Exploitation of ATP-sensitive potassium ion (KATP) channels by HPV promotes cervical cancer cell proliferation by contributing to MAPK/AP-1 signalling

Abstract

Persistent infection with high-risk human papillomaviruses (HPVs) is the causal factor in multiple human malignancies, including >99% of cervical cancers and a growing proportion of oropharyngeal cancers. Prolonged expression of the viral oncoproteins E6 and E7 is necessary for transformation to occur. Although some of the mechanisms by which these oncoproteins contribute to carcinogenesis are well-characterised, a comprehensive understanding of the signalling pathways manipulated by HPV is lacking. Here, we present the first evidence to our knowledge that the targeting of a host ion channel by HPV can contribute to cervical carcinogenesis. Through the use of pharmacological activators and inhibitors of ATP-sensitive potassium ion (KATP) channels, we demonstrate that these channels are active in HPV-positive cells and that this activity is required for HPV oncoprotein expression. Further, expression of SUR1, which forms the regulatory subunit of the multimeric channel complex, was found to be upregulated in both HPV+ cervical cancer cells and in samples from patients with cervical disease, in a manner dependent on the E7 oncoprotein. Importantly, knockdown of SUR1 expression or KATP channel inhibition significantly impeded cell proliferation via induction of a G1 cell cycle phase arrest. This was confirmed both in vitro and in in vivo tumourigenicity assays. Mechanistically, we propose that the pro-proliferative effect of KATP channels is mediated via the activation of a MAPK/AP-1 signalling axis. A complete characterisation of the role of KATP channels in HPV-associated cancer is now warranted in order to determine whether the licensed and clinically available inhibitors of these channels could constitute a potential novel therapy in the treatment of HPV-driven cervical cancer.

E7-mediated repression of miR-203 promotes LASP1-dependent proliferation in HPV-positive cervical cancer

“…1B; (35)). To confirm if LASP1 plays a role in the development of cervical cancer, we used cervical cytology samples from a cohort of HPV16+ patients and samples from healthy, HPV− patients as controls (19,36). Whilst LASP1 mRNA expression was increased in all CIN stages, LASP1 protein was only significantly increased in CIN3 (Fig.…”

“…Through the use of primary keratinocytes containing the HPV16 or 18 genomes and expression constructs of the HPV oncogenes E6 and E7, our data shows that LASP1 expression was HPV E7 dependant. HPV E7 is a critical oncogene that activates a plethora of signalling pathways to drive cell proliferation and survival (14,15,19,52,53).…”

“…Through the use of primary keratinocytes containing the HPV16 or 18 genomes and expression constructs of the HPV oncogenes E6 and E7, our data shows that LASP1 expression was HPV E7 dependant. HPV E7 is a critical oncogene that activates a plethora of signalling pathways to drive cell proliferation and survival (14,15,19,52,53). Here, our data demonstrate that LASP1 constitutes a novel oncogenic target of HPV E7 in cervical cancer that may be an attractive target for cervical cancer and other HPV− associated cancers.…”

“…All in vitro experiments were performed a minimum of three times, unless stated otherwise. The sample size for the in vivo study was selected by assuming an expected mean survival of the control animal group of approximately 40 ± 5 days (based on previous experiments in the subcutaneous SCID/HeLa flank model (19)). Data was analysed using a two-tailed, unpaired Student’s t-test performed using GraphPad PRISM 9.2.0 software, unless stated otherwise.…”

“…During productive infection HPV E5 induces proproliferative EGFR signalling, promotes immune evasion and functions as a viral-encoded ion channel (4-7) However, HPV E6 and E7 are the primary oncogenes of viral transformation (3). The most well characterised function of these oncogenes is the inactivation of the p53 and pRb tumour suppressors, respectively (8)(9)(10)(11); however, recent studies demonstrate that E6 and E7 modulate a plethora of host signalling pathways that have critical functions in cellular transformation (12)(13)(14)(15)(16)(17)(18)(19).…”