Higher expression of HPV16 derived E7_LI Transcript Observed in Men
with HIV and Recurrent Anal Cancer
Abstract
Squamous cell carcinoma of the anus (SCCA) or anal cancer (AC) is an
understudied cancer with a high occurrence rate in people with HIV
(PWH), especially men having sex with men (MSM). Furthermore, AC recurs
in approximately one fourth of patients who undergo standard care with
chemoradiation therapy (CRT). Using bulk RNA sequencing data of AC
obtained from 12 patients with non-recurrent (NR, N=9) or recurrent (R,
N=3) cancer, we previously showed upregulated expression of key immune
genes in the NR compared to the R group. Although the main causative
agent of anal cancer is high-risk human papillomavirus (HPV),
association of host and viral RNA transcript expression contributing to
AC recurrence has not been extensively studied. The objective of the
current study was to determine whether enrichment of specific HPV
genotypes and/or HPV gene expression patterns differentiate the two
groups and if any specific viral (HPV) and host (human) immune mediators
correlate with each other. Using bulk RNA sequencing data and VIRTUS 2,
we detected viral RNA reads mapping to 7 high-risk and 6 low-risk HPV
types of which the high-risk HPV16 observed in 83% (10/12) AC tumors
(7/9 non-recurrent and 3/3 recurrent). Rate of all HPV genomes trended
towards a decrease in non-recurrent anal cancer isolates and correlation
between HPV types was more commonly observed in low-risk ones. Analysis
of HPV 16 gene expression profile showed a significantly lower
positivity rate for a polycistronic transcript encoding for E7^L1 in
the non-recurrent group (1/9, NR versus 3/3, R, p value <0.05).
An unbiased correlation analysis of HPV-human transcript expression
showed a direct correlation between HPV transcripts and human genes
involved in cell growth. The data also identified human transcripts
showing an inverse correlation with HPV gene expression. These included
genes involved in negative regulation of growth, proliferation and
immune response. Taken together, these data indicate that concurrent
analyses of viral and host factors in the same tumor can identify
potential new therapeutic targets to ameliorate cancer recurrence post
treatment.