (P<0.05). In PCOSE h-Ins, gene and protein levels of PPARG were significantly higher than in CE, whereas SLC2A4 mRNA was decreased (P<0.05). In conclusion, the derepression of PPARG transcription by the high levels of p-FOXO1Ser319 could partially account for the lower levels of SLC2A4 found in PCOSE h-Ins, suggesting an alteration of the endometrial function in these patients.

Kwon IK, Wang R, Thangaraju M, et al.
PKG inhibits TCF signaling in colon cancer cells by blocking beta-catenin expression and activating FOXO4.
Oncogene. 2010; 29(23):3423-34 [PubMed] Free Access to Full Article Related Publications
Activation of cGMP-dependent protein kinase (PKG) has anti-tumor effects in colon cancer cells but the mechanisms are not fully understood. This study has examined the regulation of beta-catenin/TCF signaling, as this pathway has been highlighted as central to the anti-tumor effects of PKG. We show that PKG activation in SW620 cells results in reduced beta-catenin expression and a dramatic inhibition of TCF-dependent transcription. PKG did not affect protein stability, nor did it increase phosphorylation of the amino-terminal Ser33/37/Thr41 residues that are known to target beta-catenin for degradation. However, we found that PKG potently inhibited transcription from a luciferase reporter driven by the human CTNNB1 promoter, and this corresponded to reduced beta-catenin mRNA levels. Although PKG was able to inhibit transcription from both the CTNNB1 and TCF reporters, the effect on protein levels was less consistent. Ectopic PKG had a marginal effect on beta-catenin protein levels in SW480 and HCT116 but was able to inhibit TCF-reporter activity by over 80%. Investigation of alternative mechanisms revealed that cJun-N-terminal kinase (JNK) activation was required for the PKG-dependent regulation of TCF activity. PKG activation caused beta-catenin to bind to FOXO4 in colon cancer cells, and this required JNK. Activation of PKG was also found to increase the nuclear content of FOXO4 and increase the expression of the FOXO target genes MnSOD and catalase. FOXO4 activation was required for the inhibition of TCF activity as FOXO4-specific short-interfering RNA completely blocked the inhibitory effect of PKG. These data illustrate a dual-inhibitory effect of PKG on TCF activity in colon cancer cells that involves reduced expression of beta-catenin at the transcriptional level, and also beta-catenin sequestration by FOXO4 activation.

Shukla S, Shukla M, Maclennan GT, et al.
Deregulation of FOXO3A during prostate cancer progression.
Int J Oncol. 2009; 34(6):1613-20 [PubMed] Free Access to Full Article Related Publications
Forkhead box transcription factor FOXO3A, an important regulator of cellular function, is thought to act as a tumor suppressor. We studied whether alterations in FOXO3A activity occur in prostate tumorigenesis. Our studies demonstrate that FOXO3A activity is negatively regulated by Akt/PKB through posttranslational modifications. In prostate cancer cells, Akt activation causes increased accumulation of FOXO3A and its binding chaperone protein 14-3-3 in the cytosol. Higher levels of FOXO3A in the cytosol correlated with phosphorylation at Ser253, which accounted for its nuclear exclusion. Dominant negative Akt approach in PC-3 cells increased FOXO3A accumulation in the nucleus, causing upregulation of the downstream target, MnSOD. Conversely, stable DU145-Akt over-expressing cells exhibited decreased FOXO3A levels in the nucleus. Similar findings were noted in prostate tumor specimens, in which marked cytoplasmic accumulation of FOXO3A and 14-3-3 in prostate tumors was observed with increasing Gleason grade, in contrast to exclusively nuclear accumulation in benign prostate cells. These findings correlate with decreased FOXO3A DNA binding activity along with down-modulation of FOXO3A transcriptional activity with increasing tumor grade. Our findings demonstrate that tumor associated alterations and redistribution of FOXO3A are frequent events in the etiology of prostate cancer.

