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Autophagy buffers Ras-induced genotoxic stress enabling malignant transformation in keratinocytes primed by human papillomavirus.

ABSTRACT: Malignant transformation involves an orchestrated rearrangement of cell cycle regulation mechanisms that must balance autonomic mitogenic impulses and deleterious oncogenic stress. Human papillomavirus (HPV) infection is highly prevalent in populations around the globe, whereas the incidence of cervical cancer is 0.15%. Since HPV infection primes cervical keratinocytes to undergo malignant transformation, we can assume that the balance between transforming mitogenic signals and oncogenic stress is rarely attained. We showed that highly transforming mitogenic signals triggered by HRas^G12V activity in E6E7-HPV-keratinocytes generate strong replication and oxidative stresses. These stresses are counteracted by autophagy induction that buffers the rapid increase of ROS that is the main cause of genotoxic stress promoted by the oncoprotein. As a result, autophagy creates a narrow window of opportunity for malignant keratinocytes to emerge. This work shows that autophagy is crucial to allow the transition of E6E7 keratinocytes from an immortalized to a malignant state caused by HRas^G12V.

SUBMITTER: Cararo-Lopes E

PROVIDER: S-EPMC7892846 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Autophagy buffers Ras-induced genotoxic stress enabling malignant transformation in keratinocytes primed by human papillomavirus.

Cararo-Lopes Eduardo E Dias Matheus H MH da Silva Marcelo S MS Zeidler Julianna D JD Vessoni Alexandre T AT Reis Marcelo S MS Boccardo Enrique E Armelin Hugo A HA

Cell death & disease 20210218 2

Malignant transformation involves an orchestrated rearrangement of cell cycle regulation mechanisms that must balance autonomic mitogenic impulses and deleterious oncogenic stress. Human papillomavirus (HPV) infection is highly prevalent in populations around the globe, whereas the incidence of cervical cancer is 0.15%. Since HPV infection primes cervical keratinocytes to undergo malignant transformation, we can assume that the balance between transforming mitogenic signals and oncogenic stress ...[more]

PMID: 33602932

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Project description:Human papillomavirus (HPV) infection of the genital tract is common; however, only about 10 to 15% of infections persist, and approximately 10 to 15% of these persistent infections result in cancer. Basal epidermal stem cells are the presumed target cells for HPV infection, providing a reservoir of latently infected cells that persist over time and initiate lesions. However, it is not known whether stem cell density has any influence on transformation of human keratinocytes by HPV. We explored the relationship between stem cell properties of normal human keratinocytes and their susceptibility to transformation by HPV16 DNA. Normal human keratinocyte isolates (NHKc) derived from different donors were cultured in three-dimensional anchorage-free suspension to assess their spheroid-forming ability. NHKc spheroids were then plated back into plastic monolayer culture and transfected with full-length HPV16 DNA, which we have previously shown to integrate into the host cell genome upon transfection. Spheroid-derived NHKc (SD-NHKc) and fluorescence-activated cell sorting-purified populations of basal stem-like keratinocytes, expressing low levels of epidermal growth factor receptor and high levels of integrin alpha 6 (EGFRlo/ITG?6hi), responded to transfection with HPV16 DNA with more vigorous proliferation, greater immortalization efficiency, and faster progression to differentiation resistance than autologous mass-cultured cells. Conversely, cells committed to terminal differentiation (EGFRhi/ITG?6lo) grew slowly after transfection with HPV16 and failed to generate immortalized or DR clones. HPV16 DNA induced stem cell properties in mass-cultured NHKc. We conclude that HPV16 preferentially immortalizes basal keratinocytes with stem cell properties and that these cells readily achieve a differentiation-resistant phenotype upon immortalization by HPV16.IMPORTANCE This paper explores the relationship between the stem cell properties of normal human epidermal cells in culture and these cells' susceptibility to transformation by HPV16 DNA, the HPV type present in about 50% of cervical cancers. We report variable susceptibilities to HPV16-mediated transformation among different keratinocyte isolates derived from neonatal foreskin. Our findings provide strong experimental evidence that HPV16 preferentially transforms basal keratinocytes with stem cell properties. Insights gained from these studies increase our understanding of the host cell-specific factors influencing individual susceptibility to HPV-driven transformation and the contributing factors leading to preneoplastic and neoplastic progression of HPV-positive lesions.

Dataset Information

Autophagy buffers Ras-induced genotoxic stress enabling malignant transformation in keratinocytes primed by human papillomavirus.

Publications

Autophagy buffers Ras-induced genotoxic stress enabling malignant transformation in keratinocytes primed by human papillomavirus.

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