Putative regulatory sequence in human papillomavirus type 16 E2 open reading frame

Area of Science:

• Molecular biology
• Virology
• Cancer research

Background:

• Human papillomavirus type 16 (HPV16) is a significant oncogenic virus.
• Estrogen receptor-positive breast cancer cells (MCF-7) are commonly studied in relation to hormonal influences.
• The E2 open reading frame (ORF) of HPV16 plays a role in viral replication and gene regulation.

Purpose of the Study:

• To investigate the influence of estrogen on the HPV16 E2 ORF.
• To determine if a putative estrogen responsive element (ERE) within the HPV16 E2 ORF mediates estrogenic effects.
• To analyze the silencer activity associated with the HPV16 E2 ORF fragment.

Main Methods:

• Amplification and cloning of a specific HPV16 E2 ORF fragment (nt. 3142-3255) containing a putative ERE into a pBLCAT2 plasmid.
• Transfection of the constructed plasmids (sense and anti-sense orientations) into MCF-7 cells.
• Assay of chloramphenicol acetyltransferase (CAT) activity in the presence and absence of beta-estradiol.

Main Results:

• Estrogen treatment did not alter CAT activity in transfected MCF-7 cells.
• A significant silencer effect was observed in cells transfected with both sense and anti-sense HPV16 E2 ORF plasmids.
• Synthetic fragments of the putative ERE failed to confirm its role in the observed silencer activity.

Conclusions:

• The HPV16 E2 ORF fragment exhibits estrogen-independent silencer activity in MCF-7 cells.
• The putative ERE within the studied HPV16 E2 ORF fragment is not responsible for this silencer effect.
• Further investigation is needed to elucidate the mechanism of the observed silencer activity and its potential role in HPV-associated pathogenesis.