Homeobox B9 is overexpressed in hepatocellular carcinomas and promotes tumor cell proliferation both in vitro and in vivo

Homeobox B9 promotes the invasion and metastasis of hepatocellular carcinoma cells via the EZH2-MIR203A-SNAI2 axis

BACKGROUND

Research has elucidated that homeobox B9 (HOXB9), an important transcriptional activator, plays a pivotal role in promoting the invasion and metastasis of hepatocellular carcinoma (HCC) cells. However, the mechanism by which HOXB9 promotes the invasion and metastasis of HCC cells is incompletely understood and needs further exploration.

METHODS

HOXB9 and snail family transcriptional repressor 2 (SNAI2) expression were analyzed using qRT-PCR and western blotting. The invasion and metastasis of hepatocellular carcinoma (HCC) cells were investigated using in vitro and in vivo assays. The H3K27me3 enrichment and HOXB9 interaction with microRNA 203a (MIR203A) or SNAI2 were detected using ChIP-qPCR. Transcriptional activities of SNAI2 and MIR203A promoter were detected using dual-luciferase reporter assays. Co-IP and GST pull-down assays were performed to confirm the binding between HOXB9 and EZH2.

RESULTS

HOXB9 and SNAI2 were highly expressed in HCC tissues and their expression was positively intercorrelated and associated with poor prognosis in patients with HCC. In vitro and in vivo experiments confirmed that HOXB9 can upregulate the expression of SNAI2 to promote the invasion and metastasis of HCC cells. Furthermore, HOXB9 elevated SNAI2 expression by inhibiting MIR203A expression, a tumor suppressor gene, in HCC cells. Mechanistically, HOXB9 recruited enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) through interaction with its WD-binding domain, which increased EZH2-mediated histone H3 lysine 27 trimethylation (H3K27me3) at the MIR203A promoter region, in turn repressing the transcriptional activity and expression of MIR203A and consequently increasing the SNAI2 level in HCC cells. Finally, empirical evidence from in vitro and in vivo studies confirmed that mitigation of the HOXB9-mediated enhancement of epigenetic silencing of MIR203A inhibited SNAI2 expression, impeding the invasion and metastasis of HCC cells.

CONCLUSIONS

Our study reveals a novel mechanism by which HOXB9 promotes the invasion and metastasis of HCC cells and expands the understanding of the function of HOXB9 in tumor progression and provides a novel therapeutic strategy for curtailing HCC invasion and metastasis.

HOXA9 versus HOXB9; particular focus on their controversial role in tumor pathogenesis

The Homeobox (HOX) gene family is essential to regulating cellular processes because it maintains the exact coordination required for tissue homeostasis, cellular differentiation, and embryonic development. The most distinctive feature of this class of genes is the presence of the highly conserved DNA region known as the homeobox, which is essential for controlling their regulatory activities. Important players in the intricate process of genetic regulation are the HOX genes. Many diseases, especially in the area of cancer, are linked to their aberrant functioning. Due to their distinctive functions in biomedical research-particularly in the complex process of tumor advancement-HOXA9 and HOXB9 have drawn particular attention. HOXA9 and HOXB9 are more significant than what is usually connected with HOX genes since they have roles in the intricate field of cancer and beyond embryonic processes. The framework for a focused study of the different effects of HOXA9 and HOXB9 in the context of tumor biology is established in this study.

HOXB9 promotes laryngeal squamous cell carcinoma progression by upregulating MMP12

Transcriptional factor HOXB9, a part of the HOX gene family, plays a crucial role in the development of diverse cancer types. This study aimed to elucidate the regulatory mechanism of HOXB9 on the proliferation and invasion of laryngeal squamous cell carcinoma (LSCC) cells to provide guidance for the development and prognosis of LSCC. The CRISPR/Cas9 method was employed in LSCC cell lines to knock out the HOXB9 gene and validate its effects on the proliferation, migration, invasion, and regulation of LSCC cells. CCK-8 and flow cytometry were used to detect cell viability and proliferation; Tunnel was used to detect cell apoptosis, and transwell was used to detect cell migration and invasion. The effect of HOXB9 on tumor growth was tested in nude mice. The downstream target genes regulated by HOXB9 were screened by microarray analysis and verified by Western blotting, immunohistochemistry, chromatin immunoprecipitation, and double-luciferase reporter assays. The current research investigated molecular pathways governed by HOXB9 in the development of LSCC. Additionally, both laboratory- and living-organism-based investigations revealed that disrupting the HOXB9 gene through the CRISPR/CAS9 mechanism restrained cellular growth, movement, and infiltration, while enhancing cellular apoptosis. Detailed analyses of LSCC cell strains and human LSCC samples revealed that HOXB9 promoted LSCC progression by directly elevating the transcriptional activity of MMP12. HOXB9 could influence changes in LSCC cell functions, and the mechanism of action might be exerted through its downstream target gene, MMP12.

