HOXA7

Gene Summary

Gene:HOXA7; homeobox A7
Aliases: ANTP, HOX1, HOX1A, HOX1.1
Location:7p15.2
Summary:In vertebrates, the genes encoding the class of transcription factors called homeobox genes are found in clusters named A, B, C, and D on four separate chromosomes. Expression of these proteins is spatially and temporally regulated during embryonic development. This gene is part of the A cluster on chromosome 7 and encodes a DNA-binding transcription factor which may regulate gene expression, morphogenesis, and differentiation. For example, the encoded protein represses the transcription of differentiation-specific genes during keratinocyte proliferation, but this repression is then overcome by differentiation signals. This gene is highly similar to the antennapedia (Antp) gene of Drosophila. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:homeobox protein Hox-A7
HPRD
Source:NCBIAccessed: 27 February, 2015

Ontology:

What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 28 February 2015 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 27 February, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

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: HOXA7 (cancer-related)

Xavier FC, Destro MF, Duarte CM, Nunes FD
Epigenetic repression of HOXB cluster in oral cancer cell lines.
Arch Oral Biol. 2014; 59(8):783-9 [PubMed] Related Publications
OBJECTIVE: Aberrant DNA methylation is a fundamental transcriptional control mechanism in carcinogenesis. The expression of homeobox genes is usually controlled by an epigenetic mechanism, such as the methylation of CpG islands in the promoter region. The aim of this study was to describe the differential methylation pattern of HOX genes in oral squamous cell carcinoma (OSCC) cell lines and transcript status in a group of hypermethylated and hypomethylated genes.
DESIGN: Quantitative analysis of DNA methylation was performed on two OSCC cell lines (SCC4 and SCC9) using a method denominated Human Homeobox Genes EpiTect Methyl qPCR Arrays, which allowed fast, precise methylation detection of 24 HOX specific genes without bisulfite conversion.
RESULTS: Methylation greater than 50% was detected in HOXA11, HOXA6, HOXA7, HOXA9, HOXB1, HOXB2, HOXB3, HOXB4, HOXB5, HOXB6, HOXC8 and HOXD10. Both cell lines demonstrated similar hypermethylation status for eight HOX genes. A similar pattern of promoter hypermethylation and hypomethylation was demonstrated for the HOXB cluster and HOXA cluster, respectively. Moreover, the hypermethylation profile of the HOXB cluster, especially HOXB4, was correlated with decreased transcript expression, which was restored following treatment with 5-aza-2'-deoxycytidine.
CONCLUSIONS: The homeobox methylation profile in OSCC cell lines is consistent with an epigenetic biomarker.

Zhang Y, Cheng JC, Huang HF, Leung PC
Homeobox A7 stimulates breast cancer cell proliferation by up-regulating estrogen receptor-alpha.
Biochem Biophys Res Commun. 2013; 440(4):652-7 [PubMed] Related Publications
Breast cancer is the most common hormone-dependent malignancy in women. Homeobox (HOX) transcription factors regulate many cellular functions, including cell migration, proliferation and differentiation. The aberrant expression of HOX genes has been reported to be associated with human reproductive cancers. Estradiol (E2) and its nuclear receptors, estrogen receptor (ER)-alpha and ER-beta, are known to play critical roles in the regulation of breast cancer cell growth. However, an understanding of the potential relationship between HOXA7 and ER in breast cancer cells is limited. In this study, our results demonstrate that knockdown of HOXA7 in MCF7 cells significantly decreased cell proliferation and ERα expression. In addition, HOXA7 knockdown attenuated E2-induced cell proliferation as well as progesterone receptor (PR) expression. The stimulatory effects of E2 on cell proliferation and PR expression were abolished by co-treatment with ICI 182780, a selective ERα antagonist. In contrast, overexpression of HOXA7 significantly stimulated cell proliferation and ERα expression. Moreover, E2-induced cell proliferation, as well as PR expression, was enhanced by the overexpression of HOXA7. Neither knockdown nor overexpression of HOXA7 affected the ER-beta levels. Our results demonstrate a novel mechanistic role for HOXA7 in modulating breast cancer cell proliferation via regulation of ERα expression. This finding contributes to our understanding of the role HOXA7 plays in regulating the proliferation of ER-positive cancer cells.

Dou L, Li J, Zheng D, et al.
MicroRNA-142-3p inhibits cell proliferation in human acute lymphoblastic leukemia by targeting the MLL-AF4 oncogene.
Mol Biol Rep. 2013; 40(12):6811-9 [PubMed] Related Publications
The mixed-lineage leukemia (MLL)-AF4 fusion protein encoded by the chromosomal translocation t(4;11) predicts a poorer prognosis in acute lymphoblastic leukemia (ALL) than in other MLL-associated leukemias. However, the detailed mechanism underlying regulation of MLL-AF4 expression remains largely unknown. In this study, we showed that microRNA (miR)-142-3p was significantly downregulated in ALL patients expressing MLL-AF4. Upregulation of miR-142-3p decreased MLL-AF4 expression in the RS4;11 leukemic cell line, which suggests that MLL-AF4 is a direct target of miR-142-3p. Ectopic expression of miR-142-3p remarkably suppressed cell proliferation and induced apoptosis in RS4;11 cells expressing the MLL-AF4 fusion protein. We also found that exogenous expression of miR-142-3p strongly reduced the expression of MLL-AF4 target genes such as homeobox A (HOXA)9, HOXA7, and HOXA10 in RS4;11 cells. Taken together, our results indicate that miR-142-3p functions as a growth suppressor in MLL-AF4(+) ALL, and its suppressive effects are mediated primarily through repression of MLL-AF4 expression.

