Deregulated HOXB7 Expression Predicts Poor Prognosis of Patients with Esophageal Squamous Cell Carcinoma and Regulates Cancer Cell Proliferation In Vitro and In Vivo

Molecular implications of HOX genes targeting multiple signaling pathways in cancer

Homeobox (HOX) genes encode highly conserved homeotic transcription factors that play a crucial role in organogenesis and tissue homeostasis. Their deregulation impacts the function of several regulatory molecules contributing to tumor initiation and progression. A functional bridge exists between altered gene expression of individual HOX genes and tumorigenesis. This review focuses on how deregulation in the HOX-associated signaling pathways contributes to the metastatic progression in cancer. We discuss their functional significance, clinical implications and ascertain their role as a diagnostic and prognostic biomarker in the various cancer types. Besides, the mechanism of understanding the theoretical underpinning that affects HOX-mediated therapy resistance in cancers has been outlined. The knowledge gained shall pave the way for newer insights into the treatment of cancer.

HOXB7 acts as an oncogenic biomarker in head and neck squamous cell carcinoma

Background

The homeobox gene Homeobox B7 (HOXB7) is overexpressed across a range of cancers and promotes tumorigenesis through varying effects on proliferation, survival, migration and invasion. However, its expression pattern and oncogenic role of HOXB7 in head and neck squamous cell carcinoma (HNSCC) remain largely unexplored. Here, we aimed to explore the expression pattern of HOXB7, its clinical significance as well as functional roles in HNSCC.

Methods

HOXB7 mRNA expression in HNSCC was determined by data mining and analyses from TCGA (The Cancer Genome Atlas) and GEO (Gene Expression Omnibus) datasets. The protein abundance of HOXB7 was measured by immunohistochemistry in 119 primary HNSCC samples and associations between its expression and clinicopathological parameters and patient survival were evaluated. The pro-tumorigenic roles of HOXB7 in HNSCC were further delineated in vitro by loss-of-function assay. And a xenograft tumor model was established in nude mice to assess the role of HOXB7 in tumor growth. Connectivity Map (CMap) analysis was performed to identify bioactive small molecules which might be potential inhibitors for HOXB7.

Results

Bioinformatics analyses showed that HOXB7 mRNA was significantly overexpressed in 8 independent HNSCC datasets from TCGA and GEO databases. HOXB7 protein was markedly upregulated in HNSCC samples as compared to normal counterparts and its overexpression significantly associated with high pathological grade, advanced clinical stage, cervical node metastasis (P = 0.0195, 0.0152, 0.0300) and reduced overall and disease-free survival (P = 0.0014, 0.0007). Univariate and multivariate Cox regression analyses further revealed HOXB7 as an independent prognostic factor for patients’ overall survival. Moreover, HOXB7 knockdown significantly inhibited cell proliferation, migration and invasion and induced cell apoptosis in HNSCC cells, and resulted in compromised tumour growth in vivo. Furthermore, CMap (Connectivity map) analysis has identified three potential bioactive small molecule inhibitors (NU-1025, thiamine, vinburnine) for HOXB7 targeted therapy in HNSCC.

Conclusions

Our findings revealed that overexpression of HOXB7 was associates with tumour aggressiveness and unfavourable prognosis by serving a novel prognostic biomarker in HNSCC. Moreover, HOXB7 might be involved in the development and progression of HNSCC as an oncogene, and thereby might be a potential therapeutic target for HNSCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02093-6.

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.

HOXB7 mediates cisplatin resistance in esophageal squamous cell carcinoma through involvement of DNA damage repair

Background

DNA damage repair is an important mechanism of platinum resistance. HOXB7 is one member of HOX family genes, which are essential developmental regulators and frequently dysregulated in cancer. Recently, its relevance in chemotherapy resistance and DNA damage repair has also been addressed. However, little is known regarding the association between HOXB7 and chemotherapy resistance in esophageal squamous cell carcinoma (ESCC).

Methods

The association between HOXB7 expression detected by immunohistochemisty and tumor regression grade (TRG) and long‐term survival was analyzed in 143 ESCC patients who underwent neoadjuvant chemotherapy. CCK8 assay was used to examine the effect of cisplatin in a panel of four ESCC cell lines. A stable cell strain with HOXB7 knockdown of KYSE150 and KYSE450 was established to explore the effect on cisplatin sensitivity. The interaction of HOXB7 with Ku70, Ku80 and DNA‐PKcs was determined by GST‐pull down, coimmunoprecipitation and immunofluorescent colocalization. Finally, we investigated whether disrupting HOXB7 function by a synthetic peptide HXR9 blocking the formation of HOXB7/PBX could enhance cisplatin sensitivity in vitro and in vivo.

Results

High expression of HOXB7 was associated with cisplatin resistance and worse chemotherapy efficacy. HOXB7 knockdown reinforced cisplatin sensitivity. It was identified that HOXB7 interacts with Ku70, Ku80 and DNA‐PKcs. HOXB7 knockdown was related to the downregulation of Ku70, Ku80 and DNA‐PKcs as well as arrested cell cycle in S phase. HOXB7 inhibition by HXR9 had a synergistic effect to improve cisplatin sensitivity.

Conclusion

HOXB7 may be a biomarker for the prediction of chemoresistance of ESCC and serves as a promising therapeutic target.

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.

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.

