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

Role of HOXA1-4 in the development of genetic and malignant diseases

The HOXA genes, belonging to the HOX family, encompass 11 members (HOXA1-11) and exert critical functions in early embryonic development, as well as various adult processes. Furthermore, dysregulation of HOXA genes is implicated in genetic diseases, heart disease, and various cancers. In this comprehensive overview, we primarily focused on the HOXA1-4 genes and their associated functions and diseases. Emphasis was placed on elucidating the impact of abnormal expression of these genes and highlighting their significance in maintaining optimal health and their involvement in the development of genetic and malignant diseases. Furthermore, we delved into their regulatory mechanisms, functional roles, and underlying biology and explored the therapeutic potential of targeting HOXA1-4 genes for the treatment of malignancies. Additionally, we explored the utility of HOXA1-4 genes as biomarkers for monitoring cancer recurrence and metastasis.

HOXB9 Overexpression Confers Chemoresistance to Ovarian Cancer Cells by Inducing ERCC-1, MRP-2, and XIAP

The purpose of this study was to identify the role of HOXB9 and associated molecular mechanism in acquiring chemoresistance to ovarian cancer cells. After establishing HOXB9-overexpressing cells (HOXB9-OE/SKOV3), cisplatin resistance-induced cells (Cis-R/SKOV3), and an ovarian cancer xenograft mouse model, the effects of HOXB9 were evaluated in vitro and in vivo. Expression levels of ERCC-1, MRP-2, XIAP, and Bax/Bcl-2 were assessed as putative mechanisms mediating chemoresistance. Cisplatin-induced apoptosis was significantly decreased in HOXB9-OE/SKOV3 compared to SKOV3. Cisplatin treatment of SKOV3 strongly induced ERCC-1, MRP-2, and XIAP, and apoptosis was strongly induced through the inhibition of Bcl-2 and activation of Bax. ERCC-1, MRP-2, XIAP, and Bcl-2 were also strongly induced in HOXB9 OE/SKOV3. In contrast to SKOV3, cisplatin treatment alone of HOXB9 OE/SKOV3 did not affect the expression of Bcl-2 and Bax, and consequently, there was no increase in apoptosis. HOXB9 knockdown suppressed the expression of ERCC-1 and XIAP, but did not affect MRP-2 and Bcl-2/Bax expression in HOXB9 OE/SKOV3 and Cis-R/SKOV3, and caused a small increase in apoptosis. Treatment of SKOV3 with both cisplatin and siRNA_HOXB9 led to complete suppression of ERCC-1, MRP-2, and XIAP, and significantly increased apoptosis through inhibition of Bcl-2 expression and activation of Bax. The results observed in Cis-R/SKOV3 were similar to that in HOXB9 OE/SKOV3. Our data suggest that HOXB9 overexpression may cause chemoresistance in ovarian cancer cells by differential induction of ERCC-1, MRP-2, and XIAP depending on the strength of HOXB9 expression through inhibition of the mitochondrial pathway of apoptosis, including Bax/Bcl-2.

The roles of HOXB8 through activating Wnt/β-catenin and STAT3 signaling pathways in the growth, migration and invasion of ovarian cancer cells

Ovarian cancer is one of the gynecological malignancies ranked third in incidence and first in mortality in the world. Homoboxb8 (HOXB8) has been demonstrated to play crucial roles in various tumors. However, the function of HOXB8 in ovarian cancer remains to be addressed. Quantitative real-time polymerase chain reaction, immunohistochemistry staining and western blot assays demonstrated that HOXB8 expression was up-regulated in human ovarian cancer tissues and cells. The results of CCK-8 and colony formation assays indicated that HOXB8 promoted the proliferation of ovarian cancer cells. Transwell and immunofluorescence (IF) staining assay demonstrated that HOXB8 promoted the migration and invasion of ovarian cancer cells. Importantly, mechanism analysis implied that HOXB8 increased the expression of β-catenin and phosphorylation of STAT3, and the downstream target molecules of Cyclin D1, c-Myc, TWIST1, MMP7 and MMP9, indicating that HOXB8 could promote the activation of Wnt/β-catenin and STAT3 pathways. Moreover, HOXB8 knockdown suppressed xenograft tumor growth, and inhibited the levels of HOXB8 and Ki-67, while increasing the level of E-cadherin in mice. In conclusion, HOXB8 promotes cell proliferation, migration and invasion through modulating Wnt/β-catenin and STAT3 signaling pathways in ovarian cancer, suggesting that HOXB8 may provide a promising target for the therapy of ovarian cancer.