Kang JU
Characterization of amplification patterns and target genes on the short arm of chromosome 7 in early-stage lung adenocarcinoma.
Mol Med Rep. 2013; 8(5):1373-8 [PubMed] Related Publications
Chromosomal alterations are a predominant genomic force contributing to the development of lung adenocarcinoma (ADC). High density genomic arrays were conducted to identify critical genetic landmarks that may be important mediators in the formation or progression of early‑stage ADC. In this study, the most noteworthy and consistent observation was a copy number gain on the short arm of chromosome 7, which was detected in 85.7% (12/14) of cases. Notably, three distinct regions of amplification were identified between the 7p22.3 and q11.2 regions in 28.6% (4/14) of cases; at a size of 4.1 Mbp (7p22.3‑p21.1), 2.6 Mbp (7p15.2-p14.1) and 1.5 Mbp (7p12.3‑p11.2). Variations of the 7p11.2 locus that encodes EGFR are known to be oncogenic. Furthermore, potential target genes were identified that were previously not assumed to be involved in the pathogenesis of ADC, including CALM1P2 (7p11.2), HOXA4, HOXA5, HOXA6, HOXA7, HOXA9, HOXA10, HOXA11 and HOXA13 (7p15.2) and LOC442586, LOC442589, LOC442282, FAM20C and LOC442651 (7p22.3). The present study determined critical regions on the 7p arm of chromosome 7, which were implicated in ADC. The pattern of rearrangements on the 7p arm may be a consequence of the high density of potential targets and the identified genes at the 7p regions may aid in the development of therapeutic targets for ADC.

Sun M, Song CX, Huang H, et al.
HMGA2/TET1/HOXA9 signaling pathway regulates breast cancer growth and metastasis.
Proc Natl Acad Sci U S A. 2013; 110(24):9920-5 [PubMed] Free Access to Full Article Related Publications
The ten-eleven translocation (TET) family of methylcytosine dioxygenases initiates demethylation of DNA and is associated with tumorigenesis in many cancers; however, the mechanism is mostly unknown. Here we identify upstream activators and downstream effectors of TET1 in breast cancer using human breast cancer cells and a genetically engineered mouse model. We show that depleting the architectural transcription factor high mobility group AT-hook 2 (HMGA2) induces TET1. TET1 binds and demethylates its own promoter and the promoter of homeobox A (HOXA) genes, enhancing its own expression and stimulating expression of HOXA genes including HOXA7 and HOXA9. Both TET1 and HOXA9 suppress breast tumor growth and metastasis in mouse xenografts. The genes comprising the HMGA2-TET1-HOXA9 pathway are coordinately regulated in breast cancer and together encompass a prognostic signature for patient survival. These results implicate the HMGA2-TET1-HOX signaling pathway in the epigenetic regulation of human breast cancer and highlight the importance of targeting methylation in specific subpopulations as a potential therapeutic strategy.

Ding X, Yang Z, Zhou F, et al.
Transcription factor AP-2α regulates acute myeloid leukemia cell proliferation by influencing Hoxa gene expression.
Int J Biochem Cell Biol. 2013; 45(8):1647-56 [PubMed] Related Publications
Transcription factor AP-2α mediates transcription of a number of genes implicated in mammalian development, cell proliferation and carcinogenesis. In the current study, we identified Hoxa7, Hoxa9 and Hox cofactor Meis1 as AP-2α target genes, which are involved in myeloid leukemogenesis. Luciferase reporter assays revealed that overexpression of AP-2α activated transcription activities of Hoxa7, Hoxa9 and Meis1, whereas siRNA of AP-2α inhibited their transcription activities. We found that AP-2 binding sites in regulatory regions of three genes activated their transcription by mutant analysis and AP-2α could interact with AP-2 binding sites in vivo by chromatin immunoprecipitation (ChIP). Further results showed that the AP-2α shRNA efficiently inhibited mRNA and protein levels of Hoxa7, Hoxa9 and Meis1 in AML cell lines U937 and HL60. Moreover, decreased expression of AP-2α resulted in a significant reduction in the growth and proliferation of AML cells in vitro. Remarkably, AP-2α knockdown leukemia cells exhibit decreased tumorigenicity in vivo compared with controls. Finally, AP-2α and target genes in clinical acute myeloid leukemia samples of M5b subtype revealed variable expression levels and broadly paralleled expression. These data support a role of AP-2α in mediating the expression of Hoxa genes in acute myeloid leukemia to influence the proliferation and cell survival.

Li Z, Zhang Z, Li Y, et al.
PBX3 is an important cofactor of HOXA9 in leukemogenesis.
Blood. 2013; 121(8):1422-31 [PubMed] Free Access to Full Article Related Publications
Although PBX proteins are known to increase DNA-binding/transcriptional activity of HOX proteins through their direct binding, the functional importance of their interaction in leukemogenesis is unclear.We recently reported that overexpression of a 4-homeobox-gene signature (ie, PBX3/HOXA7/HOXA9/HOXA11) is an independent predictor of poor survival in patients with cytogenetically abnormal acute myeloid leukemia (CA-AML). Here we show that it is PBX3, but not PBX1 or PBX2, that is consistently coexpressed with HOXA9 in various subtypes of CA-AML, particularly MLL-rearranged AML, and thus appears as a potential pathologic cofactor of HOXA9 in CA-AML. We then show that depletion of endogenous Pbx3 expression by shRNA significantly inhibits MLL-fusion-mediated cell transformation, and coexpressed PBX3 exhibits a significantly synergistic effect with HOXA9 in promoting cell transformation in vitro and leukemogenesis in vivo. Furthermore, as a proof of concept, we show that a small peptide, namely HXR9, which was developed to specifically disrupt the interactions between HOX and PBX proteins, can selectively kill leukemic cells with overexpression of HOXA/PBX3 genes. Collectively, our data suggest that PBX3 is a critical cofactor of HOXA9 in leukemogenesis, and targeting their interaction is a feasible strategy to treat presently therapy resistant CA-AML (eg, MLL-rearranged leukemia) in which HOXA/PBX3 genes are overexpressed.

