In vivo HPV 16 E5 mRNA: Expression pattern in patients with squamous intra-epithelial lesions of the cervix

Abstract Background Human Papillomavirus (HPV) type 16 E5 is a small protein, which is reported to display transforming activity in vitro and in animal studies. The E5 transcriptional activity, however, has been rarely reported in vivo in literature. Objectives (a) To detect the E5 transcripts in vivo in a population of HPV 16 positive patients with abnormal cytology and (b) to correlate the level of expression to the degree of the cytological lesion. Study design and methods 250 cytological samples of HPV positive women were obtained and tested for the E6/E7 mRNA expression. Patients were selected if HPV 16 only mRNA positive and with a cytology consistent with low-grade/high-grade squamous intra-epithelial (LSIL/HSIL) lesions. Selected patients were tested for the E5 transcripts by reverse RT PCR, comparing the expression level in vivo with a transfected HPV 16 E5 HaCaT cell line. Results 27 HPV 16 E6/E7 mRNA positive LSIL/HSIL patients were selected. 13 out of 17 LSIL patients were tested positive for the E5 mRNA, showing an ample range of positivity. In the HSIL group 7 out of 10 patients were tested positive, displaying lower and more homogeneous levels of expression if compared with the transfected cells. Conclusion The HPV 16 E5 transcripts levels showed a broad distribution in vivo ; the discrepancy was wider in LSIL patients, with HSIL patients displaying a more homogeneous profile. However, because of the limited number of patients, we could not draw a firm conclusion about the correlation between the E5 expression and the disease progression.