The roles of HOXB7 in promoting migration, invasion, and anti-apoptosis in gastric cancer

Expression of HOXB7 in the Lung of Patients with Idiopathic Pulmonary Fibrosis: A Proof-of-Concept Study

BACKGROUND

The molecular pathways involved in the onset and progression of idiopathic pulmonary fibrosis (IPF) still need to be fully clarified as some are shared with lung cancer development. HOXB7, a member of the homeobox (Hox) gene family, has been found involved in various cancers.

METHODS

Immunohistochemical (IHC) analysis was run on lung tissue samples from surgical lung biopsy (SLB) of 19 patients with IPF, retrospectively selected from the IPF database of the University Hospital of Modena. HOXB7 expression was analyzed and compared with that of five patients with no evidence of pulmonary fibrosis as controls.

RESULTS

The semi-quantitative analysis of IHC showed that HOXB7 protein expression was higher in IPF patients compared to controls (difference between means = 6.2 ± 2.37, p = 0.0157). Further, HOXB7 expression was higher in IPF patients with a higher extent of fibrosis (50-75%)-measured with high-resolution computer tomography-compared to those with a lower extent (0-25%) (difference between means = 25.74 ± 6.72, p = 0.004).

CONCLUSIONS

The expression of HOXB7 is higher in the lung of IPF patients compared to controls, and was represented in different cellular compartments within the lung niche. Further investigations are needed to clarify its role in the pathogenesis and progression of IPF.

Unveiling HOXB7 as a novel diagnostic and prognostic biomarker through pan-cancer computer screening

We attempted to investigate the role of HOXB7 in tumor progression and evolution by means of an extensive computer screening analysis of various cancer types. We performed univariate Cox regression and Kaplan-Meier survival analyses to assess the impact of HOXB7 on overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) in different types of cancer. Furthermore, we examined the relationship between HOXB7 and several clinical features: tumor microenvironment, immune regulatory genes, immune checkpoints, tumor mutational burden (TMB), and microsatellite instability (MSI). We performed gene set enrichment analysis to gain deeper insights into the potential molecular mechanisms of HOXB7, and validated our findings through functional assays in cells, including methyl thiazolyl tetrazolium cytotoxicity and Transwell invasion assays. HOXB7 expression was associated with different clinical characteristics in numerous malignancies. Higher HOXB7 expression was associated with worse OS, DSS, and PFI in some cancer types. In particular, HOXB7 expression was favorably associated with immune cell infiltration, immune regulatory genes, immunological checkpoints, TMB, and MSI in malignancies. Furthermore, we identified a strong link between copper death-associated gene expression and HOXB7 expression. According to the findings of this study, HOXB7 might serve as an appealing focus for tumor diagnosis and immunotherapy and a prospective indicator of prognosis.

Genome-wide investigation of lncRNAs revealed their tight association with gastric cancer

BACKGROUND

Gastric cancer (GC) is a significant health issue globally, ranking as the fifth most common cancer with over 10,000 new cases reported annually. Long non-coding RNA (lncRNA) has emerged as a critical player in cellular functions, influencing GC's development, growth, metastasis, and prognosis. However, our understanding of lncRNA's role in the pathogenesis of GC remains limited. Therefore, it is particularly important to explore the relationship between lncRNA and gastric cancer.

METHODS

we conducted a comprehensive analysis of RNA sequencing data from the GEO database and stomach adenocarcinoma (STAD) data from the TCGA database to identify lncRNAs that exhibit altered expression levels in GC and the mechanisms underlying lncRNA-mediated transcription and post-transcriptional regulation were explored.

RESULTS

This study uncovered 94 lncRNAs with differential expression and, through co-expression analysis, linked these to 1508 differentially expressed genes (DEGs). GO functional enrichment analysis highlighted that these DEGs are involved in critical pathways, such as cell adhesion and the positive regulation of cell migration. By establishing a lncRNA-miRNA-mRNA regulatory network, we found that the ceRNA mechanism, particularly involving RP11-357H14.17 and CTD-2377D24.4, could play a role in GC progression. Experimental validation of selected differentially expressed lncRNAs and mRNAs (including RP11-357H14.17-CLDN1, BBOX1, TRPM2-AS, CLDN1, PLAU, HOXB7) confirmed the RNA-seq results.

CONCLUSIONS

Overall, our findings highlight the critical role of the lncRNA-mRNA regulatory network in the development and progression of GC, offering potential biomarkers for diagnosis and targets for innovative treatment strategies.