The relationship between homeobox B7 expression and the clinical characteristics of patient with prostate cancer

BACKGROUND

The prognosis of patients with prostate cancer (PCa) remains poor.

METHODS

GSE16560, GSE32448, GSE79957, GSE17951, and TCGA-PRAD were reanalyzed to evaluate the expression of homeobox B7 (HOXB7) between PCa tissues and normal prostate tissues and to characterize the correlation between the expression of HOXB7 and the clinicopathological features of patients with PCa. Gene set enrichment analysis was conducted to investigate the mechanisms.

RESULTS

HOXB7 was upregulated in PCa tissues (P = 0.0005). Both the univariate and multivariate analyses demonstrated that the expression of HOXB7 was correlated with the Gleason score and TNM staging of patients with PCa. The Gleason score and TNM staging were higher in the HOXB7 high expression group. The overall survival (hazard ratio [HR] = 0.632; 95% confidence interval [CI]: 0.4773-0.8369; P = 0.0014) and progression-free survival (HR = 0.544; 95% CI: 0.3157-0.9373; P = 0.0283) favored patients with PCa in HOXB7 low expression group over those in HOXB7 high expression group. PCa samples in HOXB7 low expression group were enriched in gene sets associated with the epithelial mesenchymal transition, apical junction, angiogenesis, ultraviolet response, and hypoxia.

CONCLUSIONS

HOXB7 might be an independent prognostic factor of patients with PCa.

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.

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.

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.

Nestin expression involves invasiveness of esophageal carcinoma and its downregulation enhances paclitaxel sensitivity to esophageal carcinoma cell apoptosis

Paclitaxel has been generally used to treat primary and metastatic esophageal carcinoma. It has been shown that nestin is highly expressed in esophageal carcinoma and that there is a strong association of nestin expression with poor prognosis in esophageal carcinoma patients. In this study, using immunohistochemistry, in situ hybridization and Western blotting we demonstrated that nestin was overexpressed in the invasive esophageal carcinoma. To further elucidate whether nestin inhibition could enhance paclitaxel sensitivity to esophageal carcinoma cells, we applied nestin siRNA in esophageal squamous cell carcinoma Eca-109 cells. Flow cytometry and TUNEL staining both showed that combination of paclitaxel treatment and nestin knockdown resulted in greater induction of apoptosis of esophageal carcinoma cells as compared with the cells transfected with control siRNA (also treated with paclitaxel). This study indicates that nestin knockdown enhances chemotherapeutic sensitivity of paclitaxel to esophageal carcinoma, and suggests that silencing of nestin could be a valuble therapeutic approach for enhancing drug sensitivity and thereby improving the treatment outcome of esophageal carcinoma patients.

HOXB7 as a promising molecular marker for metastasis in cancers: a meta-analysis

Numerous studies on carcinoma have revealed that the expression level of HOXB7 in cancerous tissues was significantly higher than that in noncancerous tissues. Elevated expression of HOXB7 is associated with the susceptibility to lymph node metastasis and distant metastasis in various tumors. In this study, a meta-analysis was performed to involve majority of relevant articles and explore the association of HOXB7 expression level with metastasis in cancer patients. Literature retrieval was conducted by searching in a number of electronic databases (up to December 1, 2015). The meta-analysis was conducted with RevMan 5.3 software and Stata SE12.0. A total of 1,532 patients with carcinoma from 14 studies were included in analysis. The results of meta-analysis demonstrated that lymph node metastasis was observed more frequently in the patients group with high expression level of HOXB7 than in the patients group with low expression level of HOXB7 (odds ratio =2.17, 95% CI: 1.74–2.71, P<0.00001, fixed-effects model). In addition, a similar result was observed in the association between HOXB7 expression and distant metastasis; the odds ratio was 1.77 (95% CI: 1.09–2.88, P=0.02, fixed-effects model). This meta-analysis demonstrated that the overexpression of HOXB7 was significantly associated with metastasis in cancer patients, which may be served as a common molecular marker for indicating cancer metastasis.

A novel therapeutic approach against B-cell non-Hodgkin's lymphoma through co-inhibition of Hedgehog signaling pathway and autophagy

B-cell non-Hodgkin's lymphoma (B-NHL) is one of the most common types of cancer in the world, with half of the patients dying due to the resistance or tolerance against the treatment. Thus, a novel therapeutic approach for B-NHL treatment was urgently needed. In this study, we investigated the potential of co-inhibition of Hedgehog signaling pathway (Hh) and autophagy in B-NHL therapy. We reported that vismodegib, an inhibitor of Hedgehog signaling pathway, could block the Hh pathway and induce cytotoxicity and apoptosis in B-NHL Raji cells. During this process, autophagy was activated as a response to Hh inhibition. Importantly, inhibition of autophagy potentiated the cytotoxicity and caspase 3-dependent apoptosis induced by vismodegib in B-NHL cells. Furthermore, clearance of ROS generation caused a decreased activity of autophagy and attenuated cytotoxicity in vismodegib-treated cells, while inhibition of autophagy accelerated the formation of ROS, indicating that ROS was required for vismodegib-induced autophagy and cytotoxicity in B-NHL cells. Our results demonstrated that co-inhibition of Hh pathway and autophagy could potently kill B-NHL cells and highlighted a novel approach for B-NHL therapy by co-inhibition of Hh pathway and cytoprotective autophagy.