Deregulated homeobox gene expression in cancer: cause or consequence?

Combination of CDX2 expression and T stage improves prognostic prediction of colorectal cancer

OBJECTIVE

Prognostic prediction of colorectal cancer (CRC) remains challenging because of its heterogeneity. Aberrant expression of caudal-type homeobox transcription factor 2 (CDX2) is strongly correlated with the prognosis of CRC.

METHODS

Tissue samples of patients with CRC who underwent surgery in Xinhua Hospital (Shanghai, China) from January 2010 to January 2013 were collected. CDX2 expression was semiquantitatively evaluated via immunohistochemistry.

RESULTS

In total, 138 patients were enrolled in this study from a prospectively maintained institutional cancer database. The median follow-up duration was 57.5 months (interquartile range, 17.0-71.0 months). In the Cox proportional hazards model, low CDX2 expression combined with stage T4 CRC was significantly the worst prognostic factor for disease-free survival (hazard ratio = 7.020, 95% confidence interval = 3.922-12.564) and overall survival (hazard ratio = 5.176, 95% CI = 3.237-10.091). In the Kaplan-Meier survival analysis, patients with low CDX2 expression and stage T4 CRC showed significantly worse disease-free survival and overall survival than those with low CDX2 expression alone.

CONCLUSION

CDX2 expression combined with the T stage was more accurate for predicting the prognosis of CRC. Determining the prognosis of CRC using more than one variable is valuable in developing appropriate treatment and follow-up strategies.

A Case of Identity: HOX Genes in Normal and Cancer Stem Cells

Stem cells are undifferentiated cells that have the unique ability to self-renew and differentiate into many different cell types. Their function is controlled by core gene networks whose misregulation can result in aberrant stem cell function and defects of regeneration or neoplasia. HOX genes are master regulators of cell identity and cell fate during embryonic development. They play a crucial role in embryonic stem cell differentiation into specific lineages and their expression is maintained in adult stem cells along differentiation hierarchies. Aberrant HOX gene expression is found in several cancers where they can function as either oncogenes by sustaining cell proliferation or tumor-suppressor genes by controlling cell differentiation. Emerging evidence shows that abnormal expression of HOX genes is involved in the transformation of adult stem cells into cancer stem cells. Cancer stem cells have been identified in most malignancies and proved to be responsible for cancer initiation, recurrence, and metastasis. In this review, we consider the role of HOX genes in normal and cancer stem cells and discuss how the modulation of HOX gene function could lead to the development of novel therapeutic strategies that target cancer stem cells to halt tumor initiation, progression, and resistance to treatment.

Targeting HOX/PBX dimer formation as a potential therapeutic option in esophageal squamous cell carcinoma

Homeobox genes are known to be classic examples of the intimate relationship between embryogenesis and tumorigenesis, which are a family of transcriptional factors involved in determining cell identity during early development, and also dysregulated in many malignancies. Previously, HOXB7, HOXC6 and HOXC8 were found abnormally upregulated in esophageal squamous cell carcinoma (ESCC) tissues compared with normal mucosa and seen as poor prognostic predictors for ESCC patients, and were shown to promote cell proliferation and anti‐apoptosis in ESCC cells. These three HOX members have a high level of functional redundancy, making it difficult to target a single HOX gene. The aim of the present study was to explore whether ESCC cells are sensitive to HXR9 disrupting the interaction between multiple HOX proteins and their cofactor PBX, which is required for HOX functions. ESCC cell lines (KYSE70, KYSE150, KYSE450) were treated with HXR9 or CXR9, and coimmunoprecipitation and immunofluorescent colocalization were carried out to observe HOX/PBX dimer formation. To further investigate whether HXR9 disrupts the HOX pro‐oncogenic function, CCK‐8 assay and colony formation assay were carried out. Apoptosis was assessed by flow cytometry, and tumor growth in vivo was investigated in a xenograft model. RNA‐seq was used to study the transcriptome of HXR9‐treated cells. Results showed that HXR9 blocked HOX/PBX interaction, leading to subsequent transcription alteration of their potential target genes, which are involved in JAK‐signal transducer and activator of transcription (STAT) activation and apoptosis inducement. Meanwhile, HXR9 showed an antitumor phenotype, such as inhibiting cell proliferation, inducing cell apoptosis and significantly retarding tumor growth. Therefore, it is suggested that targeting HOX/PBX may be a novel effective treatment for ESCC.

Elevated HOXA13 expression promotes the proliferation and metastasis of gastric cancer partly via activating Erk1/2

Purpose

HOXA13 is a transcription factor of the Homeobox (HOX) gene family, which is highly evolutionarily conserved. HOXA13 is upregulated and associated with oncogenic properties in some cancers. Here, we studied the potential mechanism of HOXA13-mediated proliferation and metastasis in gastric cancer (GC).

Methods

Quantitative real-time PCR, Western blot, and immunohistochemistry were used to detect HOXA13 expression levels in GC. In vitro and in vivo assays were performed to investigate the function of HOXA13 in GC cell proliferation, migration, and invasion. RNA-Seq transcriptome analysis was performed to study the underlying mechanism of HOXA13-mediated aggressiveness in GC.

Results

HOXA13 mRNA and protein expression levels were upregulated in GC tissues. According to Cell Counting Kit-8 and colony formation assays, we found that HOXA13 over-expression promoted proliferation. Flow cytometry analysis showed that HOXA13 overexpression or knockdown led to G1-S phase transition or G1 phase arrest, respectively. Western blot analysis results showed that HOXA13 overexpression increased cyclin D1 expression, while knockdown decreased its expression. Wound healing and transwell assay results demonstrated that HOXA13 overexpression promoted the migration and invasion of GC cells. Western blot analysis results also showed that HOXA13 overexpression upregulated N-cadherin and vimentin and downregulated E-cadherin, while HOXA13 knockdown led to the opposite results, indicating that HOXA13 might participate in epithelial to mesenchymal transition. These results were verified in vivo by tumor xenograft and metastasis assays. Mechanistically, using RNA-Seq transcriptome analysis, we found that Erk1/2 activation played an important role in HOXA13-induced GC progression.

Conclusion

Our results show that HOXA13 plays an important role in GC development. HOXA13 overexpression promotes proliferation and metastasis partly via activation of Erk1/2 in GC. Thus, HOXA13, together with Erk1/2, may be promising targets for novel anticancer strategies.

Experimental and clinicopathological analysis of HOXB9 in gastric cancer

The association between homeobox (HOX)B9 expression and tumor malignancy was identified recently. It was reported that HOXB9 induced tumor angiogenesis, and associated with poor prognosis in patients with breast and colon cancer. On the other hand, regional lymph nodes are the most common site of tumor spread, and lymph node metastasis is a major prognostic factor in gastric cancer. It was hypothesized that HOXB9 promotes tumor lymphangiogenesis and induces tumor progression, invasion and metastasis in gastric cancer. The aim of the present study was to evaluate the correlation between HOXB9 expression, prognosis and clinicopathologic factors in patients with gastric cancer, and to assess the contribution of HOXB9 expression to tumor cell lymphangiogenesis in vitro. HOXB9 expression was evaluated by immunohistochemistry in resected tumor tissues from 58 patients with gastric cancer, and the association between prognosis and clinicopathologic factors was determined. HOXB9 gene was overexpressed in human gastric cancer TMK-1 cells and the effect of HOXB9 overexpression on the expression of vascular endothelial growth factor (VEGF)-C, VEGF-D and VEGF receptor (R)-3 was determined. It was demonstrated that the depth of tumor invasion, the number of node metastases, lymphatic invasion and vascular invasion were significantly associated with HOXB9 expression. Overall survival was decreased in patients with HOXB9 expression. The mRNA expression of VEGF-D but not of VEGF-C and VEGFR-3 was increased in HOXB9-overexpressing TMK-1 cells compared with control cells. In conclusion, HOXB9 expression was positively correlated with gastric cancer progression and lymphangiogenesis marker expression. HOXB9 may be associated with lymphogenic metastasis.