Kousparou CA, Yiacoumi E, Deonarain MP, Epenetos AA
Generation of a selectively cytotoxic fusion protein against p53 mutated cancers.
BMC Cancer. 2012; 12:338 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: A significant number of cancers are caused by defects in p21 causing functional defects in p21 or p53 tumour-suppressor proteins. This has led to many therapeutic approaches including restoration by gene therapy with wild-type p53 or p21 using viral or liposomal vectors, which have toxicity or side-effect limitations. We set out to develop a safer, novel fusion protein which has the ability to reconstitute cancer cell lines with active p21 by protein transduction.
METHODS: The fusion protein was produced from the cell-translocating peptide Antennapedia (Antp) and wild-type, full-length p21 (Antp-p21). This was expressed and refolded from E. coli and tested on a variety of cell lines and tumours (in a BALB/c nude xenograft model) with differing p21 or p53 status.
RESULTS: Antp-p21 penetrated and killed cancer cells that do not express wild type p53 or p21. This included cells that were matched to cogenic parental cell lines. Antp-p21 killed cancer cells selectively that were malignant as a result of mutations or nuclear exclusion of the p53 and p21 genes and over-expression of MDM2. Non-specific toxicity was excluded by showing that Antp-p21 penetrated but did not kill p53- or p21- wild-type cells. Antp-p21 was not immunogenic in normal New Zealand White rabbits. Recombinant Antp peptide alone was not cytotoxic, showing that killing was due to the transduction of the p21 component of Antp-p21. Antp-p21 was shown to penetrate cancer cells engrafted in vivo and resulted in tumour eradication when administered with conventionally-used chemotherapeutic agents, which alone were unable to produce such an effect.
CONCLUSIONS: Antp-p21 may represent a new and promising targeted therapy for patients with p53-associated cancers supporting the concept that rational design of therapies directed against specific cancer mutations will play a part in the future of medical oncology.

Di Vinci A, Brigati C, Casciano I, et al.
HOXA7, 9, and 10 are methylation targets associated with aggressive behavior in meningiomas.
Transl Res. 2012; 160(5):355-62 [PubMed] Related Publications
Meningioma is one of the most common intracranial tumors and is graded according to the World Health Organization (WHO) classification system. Although these tumors are often surgically curable, a malignant behavior also may occur in meningiomas with benign histologic profiles (WHO I). Thus, it is mandatory to identify biomolecular parameters useful to improve the classification of these tumors. HOXA genes belong to the HOX gene family that encodes homeodomain-containing transcription factors known to be key regulators of embryonic development, involved in cell growth and differentiation and in the development of the central nervous system. Moreover, altered HOXA gene methylation and expression have prognostic value in many tumors. The purpose of this study was to determine whether the level of HOXA3, 7, 9, and 10 methylation in meningioma could be a biomarker linked to the pathologic characteristics of the tumor. We found that methylation levels of HOXA7, 9, and 10 in 131 meningioma samples were significantly higher in WHO II/III tumors compared with WHO I tumors. Moreover, in newly diagnosed WHO I meningiomas, HOXA7, 9, and 10 methylation was significantly lower than in WHO I samples derived from recurring tumors, and multiple meningiomas presented significantly higher HOXA 10 methylation with respect to solitary meningiomas. This study demonstrates that HOXA7, 9, and 10 are methylation targets in meningioma, associated with histopathology and clinical aggressiveness parameters. Our findings suggest the possibility of detecting the malignancy potential of meningioma by assessing the HOXA methylation level and identifying patients at higher risk who could benefit from closer follow-up or postoperative adjuvant treatments.

Li Z, Huang H, Li Y, et al.
Up-regulation of a HOXA-PBX3 homeobox-gene signature following down-regulation of miR-181 is associated with adverse prognosis in patients with cytogenetically abnormal AML.
Blood. 2012; 119(10):2314-24 [PubMed] Free Access to Full Article Related Publications
Increased expression levels of miR-181 family members have been shown to be associated with favorable outcome in patients with cytogenetically normal acute myeloid leukemia. Here we show that increased expression of miR-181a and miR-181b is also significantly (P < .05; Cox regression) associated with favorable overall survival in cytogenetically abnormal AML (CA-AML) patients. We further show that up-regulation of a gene signature composed of 4 potential miR-181 targets (including HOXA7, HOXA9, HOXA11, and PBX3), associated with down-regulation of miR-181 family members, is an independent predictor of adverse overall survival on multivariable testing in analysis of 183 CA-AML patients. The independent prognostic impact of this 4-homeobox-gene signature was confirmed in a validation set of 271 CA-AML patients. Furthermore, our in vitro and in vivo studies indicated that ectopic expression of miR-181b significantly promoted apoptosis and inhibited viability/proliferation of leukemic cells and delayed leukemogenesis; such effects could be reversed by forced expression of PBX3. Thus, the up-regulation of the 4 homeobox genes resulting from the down-regulation of miR-181 family members probably contribute to the poor prognosis of patients with nonfavorable CA-AML. Restoring expression of miR-181b and/or targeting the HOXA/PBX3 pathways may provide new strategies to improve survival substantially.

Jo S, Lee H, Kim S, et al.
Inhibition of PCGF2 enhances granulocytic differentiation of acute promyelocytic leukemia cell line HL-60 via induction of HOXA7.
Biochem Biophys Res Commun. 2011; 416(1-2):86-91 [PubMed] Related Publications
This study tested the hypothesis that Polycomb Repressive Complex 1 (PRC1) may play a negative role in the granulocytic differentiation of acute promyelocytic leukemia (APL) cells. We first examined the expression of PRC1 genes during all-trans retinoic acid (ATRA)-mediated differentiation of human HL-60 cells, and identified PCGF2 as a gene down-regulated by ATRA in a time-dependent manner. Upon gene silencing of PCGF2 with lentiviral short hairpin RNA, granulocytic differentiation was induced as assessed by differentiation marker gene expression, nitroblue tetrazolium staining, Wright-Giemsa staining, and cell cycle analysis. We next identified HOXA7 as a homeobox gene up-regulated by ATRA and successfully induced granulocytic differentiation by overexpression of HOXA7. We next tested the relationship between PCGF2 and HOXA7 by quantifying the changes in HOXA7 and PCGF2 expression upon PCGF2 gene silencing and HOXA7 overexpression, respectively. HOXA7 expression was up-regulated by PCGF2 gene silencing, while PCGF2 expression remained unchanged by ectopic HOXA7 expression, suggesting PCGF2 as acting upstream of HOXA7. Finally, chromatin immunoprecipitation assay was performed with HOXA7 chromatin. We observed gene-specific reduction in direct binding of Pcgf2 protein to HOXA7 chromatin upon PCGF2 gene silencing. Taken together, these results support the notion that down-regulation of PCGF2 is sufficient to induce granulocytic differentiation of HL-60 cells via de-repression of HOXA7 gene expression. In conclusion, we report that PCGF2, a PRC1 gene, played a negative role in the granulocytic differentiation of human APL cells.

