The homeobox transcription factor HOXC13 upregulates human papillomavirus E1 gene expression and contributes to viral genome maintenance

Differential requirement of the transcription factor HOXC13 for the stable maintenance of human papillomavirus genome among high-risk genotypes

The viral genome of the high-risk human papillomavirus (HPV), the causative agent of cervical cancer, is stably maintained as extrachromosomal episomes that establish persistent infection. We previously identified homeobox-transcription factor HOXC13 as an important host protein mediating the short-term retention of the HPV16 and HPV18 genomes in normal human immortalized keratinocytes (NIKS). Here, we used CRISPR-Cas9 technology to construct HOXC13 knockout (KO) NIKS cells to determine whether HOXC13 is required for the long-term maintenance of high-risk HPV genomes. HPV16, HPV18, HPV52, and HPV58 whole genomes were transfected into HOXC13 KO cells, and the copy number of viral genomes per cell was monitored over cell passages. Copy numbers of HPV16, HPV52, and HPV58 genomes decreased continuously in HOXC13 KO cells, whereas HPV18 genomes remained stable throughout passages. Thus, HOXC13 is critical for the stable maintenance of the viral genomes of HPV16, HPV52, and HPV58, but not HPV18.

H3K27ac-induced RHOXF2 activates Wnt2/β-catenin pathway by binding to HOXC13 to aggravate the malignant progression of triple negative breast cancer

Triple negative breast cancer (TNBC) is insensitive to conventional targeted therapy and endocrine therapy, and is characterized by high invasiveness and high recurrence rate. This study aimed to explore the role and mechanism of RHOXF2 and HOXC13 on the malignant progression of TNBC. RT-qPCR and western blot were used to detect RHOXF2 and HOXC13 expression in TNBC cells. The proliferation, colony formation, invasion, migration, apoptosis and cell cycle of TNBC cells after transfection were analyzed by CCK-8 assay, colony formation assay, transwell assay, wound healing assay and flow cytometry analysis. Co-Immunoprecipitation and GST pull-down assays were used to analyze the combination between RHOXF2 and HOXC13. ChIP-PCR and luciferase reporter gene assay were used to examine the regulation of H3K27ac on RHOXF2. Besides, the expression of Ki67 and cleaved Caspase3 in tumor tissues of nude mice was determined by immunofluorescence. Results revealed that RHOXF2 and HOXC13 expression was increased in TNBC cells. RHOXF2 knockdown suppressed the proliferation, invasion and migration, as well as induced G0/G1 cell cycle arrest and apoptosis of TNBC cells. Besides, RHOXF2 could bind to HOXC13 and RHOXF2 knockdown suppressed HOXC13 expression in TNBC cells. Furthermore, HOXC13 overexpression reversed the impacts of RHOXF2 downregulation on the proliferation, invasion, migration, G0/G1 cell cycle arrest and apoptosis of TNBC cells. In addition, RHOXF2 silencing limited the tumor volume in nude mice, which was reversed by HOXC13 overexpression. Moreover, RHOXF2 knockdown interfered with Wnt2/β-catenin pathway in vitro and in vivo by binding to HOXC13. Importantly, H3K27ac acetylation could activate the expression of RHOXF2 promoter region. In conclusion, RHOXF2 activated by H3K27ac functioned as a tumor promoter in TNBC via mediating Wnt2/β-catenin pathway by binding to HOXC13, which provided promising insight into exploration on TNBC therapy.

Identification of target cells of human papillomavirus 18 using squamocolumnar junction organoids

Human papillomavirus 18 (HPV18) is a highly malignant HPV genotype among high-risk HPVs, characterized by the difficulty of detecting it in precancerous lesions and its high prevalence in adenocarcinomas. The cellular targets and molecular mechanisms underlying its infection remain unclear. In this study, we aimed to identify the cells targeted by HPV18 and elucidate the molecular mechanisms underlying HPV18 replication. Initially, we established a lentiviral vector (HPV18LCR-GFP vector) containing the HPV18 long control region promoter located upstream of EGFP. Subsequently, HPV18LCR-GFP vectors were transduced into patient-derived squamocolumnar junction organoids, and the presence of GFP-positive cells was evaluated. Single-cell RNA sequencing of GFP-positive and GFP-negative cells was conducted. Differentially expressed gene analysis revealed that 169 and 484 genes were significantly upregulated in GFP-positive and GFP-negative cells, respectively. Pathway analysis showed that pathways associated with cell cycle and viral carcinogenesis were upregulated in GFP-positive cells, whereas keratinization and mitophagy/autophagy-related pathways were upregulated in GFP-negative cells. siRNA-mediated luciferase reporter assay and HPV18 genome replication assay validated that, among the upregulated genes, ADNP, FHL2, and NPM3 were significantly associated with the activation of the HPV18 early promoter and maintenance of the HPV18 genome. Among them, NPM3 showed substantially higher expression in HPV-related cervical adenocarcinomas than in squamous cell carcinomas, and NPM3 knockdown of HPV18-infected cells downregulated stem cell-related genes. Our new experimental model allows us to identify novel genes involved in HPV18 early promoter activities. These molecules might serve as therapeutic targets in HPV18-infected cervical lesions.