Pan-cancer analysis of Homeobox B9 as a predictor for prognosis and immunotherapy in human tumors

BACKGROUND

Although several animal and cell studies have described the association between HOXB9 and cancers, there is no pan-cancer investigation of HOXB9. In this article, we explored the expression levels and prognosis of HOXB9 in pan-cancer. We evaluated the correlation of HOXB9 expression level with the efficacy of immunotherapy.

METHODS

We conducted a survival analysis of HOXB9 in various types of cancer using publicly available databases. We also examined the relationship between HOXB9 expression levels and several factors including prognosis, immune infiltration, immune checkpoint genes, tumor mutational burden, microsatellite instability, mismatch repair, and DNA methylation. TIMER2.0 tool was conducted to explore the immune cell infiltrations related to HOXB9 in this analysis.

RESULTS

It was discovered through a comprehensive analysis of multiple public datasets that HOXB9 expression was highly expressed in most tumor tissues and cancer cell lines and that distinct associations exist between HOXB9 expression and tumor patient prognosis. Besides, HOXB9 expression was closely associated with immune cell infiltration and checkpoint genes in many cancers. Further, HOXB9 was associated with immune cell infiltration, TMB, MSI, MMR, and DNA methylation. It was also confirmed that HOXB9 was highly expressed in clinical GBM tissues. Experiments further revealed that knockdown of HOXB9 expression could suppress proliferation, migration, and invasion of glioma cells.

CONCLUSIONS

The results revealed that HOXB9, a robust tumor biomarker, has a significant prognostic value. HOXB9 may act as a new predictor to assess cancer prognosis and therapeutic efficacy of the immune in various cancers.

Homeobox B9 Promotes the Progression of Hepatocellular Carcinoma via TGF-β1/Smad and ERK1/2 Signaling Pathways

Objectives

Homeobox B9 (HOXB9), a homeodomain-containing transcription factor, may play a role in hepatocellular carcinoma (HCC) progression. However, the exact mechanisms underlying its action remain unclear. Materials and methods. Immunohistochemistry was used to investigate the expression of HOBX9 and its prognostic values in HCC patients. HCC cells were transfected with pBabe-HOXB9 and shHOXB9 plasmids, and MTT assay, Transwell assays, and xenograft mouse models were employed to determine the effects of HOXB9 on HCC cell proliferation, migration, and invasion in vitro and in vivo. The biological mechanisms involved in the role of HOXB9 were determined with Western blot and RT-qPCR methods.

Results

HOXB9 expression was significantly increased in HCC tissues and cell lines. Patients with higher HOXB9 levels were associated with poor prognosis. Overexpression of HOXB9 in BEL-7405 cells promoted proliferation, migration, and invasion, whereas knockdown of HOXB9 in HepG2 cells significantly reduced cell proliferation, migration, and invasion abilities. Mechanically, a positive correlation was found between HOXB9 expression and transforming growth factor-β1 (TGF-β1) and extracellular signal-regulated kinase (ERK)1/2 pathway in HCC tissues. HOXB9 overexpression stimulated TGF-β1/Smads signaling pathway in BEL-7405 cells. In contrast, HOXB9 knockdown inhibited the TGF-β1/Smads signaling pathway in HepG2 cells. In addition, the treatment with TGF-β1 inhibitor, LY364947, significantly reserved HOXB9 overexpression-induced cell proliferation, migration, and invasion abilities.

Conclusions

These findings validated that HOXB9 promoted proliferation, migration, and invasion in HCC cells by stimulating the TGF-β1/Smads and ERK1/2 signaling pathway. HOXB9 could be a promising prognostic biomarker and a potential therapeutic target in HCC.

miR-557 suppressed the malignant behaviours of osteosarcoma cells by reducing HOXB9 and deactivating the EMT process

MicroRNAs (miRNAs) are vital gene regulators, which play a profound role in the process of forming and developing many diseases, especially tumour. The study intends to excavate the potential regulatory mechanisms of miR-557 and its targeting gene Homeobox B9 (HOXB9) in osteosarcoma. GEO dataset on osteosarcoma was applied to detect the expression of miR-557 and HOXB9. Associations between miR-557 and HOXB9 were speculated by prediction software and verified by dual luciferase assay. Cell proliferation, colony formation and mobility were measured by cell counting kit-8, plate clone formation and transwell assays. Expression of mesenchymal transitions (MTs) related proteins was assessed by western blot analysis. Low expression of miR-557 was presented in osteosarcoma tissues and cell lines. Upregulation of miR-557 restrained osteosarcoma cells proliferation, movement and MT process. HOXB9, served as a target gene of miR-557, was highly expressed in osteosarcoma, and its high expression was associated with poor prognosis in patients with osteosarcoma. In addition, overexpression of HOXB9 attenuated the inhibitory effects of miR-557 on tumour progression by MT process. Overexpression of miR-557 suppressed the growth, metastasis and MT process of osteosarcoma cells by targeting HOXB9, affording novel molecular selection for targeted therapy of osteosarcoma.