Loss of Nuclear Functions of HOXA10 Is Associated With Testicular Cancer Proliferation

Background: HOXA10 is a key transcriptional factor that regulates testis development as reported from previous transgenic mouse models and human inherited diseases. However, whether it also plays important roles in promoting the development of testicular cancer is not well-understood. Objective: To study the expression of HOXA10 and its regulated signaling pathways in testicular cancers. Design, Setting, and Participants: A tissue microarray was constructed with benign and cancerous testis. TCam2, NT-2, and NCCIT cell models were applied in this study. Intervention: Immunohistochemistry and immunofluorescence were performed to measure the expression and cellular localization of HOXA10 in testicular cancer tissues and cell models. Cell proliferation and cell cycling rates were determined by BrdU incorporation and flow cytometry assays. HOXA10 transcriptomes were profiled with Ampliseq RNA-seq in testicular cancer cells. Immunoblotting assays were used to detect HOXA10-regulated signaling. Results: HOXA10 is a nuclear protein in benign spermatocytes. Reduced nuclear expression and increased cytoplasmic expression of HOXA10 are associated with testicular cancers. These changes are consistent in both seminoma and non-seminoma. Enhanced HOXA10 expression in testicular cancer cell models inhibits cell proliferation and delays cell cycle progression through G2/M phases. These functions of HOXA10 mainly affect the TP53, cKit, STAT3, AKT, and ERK signaling pathways. Conclusions: Loss of nuclear functions of HOXA10 enhances proliferation of testicular cancer cells, suggesting that downregulation of HOXA10 transcription activity may promote the development of testicular cancers.

The expression of EMX2 lead to cell cycle arrest in glioblastoma cell line

Background

Glioblastoma (GB) is a highly invasive primary brain tumor that nearly always systematically recurs at the site of resection despite aggressive radio-chemotherapy. Previously, we reported a gene expression signature related to tumor infiltration. Within this signature, the EMX2 gene encodes a homeodomain transcription factor that we found was down regulated in glioblastoma. As EMX2 is reported to play a role in carcinogenesis, we investigated the impact of EMX2 overexpression in glioma-related cell lines.

Methods

For that purpose, we constructed tetracycline-inducible EMX2 expression lines. Transfected cell phenotypes (proliferation, cell death and cell cycle) were assessed in time-course experiments.

Results

Restoration of EMX2 expression in U87 glioblastoma cells significantly inhibited cell proliferation. This inhibition was reversible after EMX2 removal from cells. EMX2-induced proliferative inhibition was very likely due to cell cycle arrest in G1/S transition and was not accompanied by signs of cell death.

Conclusion

Our results suggest that EMX2 may constitute a putative therapeutic target for GB treatment.

Further studies are required to decipher the gene networks and transduction signals involved in EMX2’s effect on cell proliferation.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5094-y) contains supplementary material, which is available to authorized users.

HOXC6 promotes cervical cancer progression via regulation of Bcl-2

Homeobox C6 ( HOXC6) is a transcription factor that plays an important role in the development of several cancers. However, it is unknown whether HOXC6 regulates cervical cancer progression. In this study, we used quantitative PCR and Western blots to demonstrate that HOXC6 overexpression is associated with cervical cancer progression. These results are also supported by the public RNA-seq data showing that HOXC6 overexpression is correlated with poor patient survival. In vitro and in vivo experiments revealed that enhanced HOXC6 expression results in cervical cancer cell proliferation, cell cycle progression, anchorage colony formation, and xenograft tumor growth. Mechanistically, we show that HOXC6 up-regulates BCL2 expression through transcription regulation. Together, these results led us to conclude that overexpression of HOXC6 expression can enhance BCL2-mediated antiapoptotic effects to promote cervical cancer cell cycle progression and proliferation.-Wang, Y., Wang, C., Liu, N., Hou, J., Xiao, W., Wang, H. HOXC6 promotes cervical cancer progression via regulation of Bcl-2.

Overexpression of HOXC10 promotes angiogenesis in human glioma via interaction with PRMT5 and upregulation of VEGFA expression

High levels of angiogenesis are associated with poor prognosis in patients with gliomas. However, the molecular mechanisms underlying tumor angiogenesis remain unclear.

Methods: The effect of homeobox C10 (HOXC10) on tube formation, migration, and proliferation of human umbilical vein endothelial cells (HUVECs) and on chicken chorioallantoic membranes (CAMs) was examined. An animal xenograft model was used to examine the effect of HOXC10 on xenograft angiogenesis or the effect of bevacizumab, a monoclonal antibody against vascular endothelial growth factor A (VEGFA), on HOXC10-overexpressing xenografts. A chromatin immunoprecipitation assay was applied to investigate the mechanism in which HOXC10 regulated VEGFA expression.

Results: Overexpressing HOXC10 enhanced the capacity of glioma cells to induce tube formation, migration and proliferation of HUVECs, and neovascularization in CAMs, while silencing HOXC10 had the opposite result. We observed that CD31 staining was significantly increased in tumors formed by HOXC10-overexpressing U251MG cells but reduced in HOXC10-silenced tumors. Mechanistically, HOXC10 could transcriptionally upregulate VEGFA expression by binding to its promoter. Strikingly, treatment with bevacizumab, a monoclonal antibody against VEGFA, significantly inhibited the growth of HOXC10-overexpressing tumors and efficiently impaired angiogenesis. Protein arginine methyltransferase 5 (PRMT5) and WD repeat domain 5 (WDR5), both of which regulate histone post-translational modifications, were required for HOXC10-mediated VEGFA upregulation. Importantly, a significant correlation between HOXC10 levels and VEGFA expression was observed in a cohort of human gliomas.

Conclusions: This study suggests that HOXC10 induces glioma angiogenesis by transcriptionally upregulating VEGFA expression, and may represent a potential target for antiangiogenic therapy in gliomas.

Comparative Serum Challenges Show Divergent Patterns of Gene Expression and Open Chromatin in Human and Chimpanzee

Humans experience higher rates of age-associated diseases than our closest living evolutionary relatives, chimpanzees. Environmental factors can explain many of these increases in disease risk, but species-specific genetic changes can also play a role. Alleles that confer increased disease susceptibility later in life can persist in a population in the absence of selective pressure if those changes confer positive adaptation early in life. One age-associated disease that disproportionately affects humans compared with chimpanzees is epithelial cancer. Here, we explored genetic differences between humans and chimpanzees in a well-defined experimental assay that mimics gene expression changes that happen during cancer progression: A fibroblast serum challenge. We used this assay with fibroblasts isolated from humans and chimpanzees to explore species-specific differences in gene expression and chromatin state with RNA-Seq and DNase-Seq. Our data reveal that human fibroblasts increase expression of genes associated with wound healing and cancer pathways; in contrast, chimpanzee gene expression changes are not concentrated around particular functional categories. Chromatin accessibility dramatically increases in human fibroblasts, yet decreases in chimpanzee cells during the serum response. Many regions of opening and closing chromatin are in close proximity to genes encoding transcription factors or genes involved in wound healing processes, further supporting the link between changes in activity of regulatory elements and changes in gene expression. Together, these expression and open chromatin data show that humans and chimpanzees have dramatically different responses to the same physiological stressor, and how a core physiological process can evolve quickly over relatively short evolutionary time scales.