Lee MJ, Yu GR, Yoo HJ, et al.
ANXA8 down-regulation by EGF-FOXO4 signaling is involved in cell scattering and tumor metastasis of cholangiocarcinoma.
Gastroenterology. 2009; 137(3):1138-50, 1150.e1-9 [PubMed] Related Publications
BACKGROUND & AIMS: The sarcomatoid change in cholangiocarcinoma (CC) contributes to more aggressive intrahepatic spread and widespread metastasis. Therefore, the aim of this study was to identify the molecular mechanisms of CC metastasis during tumor progression and sarcomatoid change.
METHODS: Using the subtraction suppression hybridization (SSH) method, we identified altered expression of the candidate gene ANXA8 and epidermal growth factor receptor (EGFR) in sarcomatoid CC cells. We assessed ANXA8 expression during the progression of CC in cells and tissues and examined its functional significance by performing in vitro cell experiments and using in vivo animal models.
RESULTS: ANXA8 is highly expressed in human and hamster CCs but is down-regulated with tumor dedifferentiation. ANXA8 is transcriptionally down-regulated by epidermal growth factor (EGF), which is correlated with the morphologic changes of the epithelial-to-mesenchymal transition (EMT) in the CC cells. Furthermore, ectopic ANXA8 reverses the morphology of cells, and this is associated with focal adhesion kinase expression and altered F-actin dynamics. EGFR and its downstream targets, phosphatidylinositol-3-kinase and Akt, are linked to the phosphorylation of FOXO4, which leads to the inhibition of ANXA8 transcription. In addition, an in vitro cell invasion assay and in vivo spontaneous metastasis assay reveal that ANXA8 inhibits the cell migratory and metastatic characteristics of CC cells.
CONCLUSIONS: These findings suggest that FOXO4 and ANXA8 play key roles in growth factor-mediated tumor progression and metastasis during the EMT change in CC.

Sakamoto A, Akieda S, Oda Y, et al.
Mutation analysis of the Gadd45 gene at exon 4 in atypical fibroxanthoma.
BMC Dermatol. 2009; 9:1 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Atypical fibroxanthoma (AFX) histologically mimics high-grade sarcoma in the skin, although it follows a benign clinical course. AFX occurs in the sun-exposed skin and for this reason, an association with ultraviolet light has long been suspected. Bax and Gadd45 are p53 effector proteins. Bax is a programmed cell death protein and belongs to the Bcl-2 family. Gadd45 is a multifunctional DNA damage-inducible gene associated with the process of DNA damage.
METHODS: Immunohistochemical expression of Bax was analyzed in 7 cases of AFX, and in 7 cases of benign fibrous histiocytoma (BFH) used as a comparison. The expression pattern of Bax was compared to previously reported p53 and Gadd45 expressions in a correspondent series. Mutation of the Gadd45 gene at exon 4 was also analyzed in AFX.
RESULTS: AFX and BFH showed immunoreactivities respectively for Bax (3/7, 0/7), Gadd45 (4/7, 1/7) and p53 (2/7, 0/7). There was no exact correlation between p53 expression and Bax or Gadd45 expression. However, the pattern of expression between Bax and Gadd45 was also the same, with the exception of one case. No mutation of the Gadd45 gene at exon 4 was observed in a series of 6 AFX cases where DNA was available (0/6).
CONCLUSION: These results suggest a possible association between Bax and Gadd45 in AFX, and may refute any possibility of dysfunction of Gadd45 in terms of gene mutation, at least at exon 4 of the Gadd45 gene.

Pouryazdanparast P, Yu L, Cutlan JE, et al.
Diagnostic value of CD163 in cutaneous spindle cell lesions.
J Cutan Pathol. 2009; 36(8):859-64 [PubMed] Related Publications
BACKGROUND: The histologic diagnosis of atypical fibroxanthoma (AFX) can sometimes be challenging. No specific marker exists to confirm the diagnosis other than excluding other entities. CD163 has been shown to have great specificity for tumors of monocyte/histiocyte lineage. In this study, we evaluated the diagnostic utility of CD163 in diagnosing AFX and in identifying skin lesions with histiocytic/dendritic derivation.
METHODS: A total of 157 cases, including 14 AFXs, 5 spindle cell squamous cell carcinomas (SCCs), and 7 spindle cell/desmoplastic melanomas, along with other cutaneous spindle cell and histiocytic/fibrohistiocytic lesions, were stained with CD163.
RESULTS: CD163 was expressed in 11 of 14 (79%) AFXs, with moderate to strong intensity. No staining was observed in cases of spindle cell SCC (0/5) and dermatofibrosarcoma protuberans (0/10). Rare spindle cell/desmoplastic melanomas (2/7) and cutaneous leiomyosarcomas (1/5) demonstrated positive staining. CD163 reactivity was seen in 24 of 29 of benign fibrous histiocytomas (BFHs), including 8 of 8 cellular fibrous histiocytomas and 6 of 9 epithelioid cell histiocytomas. The majority of cutaneous histiocytic lesions, including juvenile xanthogranuloma, Langerhans cell histiocytosis and Rosai-Dorfman disease, were positive for CD163.
CONCLUSION: CD163 is a useful adjunct in distinguishing AFX from other malignant cutaneous spindle cell tumors and offers improved specificity in identifying cutaneous histiocytic/dendritic lesions.

