Two conserved amino acids differentiate the biology of high‐risk and low‐risk HPV E5 proteins

Abstract

The high-risk alpha human papillomaviruses (HPVs) are responsible for 99% of cervical cancers. While the biological functions of the HPV E6 and E7 oncoproteins are well-characterized, the function of E5 has remained elusive. Here, we examined gene expression changes induced by E5 proteins from high-risk HPV-16 and low-risk HPV-6b in multiple pools of primary human keratinocytes. Surprisingly, microarray analysis revealed that over 700 genes were significantly regulated by HPV-6b E5, while only 25 genes were consistently and significantly regulated by HPV-16 E5 in three biological replicates. However, we observed that more than thousand genes were altered in individual sample compared with vector. The gene expression profile induced by 16E5 in primary genital keratinocytes was very different from what has been previously published using immortalized HaCaT cells. Genes altered by HPV-16 E5 were unaffected by HPV-6b E5. Our data demonstrate that E5 proteins from the high-and low-risk HPVs have different functions in the HPV-host cell. Interestingly, conversion of two amino acids in HPV-16 E5 to the low-risk HPV-6b sequence eliminated the induction of high-risk related cellular genes.

Preclinical Immunogenicity and Efficacy Studies for Therapeutic Vaccines for Human Papillomavirus-Type-16-Associated Cancer

“…The vaccines either supply segments of E5, E6, and E7 or E2, E5, E6, and E7, which are expressed as fusion proteins within HSV-1 gD. Sequences with E6 and E7 that may contribute to transformation were removed; a sequence within E5 that is only carried by oncogenic types of HPV [ 56 ] is present in the gDE7652 but not the gDE765 sequence and may have to be modified prior to use in humans. As shown previously [ 26 , 30 , 41 , 54 ] and confirmed in this study, gD, which inhibits an early T cell checkpoint, increases and broadens CD8 + T cell responses.…”

Herpes Simplex Virus, Human Papillomavirus, and Cervical Cancer: Overview, Relationship, and Treatment Implications

“…They also have a greater expression of the antioxidant GSH than all other cells [114]. Notably, high-risk and low-risk E5 proteins have different roles in HPV infection, and the difference is mediated by just two amino acids [115].…”

Identification of HPV oncogene and host cell differentiation associated cellular heterogeneity in cervical cancer via single‐cell transcriptomic analysis

“…11,[16][17][18][19][20] These genes and their induced cellular changes with cell proliferation, apoptosis, genomic stability, and transformation directly or indirectly contribute to host cell transformation, cancer initiation, and malignant phenotype maintenance. 13,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] To date, many processes that underlie the HPV life cycle and oncogenesis remain largely unknown due to a lack of systems that model natural HPV productive and abortive life cycles. There are several cancer lines with HPV16 or 18, keratinocyte systems (immortalized HaCat cells or primary keratinocytes) with transfection of HPV genomes, keratinocytes (immortalized HaCat cells or primary keratinocytes) infected with quasivirus, pseudovirus, or "native" HPV particles, or immortalized cell lines with E6/E7, SV40, hTERT, while there are only two or three patient-derived cell systems, for example, W12 (HPV16) and 9E (HPV31).…”

“…E5, E6, and E7 proteins are required to evade the innate immune responses of the host cells and to create an environment to support HPV replication in the superficial layers 11,16–20 . These genes and their induced cellular changes with cell proliferation, apoptosis, genomic stability, and transformation directly or indirectly contribute to host cell transformation, cancer initiation, and malignant phenotype maintenance 13,21–35 . To date, many processes that underlie the HPV life cycle and oncogenesis remain largely unknown due to a lack of systems that model natural HPV productive and abortive life cycles.…”