Analysis of differentially expressed genes and the promoters in bovine endometrium throughout estrus cycle and early pregnancy

Endometrial gene expression is primarily regulated by the ovarian steroids and pregnancy recognition factors. This study was aimed to characterize differential expression genes (DEGs) in bovine endometrium together with the analysis of their promoter region. Bovine uteri at follicular stage (FS), luteal stage (LS), and implantation stage (IS) at Day 18 of pregnancy were collected. Total RNA extracted and prepared cDNA were then subjected to high-throughput sequencing. For promoter analysis, 1 kb upstream promoter region of each DEG was analyzed. The numbers of highly expressed DEGs were 496 and 597 at FS and LS, respectively. When compared the gene expression of IS with LS, 383 and 346 DEGs showed higher and lower expression at IS, respectively. It was also observed that 20-30 transcription factors (TFs) were included in each DEGs. In addition, promoter analyses estimated 150-160 TFs for each stage. DLX4 and interferon regulatory factor 4 (IRF4) at FS, and IRF5, IRF9, STAT1, and STAT2 at IS were in common to DEGs and estimated TFs, respectively. This study highlighted potential molecular mechanisms controlling endometrial function during estrus cycle and IS, which will further guide to better understand the endometrial functions in future studies.

Homeobox oncogene activation by pan-cancer DNA hypermethylation

BACKGROUND

Cancers have long been recognized to be not only genetically but also epigenetically distinct from their tissues of origin. Although genetic alterations underlying oncogene upregulation have been well studied, to what extent epigenetic mechanisms, such as DNA methylation, can also induce oncogene expression remains unknown.

RESULTS

Here, through pan-cancer analysis of 4174 genome-wide profiles, including whole-genome bisulfite sequencing data from 30 normal tissues and 35 solid tumors, we discover a strong correlation between gene-body hypermethylation of DNA methylation canyons, defined as broad under-methylated regions, and overexpression of approximately 43% of homeobox genes, many of which are also oncogenes. To gain insights into the cause-and-effect relationship, we use a newly developed dCas9-SunTag-DNMT3A system to methylate genomic sites of interest. The locus-specific hypermethylation of gene-body canyon, but not promoter, of homeobox oncogene DLX1, can directly increase its gene expression.

CONCLUSIONS

Our pan-cancer analysis followed by functional validation reveals DNA hypermethylation as a novel epigenetic mechanism for homeobox oncogene upregulation.

Homeobox C10 inhibits the osteogenic differentiation potential of mesenchymal stem cells

PURPOSE

Mesenchymal stem cells (MSCs) are a reliable cell source for tissue regeneration. However, the molecular mechanisms underlying the directed differentiation of MSCs remain unclear which impedes potential clinical applications. Recent studies have discovered that Homeobox (HOX) genes are involved in the differentiation regulation of MSCs and bone formation. In this study, we investigate the HOXC10 function in the osteogenic differentiation potential of MSCs.

MATERIALS AND METHODS

Stem cells from apical papilla (SCAPs) and adipose-derived stem cells (ADSCs) were used in this study. Alkaline phosphatase (ALP) activity assays, ALP staining, Alizarin red staining, quantitative calcium analysis, osteogenesis-associated gene expression, and in vivo transplantation experiments were used to study osteogenic differentiation potential.

RESULTS

Our results showed that overexpression of HOXC10 in SCAPs inhibited ALP activity and mineralization in vitro and decreased the mRNA expression of collagen alpha-1 (I) chain, bone sialoprotein, osteocalcin, and a key transcription factor, runt-related transcription factor 2, in SCAPs. Depletion of HOXC10 promoted osteogenic differentiation in SCAPs in vitro. In addition, in vivo transplantation experiments in nude mice confirmed that SCAPs osteogenesis was triggered when HOXC10 was downregulated. Furthermore, depletion of HOXC10 also enhanced osteogenic differentiation in ADSCs.

CONCLUSIONS

Taken together, these results indicated that HOXC10 decreased the MSC osteogenic differentiation potential. Thus, inhibition of HOXC10 in MSCs might have the potential to improve tissue regeneration and provide insight into the mechanism underlying the directed differentiation of MSCs.

BP1, a potential biomarker for breast cancer prognosis

Homeobox genes are critical in tumor development. An isoform protein of DLX4 called BP1 is expressed in 80% of invasive ductal breast carcinomas. BP1 overexpression is implicated in an aggressive phenotype and poor prognosis. BP1 upregulation is associated with estrogen receptor negativity so those tumors do not respond to antiestrogens. Breast cancer is the second leading cause of death in women. BP1 could serve as both a novel prognostic biomarker for breast cancer and a therapeutic target. In this review, we address the role of BP1 protein in tumorigenesis of breast cancer and four other malignancies. A number of functions of BP1 in cancer are also discussed.

CDX2 expression is concordant between primary colorectal cancer lesions and corresponding liver metastases independent of chemotherapy: a single-center retrospective study in Japan

Objective

Loss of caudal-type homeobox transcription factor 2 (CDX2) expression in colorectal cancers (CRCs) has recently been proposed as a promising predictive biomarker for not only prognosis but also response to chemotherapy. However, the relationship between alterations in CDX2 expression during cancer progression and response to chemotherapy remains unclear. We herein aimed to determine the concordance of CDX2 expression between primary CRCs and corresponding liver metastases, in association with chemotherapy.

Results

Primary CRCs exhibited heterogeneous CDX2 expression. Seven of the 144 CRCs in the cohort (4.9%, 95% confidential interval, 2.0%–9.8%) were CDX2-negative. The concordance rate of the CDX2 expression status in patients who did not receive chemotherapy was 100% (P = 0.041), whereas the concordance rate among patients who received chemotherapy only after primary resection was 96.3% (P = 0.005). Moreover, the concordance rate in patients who received chemotherapy before both primary resection and liver metastasectomy was 100% (P < 0.001).

Conclusion

CDX2 expression status was highly concordant between primary CRCs and corresponding liver metastases, independent of chemotherapy, suggesting that the CDX2 expression status in CRCs was not affected by metastasis or chemotherapy.

Methods

A total of 144 consecutive patients with CRC who were treated at a single center in Japan between 2006 and 2014 were included. Formalin-fixed paraffin-embedded whole sections of surgically resected primary CRCs and corresponding liver metastases were assessed for CDX2 expression by immunohistochemistry.

A switch in transcription and cell fate governs the onset of an epigenetically-deregulated tumor in Drosophila

Tumor initiation is often linked to a loss of cellular identity. Transcriptional programs determining cellular identity are preserved by epigenetically-acting chromatin factors. Although such regulators are among the most frequently mutated genes in cancer, it is not well understood how an abnormal epigenetic condition contributes to tumor onset. In this work, we investigated the gene signature of tumors caused by disruption of the Drosophila epigenetic regulator, polyhomeotic (ph). In larval tissue ph mutant cells show a shift towards an embryonic-like signature. Using loss- and gain-of-function experiments we uncovered the embryonic transcription factor knirps (kni) as a new oncogene. The oncogenic potential of kni lies in its ability to activate JAK/STAT signaling and block differentiation. Conversely, tumor growth in ph mutant cells can be substantially reduced by overexpressing a differentiation factor. This demonstrates that epigenetically derailed tumor conditions can be reversed when targeting key players in the transcriptional network.

When an animal is developing as an embryo, different cells start to specialize into the specific cell types needed to form the tissues and organs of the body. How an individual cell commits to become a certain type of cell is mostly determined by which of the genes in its DNA are active. In animal cells, DNA is wrapped around proteins called histones, and one way that cells can maintain their distinct pattern of gene activity is via chemical tags on the histones. These tags can switch nearby genes on or off, and are added or removed by other proteins called epigenetic regulators. The epigenetic tags are also stably inherited when the cell divides, meaning that a cell’s identity can be maintained over many cell generations.

If epigenetic regulators fail to work properly or get disrupted, the pattern of gene activity in a cell becomes altered. As a consequence, that cell can lose its identity and will often turn into a cancer cell. In fact, mutations in epigenetic regulators are found in several human cancers. It is not yet understood how these changes in gene expression lead cells to become cancerous.

Torres et al. have now analyzed an epigenetic regulator called Polyhomeotic in developing larvae of the fruit fly, Drosophila melanogaster. The results show that when Polyhomeotic is not produced the fly larvae develop tumors. Moreover, the mutant cells without Polyhomeotic had different gene expression profiles compared to normal cells. This in turn caused the mutant cells, which had previously committed to a certain fate, to become more like the unspecialized cells found in early embryos.