Thalidomide suppresses migration and invasion of colorectal cancer cells by inhibiting HOXB7-mediated activation of the Wnt/β-catenin signaling pathway

Heaps of studies have verified the effects of thalidomide (THA) on colorectal cancer (CRC). Howbeit, the corresponding mechanism awaits illustration, which is the foothold of this study. Following the treatment of 0, 1.94, 7.75, or 19.36 μM THA, CRC cell viability, apoptosis, migration, and invasion were evaluated by methyl tetrazolium, flow cytometry, wound-healing, and transwell assays. Homeobox B7 (HOXB7) expression in CRC was analyzed and detected by bioinformatics analysis, quantitative real-time PCR or western blot. After the corresponding transfection or treatment with inhibitor of catenin-responsive transcription-3 (iCRT-3), abovementioned CRC cell biological behaviors as well as expression levels of HOXB7 and β-catenin were evaluated. 7.75 and 19.36 μM THA dwindled CRC cell viability, migration, and invasion, and facilitated apoptosis. HOXB7 upregulation was detected in CRC cells, which promoted the viability, migration, invasion, and β-catenin expression, and weakened the apoptosis of CRC cells. Also, HOXB7 upregulation counteracted the effects of THA on CRC cells. iCRT-3 restrained β-catenin expression, viability, migration, and invasion, whereas promoting the apoptosis of CRC cells. In addition, iCRT-3 antagonized the effects of overexpressed HOXB7 on CRC cells. THA inhibits the migration and invasion of CRC cells, which is achieved by suppressing HOXB7-mediated activation of Wnt/β-catenin signaling pathway.

Cell Cycle-Related Gene SPC24: A Novel Potential Diagnostic and Prognostic Biomarker for Laryngeal Squamous Cell Cancer

Laryngeal squamous cell cancer (LSCC) is a common malignant tumor with a high degree of malignancy, and its etiology remains unclear. Therefore, screening potential biomarkers is necessary to facilitate the treatment and diagnosis of LSCC. Robust rank aggregation (RRA) analysis was used to integrate two gene expression datasets of LSCC patients from the Gene Expression Omnibus (GEO) database and identify differentially expressed genes (DEGs) between LSCC and nonneoplastic tissues. A gene coexpression network was constructed using weighted gene correlation network analysis (WGCNA) to explore potential associations between the module genes and clinical features of LSCC. Combining differential gene expression analysis and survival analysis, we screened potential hub genes, including CDK1, SPC24, HOXB7, and SELENBP1. Subsequently, western blotting and immunohistochemistry were used to test the protein levels in clinical specimens to verify our findings. Finally, four candidate diagnostic and prognostic biomarkers (CDK1, SPC24, HOXB7, and SELENBP1) were identified. We propose, for the first time, that SPC24 is a gene that may associate with LSCC malignancy and is a novel therapeutic target. These findings may provide important mechanistic insight of LSCC.

Downstream of the HOX genes: explaining conflicting tumour suppressor and oncogenic functions in cancer

The HOX genes are a highly conserved group of transcription factors that have key roles in early development, but which are also highly expressed in most cancers. Many studies have found strong associative relationships between the expression of individual HOX genes in tumours and clinical parameters including survival. For the majority of HOX genes, high tumour expression levels seem to be associated with a worse outcome for patients, and in some cases this has been shown to result from the activation of pro-oncogenic genes and pathways. However, there are also many studies that indicate a tumour suppressor role for some HOX genes, sometimes with conclusions that contradict earlier work. In this review, we have attempted to clarify the role of HOX genes in cancer by focusing on their downstream targets as identified in studies that provide experimental evidence for their activation or repression. On this basis, the majority of HOX genes would appear to have a pro-oncogenic function, with the notable exception of HOXD10, which acts exclusively as a tumour suppressor. HOX proteins regulate a wide range of target genes involved in metastasis, cell death, proliferation, and angiogenesis, and activate key cell signalling pathways. Furthermore, for some functionally related targets, this regulation is achieved by a relatively small subgroup of HOX genes.

Long non-coding RNA SNHG8 promotes prostate cancer progression through repressing miR-384 and up-regulating HOXB7

BACKGROUND

Multiple long non-coding RNAs (lncRNAs) have been demonstrated to function as vital regulators in the progression of prostate cancer (PCa). In the present study, we aimed to probe the function of lncRNA small nucleolar RNA host gene 8 (SNHG8) in PCa progression.