HOXC13 promotes cell proliferation, metastasis and glycolysis in breast cancer by regulating DNMT3A

Breast cancer (BC) is a life-threatening malignant tumor that affects females more commonly than males. The mechanisms underlying BC proliferation, metastasis and glycolysis require further investigation. Homeobox C13 (HOXC13) is highly expressed in BC; however, the specific mechanisms in BC are yet to be fully elucidated. Therefore, the aim of the present study was to investigate the role of HOXC13 in BC proliferation, migration, invasion and glycolysis. In the present study, the UALCAN database was used to predict the expression levels of HOXC13 in patients with BC. Western blot analysis and reverse transcription-quantitative PCR were used to determine the expression levels of HOXC13 in BC cell lines. Moreover, HOXC13 knockdown was induced using cell transfection, and the viability, proliferation and apoptosis of cells were detected using Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine staining and flow cytometry. Migration, invasion and epithelial-mesenchymal transition (EMT) were measured using wound healing assay, Transwell assay and western blotting. In addition, XF96 extracellular flux analyzer and corresponding kits were used to detect glycolysis. The JASPAR database was used to predict promoter binding sites for the transcription factors HOXC13 and DNA methyltransferase 3α (DNMT3A). HOXC13 expression was silenced and DNMT3A was simultaneously overexpressed using cell transfection. The results of the present study revealed that HOXC13 expression was significantly elevated in BC tissues and cells. Following HOXC13 knockdown in BC cells, the viability, proliferation, glycolysis, migration, invasion and EMT were significantly decreased, and apoptosis was significantly increased. In addition, HOXC13 positively regulated the transcription of DNMT3A in BC cells, thus playing a regulatory role in the malignant progression of cells. In conclusion, HOXC13 promoted cell viability, proliferation, migration, invasion, EMT and glycolysis in BC by regulating DNMT3A.

Variants Identified in the HOXC13 and HOXD13 Genes Suggest Association with Cervical Cancer in a Cohort of Mexican Women

HOX genes have been associated with carcinogenesis. However, the molecular mechanism by which tumors are generated remains unclear. The HOXC13 and HOXD13 genes are of interest for their involvement in the development of genitourinary structures. The aim of this first study in the Mexican population was to search for and analyze variants in the coding region of the HOXC13 and HOXD13 genes in women with cervical cancer. Samples from Mexican women with cervical cancer and healthy women were sequenced (50/50). Allelic and genotypic frequencies were compared between groups. The functional impact of the proteins was determined with two bioinformatics servers (SIFT and PolyPhen-2), and the oncogenic potential of the identified nonsynonymous variants was determined using the CGI server. We identified five unreported gene variants: c.895C>A p.(Leu299Ile) and c.777C>T p.(Arg259Arg) in the HOXC13 gene and c.128T>A p.(Phe43Tyr), c.204G>A p.(Ala68Ala), and c.267G>A p.(Ser89Ser) in the HOXD13 gene. In this study, we suggest that the non-synonymous variants c.895C>A p.(Leu299Ile) and c.128T>A p.(Phe43Tyr) could represent a risk factor for the development of the disease, although additional studies in larger patient populations and in different ethnic groups are needed in order to support the results observed.

Role of HPV16 E1 in cervical carcinogenesis

Cervical cancer is the fourth most common cancer in women worldwide. More than 90% of cases are caused by the human papillomavirus (HPV). Vaccines developed only guard against a few HPV types and do not protect people who have already been infected. HPV is a small DNA virus that infects the basal layer of the stratified epithelium of the skin and mucosa through small breaks and replicates as the cells differentiate. The mucosal types of HPV can be classified into low-risk and high-risk groups, based on their association with cancer. Among HPV types in high-risk group, HPV type 16 (HPV-16) is the most common, causing 50% of all cancer cases. HPV infection can occur as transient or persistent infections, based on the ability of immune system to clear the virus. Persistent infection is characterized by the integration of HPV genome. HPV-16 exhibits a different integration pattern, with only 50% reported to be integrated at the carcinoma stage. Replication of the HPV genome depends on protein E1, an ATP-dependent helicase. E1 is essential for the amplification of the viral episome in infected cells. Previous studies have shown that E1 does not only act as a helicase protein but is also involved in recruiting and interacting with other host proteins. E1 has also been deemed to drive host cell proliferation. Recent studies have emphasized the emerging role of HPV E1 in cervical carcinogenesis. In this review, a possible mechanism by which E1 drives cell proliferation and oncogenesis will be discussed.

HOXC13 promotes cervical cancer proliferation, invasion and Warburg effect through β-catenin/c-Myc signaling pathway

Cervical cancer (CC) is one of the most common malignancy and is the second leading cause of death in gynecologic malignancies worldwide. The homeobox transcription factor homeobox C13 (HOXC13) has been demonstrated to play crucial roles in various cancers. However, its function in CC remains to be addressed. In the present study, upregulation of HOXC13 expression in human CC tissues was found in The Cancer Genome Atlas (TCGA) dataset and clinical samples and was associated with tumor size, FIGO stage and lymph node metastasis. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot assays suggested that the expression of HOXC13 was up-regulated in CC cells. Cell Counting Kit (CCK)-8, colony formation and cell cycle analysis assays indicated that HOXC13 promoted the proliferation and cycle progression of CC cells in vitro. Of note, knockdown of HOXC13 hinders tumor growth of xenograft tumor mice in vivo. Moreover, transwell and glycolysis measurement assays demonstrated that HOXC13 enhanced the migration, invasion and glycolysis of CC cells in vitro. Further mechanism analysis suggested that HOXC13 participated in CC progression through regulation of the β-catenin/c-Myc signaling pathway. Collectively, HOXC13 facilitated cell proliferation, migration, invasion and glycolysis through modulating β-catenin/c-Myc signaling pathway in CC, indicating that HOXC13 may provide a promising therapeutic target for the therapy of CC.