Torres et al. next showed that, among the genes that were incorrectly regulated when Polyhomeotic’s activity was compromised, one gene called knirps was switched on by mistake, which led the mutant cells to become tumor cells. When the activity of knirps was reduced instead, almost no tumors grew. Additionally, Torres et al. found that the protein encoded by knirps activates a signaling pathway that keeps tumor cells unspecialized by blocking their normal progress to a more mature and specialized state – a process known as differentiation. Experimentally raising the levels of a different molecule that ultimately promotes differentiation caused the tumor cells to grow less.

These findings suggest that tumors caused when epigenetic regulation goes awry may be reversed by targeting key genes such as knirps. Further work is now needed to test whether these findings will also extend to humans. Forcing cancer cells from a highly dividing, non-specialized state into a dead-end, mature state may lead to new ways to treat cancer.

HOXB4 Promotes Hemogenic Endothelium Formation without Perturbing Endothelial Cell Development

Generation of hematopoietic stem cells (HSCs) from pluripotent stem cells, in vitro, holds great promise for regenerative therapies. Primarily, this has been achieved in mouse cells by overexpression of the homeotic selector protein HOXB4. The exact cellular stage at which HOXB4 promotes hematopoietic development, in vitro, is not yet known. However, its identification is a prerequisite to unambiguously identify the molecular circuits controlling hematopoiesis, since the activity of HOX proteins is highly cell and context dependent. To identify that stage, we retrovirally expressed HOXB4 in differentiating mouse embryonic stem cells (ESCs). Through the use of Runx1(-/-) ESCs containing a doxycycline-inducible Runx1 coding sequence, we uncovered that HOXB4 promoted the formation of hemogenic endothelium cells without altering endothelial cell development. Whole-transcriptome analysis revealed that its expression mediated the upregulation of transcription of core transcription factors necessary for hematopoiesis, culminating in the formation of blood progenitors upon initiation of Runx1 expression.

HOXB7 overexpression promotes cell proliferation and correlates with poor prognosis in gastric cancer patients by inducing expression of both AKT and MARKs

Increased expression of HOXB7 has been reported to correlate with the progression in many cancers. However, the specific mechanism by which it promotes the evolution of gastric cancer (GC) is poorly understood.In this study, we sought to investigate the role of HOXB7 in GC by assessing HOXB7 expression in patient tissue and its correlation to clinical characteristics. We found that GC tissues showed increased expression of HOXB7 and that the HOXB7 expression was significantly associated with Lauren classification, invasion depth, lymphatic metastasis and poor prognosis, and could serve as an independent prognostic factor. To further investigate the role of HOXB7 in GC, we generated stable GC cell lines and both over-expressed and knocked down HOXB7 expression. Over-expression of HOXB7 in GC cell lines enhanced cell proliferation, colony formation, migration and invasion ability, whereas the opposite trends were observed upon reduction of HOXB7 expression by knockdown. These findings were further supported by our in vivo studies which show that HOXB7 expression can affect the GC cells' subcutaneous growth and lung metastases. A Phospho-MAPK Array Kit was used to explore the possible mechanism of HOXB7-induced cell proliferation and invasion. We found that the AKT signaling pathway and the two members of the MAPK pathway, were involved in those promoting effects. In conclusion, our results showed that increased expression of HOXB7 might play an important role in promoting GC proliferation, migration and invasion by inducing both AKT and MAPK pathways, thus resulting in progression of, and poor prognosis in GC patients.

Lineage Plasticity in Cancer Progression and Treatment

Historically, it has been widely presumed that differentiated cells are determined during development and become irreversibly committed to their designated fates. In certain circumstances, however, differentiated cells can display plasticity by changing their identity, either by dedifferentiation to a progenitor-like state or by transdifferentiation to an alternative differentiated cell type. Such cellular plasticity can be triggered by physiological or oncogenic stress, or it can be experimentally induced through cellular reprogramming. Notably, physiological stresses that promote plasticity, such as severe tissue damage, inflammation, or senescence, also represent hallmarks of cancer. Furthermore, key drivers of cellular plasticity include major oncogenic and tumor suppressor pathways and can be exacerbated by drug treatment. Thus, plasticity may help cancer cells evade detection and treatment. We propose that cancer can be considered as a disease of excess plasticity, a notion that has important implications for intervention and treatment.

RKIP and peroxiredoxin 2 expression predicts the proliferative potential of gastric cancer stem cells

Gastric cancer is associated with a high mortality rate, with the development of gastric cancer stem cells underlying this. Gastric cancer stem cells are responsible for tumor initiation, progression and recurrence. However, the link between gastric cancer and gastric cancer stem cells remains to be fully understood. Murine models mimic a human microenvironment more accurately than in vitro studies and are useful models for understanding the behavior of different markers. The present study compared the expression of cluster of differentiation 44 (CD44), a stem cell marker, with the expression of other cancer-associated markers, including Raf kinase inhibitor protein (RKIP) and peroxiredoxin 2, in different pathological conditions of gastric cancer development using histological, immunohistological and western blot analyses. Initially, the murine model of gastric cancer was established using N-methyl-N-nitrosourea, a chemical carcinogen. Following initiation of cancer, immunohistochemistry was used to compare the expression of CD44, RKIP and peroxiredoxin 2 at different stages of cancer development. The results suggested CD44 and peroxiredoxin 2 expression was upregulated as the tumor progressed. However, expression of RKIP, a metastasis suppressor, was elevated in the initial stage of gastric cancer and suppressed during the aggressive stages. In agreement with previous data suggesting higher expressions of RKIP in the initial stages of cancer and its downregulation in the advanced stage, the results of the present study revealed that RKIP exhibited a negative effect on initial tumor development, and that the downregulation of RKIP in the advanced stages of cancer facilitated CD44 and peroxiredoxin 2 overexpression.

Homeobox genes for embryo implantation: From mouse to human

The proper development of uterus to a state of receptivity and the attainment of implantation competency for blastocyst are 2 indispensable aspects for implantation, which is considered to be a critical event for successful pregnancy. Like many developmental processes, a large number of transcription factors, such as homeobox genes, have been shown to orchestrate this complicated but highly organized physiological process during implantation. In this review, we focus on progress in studies of the role of homeobox genes, especially the Hox and Msx gene families, during implantation, together with subsequent development of post-implantation uterus and related reproductive defects in both mouse models and humans, that have led to better understanding of how implantation is precisely regulated and provide new insights into infertility.

HOXA13 contributes to gastric carcinogenesis through DHRS2 interacting with MDM2 and confers 5-FU resistance by a p53-dependent pathway

5-FU-based chemotherapy is recently most recommended as the first-line treatment for gastric cancer (GC). However, 5-FU resistance is common for many postoperative GC patients. Homeobox A13 (HOXA13) is a member of homeobox genes highly expressed in many human tumors. Its potential roles and mechanisms of resistance to 5-FU in GC are poorly understood. In this study, we discovered that HOXA13 played an oncogenic role in vivo and in vitro. The patients with HOXA13 overexpression were closely related with poor prognosis and more prone to be resistant to 5-FU. Moreover, dehydrogenase/reductase 2 (DHRS2) was identified as a downstream gene of HOXA13. HOXA13 played a role of carcinogenesis through directly down-regulating DHRS2 to increase MDM2. Furthermore, HOXA13 conferred 5-FU resistance through MRP1 by a p53-dependent pathway. Therefore, HOXA13 might serve as a potential signature that recognized patients who were insensitive to 5-FU, and timely recommended them to other chemotherapy regimens.