Gough SM, Slape CI, Aplan PD
NUP98 gene fusions and hematopoietic malignancies: common themes and new biologic insights.
Blood. 2011; 118(24):6247-57 [PubMed] Free Access to Full Article Related Publications
Structural chromosomal rearrangements of the Nucleoporin 98 gene (NUP98), primarily balanced translocations and inversions, are associated with a wide array of hematopoietic malignancies. NUP98 is known to be fused to at least 28 different partner genes in patients with hematopoietic malignancies, including acute myeloid leukemia, chronic myeloid leukemia in blast crisis, myelodysplastic syndrome, acute lymphoblastic leukemia, and bilineage/biphenotypic leukemia. NUP98 gene fusions typically encode a fusion protein that retains the amino terminus of NUP98; in this context, it is important to note that several recent studies have demonstrated that the amino-terminal portion of NUP98 exhibits transcription activation potential. Approximately half of the NUP98 fusion partners encode homeodomain proteins, and at least 5 NUP98 fusions involve known histone-modifying genes. Several of the NUP98 fusions, including NUP98-homeobox (HOX)A9, NUP98-HOXD13, and NUP98-JARID1A, have been used to generate animal models of both lymphoid and myeloid malignancy; these models typically up-regulate HOXA cluster genes, including HOXA5, HOXA7, HOXA9, and HOXA10. In addition, several of the NUP98 fusion proteins have been shown to inhibit differentiation of hematopoietic precursors and to increase self-renewal of hematopoietic stem or progenitor cells, providing a potential mechanism for malignant transformation.

Di Vinci A, Casciano I, Marasco E, et al.
Quantitative methylation analysis of HOXA3, 7, 9, and 10 genes in glioma: association with tumor WHO grade and clinical outcome.
J Cancer Res Clin Oncol. 2012; 138(1):35-47 [PubMed] Related Publications
PURPOSE: The purpose of this study was to determine whether specific HOXA epigenetic signatures could differentiate glioma with distinct biological, pathological, and clinical characteristics.
METHODS: We evaluated HOXA3, 7, 9, and 10 methylation in 63 glioma samples by MassARRAY and pyrosequencing.
RESULTS: We demonstrated the direct statistical correlation between the level of methylation of all HOXA genes examined and WHO grading. Moreover, in glioblastoma patients, higher level of HOXA9 and HOXA10 methylation significantly correlated with increased survival probability (HOXA9-HR: 0.36, P = 0.007; HOXA10-HR: 0.46, P = 0.045; combined HOXA9 and 10-HR 0.28, P = 0.004).
CONCLUSIONS: This study identifies HOXA3, 7, 9, and 10 as methylation targets mainly in high-grade glioma and hypermethylation of the HOXA9 and 10 as prognostic factor in glioblastoma patients. Our data indicate that these epigenetic changes may be biomarkers of clinically different subgroups of glioma patients that could eventually benefit from personalized therapeutic strategies.

Dou L, Zheng D, Li J, et al.
Methylation-mediated repression of microRNA-143 enhances MLL-AF4 oncogene expression.
Oncogene. 2012; 31(4):507-17 [PubMed] Related Publications
Fusion proteins containing the amino terminus of mixed lineage leukemia (MLL) are common in acute lymphoblastic leukemia (ALL) due to translocations. The MLL-AF4 fusion protein is generated by the translocation t(4;11)(q21;q23), and t(4;11)-positive ALL patients (MLL-AF4 ALL), have a notoriously poorer prognosis compared with patients with other MLL-associated leukemias. The detailed role of this fusion protein in leukemogenesis is not well understood. MicroRNAs (miRNAs) targeting the AF4 3' untranslated regions may modulate MLL-AF4 fusion protein levels, raising the question of whether regulation of these miRNAs are involved in the progression of MLL-AF4 ALL. In this study, we show that miR-143 was identified as a regulator of MLL-AF4 expression in MLL-AF4 ALL samples. Restoration of miR-143 in MLL-AF4-positive RS4;11 and MV4-11 cells induced apoptosis, negatively contributing to leukemia cell growth by reducing MLL-AF4 fusion protein levels. Furthermore, miR-143 was epigenetically repressed by promoter hypermethylation in MLL-AF4-positive primary blasts and cell lines, but not in normal bone marrow cells and MLL-AF4-negative primary blasts, which was directly associated with expression of the MLL-AF4 oncogene. This is the first study to show that miR-143 functions as a tumor suppressor in MLL-AF4 B-cell ALL. These data reveal the therapeutic promise of upregulating miR-143 expression for MLL-AF4 B-cell ALL.

Cillo C, Schiavo G, Cantile M, et al.
The HOX gene network in hepatocellular carcinoma.
Int J Cancer. 2011; 129(11):2577-87 [PubMed] Related Publications
Liver organogenesis and cancerogenesis share common mechanisms. HOX genes control normal development, primary cellular processes and are characterized by a unique genomic network organization. Less is known about the involvement of HOX genes with liver cancerogenesis. The comparison of the HOX gene network expression between nontumorous livers and hepatocellular carcinomas (HCCs) highlights significant differences in the locus A HOX genes, located on chromosome 7, with a consistent overexpression of HOXA13 mRNA thus validating this gene deregulation as a feature of HCC. HOXA13 is a determinant of gut primordia and posterior body structures. Transcriptome analysis of HCC/nontumorous liver mRNAs, selected on the basis of HOXA13 overexpression, recognizes a set of deregulated genes. The matching of these genes with previously reported HCC transcriptome analysis identifies cell-cycle and nuclear pore-related HCC phenotype displaying poor prognosis. HOXA13 and HOXA7 homeoproteins share a consensus sequence that physically links eIF4E nuclear bodies acting on the export of specific mRNAs (c-myc, FGF-2, vascular endothelial growth factor (VEGF), ornithine decarboxylase (ODC) and cyclin D1). We report the protein-protein interaction between HOXA13 and eIF4E in liver cancer cells and the deregulation of eIF4E mRNA and protein in cell cycle/nuclear pore HCC group phenotype and in T4 stage HCCs, respectively. Thus, transcriptional and post-transcriptional HOXA13 deregulation is involved in HCC possibly through the mRNA nuclear export of eIF4E-dependent transcripts.