METHODS

A quantitative real-time polymerase chain reaction and western blotting were utilized to measure SNHG8, microRNA-384 (miR-384) and homeobox B7 (HOXB7) expression. Call-couting kit-8 and bromodeoxyuridine experiments were employed to evaluate PCa cell proliferation. Transwell experiments were performed to detect PCa cell migration and invasion. Dual-luciferase reporter experiments and RNA immunoprecipitation experiments were conducted to determine the targeting relationships among miR-384, SNHG8 and HOXB7.

RESULTS

SNHG8 was up-regulated in PCa tissues and cells. Silencing of SNHG8 suppressed the proliferation, migration and invasion of PCa cells. SNHG8 functioned as a molecular sponge to repress miR-384. The effects of SNHG8 knockdown on PCa cell proliferation, migration and invasion were counteracted by miR-384 inhibition. HOXB7 was confirmed to be a target gene of miR-384. SNHG8 knockdown repressed HOXB7 expression via targeting miR-384.

CONCLUSIONS

SNHG8 promotes PCa cell proliferation, migration and invasion via decoying miR-384 and up-regulating HOXB7.

LncRNA MAGI2-AS3 Overexpression Sensitizes Esophageal Cancer Cells to Irradiation Through Down-Regulation of HOXB7 via EZH2

Background

Accumulating evidence has suggested that aberrant expression of long non-coding RNAs (lncRNAs) may contribute to cancer progression in association with radioresistance. The current study aimed to identify the potential role of lncRNA MAGI2-AS3 and the underlying mechanism in its regulation of the radio-sensitivity of esophageal cancer cells.

Methods and Results

Initially, we detected high expression of HOXB7 from microarray-based gene expression profiling of esophageal cancer. Then, we identified the interactions among MAGI2-AS3, HOXB7, and EZH2 by dual-luciferase reporter gene assay, RNA pull-down assay, RIP assay and ChIP assay. HOXB7 was highly-expressed, while MAGI2-AS3 was poorly-expressed in esophageal cancer tissues and cells. The effect of MAGI2-AS3 and HOXB7 on esophageal cancer cell proliferation and apoptosis as well as tumorigenicity of radioresistant cells was examined by gain- and loss-of-function experiments. Interestingly, MAGI2-AS3 down-regulated HOXB7 through interaction with EZH2, which promoted cell apoptosis and inhibited proliferation and radio-resistance. Besides, down-regulation of MAGI2-AS3 exerted a promoting effect on these malignant phenotypes.

Conclusion

Taken together, our results reveal the potential role of MAGI2-AS3 over-expression in controlling esophageal cancer resistance to radiotherapy by down-regulating HOXB7, this providing a candidate biomarker for resistance to radiotherapy.

Recent Advances in Liver Cancer Stem Cells: Non-coding RNAs, Oncogenes and Oncoproteins

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies worldwide, with high morbidity, relapse, metastasis and mortality rates. Although liver surgical resection, transplantation, chemotherapy, radiotherapy and some molecular targeted therapeutics may prolong the survival of HCC patients to a certain degree, the curative effect is still poor, primarily because of tumor recurrence and the drug resistance of HCC cells. Liver cancer stem cells (LCSCs), also known as liver tumor-initiating cells, represent one small subset of cancer cells that are responsible for disease recurrence, drug resistance and death. Therefore, understanding the regulatory mechanism of LCSCs in HCC is of vital importance. Thus, new studies that present gene regulation strategies to control LCSC differentiation and replication are under development. In this review, we provide an update on the latest advances in experimental studies on non-coding RNAs (ncRNAs), oncogenes and oncoproteins. All the articles addressed the crosstalk between different ncRNAs, oncogenes and oncoproteins, as well as their upstream and downstream products targeting LCSCs. In this review, we summarize three pathways, the Wnt/β-catenin signaling pathway, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway, and interleukin 6/Janus kinase 2/signal transducer and activator of transcription 3 (IL6/JAK2/STAT3) signaling pathway, and their targeting gene, c-Myc. Furthermore, we conclude that octamer 4 (OCT4) and Nanog are two important functional genes that play a pivotal role in LCSC regulation and HCC prognosis.