Epigenetic dysregulation of key developmental genes in radiation-induced rat mammary carcinomas

With the increase in the number of long-term cancer survivors worldwide, there is a growing concern about the risk of secondary cancers induced by radiotherapy. Epigenetic modifications of genes associated with carcinogenesis are attractive targets for the prevention of cancer owing to their reversible nature. To identify genes with possible changes in functionally relevant DNA methylation patterns in mammary carcinomas induced by radiation exposure, we performed microarray-based global DNA methylation and expression profiling in γ-ray-induced rat mammary carcinomas and normal mammary glands. The gene expression profiling identified dysregulation of developmentally related genes, including the downstream targets of polycomb repressive complex 2 (PRC2) and overexpression of enhancer of zeste homolog 2, a component of PRC2, in the carcinomas. By integrating expression and DNA methylation profiles, we identified ten hypermethylated and three hypomethylated genes that possibly act as tumor-suppressor genes and oncogenes dysregulated by aberrant DNA methylation; half of these genes encode developmental transcription factors. Bisulfite sequencing and quantitative PCR confirmed the dysregulation of the polycomb-regulated developmentally related transcription-factor genes Dmrt2, Hoxa7, Foxb1, Sox17, Lhx8, Gata3 and Runx1. Silencing of Hoxa7 was further verified by immunohistochemistry. These results suggest that, in radiation-induced mammary gland carcinomas, PRC2-mediated aberrant DNA methylation leads to dysregulation of developmentally related transcription-factor genes. Our findings provide clues to molecular mechanisms linking epigenetic regulation and radiation-induced breast carcinogenesis and underscore the potential of such epigenetic mechanisms as targets for cancer prevention.

Silencing homeobox C6 inhibits colorectal cancer cell proliferation

Homeobox C6 (HOXC6), a member of the homeobox family that encodes highly conserved transcription factors, plays a vital role in various carcinomas. In this study, we used a tissue microarray (TMA) consisting of 462 CRC samples to demonstrate that HOXC6 is more abundantly expressed in colorectal cancer (CRC) tissues than adjacent normal mucosa. Clinicopathological data indicated that higher HOXC6 expression correlated with poor overall survival and was associated with primary tumor location in the right colon, primary tumor (pT) stage 3/4 and primary node (pN) stage 1/2. Multivariate analysis showed that high HOXC6 expression was an independent risk factor for poor CRC patient prognosis. HOXC6 downregulation via lentivirus-mediated expression of HOXC6-targeting shRNA reduced HCT116 cell viability and colony formation in vitro, and reduced growth of subcutaneous xenografts in nude mouse. HOXC6 thus appears to promote CRC cell proliferation and tumorigenesis through autophagy inhibition and mTOR pathway activation.

The untold stories of the speech gene, the FOXP2 cancer gene

FOXP2 encodes a transcription factor involved in speech and language acquisition. Growing evidence now suggests that dysregulated FOXP2 activity may also be instrumental in human oncogenesis, along the lines of other cardinal developmental transcription factors such as DLX5 and DLX6 [1-4]. Several FOXP familymembers are directly involved during cancer initiation, maintenance and progression in the adult [5-8]. This may comprise either a pro-oncogenic activity or a deficient tumor-suppressor role, depending upon cell types and associated signaling pathways. While FOXP2 is expressed in numerous cell types, its expression has been found to be down-regulated in breast cancer [9], hepatocellular carcinoma [8] and gastric cancer biopsies [10]. Conversely, overexpressed FOXP2 has been reported in multiple myelomas, MGUS (Monoclonal Gammopathy of Undetermined Significance), several subtypes of lymphomas [5,11], as well as in neuroblastomas [12] and ERG fusion-negative prostate cancers [13]. According to functional evidences reported in breast cancer [9] and survey of recent transcriptomic and proteomic analyses of different tumor biopsies, we postulate that FOXP2 dysregulation may play a main role throughout cancer initiation and progression. In some cancer conditions, FOXP2 levels are now considered as a critical diagnostic marker of neoplastic cells, and in many situations, they even bear strong prognostic value [5]. Whether FOXP2 may further become a therapeutic target is an actively explored lead. Knowledge reviewed here may help improve our understanding of FOXP2 roles during oncogenesis and provide cues for diagnostic, prognostic and therapeutic analyses.

Cooperativity of HOXA5 and STAT3 Is Critical for HDAC8 Inhibition-Mediated Transcriptional Activation of PD-L1 in Human Melanoma Cells

Although the expression of programmed death-ligand 1 (PD-L1) is an important mechanism by which cancer cells evade the immune system, PD-L1 expression in cancer cells is commonly associated with patients' responses to treatment with anti-programmed death 1/PD-L1 antibodies. However, how PD-L1 expression is regulated in melanoma cells remains to be fully elucidated. Here we report that the class I histone deacetylase (HDAC) HDAC8 controls transcriptional activation of PD-L1 by a transcription complex consisting of transcription factors homeobox A5 and signal transducer and activator of transcription 3. Inhibition of HDAC8 upregulated PD-L1 in melanoma cells. This was due to an increase in the activity of a fragment of the PD-L1 gene promoter that is enriched with binding sites for both homeobox A5 and signal transducer and activator of transcription 3. Indeed, knockdown of homeobox A5 or signal transducer and activator of transcription 3 abolished upregulation of PD-L1 by HDAC8 inhibition. Moreover, homeobox A5 and signal transducer and activator of transcription 3 were physically associated and appeared interdependent in activating PD-L1 transcription. Functional studies showed that HDAC8-mediated regulation of PD-L1 expression participated in modulating anti-melanoma T-cell responses. Collectively, these results identify HDAC8 as an important epigenetic regulator of PD-L1 expression, with implications for better understanding of the interaction between melanoma cells and the immune system.

Selector genes display tumor cooperation and inhibition in Drosophila epithelium in a developmental context-dependent manner

During animal development, selector genes determine identities of body segments and those of individual organs. Selector genes are also misexpressed in cancers, although their contributions to tumor progression per se remain poorly understood. Using a model of cooperative tumorigenesis, we show that gain of selector genes results in tumor cooperation, but in only select developmental domains of the wing, haltere and eye-antennal imaginal discs of Drosophila larva. Thus, the field selector, Eyeless (Ey), and the segment selector, Ultrabithorax (Ubx), readily cooperate to bring about neoplastic transformation of cells displaying somatic loss of the tumor suppressor, Lgl, but in only those developmental domains that express the homeo-box protein, Homothorax (Hth), and/or the Zinc-finger protein, Teashirt (Tsh). In non-Hth/Tsh-expressing domains of these imaginal discs, however, gain of Ey in lgl^- somatic clones induces neoplastic transformation in the distal wing disc and haltere, but not in the eye imaginal disc. Likewise, gain of Ubx in lgl^- somatic clones induces transformation in the eye imaginal disc but not in its endogenous domain, namely, the haltere imaginal disc. Our results reveal that selector genes could behave as tumor drivers or inhibitors depending on the tissue contexts of their gains.

Engrailed-2 promoter hyper-methylation is associated with its downregulation in clear cell renal cell carcinoma

In a previous study by the present authors, it was identified that the expression of engrailed-2 (EN2) gene was downregulated in clear cell renal cell carcinoma (cc-RCC). The aim of the present study was to determine whether aberrant methylation was the mechanism underlying the silencing of EN2 gene in cc-RCC. A total of forty paired cc-RCC tissues, four cc-RCC cell lines and one normal human proximal tubule epithelial cell line were evaluated for EN2 gene methylation status using methylation-specific polymerase chain reaction (PCR). Following treatment with 5-Aza-dc, reverse transcription-quantitative PCR and western blot analysis were performed to examine the expression of EN2. Furthermore, cell proliferation, apoptosis and invasion assays were conducted to analyze the inhibitory effects of EN2 re-expression in 786-O cells. The results of the present study demonstrated that hyper-methylation of EN2 was identified in 12/40 cc-RCC tissues and all cc-RCC cell lines. The methylation status of the EN2 gene was revealed to be associated with histological grade and tumor size in cc-RCC. Following 5-Aza-dc treatment, demethylation of the EN2 gene was identified in 786-O cells, in conjunction with EN2 re-expression. Furthermore, re-activation of the EN2 gene markedly inhibited the proliferative and invasive capacities of cc-RCC. The results of the present study demonstrated that the EN2 gene promoter was hyper-methylated in cc-RCC, which may underlie the silencing of the EN2 gene in cc-RCC.