Orlovsky K, Kalinkovich A, Rozovskaia T, et al.
Down-regulation of homeobox genes MEIS1 and HOXA in MLL-rearranged acute leukemia impairs engraftment and reduces proliferation.
Proc Natl Acad Sci U S A. 2011; 108(19):7956-61 [PubMed] Free Access to Full Article Related Publications
Rearrangements of the MLL (ALL1) gene are very common in acute infant and therapy-associated leukemias. The rearrangements underlie the generation of MLL fusion proteins acting as potent oncogenes. Several most consistently up-regulated targets of MLL fusions, MEIS1, HOXA7, HOXA9, and HOXA10 are functionally related and have been implicated in other types of leukemias. Each of the four genes was knocked down separately in the human precursor B-cell leukemic line RS4;11 expressing MLL-AF4. The mutant and control cells were compared for engraftment in NOD/SCID mice. Engraftment of all mutants into the bone marrow (BM) was impaired. Although homing was similar, colonization by the knockdown cells was slowed. Initially, both types of cells were confined to the trabecular area; this was followed by a rapid spread of the WT cells to the compact bone area, contrasted with a significantly slower process for the mutants. In vitro and in vivo BrdU incorporation experiments indicated reduced proliferation of the mutant cells. In addition, the CXCR4/SDF-1 axis was hampered, as evidenced by reduced migration toward an SDF-1 gradient and loss of SDF-1-augmented proliferation in culture. The very similar phenotype shared by all mutant lines implies that all four genes are involved and required for expansion of MLL-AF4 associated leukemic cells in mice, and down-regulation of any of them is not compensated by the others.

Acosta D, Suzuki M, Connolly D, et al.
DNA methylation changes in murine breast adenocarcinomas allow the identification of candidate genes for human breast carcinogenesis.
Mamm Genome. 2011; 22(3-4):249-59 [PubMed] Related Publications
Epigenetic inactivation due to aberrant promoter methylation is a key process in breast tumorigenesis. Murine models for human breast cancer have been established for nearly every important human oncogene or tumor suppressor gene. Mouse-to-human comparative gene expression and cytogenetic profiling have been widely investigated for these models; however, little is known about the conservation of epigenetic alterations during tumorigenesis. To determine if this key process in human breast tumorigenesis is also mirrored in a murine breast cancer model, we mapped cytosine methylation changes in primary adenocarcinomas and paired lung metastases derived from the polyomavirus middle T antigen mouse model. Global changes in methylcytosine levels were observed in all tumors when compared to the normal mammary gland. Aberrant methylation and associated gene silencing was observed for Hoxa7, a gene that is differentially methylated in human breast tumors, and Gata2, a novel candidate gene. Analysis of HOXA7 and GATA2 expression in a bank of human primary tumors confirms that the expression of these genes is also reduced in human breast cancer. In addition, HOXA7 hypermethylation is observed in breast cancer tissues when compared to adjacent tumor-free tissue. Based on these studies, we present a model in which comparative epigenetic techniques can be used to identify novel candidate genes important for human breast tumorigenesis, in both primary and metastatic tumors.

Libório TN, Acquafreda T, Matizonkas-Antonio LF, et al.
In situ hybridization detection of homeobox genes reveals distinct expression patterns in oral squamous cell carcinomas.
Histopathology. 2011; 58(2):225-33 [PubMed] Related Publications
AIMS: To analyse the expression of three homeobox genes (HOXA7, PITX1 and PRRX1) in oral squamous cell carcinomas (OSCC) and the relationship of such expression to certain distinct histopathological features of OSCC and in comparison to adjacent non-neoplastic epithelium (NT).
METHODS AND RESULTS: Digoxigenin-labelled riboprobes that are specific for each homeobox gene were generated and in situ hybridization was carried out on frozen sections. In NT samples, HOXA7 and PITX1 transcripts were found more frequently in all epithelial layers, while PRRX1 was expressed in the basal layer. With OSCC samples, expression of the three genes was associated with all histological features. However, the HOXA7 and PITX1 signals were more intense in sheets and nests and PRRX1 in small nests and isolated cells.
CONCLUSION: HOXA7, PIXT1 and PRRX1 homeobox genes have different patterns of expression in OSCC depending on its histological features.

Gessner A, Thomas M, Castro PG, et al.
Leukemic fusion genes MLL/AF4 and AML1/MTG8 support leukemic self-renewal by controlling expression of the telomerase subunit TERT.
Leukemia. 2010; 24(10):1751-9 [PubMed] Related Publications
MLL/AF4 and AML/MTG8 represent two leukemic fusion genes, which are most frequently found in infant acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML), respectively. We examined the influence of MLL/AF4 and AML1/MTG8 fusion genes on the expression of TERT coding for the telomerase protein subunit, and subsequently telomerase activity in t(4;11)-positive ALL and t(8;21)-positive cell lines, respectively. MLL/AF4 suppression diminished telomerase activity and expression of TERT. Blocking pro-apoptotic caspase activation in conjunction with MLL/AF4 knockdown enhanced the inhibition of TERT gene expression, which suggests that MLL/AF4 depletion does not reduce TERT expression levels by inducing apoptosis. Knockdown of HOXA7, a direct transcriptional target of MLL/AF4 fusion gene, caused a reduction of telomerase and TERT to an extent similar to that observed with MLL/AF4 suppression. Chromatin immunoprecipitation of SEM cells, using ectopically expressed FLAG-tagged Hoxa7, indicates HOXA7 binding site in the TERT promoter region. Furthermore, suppression of the AML1/MTG8 fusion gene was associated with severely reduced clonogenicity, induction of replicative senescence, impaired TERT expression and accelerated telomere shortening. We thus present findings that show a mechanistic link between leukemic fusion proteins, essential for development and maintenance of leukemia, and telomerase, a key element of both normal and malignant self-renewal.