Brenkman AB, de Keizer PL, van den Broek NJ, et al.
The peptidyl-isomerase Pin1 regulates p27kip1 expression through inhibition of Forkhead box O tumor suppressors.
Cancer Res. 2008; 68(18):7597-605 [PubMed] Related Publications
The Forkhead box O (FOXO) protein family is an evolutionarily conserved subclass of transcription factors recently identified as bona fide tumor suppressors. Preventing the accumulation of cellular damage due to oxidative stress is thought to underlie its tumor-suppressive role. Oxidative stress, in turn, also feedback controls FOXO4 function. Regulation of this process, however, is poorly understood but may be relevant to the ability of FOXO to control tumor suppression. Here, we characterize novel FOXO4 phosphorylation sites after increased cellular oxidative stress and identify the isomerase Pin1, a protein frequently found to be overexpressed in cancer, as a critical regulator of p27(kip1) through FOXO4 inhibition. We show that Pin1 requires these phosphorylation events to act negatively on FOXO4 transcriptional activity. Consistent with this, oxidative stress induces binding of Pin1 to FOXO, thereby attenuating its monoubiquitination, a yet uncharacterized mode of substrate modulation by Pin1. We have previously shown that monoubiquitination is involved in controlling nuclear translocation in response to cellular stress, and indeed, Pin1 prevents nuclear FOXO4 accumulation. Interestingly, Pin1 acts on FOXO through stimulation of the activity of the deubiquitinating enzyme HAUSP/USP7. Ultimately, this results in decreased transcriptional activity towards target genes, including the cell cycle arrest gene p27(kip1). Notably, in a primary human breast cancer panel, low p27(kip1) levels inversely correlated with Pin1 expression. Thus, Pin1 is identified as a novel negative FOXO regulator, interconnecting FOXO phosphorylation and monoubiquitination in response to cellular stress to regulate p27(kip1).

Lee EJ, Kim JM, Lee MK, Jameson JL
Splice variants of the forkhead box protein AFX exhibit dominant negative activity and inhibit AFXalpha-mediated tumor cell apoptosis.
PLoS One. 2008; 3(7):e2743 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Loss-of-function in the apoptosis-inducing genes is known to facilitate tumorigenesis. AFX (FOXO4), a member of forkhead transcription factors functions as a tumor suppressor and has 2 isoforms, AFXalpha (505 a.a.) and AFXzeta (450 a.a.). In human cancer cells, we identified an N-terminally deleted form of AFXalpha (alpha198-505), translated from a downstream start and 2 short N-terminal AFX proteins (90, and 101 a.a.) produced by aberrant splicing.
METHODS AND FINDINGS: We investigated the expression and role of these AFX variants. Cell transduction study revealed that short N-terminal AFX proteins were not stable. Though alpha(198-505) protein expression was detected in the cytoplasm and nucleus, alpha(198-505) expressing cells did not show a nucleocytoplasmic shuttling mediated by PI3 kinase signaling. Whereas, we observed this shuttling in cells expressing either AFXalpha or AFXzeta protein. AFXzeta and alpha(198-505) lost the ability to transactivate BCL6 or suppress cyclin D2 gene expression. These variants did not induce cancer cell death whereas AFXalpha resulted in apoptosis. We found that AFXzeta and alpha(198-505) suppress the AFXalpha stimulation of BCL6 promoter in a dose dependent manner, indicating dominant negative activity. These variants also inhibited AFXalpha induction of apoptosis.
CONCLUSIONS: Loss of function by aberrant splicing and the dominant negative activity of AFX variants may provide a mechanism for enhanced survival of neoplastic cells.

