E6/E7 Functional Differences among Two Natural Human Papillomavirus 18 Variants in Human Keratinocytes

Area of Science:

• Oncology
• Virology
• Cell Biology

Background:

• Human papillomavirus type 18 (HPV-18) variants, particularly from lineages A and B, are implicated in cervical cancer.
• Previous research suggests lineage A variants may possess higher oncogenic potential than lineage B.
• Limited functional studies exist on HPV-18 variants, especially using natural host cells.

Purpose of the Study:

• To functionally characterize primary human keratinocytes (PHKs) immortalized by HPV-18 A1 and B1 sublineages.
• To compare the oncogenic potential and cellular behaviors of PHKs immortalized by different HPV-18 variants.

Main Methods:

• Immortalization of primary human keratinocytes (PHKs) using E6/E7 genes from HPV-18 A1 and B1 sublineages.
• Assessment of immortalization rate, colony formation (monolayer and 3D), invasion, apoptosis resistance, morphology, proliferation, and migration.
• Qualitative analysis of cell grouping and invasion patterns.

Main Results:

• PHKs immortalized with HPV-18 A1 (PHK18A1) demonstrated significantly faster immortalization and higher colony formation than those with HPV-18 B1 (PHK18B1).
• PHK18A1 exhibited greater invasion ability and increased resistance to actinomycin-D-induced apoptosis.
• Distinct cellular behaviors were observed: PHK18A1 formed compact colonies and invaded/migrated in clusters, while PHK18B1 formed looser colonies and showed single-cell invasion/migration.

Conclusions:

• HPV-18 A1 and B1 sublineages induce qualitative differences in immortalized human keratinocytes.
• The observed functional and morphological differences suggest varying oncogenic potentials, potentially correlating with different cervical cancer histological subtypes.
• Further research is needed to elucidate the underlying mechanisms driving these variant-specific cellular behaviors.