Upregulation of homeobox gene is correlated with poor survival outcomes in cervical cancer

HOX family members encode transcription factors crucial for embryogenesis and may be associated with carcinogenesis. Here, we evaluated the expression of 39 HOX genes in cervical cancer by using clinicopathological information and gene expression data of 308 patients from The Cancer Genome Atlas (TCGA) database. Correlations between mRNA expression of HOX family members and clinicopathological variables were explored. Seventy-three (23.7%) patients died during the follow-up period (median, 22.0 months). Overall mortality was significantly associated with advanced FIGO stage, lymph node metastasis, lymphovascular invasion, and increased HOXA1, HOXA5, HOXA6, and HOXC11 mRNA expression. Kaplan–Meier survival analysis revealed that overall survival was significantly shorter in patients with high HOXA rather than low HOXA expression (HOXA1, P = 0.012; HOXA5, P = 0.008; and HOXA6, P = 0.006). Upregulated HOXA1, HOXA5, and HOXA6 expression are significantly correlated with unfavorable overall survival and increased mortality in cervical cancer patients. Therefore, HOXA expression is a potential cervical cancer prognostic indicator.

EMX2 gene expression predicts liver metastasis and survival in colorectal cancer

BACKGROUND

The Empty Spiracles Homeobox (EMX-) 2 gene has been associated with regulation of growth and differentiation in neuronal development. While recent studies provide evidence that EMX2 regulates tumorigenesis of various solid tumors, its role in colorectal cancer remains unknown. We aimed to assess the prognostic significance of EMX2 expression in stage III colorectal adenocarcinoma.

METHODS

Expression levels of EMX2 in human colorectal cancer and adjacent mucosa were assessed by qRT-PCR technology, and results were correlated with clinical and survival data. siRNA-mediated knockdown and adenoviral delivery-mediated overexpression of EMX2 were performed in order to investigate its effects on the migration of colorectal cancer cells in vitro.

RESULTS

Compared to corresponding healthy mucosa, colorectal tumor samples had decreased EMX2 expression levels. Furthermore, EMX2 down-regulation in colorectal cancer tissue was associated with distant metastasis (M1) and impaired overall patient survival. In vitro knockdown of EMX2 resulted in increased tumor cell migration. Conversely, overexpression of EMX2 led to an inhibition of tumor cell migration.

CONCLUSIONS

EMX2 is frequently down-regulated in human colorectal cancer, and down-regulation of EMX2 is a prognostic marker for disease-free and overall survival. EMX2 might thus represent a promising therapeutic target in colorectal cancer.

Increased HOXC6 expression predicts chemotherapy sensitivity in patients with esophageal squamous cell carcinoma

Increased expression of homeobox C6 (HOXC6) predicts poor prognosis of patients with esophageal squamous cell carcinoma (ESCC) and promotes ESCC cell proliferation. Additionally, the expression of HOXC6 was upregulated in chemosensitive ESCC cell lines. Therefore, it was hypothesized that HOXC6 may be associated with chemosensitivity of ESCC. Patients with ESCC who underwent neoadjuvant chemotherapy followed by surgery by a single-surgeon team between January 2000 and December 2012 were enrolled in the present study. Pretreatment biopsy specimens and postoperative resection samples were collected. Immunohistochemistry was performed to examine HOXC6 expression, and the association between HOXC6 expression and tumor regression grade (TRG) was analyzed. In cell lines exhibiting stable knockdown of HOXC6, Cell Counting Kit-8 assays were used to evaluate the chemosensitivity of cells to various concentrations of cisplatin and paclitaxel. A total of 51 pretreatment biopsy specimens were assessed, and patients with increased expression of HOXC6 in pretreatment biopsy specimens exhibited higher TRGs. A total of 186 surgical samples were evaluated; HOXC6 was expressed at a decreased level in patients with higher TRG and at a high level in patients with lower TRG. In addition, downregulation of HOXC6 decreased the sensitivity of ESCC cell lines to cisplatin and paclitaxel, resulting in an increased half-maximal inhibitory concentration. Increased expression of HOXC6 prior to treatment was associated with chemosensitivity in ESCC tissues.

Prognostic significance of CDX2 immunoexpression in poorly differentiated clusters of colorectal carcinoma

CDX2 is a transcription factor that acts as a tumor suppressor in colorectal cancer (CRC). Its loss triggers metastatic process and tumor progression; however, its prognostic role in patients with CRC is still controversial. Poorly differentiated clusters (PDCs) are aggregates of neoplastic cells which likely have high metastatic potential in CRC. In this study, we analyzed and compared CDX2 expression in PDC (CDX2-PDC) and corresponding main tumor (CDX2 main tumor) in 42 CRCs showing at least 10 PDC (PDC G3). Five of 42 CRCs (12%) were classified as CDX2 main tumor negative (4/5 were also PDC-CDX2 negative); all had tumor recurrence and died of CRC. Twenty nine of 42 cases were CDX2-PDC negative. Among CRC CDX2 main tumor positive, 15 had recurrences and 13 died from CRC; 13 and 11 of them, respectively, were CDX2-PDC negative. By assigning one point to CDX2 main tumor or CDX2-PDC positivity, we assessed CDX2-staining score for each case. Twelve cases had CDX2-staining score 2 (CDX2 positive in main tumor and PDC); 26 had score 1 (CDX2 positive in main tumor or PDC), and 4 had CDX2 score 0 (CDX2 negative in main tumor and PDC). In our patients, CDX2-staining score had higher prognostic value compared to CDX2 main tumor or CDX2-PDC alone. In addition, it represented a significant and independent prognostic variable for disease-free survival (DFS) and cancer-specific survival (CSS). Our findings suggest that, although loss of CDX2 in the main tumor identifies high-risk patients with high specificity, CDX2-PDC should also be considered in CDX2 main tumor positive cases to predict prognosis.

Downregulation of Homeobox B7 Inhibits the Tumorigenesis and Progression of Osteosarcoma

Homeobox B7 (HOXB7), a member of the HOX gene family, plays a role in tumorigenesis. However, until now the expression status and role of HOXB7 in osteosarcoma remain unclear. Therefore, the present study aimed to investigate the functional role and mechanism of HOXB7 in osteosarcoma. Our results demonstrated that HOXB7 was overexpressed in osteosarcoma cell lines. Downregulation of HOXB7 significantly inhibited osteosarcoma cell proliferation in vitro, as well as attenuated xenograft tumor growth in vivo. Downregulation of HOXB7 also inhibited the migration and invasion of osteosarcoma cells. Furthermore, downregulation of HOXB7 significantly suppressed the protein expression levels of p-PI3K and p-Akt in U2OS cells. In summary, our data demonstrated that downregulation of HOXB7 inhibited proliferation, invasion, and tumorigenesis, partly through suppressing the PI3K/Akt signaling pathway in osteosarcoma cells. Our findings provide new insights into the role of HOXB7 in osteosarcoma and new therapeutic targets for the treatment of osteosarcoma.

HOXA13 is associated with unfavorable survival and acts as a novel oncogene in prostate carcinoma

AIM

To investigate the clinical relevance and functional role of HOXA13 in prostate cancer Methods: PCR, western blot and immunohistochemistry were performed to determine the expression. Kaplan-Meier and Cox regression survival analyses investigated the clinical relevance. Cell viability, flow cytometry and transwell assays were used to determine the functional roles.

RESULTS

HOXA13 expression is sharply increased in carcinoma tissues and is significantly associated with poor prognosis of prostate cancer patients. Interestingly, nucleus not cytoplasm HOXA13 expression is associated with unfavorable survival of the patients. Furthermore, nucleus HOXA13 expression represents an unfavorable and independent prognosis factor of histological grade 2 or Gleason grade <8 patients. Functionally, forced expression of HOXA13 obviously promotes tumor cell proliferation, migration and invasion, whereas inhibits tumor cell apoptosis.