Maiese K, Chong ZZ, Shang YC
OutFOXOing disease and disability: the therapeutic potential of targeting FoxO proteins.
Trends Mol Med. 2008; 14(5):219-27 [PubMed] Free Access to Full Article Related Publications
Forkhead transcription factors have a 'winged helix' domain and regulate processes that range from cell longevity to cell death. Of the mammalian forkhead family members in the O class, FoxO1, FoxO3a and FoxO4 can fill a crucial void for the treatment of disorders that include aging, cancer, diabetes, infertility, neurodegeneration and immune system dysfunction. Yet, observations that forkhead family members also can compromise clinical utility have fueled controversy and highlight the necessity to further outline the integrated cellular pathways governed by these transcription factors. Here we discuss recent advances that have elucidated the unique cellular pathways and clinical potential of targeting FoxO proteins to develop novel therapeutic strategies and avert potential pitfalls that might be closely intertwined with its benefits for patient care.

Wilkerson AE, Glasgow MA, Hiatt KM
Immunoreactivity of CD99 in invasive malignant melanoma.
J Cutan Pathol. 2006; 33(10):663-6 [PubMed] Related Publications
BACKGROUND: CD99, also known as p30/32, is a glycoprotein product of the MIC2 gene. It was originally utilized in immunohistochemistry as a unique marker for Ewing sarcoma, other primitive neuroectodermal tumors, and subsequently in other tumors. Its expression in malignant melanoma (MM) has not been well documented, with just two isolated cases of MM recently reported. Recent studies have documented CD99 expression in a significant percentage of atypical fibroxanthomas (AFX), posing potential diagnostic problems in differentiating these two entities. As mistaking MM for AFX based on immunohistochemical staining pattern has significant consequences, we sought to determine the percentage of invasive MM in our archives that have this staining pattern.
METHODS: Seventy-eight cases of invasive melanoma were retrieved from our files. Each case was stained with mouse anti-human CD99 and evaluated for membranous expression.
RESULTS: Our evaluation revealed that 47 of 78 MM cases (60%) stain positive for CD99.
CONCLUSION: This study is the first to demonstrate, in a large series, the prevalence of CD99 expression in primary cutaneous melanoma. Additionally, this introduces in the histologic differential diagnosis of CD99 expressing dermal spindle cell lesions.

Hartel PH, Jackson J, Ducatman BS, Zhang P
CD99 immunoreactivity in atypical fibroxanthoma and pleomorphic malignant fibrous histiocytoma: a useful diagnostic marker.
J Cutan Pathol. 2006; 33 Suppl 2:24-8 [PubMed] Related Publications
Atypical fibroxanthoma (AFX), a benign lesion, and pleomorphic malignant fibrous histiocytoma (MFH) are thought to represent points along the same neoplastic spectrum but with different prognoses and treatments. Diagnosis based on histology and clinical parameters alone is sometimes difficult, and a reliable cost-effective immunohistochemical marker to help distinguish these lesions would be beneficial. The diagnosis of AFX or MFH was based upon published clinical and microscopic criteria. Formalin-fixed, paraffin-embedded tissues of 17 cases of AFX and 26 cases of MFH were immunostained with monoclonal antibody to CD99. For all cases, CD99 expression was scored on a four-tiered scale: negative, weak (1+), moderate (2+), or strong (3+). Two pathologists blinded to tumor diagnoses and type of immunostain evaluated each case independently. The interobserver correlation coefficient was calculated. Seventeen patients with AFX (16 males and one female; mean age = 79) and 26 patients with MFH (16 males and 10 females; mean age = 60) were included. AFX lesions were from the head and the face, mean size = 1.5 cm, and MFH lesions were from the head, the neck, the trunk, and the upper/lower extremities, mean size = 5.2 cm. The 17 cases of AFX demonstrated moderate or strong (2 to 3+) immunoreactivity with CD99, compared to nine of 26 (35%) MFH cases (chi-square = 18.38; p < 0.001; interobserver correlation coefficient = 0.83). Of these, 16 of 17 (94%) AFX cases stained diffusely with CD99, while only four of 26 (15%) MFH cases stained diffusely. Control slides were adequate. Our study demonstrated that CD99 can help distinguish AFX from MFH, in addition to other immunohistochemistry as well as clinical and histologic criteria.

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