Starkova J, Zamostna B, Mejstrikova E, et al.
HOX gene expression in phenotypic and genotypic subgroups and low HOXA gene expression as an adverse prognostic factor in pediatric ALL.
Pediatr Blood Cancer. 2010; 55(6):1072-82 [PubMed] Related Publications
BACKGROUND: HOX genes play an important role in both normal lymphopoiesis and leukemogenesis. However, HOX expression patterns in leukemia cells compared to normal lymphoid progenitors have not been systematically studied in acute lymphoblastic leukemia (ALL) subtypes.
PROCEDURE: The RNA expression levels of HOXA, HOXB, and CDX1/2 genes were analyzed by qRT-PCR in a cohort of 61 diagnostic pediatric ALL samples and FACS-sorted subpopulations of normal lymphoid progenitors.
RESULTS: The RNA expression of HOXA7-10, HOXA13, and HOXB2-4 genes was exclusively detected in leukemic cells and immature progenitors. The RNA expression of HOXB6 and CDX2 genes was exclusively detected in leukemic cells but not in B-lineage cells at any of the studied developmental stages. HOXA3-4, HOXA7, and HOXB3-4 genes were differentially expressed between BCP-ALL and T-ALL subgroups, and among genotypically defined MLL/AF4, TEL/AML1, BCR/ABL, hyperdiploid and normal karyotype subgroups. However, this differential expression did not define specific clusters in hierarchical cluster analysis. HOXA7 gene was low expressed at the RNA level in patients with hyperdiploid leukemia, whereas HOXB7 and CDX2 genes were low expressed in TEL/AML1-positive and BCR/ABL-positive cases, respectively. In contrast to previous findings in acute myeloid leukemia, high HOXA RNA expression was associated with an excellent prognosis in Cox's regression model (P = 0.03). In MLL/AF4-positive ALL, lower HOXA RNA expression correlated with the methylation status of their promoters.
CONCLUSIONS: HOX gene RNA expression cannot discriminate leukemia subgroups or relative maturity of leukemic cells. However, HOXA RNA expression correlates with prognosis, and particular HOX genes are expressed in specific genotypically characterized subgroups.

Nacheva EP, Brazma D, Virgili A, et al.
Deletions of immunoglobulin heavy chain and T cell receptor gene regions are uniquely associated with lymphoid blast transformation of chronic myeloid leukemia.
BMC Genomics. 2010; 11:41 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Chronic myelogenous leukemia (CML) results from the neoplastic transformation of a haematopoietic stem cell. The hallmark genetic abnormality of CML is a chimeric BCR/ABL1 fusion gene resulting from the Philadelphia chromosome rearrangement t(9;22)(q34;q11). Clinical and laboratory studies indicate that the BCR/ABL1 fusion protein is essential for initiation, maintenance and progression of CML, yet the event(s) driving the transformation from chronic phase to blast phase are poorly understood.
RESULTS: Here we report multiple genome aberrations in a collection of 78 CML and 14 control samples by oligonucleotide array comparative genomic hybridization. We found a unique signature of genome deletions within the immunoglobulin heavy chain (IGH) and T cell receptor regions (TCR), frequently accompanied by concomitant loss of sequences within the short arm regions of chromosomes 7 and 9, including IKZF1, HOXA7, CDKN2A/2B, MLLT3, IFNA/B, RNF38, PAX5, JMJD2C and PDCD1LG2 genes.
CONCLUSIONS: None of these genome losses were detected in any of the CML samples with myeloid transformation, chronic phase or controls, indicating that their presence is obligatory for the development of a malignant clone with a lymphoid phenotype. Notably, the coincidental deletions at IGH and TCR regions appear to precede the loss of IKZF1 and/or p16 genes in CML indicating a possible involvement of RAG in these deletions.

Yang YC, Wang SW, Wu IC, et al.
A tumorigenic homeobox (HOX) gene expressing human gastric cell line derived from putative gastric stem cell.
Eur J Gastroenterol Hepatol. 2009; 21(9):1016-23 [PubMed] Related Publications
GOAL: Study the mechanism of gastric tumor development.
BACKGROUND: We have generated and characterized a novel human gastric cell line, KMU-CS12 (CS12), from an immortal cell line, KMU-CSN (CSN; formerly named as GI2CS) which was derived from putative human gastric stem cell/progenitor cell clone, KMU-GI2.
STUDY: The characterization of the CS12 cell line includes gene expression by immunocytochemical staining, cell proliferation and differentiation potential, cyotogenetic analysis by Giemsa banding and spectral karyotype analysis (SKY), and tumorigenicity in immune-deficient congenic inbred, nude mice (BALB/cAnN-Foxn1nu/CrlNarl). The Agilent Human 1A oligo-array and RT-PCR were also employed to analyze the expression of homeobox (HOX) genes.
RESULTS: The CS12 gastric cell line showed cancer cell phenotypes, i.e. the ability of anchorage-independent growth high frequency (44%) and to the expression of Oct-4, a transcription factor expressed in embryonic stem cells and many types of cancer cells, and tumor development in immune deficient mice. SKY analysis indicated a characteristic duplication of the short arm of chromosome 7 to chromosome 12. Agilent Human 1A oligo-array analysis showed that the expression of 1145 genes was upregulated while that of 890 genes was downregulated in CS12 cells. RT-PCR revealed that homeobox genes (HOXA4, HOXA5, HOXA7, HOXA9, and HOXA13) were highly expressed in CS12 cells in culture, as well as tumor tissues developed by CS12 cells in immunodeficient mice for six to eight weeks.
CONCLUSION: Except for the duplication of the short arm of Chromosome 7 on Chromosome12, the karyotype of the tumorigenic CS12 cells is similar to the parental GI2 cells which are non-tumorigenic and normal in karyotype. This chromosomal change could be the cause for the high expression of HOXA genes and tumorigenicity of these cells found in this study. Thus HOXA genes might play an important role in gastric carcinogenesis.