CircRNA hsa_circ_0070934 functions as a competitive endogenous RNA to regulate HOXB7 expression by sponging miR‑1236‑3p in cutaneous squamous cell carcinoma

Circular ribonucleic acids (circRNAs) serve a vital role in the pathological processes of a number of diseases. Previous microarray results of circRNA expression revealed that hsa_circ_0070933 and hsa_circ_0070934, two circRNAs associated with the La ribonucleoprotein 1B gene, were highly expressed in cutaneous squamous cell carcinoma (CSCC). The present study aimed to explore the specific role of these circRNAs in CSCC. Through reverse transcription-quantitative PCR, hsa_circ_0070933 and hsa_circ_0070934 expression levels in CSCC cell lines and a human keratino-cyte cell line were detected. Additionally, direct interactions between miR-1236-3p and HOXB7 or circ-0070934 were identified using RNA binding protein immunoprecipitation assays and dual-luciferase reporter assays. Cell Counting Kit-8, 5-ethynyl-2′-deoxyuridine, Transwell invasion and flow cytometry assays were used to assess the roles of miR-1236-3p or circ-0070934 in cell invasion, proliferation and apoptosis. Subsequently, in vivo tumor formation assays were used to verify the role of circ-0070934 in CSCC. The results demonstrated that the expression of circ-0070934 was stably upregulated in a number of CSCC cell lines compared with that in normal human keratinocytes. Knockdown of circ-0070934 inhibited the invasive and proliferative potential of CSCC cells and promoted apoptosis both in vivo and in vitro. In addition, circ-0070934 modulated HOXB7 expression through competitive binding with miR-1236-3p. In conclusion, the results of the present study demonstrated the effects of the circ-0070934/miR-1236-3p/HOXB7 regulatory axis on CSCC and provided a novel insight for the pathogenesis of CSCC.

Prognostic value of expression of HOXB7 in gastric cancer

BACKGROUND

Gastric cancer (GC) is the fifth most common cancer and the third leading cause of cancer death worldwide. Identifying new targets for the treatment and predictive evaluation of GC is of great significance, especially for improving the prognosis. Few studies have focused on the clinical significance of homeobox B7 (HOXB7) expression in GC.

AIM

To assess the prognostic value of HOXB7 expression in GC.

METHODS

HOXB7 data were retrieved from the Oncomine GC database. The prognostic value of HOXB7 was assessed using an online survival analysis tool (KM Plotter database).

RESULTS

Based on the Oncomine database, HOXB7 expression in GC was significantly higher than that in normal tissue (P < 0.05). Further analysis revealed that the expression of HOXB7 gene in both intestinal and diffuse GCs was significantly higher than that in normal tissue. Moreover, KM Plotters of overall survival indicated that high HOXB7 expression was closely associated with poor survival in GC (P < 0.05). Furthermore, high HOXB7 expression was also related with overall survival in different GC subtypes (Lauren subtype) (P < 0.05).

CONCLUSION

High HOXB7 expression might be an important biological event during gastric oncogenesis, and could be a novel prognostic predictive factor for GC.

Upregulated expression of HOXB7 in intrahepatic cholangiocarcinoma is associated with tumor cell metastasis and poor prognosis

Homeobox B7 (HOXB7) protein is reported to be aberrantly expressed in a variety of cancers and to play an important role in multiple cellular processes. However, the specific mechanism by which HOXB7 promotes the malignant progression of intrahepatic cholangiocarcinoma (ICC) remains unclear. Therefore, we used quantitative real-time polymerase chain reaction (PCR) to detect the expression level of HOXB7 in 38 paired ICC tissue samples. Additionally, to assess correlation between HOXB7 and ICC prognosis, we performed immunohistochemistry (IHC) using 122 ICC tissues to detect HOXB7 expression. Cell Counting Kit-8 (CCK-8) and colony formation assays were employed to assess ICC cell proliferation, and Transwell assays were performed to estimate the invasion and migration abilities of ICC cells. The capillary tube formation assay was applied to explore the angiogenic effects of HOXB7. A xenograft tumor model was established in nude mice to assess the role of HOXB7 in tumor growth and lung metastasis. The results showed higher expression of HOXB7 in ICC tissues than in noncancerous tissues, and this increased expression was significantly associated with a poor prognosis. In addition, HOXB7 overexpression enhanced capillary tube formation, invasion and migration of ICC cells in vitro, whereas HOXB7 knockdown produced the opposite results in vitro. Moreover, the role of HOXB7 in promoting tumor growth and metastasis was verified in vivo. Further investigation revealed that the expression levels of MMP2, MMP9, VEGFa, and IL8 were elevated by HOXB7 and that the ERK pathway was activated. Our results demonstrate the prognostic value of HOXB7 and its role in metastasis and angiogenesis in ICC. HOXB7 upregulated MMP2, MMP9, VEGFa, and IL8 expression via the ERK pathway to accelerate the malignant progression of ICC.