CONCLUSION

HOXA13 is an unfavorable prognostic factor and a novel oncogene for prostate cancer.

Dysregulated expression of homeobox family genes may influence survival outcomes of patients with epithelial ovarian cancer: analysis of data from The Cancer Genome Atlas

Homeobox (HOX) family genes encode key transcription factors for embryogenesis and may be correlated with carcinogenesis. The aim of this study was to elucidate whether aberrant expression of HOX genes influences outcomes in epithelial ovarian cancer (EOC). Gene expression data and clinicopathologic information from 630 patients with EOC were downloaded from The Cancer Genome Atlas database. We explored correlations between expression levels of HOX gene family members and clinicopathological variables. Higher expression of HOXA1, A4, A5, A7, A10, A11, B13, C13, D1, and D3 was associated with advanced FIGO stage. Suboptimal residual disease after debulking surgery was significantly correlated with higher expression of HOXB9, B13, and C13. Additionally, patients with high expression of HOXC6 and C11 were significantly more likely to have poor performance status. Overall survival was significantly shorter in patients with high, rather than low, expression of two HOX genes (HOXA10 and B3), and significantly longer in patients with high rather than low HOXC5 expression. Dysregulated expression of the HOXA10, B3, and C5 was significantly correlated with overall survival in EOC patients. HOX gene expression levels are potentially useful as a prognostic indicator in EOC, and HOX genes may represent a novel and promising target for anticancer therapeutics.

Genome-wide screen for differentially methylated long noncoding RNAs identifies Esrp2 and lncRNA Esrp2-as regulated by enhancer DNA methylation with prognostic relevance for human breast cancer

The majority of long noncoding RNAs (lncRNAs) is still poorly characterized with respect to function, interactions with protein-coding genes, and mechanisms that regulate their expression. As for protein-coding RNAs, epigenetic deregulation of lncRNA expression by alterations in DNA methylation might contribute to carcinogenesis. To provide genome-wide information on lncRNAs aberrantly methylated in breast cancer we profiled tumors of the C3(1) SV40TAg mouse model by MCIp-seq (Methylated CpG Immunoprecipitation followed by sequencing). This approach detected 69 lncRNAs differentially methylated between tumor tissue and normal mammary glands, with 26 located in antisense orientation of a protein-coding gene. One of the hypomethylated lncRNAs, 1810019D21Rik (now called Esrp2-antisense (as)) was identified in proximity to the epithelial splicing regulatory protein 2 (Esrp2) that is significantly elevated in C3(1) tumors. ESRPs were shown previously to have a dual role in carcinogenesis. Both gain and loss have been associated with poor prognosis in human cancers, but the mechanisms regulating expression are not known. In-depth analyses indicate that coordinate overexpression of Esrp2 and Esrp2-as inversely correlates with DNA methylation. Luciferase reporter gene assays support co-expression of Esrp2 and the major short Esrp2-as variant from a bidirectional promoter, and transcriptional regulation by methylation of a proximal enhancer. Ultimately, this enhancer-based regulatory mechanism provides a novel explanation for tissue-specific expression differences and upregulation of Esrp2 during carcinogenesis. Knockdown of Esrp2-as reduced Esrp2 protein levels without affecting mRNA expression and resulted in an altered transcriptional profile associated with extracellular matrix (ECM), cell motility and reduced proliferation, whereas overexpression enhanced proliferation. Our findings not only hold true for the murine tumor model, but led to the identification of an unannotated human homolog of Esrp2-as which is significantly upregulated in human breast cancer and associated with poor prognosis.

MiR-136 inhibits gastric cancer-specific peritoneal metastasis by targeting HOXC10

Functions of microRNAs have been characterized in the embryologic, physiologic, and oncogenic processes, but the role of microRNAs in mediating tumor-specific organ metastasis was addressed only recently and still absent in gastric cancer peritoneal metastasis. Here, we used the microarray analysis to define the gastric cancer peritoneal metastasis-related microRNAs from highly peritoneal metastatic derivatives (GC-9811P cells) and the parental GC-9811 human gastric cancer cells. MiR-136 was found to be decreased in all peritoneal metastatic sublines when compared with that in the parental line. We further confirmed that miR-136 expression is frequently downregulated in gastric cancer peritoneal metastasis cells and tissues and its low expression is significantly associated with more peritoneal metastasis and worse prognosis. Moreover, restoring the expression of miR-136 could inhibit gastric cancer peritoneal metastasis in vitro and in vivo. Subsequent investigation characterized HOXC10 as a direct target of miR-136. In addition, knockdown of HOXC10 reduced GC-9811P cell migration and invasion, similar to the phenotype observed with miR-136 restoration in these cells, indicating that HOXC10 functions as a metastasis promoter in gastric cancer peritoneal metastasis. Upregulation of HOXC10 in parental GC-9811 cells resulted in a dramatic reduction of in vitro migration, invasion, and in vivo peritoneal metastasis. Furthermore, our results showed that ectopic expression of HOXC10 could reverse inhibition of metastasis by overexpressed miR-136 in GC-9811P cells. Our findings provide new insights into the role of miR-136 in the gastric cancer-specific peritoneal metastasis and implicate the potential application of miR-136 in gastric cancer peritoneal metastasis therapy.

HOXC6 Overexpression Is Associated With Ki-67 Expression and Poor Survival in NPC Patients

BACKGROUND: Homeobox (HOX) genes are expressed in adult cells and regulate expression of genes involved in cell proliferation as well as cell-cell and cell-extracellular matrix interactions. Dysregulation of HOX gene expression plays important roles in carcinogenesis in a variety of organs. Through data mining on a published transcriptome dataset, this study first identified Homeobox protein Hox-C6 (HOXC6) gene as one of the differentially upregulated genes in nasopharyngeal carcinoma (NPC). We aimed to evaluate HOXC6 expression and its prognostic effect in a large cohort of NPC patients.

METHODS: We retrospectively examined the HOXC6 expression and Ki-67 index by immunohistochemistry in biopsy specimens from 124 patients with non-metastasized NPC. The results were correlated with the clinicopathological variables including disease-specific survival (DSS), metastasis-free survival (MeFS), and local recurrence-free survival (LRFS).

RESULTS: HOXC6 high expression was positively correlated with increased Ki-67 labeling index, and significantly associated with increment of tumor stage (p=0.024), advanced nodal status (p<0.001) and American Joint Committee on Cancer (AJCC) stage (p=0.002). Its expression also correlated with worse prognosis in terms of DSS (p=0.008), MeFS (p=0.0047) univariately. In multivariate analyses, HOXC6 expression still remained prognostically independent to portend worse DSS (p=0.015, hazard ratio=1.988) and MeFS (p=0.036, hazard ratio=1.899), together with stage III-IV (p=0.024, DSS; p=0.043, MeFS).

CONCLUSION: In summary, our results suggest HOXC6 may play a critical role in NPC progression and may serve as a potential prognostic biomarker in NPC patients.

Polyphenolic extract of InsP 5-ptase expressing tomato plants reduce the proliferation of MCF-7 breast cancer cells

In recent years, by extensive achievements in understanding the mechanisms and the pathways affected by cancer, the focus of cancer research is shifting from developing new chemotherapy methods to using natural compounds with therapeutic properties to reduce the adverse effects of synthetic drugs on human health. We used fruit extracts from previously generated human type I InsP 5-ptase gene expressing transgenic tomato plants for assessment of the anti-cancer activity of established genetically modified tomato lines. Cellular assays (MTT, Fluorescent microscopy, Flow Cytometry analysis) were used to confirm that InsP 5-ptase fruit extract was more effective for reducing the proliferation of breast cancer cells compared to wild-type tomato fruit extract. Metabolome analysis of InsP 5-ptase expressing tomato fruits performed by LC-MS identified tomato metabolites that may play a key role in the increased anti-cancer activity observed for the transgenic fruits. Total transcriptome analysis of cancer cells (MCF-7 line) exposed to an extract of transgenic fruits revealed a number of differently regulated genes in the cells treated with transgenic extract compared to untreated cells or cells treated with wild-type tomato extract. Together, this data demonstrate the potential role of the plant derived metabolites in suppressing cell viability of cancer cells and further prove the potential application of plant genetic engineering in the cancer research and drug discovery.

