Role of FOXA1 transcription factor in Human Papillomavirus (HPV) induced carcinogenesis: an epidemiological and functional approach

Abstract

The development of tumors associated with HPV (Human Papillomavirus) is mainly due to persistent infections by oncogenic high-risk HPVs, and among them HPV-16 is the most prevalent worldwide in both pre-neoplastic lesions and cancers in different anatomical sites of men and women. High-risk HPV oncoproteins E6 and E7 associate and inactivate tumor suppressor proteins p53 and pRb respectively, resulting in apoptosis evasion, cell cycle dysregulation and other changes that together induce transformation of the infected cells. In the non-coding viral genomic region (LCR - Long Control Region) different viral and cellular Transcription Factors (TFs) bind and regulate replication and transcription of HPV. There are still no target-therapeutic treatments to contain the proliferation of HPV-infected cells, thus limiting the progression of the clinical outcome. Therefore, the search for biomarkers and associated pathways that allow the development of treatments for patients with HPV-associated tumors is justified. In this context, previous studies by our group identified that the FOXA1 TF has functional binding sites within the LCR of HPV-16 and thus the binding of FOXA1 to LCR could be associated with tumorigenesis, since this protein induces significantly viral transcription. Therefore, this project aims to investigate in an integrated manner (epidemiological and functional approach) the role of FOXA1 in carcinogenesis induced by HPV, and the associated mechanisms. In addition, we aim to evaluate the impact of FOXA1 inactivation by exploring miRNA based therapy. More specifically, we aim to: (1) evaluate the association of FOXA1 levels with the presence of HPV DNA, and clinical, histopathological and survival parameters in patients with cervical tumors; (2) evaluate the association of FOXA1 and miR-212 levels with the presence of HPV DNA, and clinical, histopathological and survival parameters in patients with oropharyngeal and oral cavity tumors; (3) evaluate the levels of FOXA1 (mRNA and protein), E6/E7 (mRNA and protein), and miR-212 in NIKs (normal immortalized keratinocytes) cells transduced or not with LCR-E6/E7 of HPV-16, whether or not overexpressing FOXA1, and in the presence of miR-212 mimetic or inhibitor; (4) through functional assays, evaluate in these cells the different hallmarks of cancer: proliferation, colony formation after plating at low density, growth independent of anchorage, migration, invasion and apoptosis. We hypothesize that high expression of FOXA1 contributes to HPV-associated carcinogenesis, by activating viral transcription and thus impacting in high levels of the viral oncoproteins E6 and E7. In this case, the high expression of FOXA1 could be used as a biomarker of tumor progression, in addition to constituting an important therapeutic target. (AU)