GRAPHICAL ABSTRACT

HomeoboxC6 affects the apoptosis of human vascular endothelial cells and is involved in atherosclerosis

Apoptosis of vascular endothelial cells (VECs) is highly important in the occurrence and development of atherosclerosis (AS). HomeboxC6 (HOXC6) is expressed in higher levels in multiple malignant tissues, and it influences the malignant biological behavior of the cancer cells. However, the effects of HOXC6 on AS and the apoptosis of VECs have not been fully elucidated. In this study, we demonstrated that HOXC6 expression was increased in aortic wall of AS rats and peripheral blood monocytes of patients with coronary heart disease. Furthermore, it was uncovered that BAX expression was upregulated, while BCL-2 expression was downregulated in the aortic wall of AS rats. The apoptosis of human VECs (HVECs) cultured normally or treated with oxidized low-density lipoprotein in vitro was decreased after transfection with HOXC6-siRNA. Moreover, the results of Western blot analysis unveiled that the expressions of proapoptotic proteins, such as BAX, caspase-3, cleaved-caspase-3, and caspase-9 were reduced, while the expression of antiapoptotic protein, BCL-2, was elevated. Meanwhile, mRNA and protein expressions of phospholipase C beta (PLCβ) were decreased, the phosphorylation levels of protein kinase C zeta (PKCζ) and nuclear transcription factor-κB-p65 (NF-κBp65) and the membrane translocation of PKCζ were reduced as well. Besides, the expression of interleukin-18 (IL-18) protein was downregulated. However, after overexpression of HOXC6, the opposite trends of the abovementioned indices were observed. Furthermore, the inhibition of apoptosis induced by HOXC6-siRNA was reversed by lysophosphatidylcholine, an activator of PKCζ. Taken together, our results indicated that HOXC6 can promote the apoptosis of HVECs and may be involved in the occurrence and development of AS, which may be partially associated with the activation of PLCβ/PKCζ/NF-κBp65/IL-18 signaling pathway.

HOX Genes in High Grade Ovarian Cancer

HOX genes are highly conserved members of the homeobox superfamily that have a crucial role in determining cellular identity. High grade ovarian cancer is the most lethal gynaecological malignancy. Our understanding of the role of HOX genes in the oncogenesis of ovarian cancer is evolving, and here we review their dysregulated expression patterns, their function in cell survival and invasion, their potential uses as biomarkers, and ways in which HOX genes are being targeted with new and existing drugs.

Knockdown of HOXB8 inhibits tumor growth and metastasis by the inactivation of Wnt/β-catenin signaling pathway in osteosarcoma

Homeobox B8 (HOXB8) is a member of HOX family and was reported to be dysregulated in human cancers. However, its expression pattern and function in human osteosarcoma (OS) remain unknown. The aim of the current study is to examine its expression and biological roles in human OS cells. Our results showed that HOXB8 was highly expressed in human OS tissues and cell lines. Knockdown of HOXB8 significantly suppressed the proliferation of OS cells in vitro and attenuated the tumor growth in a tumor xenograft model. In addition, knockdown of HOXB8 dramatically repressed the migration and invasion of OS cells. Furthermore, knockdown of HOXB8 efficiently prevented the activation of Wnt/β-catenin signaling pathway in OS cells. In conclusion, the findings of the present study demonstrated that knockdown of HOXB8 could suppress tumorigenesis and metastasis in OS through regulation of the Wnt/β-catenin signaling pathway. Thus, HOXB8 may represent a novel therapeutic target for the treatment of OS.

HOXA10‑AS: A novel oncogenic long non‑coding RNA in glioma

Glioma is the most common primary malignant tumor of the central nervous system. Emerging evidence has demonstrated that long non‑coding RNAs (lncRNAs) serve a major role of regulation in various types of human cancer, including glioma. However, the biological roles of thousands of lncRNAs remain unknown and require further identification. The present study investigated the functional role of lncRNA‑HOXA10‑AS in glioma. The present study examined the expression patterns of HOXA10‑AS in glioma and normal brain tissues, as well as glioma cell lines and normal human astrocytes (HA) via reverse transcription‑quantitative polymerase chain reaction. HOXA10‑AS knockdown cells were generated using lentiviral short hairpin RNA against HOXA10‑AS in A172 and U251 glioma cells. Cell growth was assessed by MTT assay, and a flow cytometer was used to investigate cell proliferation, cell cycle distribution and cell apoptosis. Western blot analysis was performed to analyze the expression levels of apoptosis‑related proteins. HOXA10‑AS was significantly upregulated in glioma tissues and cell lines, and increased HOXA10‑AS expression levels were associated with higher grades of glioma. Knockdown of HOXA10‑AS inhibited glioma cell proliferation and increased cell apoptosis rates compared with the control cells. HOXA10‑AS markedly regulated the expression of the homeobox A10 (HOXA10) gene. Similarly, HOXA10 expression was increased with higher grades of glioma, and silencing of HOXA10 by small interfering RNA suppressed glioma cell proliferation and induced cell apoptosis. The results of the present study demonstrated that HOXA10‑AS promoted cell growth and survival through activation of HOXA10 gene expression in glioma, which may potentially act as a novel biomarker and therapeutic target for clinical assay development.