Large-scale gene network analysis reveals the significance of extracellular matrix pathway and homeobox genes in acute myeloid leukemia: an introduction to the Pigengene package and its applications

BACKGROUND

The distinct types of hematological malignancies have different biological mechanisms and prognoses. For instance, myelodysplastic syndrome (MDS) is generally indolent and low risk; however, it may transform into acute myeloid leukemia (AML), which is much more aggressive.

METHODS

We develop a novel network analysis approach that uses expression of eigengenes to delineate the biological differences between these two diseases.

RESULTS

We find that specific genes in the extracellular matrix pathway are underexpressed in AML. We validate this finding in three ways: (a) We train our model on a microarray dataset of 364 cases and test it on an RNA Seq dataset of 74 cases. Our model showed 95% sensitivity and 86% specificity in the training dataset and showed 98% sensitivity and 91% specificity in the test dataset. This confirms that the identified biological signatures are independent from the expression profiling technology and independent from the training dataset. (b) Immunocytochemistry confirms that MMP9, an exemplar protein in the extracellular matrix, is underexpressed in AML. (c) MMP9 is hypermethylated in the majority of AML cases (n=194, Welch's t-test p-value <10^-138), which complies with its low expression in AML. Our novel network analysis approach is generalizable and useful in studying other complex diseases (e.g., breast cancer prognosis). We implement our methodology in the Pigengene software package, which is publicly available through Bioconductor.

CONCLUSIONS

Eigengenes define informative biological signatures that are robust with respect to expression profiling technology. These signatures provide valuable information about the underlying biology of diseases, and they are useful in predicting diagnosis and prognosis.

Bapx1 mediates transforming growth factor-β- induced epithelial-mesenchymal transition and promotes a malignancy phenotype of gastric cancer cells

The homeoprotein Bapx1 is an important regulator of gastroduodenal tract morphogenesis. Here, we investigated how Bapx1 influences gastric cancer (GC) prognosis and elucidated the underlying mechanisms. Bapx1 expression was greater in GC tissues compared to adjacent non-tumor tissues and expression was positively correlated with mortality, lymph node and distance metastasis. Silencing Bapx1 diminished cell invasion/migration and decreased mesenchymal phenotypes. Transforming growth factor-β (TGF-β) induced Bapx1 expression and epithelial-mesenchymal transition (EMT) in GC cells. However, down-regulated Bapx1 reversed TGF-β induced invasion, migration, morphological changes, and EMT. In summary, Bapx1 indicates poor prognosis for GC by promoting tumor migration and invasion via TGF-β-induced EMT.

Increased expression of HOXB9 in hepatocellular carcinoma predicts poor overall survival but a beneficial response to sorafenib

At advanced stages of hepatocellular carcinoma (HCC), the multikinase inhibitor sorafenib is the only effective treatment. Surrogate markers that predict the biological and clinical efficacy of sorafenib may help tailor treatment on an individual patient basis. In the present study, the clinical significance of the expression of HOXB9, a transcriptional factor, in HCC was assessed. Increased HOXB9 expression in HCC was found to be positively correlated with the expression of angiogenic factors, increased vascular invasion and was found to be associated with poor overall patient survival. Sorafenib treatment effectively suppressed the expression of angiogenic factors and activation of the Raf/MEK/ERK pathway in HOXB9-expressing HCC cell lines. Consistent with these findings, HCC patients, whose cancer expressed high levels of HOXB9, exhibited increased overall survival upon sorafenib treatment. Collectively, these results suggest that HOXB9 expression in HCC could be a surrogate marker for a beneficial response to sorafenib treatment.

A novel thymoma-associated autoimmune disease: Anti-PIT-1 antibody syndrome

Anti-PIT-1 antibody syndrome has recently been reported and characterized by acquired growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) deficiencies associated with autoimmunity to a pituitary specific transcription factor PIT-1, which plays an essential role in GH-, PRL-, and TSH-producing cells. Although circulating anti-PIT-1 antibody and PIT-1-reactive cytotoxic T cells (CTLs) were detected in the patients, the pathophysiology and precise mechanisms for the autoimmunity remain unclarified. During the follow up, thymoma was diagnosed in all 3 cases with anti-PIT-1 antibody syndrome. Immunohistochemical analysis revealed that PIT-1 was strongly expressed in neoplastic cortical thymic epithelial cells. Importantly, after thymectomy, the titer of anti-PIT-1 antibody decreased and reactivity of CTLs toward PIT-1 diminished. These data strongly suggest that the aberrant expression of PIT-1 in the thymoma plays a causal role in the development of this syndrome. Thus, we define that this syndrome is a novel thymoma-associated autoimmune disease.

HOXB13 mutations and binding partners in prostate development and cancer: Function, clinical significance, and future directions

The recent and exciting discovery of germline HOXB13 mutations in familial prostate cancer has brought HOX signaling to the forefront of prostate cancer research. An enhanced understanding of HOX signaling, and the co-factors regulating HOX protein specificity and transcriptional regulation, has the high potential to elucidate novel approaches to prevent, diagnose, stage, and treat prostate cancer. Toward our understanding of HOX biology in prostate development and prostate cancer, basic research in developmental model systems as well as other tumor sites provides a mechanistic framework to inform future studies in prostate biology. Here we describe our current understanding of HOX signaling in genitourinary development and cancer, current clinical data of HOXB13 mutations in multiple cancers including prostate cancer, and the role of HOX protein co-factors in development and cancer. These data highlight numerous gaps in our understanding of HOX function in the prostate, and present numerous potentially impactful mechanistic and clinical opportunities for future investigation.

HOXC8 regulates self-renewal, differentiation and transformation of breast cancer stem cells

BACKGROUND

Homeobox genes are master regulators of cell fate during embryonic development and their expression is altered in cancer. By regulating the balance between cell proliferation and differentiation, they maintain homeostasis of normal tissues. Here, we screened the expression of homeobox genes in mammary stem cells to establish their role in stem cells transformation in breast cancer.

METHODS

Using a Homeobox Genes PCR array, we screened 83 homeobox genes in normal cancer breast stem/progenitor cells isolated by flow cytometry. The candidate gene HOXC8 epigenetic regulation was studied by DNA methylation and miRNA expression analyses. Self-renewal and differentiation of HOXC8-overexpressing or knockdown cells were assessed by flow cytometry and mammosphere, 3D matrigel and soft agar assays. Clinical relevance of in vitro findings were validated by bioinformatics analysis of patient datasets from TCGA and METABRIC studies.

RESULTS

In this study we demonstrate altered expression of homeobox genes in breast cancer stem/progenitor cells. HOXC8 was consistently downregulated in stem/progenitor cells of all breast molecular subtypes, thus representing an interesting tumour suppressor candidate. We show that downregulated expression of HOXC8 is associated with DNA methylation at the gene promoter and expression of miR196 family members. Functional studies demonstrated that HOXC8 gain of function induces a decrease in the CD44⁺/CD24^-/low cancer stem cell population and proportion of chemoresistant cells, with a concomitant increase in CD24⁺ differentiated cells. Increased HOXC8 levels also decrease the ability of cancer cells to form mammospheres and to grow in anchorage-independent conditions. Furthermore, loss of HOXC8 in non-tumorigenic mammary epithelial cells expands the cancer stem/progenitor cells pool, increases stem cell self-renewal, prevents differentiation induced by retinoic acid and induces a transformed phenotype.

CONCLUSIONS

Taken together, our study points to an important role of homeobox genes in breast cancer stem/progenitor cell function and establishes HOXC8 as a suppressor of stemness and transformation in the mammary gland lineage.