Effect of HOXA6 on the proliferation, apoptosis, migration and invasion of colorectal cancer cells

Colorectal cancer (CRC) is one of the most common types of tumor worldwide. The morbidity and mortality rates of CRC have increased significantly in adults <50 years of age. In the present study, the effects of homeobox A6 (HOXA6) on the proliferation, apoptosis, migration and invasion of CRC cells were investigated. The results of reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis demonstrated that the expression of HOXA6 in CRC tumor tissue was higher than that in adjacent normal tissue. Appropriate cell lines and plasmids were selected by RT-PCR and western blot analyses, and recombinant plasmids were transfected into Caco2 or HT-29 cells. The results of RT-qPCR and western blot analyses demonstrated that the expression of HOXA6 was effectively enhanced, or inhibited, following transfection. The rate of cell proliferation was measured with cell counting kit-8, colony formation assay and 5-ethynyl‑2'-deoxyuridine assay, apoptosis was detected using terminal deoxynucleotidyl transferase dUTP nick end labeling and flow cytometry assays, and migration and invasion were evaluated using Transwell and wound-healing assays. The results demonstrated that the upregulation of HOXA6 promoted cell proliferation, migration and invasion, but inhibited apoptosis, whereas the downregulated expression of HOXA6 produced the opposite effects. In addition, the expression levels of apoptosis- and epithelial-mesenchymal transition (EMT)-related proteins were examined. The results of the western blot analysis revealed that the upregulated expression of HOXA6 suppressed the expression of B-cell lymphoma-2 (Bcl-2)-associated X protein, caspase-3, poly(ADP-ribose) polymerase and E-cadherin, but promoted the expression of Bcl-2, N-cadherin and Vimentin, whereas the opposite effect was observed in cells with downregulated HOXA6. These results indicated that HOXA6 regulated apoptosis through the Bcl-2 signaling pathway, and regulated migration and invasion through the EMT process. In conclusion, the present study confirmed that HOXA6 was involved in the regulation of CRC, which may inform the development of strategies for the diagnosis and treatment of CRC.

miR-196b-5p Regulates Colorectal Cancer Cell Migration and Metastases through Interaction with HOXB7 and GALNT5

Purpose: miR-196b-5p has been previously implicated in malignant transformation; however, its role in colorectal cancer has not been fully explored. In this study, we examine the clinical and biological relevance of miR-196b-5p, and the molecular pathways regulated by miR-196b-5p in colorectal cancer.Experimental Design: miR-196b-5p expression was quantitated by qRT-PCR in 2 independent cohorts composed of 292 patients with colorectal cancer in total, to explore its biomarker potential. Transient and stable gain- and loss-of-function experiments were conducted in a panel of colorectal cancer cell lines and mice, to evaluate the impact of miR-196b-5p on proliferation, chemosensitivity, migration/invasion, and metastases formation in vitro and in vivo The molecular pathways influenced by miR-196b-5p were characterized using whole transcriptome profiling, in silico target prediction tools, luciferase interaction assays, and phenocopy/rescue gene knockdown experiments.Results: Low miR-196b-5p expression was significantly associated with metastases and poor outcomes in 2 independent colorectal cancer patient cohorts (P < 0.05, log-rank test). miR-196b-5p inhibition led to significantly increased colorectal cancer cell migration/invasion and metastases formation in mice, whereas ectopic overexpression showed the opposite phenotype. Molecular profiling and target confirmation identified an interaction between miR-196b-5p and HOXB7 and GALNT5, which in turn regulated colorectal cancer cell migration.Conclusions: The association of low levels of miR-196b-5p and poor prognosis in patients with colorectal cancer can be explained by its influence on cancer cell migration and metastases formation. miR-196b-5p has an impact on colorectal cancer progression pathways through direct interaction with genes involved in cancer cell migration. Clin Cancer Res; 23(17); 5255-66. ©2017 AACR.

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.

Deregulated HOXB7 expression predicts poor prognosis of patients with malignancies of digestive system

INTRODUCTION

Numerous studies have investigated the relationship between deregulated HOXB7 expression with the clinical outcome in patients with digestive stem cancers, HOXB7 has showed negative impacts but with varying levels. We aimed to comprehensively evaluate the prediction and prognostic value of HOXB7 in digestive stem cancers.

EVIDENCE ACQUISITION

Electronic databases updated to December 1st, 2016 were retrieved to collect relevant eligible studies to quantitatively explore the potential roles of HOXB7 as a prognostic indicator in digestive system cancers.