HOXB9 enhances the ability of lung cancer cells to penetrate the blood-brain barrier

Even after multimodal therapy, the prognosis is dismal for patients with brain metastases from non-small cell lung cancer (NSCLC). Although the blood-brain barrier (BBB) limits tumor cell penetration into the brain parenchyma, some nevertheless colonize brain tissue through mechanisms that are not fully clear. Here we show that homeobox B9 (HOXB9), which is commonly overexpressed in NSCLC, promotes epithelial-to-mesenchymal transition (EMT) and tumor migration and invasion. Animal experiments showed that HOXB9 expression correlates positively with the brain metastatic potential of human NSCLC cells, while brain metastatic cells derived through in vivo selection showed greater HOXB9 expression than their cells of origin. Comparable results were obtained after immunohistochemical analysis of clinical primary NSCLC and matched brain metastasis samples obtained after surgery. Using an in vitro BBB model, knockdown and overexpression experiments showed that HOXB9-dependent expression of MMP9 in NSCLC cells leads to reduced expression of junctional proteins in cultured human vascular endothelial cells and enhanced transmigration of tumor cells. These data indicate that HOXB9 enables NSCLC cells to break away from the primary tumor by inducing EMT, and promotes brain metastasis by driving MMP9 production and degradation of intercellular adhesion proteins in endothelial cells comprising the BBB.

HOX Genes Family and Cancer: A Novel Role for Homeobox B9 in the Resistance to Anti-Angiogenic Therapies

Simple Summary

The inhibition of angiogenesis, relying on the use of drugs targeting the VEGF signaling pathway, has become one of the main strategies for cancer treatment. However, the intrinsic and acquired resistance to this type of therapy limit its efficacy. Thus, the identification of novel therapeutic targets is urgently needed. The resistance to anti-angiogenic treatment often occurs through the activation of alternative VEGF independent signaling pathways and recruitment of bone marrow-derived pro-angiogenic cells in the tumor microenvironment. HOX genes are key regulators of embryonic development, also involved in angiogenesis and in cancer progression. HOXB9 upregulation occurs in many types of cancer and it has been identified as a critical transcription factor involved in tumour resistance to anti-angiogenic drugs. Indeed, HOXB9 modulates the expression of alternative pro-angiogenic secreted factors in the tumour microenvironment leading tumor escape from the anti-angiogenic treatments. Hence, HOXB9 could serves as a novel therapeutic target to overcome the resistance to anti-angiogenic therapies.

Abstract

Angiogenesis is one of the hallmarks of cancer, and the inhibition of pro-angiogenic factors and or their receptors has become a primary strategy for cancer therapy. However, despite promising results in preclinical studies, the majority of patients either do not respond to these treatments or, after an initial period of response, they develop resistance to anti-angiogenic agents. Thus, the identification of a novel therapeutic target is urgently needed. Multiple mechanisms of resistance to anti-angiogenic therapy have been identified, including the upregulation of alternative angiogenic pathways and the recruitment of pro-angiogenic myeloid cells in the tumor microenvironment. Homeobox containing (HOX) genes are master regulators of embryonic development playing a pivotal role during both embryonic vasculogenesis and pathological angiogenesis in adults. The importance of HOX genes during cancer progression has been reported in many studies. In this review we will give a brief description of the HOX genes and their involvement in angiogenesis and cancer, with particular emphasis on HOXB9 as a possible novel target for anti-angiogenic therapy. HOXB9 upregulation has been reported in many types of cancers and it has been identified as a critical transcription factor involved in resistance to anti-angiogenic drugs.

HOXD9 promotes epithelial-mesenchymal transition and cancer metastasis by ZEB1 regulation in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor that severely threatens human health. The poor prognosis of HCC is mainly attributed to intrahepatic and extrahepatic metastases. HOXD9 proteins belong to a superfamily that regulates the development and control of many cellular processes, including proliferation, apoptosis, cell shape, and cell migration. HOXD9 can also function as an oncogene in several cancer cells. However, its biological function in human HCC requires further investigation. In this study, HOXD9 exhibited high expression in invasive HCC cells. HOXD9 overexpression can significantly enhance HCC cell migration, invasion, and metastasis, whereas silencing HOXD9 inhibits these processes. HOXD9 also promotes the epithelial-mesenchymal transition (EMT) of HCC cells. Microarray analysis suggests that ZEB1 can function as a downstream factor of HOXD9. HOXD9 can interact with the promoter region of ZEB1 and promotes ZEB1 expression. ZEB1 knockdown inhibits HOXD9-induced migration and invasion, as well as EMT in HCC cells. This study helps elucidates the oncogenic functions of HOXD9 in HCC.