DNA demethylation agent 5azadC downregulates HPV16 E6 expression in cervical cancer cell lines independently of TBX2 expression

Abstract

HPV16 is the most carcinogenic human papillomavirus and causes >50% of cervical cancers, the majority of anal cancers and 30% of oropharyngeal squamous cell carcinomas. HPV carcinogenesis relies on the continuous expression of the two main viral oncoproteins E6 and E7 that target >150 cellular proteins. Among them, epigenetic modifiers, including DNA Methyl Transferases (DNMT), are dysregulated, promoting an aberrant methylation pattern in HPV-positive cancer cells. It has been previously reported that the treatment of HPV-positive cervical cancer cells with DNMT inhibitor 5-aza-2'-deoxycytidine (5azadC) caused the downregulation of E6 expression due to mRNA destabilization that was mediated by miR-375. Recently, the T-box transcription factor 2 (TBX2) has been demonstrated to repress HPV LCR activity. In the current study, the role of TBX2 in E6 repression was investigated in HPV16 cervical cancer cell lines following 5azadC treatment. A decrease of E6 expression was accompanied by p53 and p21 restoration. While TBX2 mRNA was upregulated in 5azadC-treated SiHa and Ca Ski cells, TBX2 protein was not detectable. Furthermore, the overexpression of TBX2 protein in cervical cancer cells did not allow the repression of E6 expression. The TBX2 transcription factor is therefore unlikely to be associated with the repression of E6 following 5azadC treatment of SiHa and Ca Ski cells.

DNA methylation database for gynecological cancer detection, classification and assay development

“…CIN lesions are subdivided into low, medium and high risk. Gray dotted guidelines for z-score of [-2, -1, 1, 2].…”

“…DNA methylation plays a crucial role in gene regulation and occurs mainly at CG dinucleotide sequences in mammalian genomes [1]. In HPV-induced cancers of the cervix and vulva HPV infection is the key driver of DNA methylation changes as the HPV genes E6 and E7 affect the activity of DNA methyltransferases [2]. For HPV-independent cancers DNA methylation changes are often induced by mutations in genes involved in epigenetic processes such as DNA methyltransferases [3].…”

DNMT family induces down-regulation of NDRG1 via DNA methylation and clinicopathological significance in gastric cancer

“…In a case report, azacitidine was used to treat a 57-year-old woman newly diagnosed with MDS during palliative chemotherapy for metastatic breast cancer, azacitidine showed promising effects for MDS, and also stabilized the patient’s lung and lymph node metastases without any major toxicity ( Baek et al, 2019 ). An increasing number of clinical trials of demethylating treatment is ongoing, some of which have presented exciting effects ( Linnekamp et al, 2017 ; Perrard et al, 2020 ; Singal et al, 2015 ; Jansen et al, 2019 ) ( Table 3 ). A Phase I study showed the security of decitabine treated by hepatic arterial infusion, and a dose level of 20 mg/m 2 /day on five consecutive days every 4 weeks could be considered for further investigation in combinatorial immunotherapy regimens in patients with Unresectable Liver-predominant Metastases From Colorectal Cancer ( Singal et al, 2015 ).…”

DNMT family induced down-regulation of NDRG1 via DNA methylation and clinicopathological significance in gastric cancer

“…In a case report, azacitidine was used to treat a 57-year-old woman newly diagnosed with MDS during palliative chemotherapy for metastatic breast cancer, azacitidine showed promising effects for MDS, and also stabilized the patient's lung and lymph node metastases without any major toxicity 30 . Now, An increasing number of clinical trials of demethylating treatment is ongoing，some have presented exciting effects [31][32][33][34] (Table 2). A Phase I study showed the security of decitabine treated by hepatic arterial infusionin, and a dose level of 20 mg/m2/day on five consecutive days every 4 weeks could be considered for further investigation in combinatorial immunotherapy regimens in patients with Unresectable Liver-predominant Metastases From Colorectal Cancer 33 .…”