EVIDENCE SYNTHESIS

A total of 9 studies (N.=1298) was included in this synthetical meta-analysis. The pooled hazard ratios suggested that high expression of HOXB7 protein was associated with poor prognosis of OS in patients with digestive system cancers (HR=1.97, 95% CI: 1.65-2.28, P=0.000), and HOXB7 protein could act as an independent prognostic factor for predicting OS of patients with digestive system cancers (HR=2.02, 95% CI: 1.69-2.36, P=0.000). Statistical significance was also observed in subgroup meta-analysis based on the cancer type, histology type, country, sample size and publication date. Furthermore, we examined the correlations between HOXB7 protein and clinicopathological features. It showed that altered expression of HOXB7 protein was correlated with tumor invasion (P=0.000), lymph node status (P=0.000), distant metastasis (P=0.001) and TNM stage (P=0.000). However, the expression of HOXB7 protein was not associated with age (P=0.64), gender (P=0.40) or levels of differentiation (P=0.19).

CONCLUSIONS

High expression of HOXB7 protein was associated with poor prognosis of patients with digestive system cancers, as well as clinicopathologic characteristics, including the tumor invasion, lymph node status, distant metastasis and TNM stage. The expression of HOXB7 protein was not associated with age, gender or levels of differentiation. HOXB7 protein expression level in tumor tissue might serve as a novel prognostic marker for digestive system cancers.

HOXB7 accelerates the malignant progression of hepatocellular carcinoma by promoting stemness and epithelial-mesenchymal transition

Background

Homeobox B7 (HOXB7) has been identified associated with poor prognosis of hepatocellular carcinoma (HCC). However, the specific mechanism by which HOXB7 promotes the malignant progression of HCC remains to be determined.

Methods

Immunohistochemistry (IHC) was used to detect the expression level of HOXB7 in 77-paired HCC tissue samples, and the correlation between HOXB7 and HCC prognosis was assessed. The location of HOXB7 was confirmed by immunofluorescence. Cell Titer-Blue assay was used to assess the proliferation of hepatoma cells. The stem-like properties of hepatoma cells were analysed by sphere formation and clone formation assays. The effect of HOXB7 on expression of cancer stem cell markers was evaluated. Transwell and wound-healing assays were performed to estimate the invasion and migration abilities of hepatoma cells. A xenograft tumor model was established in nude mice to assess the role of HOXB7 in tumor growth. Bioluminescence imaging was used to survey the effect of HOXB7 on the metastatic ability of hepatoma cells in vivo.

Results

Higher expression of HOXB7 was detected in HCC tissues compared with noncancerous tissues and significantly associated with poor prognosis of HCC. In addition, HOXB7 knockdown suppressed the cell proliferation, clone formation, sphere formation, invasion and migration of hepatoma cells in vitro; conversely, these biological abilities of hepatoma cells were enhanced by HOXB7 overexpression. Moreover, the cancer stem cell markers EPCAM and NANOG were up-regulated by HOXB7. The role of HOXB7 in promoting tumor growth and metastasis was verified in vivo. Further investigation revealed that c-Myc and Slug expression was elevated by HOXB7 and the AKT pathway was activated.

Conclusion

Overexpression of HOXB7 was significantly correlated with poor prognosis of HCC. HOXB7 up-regulated c-Myc and Slug expression via the AKT pathway to promote the acquisition of stem-like properties and facilitate epithelial-mesenchymal transition of hepatoma cells, accelerating the malignant progression of HCC.

Impact of homeobox genes in gastrointestinal cancer

Homeobox genes, including HOX and non-HOX genes, have been identified to be expressed aberrantly in solid tumors. In gastrointestinal (GI) cancers, most studies have focused on the function of non-HOX genes including caudal-related homeobox transcription factor 1 (CDX1) and CDX2. CDX2 is a crucial factor in the development of pre-cancerous lesions such as Barrett’s esophagus or intestinal metaplasia in the stomach, and its tumor suppressive role has been investigated in colorectal cancers. Recently, several HOX genes were reported to have specific roles in GI cancers; for example, HOXA13 in esophageal squamous cell cancer and HOXB7 in stomach and colorectal cancers. HOXD10 is upregulated in colorectal cancer while it is silenced epigenetically in gastric cancer. Thus, it is essential to examine the differential expression pattern of various homeobox genes in specific tumor types or cell lineages, and understand their underlying mechanisms. In this review, we summarize the available research on homeobox genes and present their potential value for the prediction of prognosis in GI cancers.