Schimanski CC, Frerichs K, Rahman F, et al.
High miR-196a levels promote the oncogenic phenotype of colorectal cancer cells.
World J Gastroenterol. 2009; 15(17):2089-96 [PubMed] Free Access to Full Article Related Publications
AIM: To analyze the relevance of the microRNA miR-196a for colorectal oncogenesis.
METHODS: The impact of miR-196a on the restriction targets HoxA7, HoxB8, HoxC8 and HoxD8 was analyzed by reverse transcription polymerase chain reaction (RT-PCR) after transient transfection of SW480 cancer cells. The miR-196a transcription profile in colorectal cancer samples, mucosa samples and diverse cancer cell lines was quantified by RT-PCR. Transiently miR-196a-transfected colorectal cancer cells were used for diverse functional assays in vitro and for a xenograft lung metastasis model in vivo.
RESULTS: HoxA7, HoxB8, HoxC8 and HoxD8 were restricted by miR-196a in a dose-dependent and gene-specific manner. High levels of miR-196a activated the AKT signaling pathway as indicated by increased phosphorylation of AKT. In addition, high levels of miR-196a promoted cancer cell detachment, migration, invasion and chemosensitivity towards platin derivatives but did not impact on proliferation or apoptosis. Furthermore, miR-196a increased the development of lung metastases in mice after tail vein injection.
CONCLUSION: miR-196a exerts a pro-oncogenic influence in colorectal cancer.

Ota T, Klausen C, Salamanca MC, et al.
Expression and function of HOXA genes in normal and neoplastic ovarian epithelial cells.
Differentiation. 2009; 77(2):162-71 [PubMed] Related Publications
We studied the roles of three HOXA genes in cultured normal ovarian surface epithelial (OSE) cells and ovarian cancer cells. They included HOXA4 and HOXA7 because, by cDNA microarray analysis, these were more highly expressed in invasive ovarian carcinomas than in benign or borderline (noninvasive) ovarian tumors, and HOXA9 because it characterizes normal oviductal epithelium, which resembles ovarian serous adenocarcinomas. The three HOXA genes were more highly expressed when OSE cells were dividing and motile than when they were confluent and stationary, and also when they dispersed in response to EGF treatment or to reduced calcium concentrations in culture media. The expression of the HOXA genes varied among ovarian cancer cell lines, but was highest in lines with compact epithelial morphologies. We focused on HOXA4 as the most highly expressed in the ovarian carcinoma array. HOXA4 expression did not parallel proliferative activities of either OSE or ovarian cancer lines. Moreover, modifying HOXA4 expression in ovarian cancer cell lines did not alter either E-cadherin expression or CA125 secretion. However, HOXA4 downregulation enhanced EGFR phosphorylation and migration in serum-starved OSE and ovarian cancer cells in response to EGF, and enhanced migration of all ovarian cancer lines in 5% serum even without EGF treatment. Thus, HOXA4 expression does not correlate with proliferation or with epithelial differentiation, but it increases in response to OSE cell dispersion and negatively regulates EGFR activation and the motility of OSE and of ovarian cancer cells. HOXA4 expression was highest in cancer lines with compact epithelial growth patterns, suggesting, again, an anti-dispersion function. In summary, increased HOXA4 expression in ovarian cancer appears to constitute a tumor-suppressive, homeostatic response to aberrant cell behavior, and, in particular, to cell dispersion and migration.

Youn JI, Park SH, Jin HT, et al.
Enhanced delivery efficiency of recombinant adenovirus into tumor and mesenchymal stem cells by a novel PTD.
Cancer Gene Ther. 2008; 15(11):703-12 [PubMed] Related Publications
Protein transduction domains (PTDs) are small peptides that facilitate the transduction of large molecules such as polyproteins, DNA and viruses into a eukaryotic cell. Here, we demonstrated that a novel PTD (HP4) derived from herring protamine appeared to enter C6Bu1 rat glioma cell lines more rapidly than other known PTDs such as Tat, Antp and Hph-1. Moreover, HP4 significantly enhanced in vitro transduction of recombinant adenoviruses (rAds) into various cancer cell lines, mesenchymal stem cells (MSCs) and dendritic cells, which are relatively resistant to rAd infection. Enhancement of rAd delivery into C6Bu1 and MSCs by HP4 is 20 and 7 times higher than that by Tat, respectively. The increase in the expression of rAd encoding IL-12N220L by HP4 is proportional to its antitumor effect in the ex vivo transduced mouse colon cancer model. Thus, these results suggest that HP4 could be utilized to improve the transduction efficiency of rAd, resulting in enhanced efficacy of rAd-mediated gene therapy, especially for ex vivo-transduced cell therapy.

Dou Y, Hess JL
Mechanisms of transcriptional regulation by MLL and its disruption in acute leukemia.
Int J Hematol. 2008; 87(1):10-8 [PubMed] Related Publications
Fusion of the mixed lineage leukemia protein (MLL) to one of over 50 different translocation partners converts it into a potent leukemogenic oncoprotein. The resulting fusion proteins transform primarily through upregulation of A-cluster Hox genes, including Hoxa9 and the Hox cofactor Meis1. Considerable progress has been made in delineating the differences between normal Hox gene regulation by MLL and deregulated transcription in MLL-induced leukemias. Some MLL translocation partners dimerize the truncated MLL molecule. Other translocation partners appear to recruit nuclear coactivator complexes that have diverse enzymatic activities that impinge on transcriptional elongation pathways. These enzymatic activities, including RNA polymerase II phosphorylation as well as histone H3 lysine 79 methylation present attractive targets for the development of future MLL-directed therapy.

Ota T, Gilks CB, Longacre T, et al.
HOXA7 in epithelial ovarian cancer: interrelationships between differentiation and clinical features.
Reprod Sci. 2007; 14(6):605-14 [PubMed] Related Publications
Interrelationships between HOXA7 expression and ovarian cancer progression are investigated by cDNA array and by immunohistochemistry of normal ovaries and 538 epithelial ovarian tumor microarrays. Outcomes of patients and HOXA7 expression were compared by Kaplan-Meier survival curves. HOXA7 mRNA expression was higher in carcinomas than in benign tumors. HOXA7 protein was absent in normal surface epithelium but appeared in metaplastic regions. All carcinomas stained for HOXA7 protein, with staining intensities unrelated to histotype, grade, or patient outcome. There were significant associations of strong HOXA7 staining of stroma and tumor nuclei with the clear cell histotype (stroma: P = .0022, nuclei: P = .0003) and of weak/absent staining with serous carcinomas. Tumor E-cadherin expression correlated significantly with HOX7 staining in stroma (P = .0002) but not within tumors. HOXA7 staining of tumor cell nuclei is correlated significantly with improved disease-specific survival (P = .0104), which is suggestive of the biological and potentially clinical importance of subcellular HOXA7 localization.

Wang GG, Cai L, Pasillas MP, Kamps MP
NUP98-NSD1 links H3K36 methylation to Hox-A gene activation and leukaemogenesis.
Nat Cell Biol. 2007; 9(7):804-12 [PubMed] Related Publications
Nuclear receptor-binding SET domain protein 1 (NSD1) prototype is a family of mammalian histone methyltransferases (NSD1, NSD2/MMSET/WHSC1, NSD3/WHSC1L1) that are essential in development and are mutated in human acute myeloid leukemia (AML), overgrowth syndromes, multiple myeloma and lung cancers. In AML, the recurring t(5;11)(q35;p15.5) translocation fuses NSD1 to nucleoporin-98 (NUP98). Here, we present the first characterization of the transforming properties and molecular mechanisms of NUP98-NSD1. We demonstrate that NUP98-NSD1 induces AML in vivo, sustains self-renewal of myeloid stem cells in vitro, and enforces expression of the HoxA7, HoxA9, HoxA10 and Meis1 proto-oncogenes. Mechanistically, NUP98-NSD1 binds genomic elements adjacent to HoxA7 and HoxA9, maintains histone H3 Lys 36 (H3K36) methylation and histone acetylation, and prevents EZH2-mediated transcriptional repression of the Hox-A locus during differentiation. Deletion of the NUP98 FG-repeat domain, or mutations in NSD1 that inactivate the H3K36 methyltransferase activity or that prevent binding of NUP98-NSD1 to the Hox-A locus precluded both Hox-A gene activation and myeloid progenitor immortalization. We propose that NUP98-NSD1 prevents EZH2-mediated repression of Hox-A locus genes by colocalizing H3K36 methylation and histone acetylation at regulatory DNA elements. This report is the first to link deregulated H3K36 methylation to tumorigenesis and to link NSD1 to transcriptional regulation of the Hox-A locus.

Rauch T, Wang Z, Zhang X, et al.
Homeobox gene methylation in lung cancer studied by genome-wide analysis with a microarray-based methylated CpG island recovery assay.
Proc Natl Acad Sci U S A. 2007; 104(13):5527-32 [PubMed] Free Access to Full Article Related Publications
De novo methylation of CpG islands is a common phenomenon in human cancer, but the mechanisms of cancer-associated DNA methylation are not known. We have used tiling arrays in combination with the methylated CpG island recovery assay to investigate methylation of CpG islands genome-wide and at high resolution. We find that all four HOX gene clusters on chromosomes 2, 7, 12, and 17 are preferential targets for DNA methylation in cancer cell lines and in early-stage lung cancer. CpG islands associated with many other homeobox genes, such as SIX, LHX, PAX, DLX, and Engrailed, were highly methylated as well. Altogether, more than half (104 of 192) of all CpG island-associated homeobox genes in the lung cancer cell line A549 were methylated. Analysis of paralogous HOX genes showed that not all paralogues undergo cancer-associated methylation simultaneously. The HOXA cluster was analyzed in greater detail. Comparison with ENCODE-derived data shows that lack of methylation at CpG-rich sequences correlates with presence of the active chromatin mark, histone H3 lysine-4 methylation in the HOXA region. Methylation analysis of HOXA genes in primary squamous cell carcinomas of the lung led to the identification of the HOXA7- and HOXA9-associated CpG islands as frequent methylation targets in stage 1 tumors. Homeobox genes are potentially useful as DNA methylation markers for early diagnosis of the disease. The finding of widespread methylation of homeobox genes lends support to the hypothesis that a substantial fraction of genes methylated in human cancer are targets of the Polycomb complex.

Eklund EA
The role of HOX genes in malignant myeloid disease.
Curr Opin Hematol. 2007; 14(2):85-9 [PubMed] Related Publications
PURPOSE OF REVIEW: The Hox family of homeodomain transcription factors plays an important role in regulating definitive hematopoiesis. Recent studies indicate that a common characteristic of poor prognosis acute myeloid leukemia is dysregulated expression of a key group of these Hox proteins. The purpose of this review is to outline recent progress in understanding the role that dysregulation of HOX-gene expression plays in the pathogenesis of myeloid leukemogenesis.
RECENT FINDINGS: A number of recent studies correlate increased expression of HOXA-genes with poor prognosis cytogenetics in acute myeloid leukemia and mixed lineage leukemia. These studies determine that specific ABD HOXA-genes (HoxA7, 9 and 10) are dysregulated as a group. Many such studies also document co-overexpression of homeodomain proteins of the Meis and Pbx families in poor prognosis leukemia. This is of interest, since Meis and Pbx proteins are common DNA-binding partners for Hox proteins.
SUMMARY: These findings suggest that a key characteristic of poor prognosis acute myeloid leukemia is increased, differentiation-stage inappropriate expression of the Abd HoxA proteins and their DNA-binding partners. Such results suggest that dysregulation of the 'Hox code' is important in the pathogenesis of myeloid malignancy.

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