HPV positive neuroendocrine cervical cancer cells are dependent on Myc but not E6/E7 viral oncogenes

Abstract

Using conditional cell reprogramming, we generated a stable cell culture of an extremely rare and aggressive neuroendocrine cervical cancer. The cultured cells contained HPV-16, formed colonies in soft agar and rapidly produced tumors in immunodeficient mice. The HPV-16 genome was integrated adjacent to the Myc gene, both of which were amplified 40-fold. Analysis of RNA transcripts detected fusion of the HPV/Myc genes, arising from apparent microhomologous recombination. Spectral karyotyping (SKY) and fluorescent-in-situ hybridization (FISH) demonstrated coordinate localization and translocation of the amplified Myc and HPV genes on chromosomes 8 and 21. Similar to the primary tumor, tumor cell cultures expressed very high levels of the Myc protein and, in contrast to all other HPV-positive cervical cancer cell lines, they harbored a gain-of-function mutation in p53 (R273C). Unexpectedly, viral oncogene knockdown had no effect on the growth of the cells, but it did inhibit the proliferation of a conventional HPV-16 positive cervical cancer cell line. Knockdown of Myc, but not the mutant p53, significantly inhibited tumor cell proliferation. On the basis of these data, we propose that the primary driver of transformation in this aggressive cervical cancer is not HPV oncogene expression but rather the overexpression of Myc.

Insertional oncogenesis by HPV70 revealed by multiple genomic analyses in a clinically HPV‐negative cervical cancer

“…Tumorigenesis by insertion of viral DNA near oncogenes is a thoroughly established oncogenic mechanism . The frequent detection of HPV DNA near oncogenes in virally induced human tumors indicates that insertional oncogenesis is a key mechanism in HPV‐induced tumors, and that it may act in concert with HPV‐encoded oncogenes, perhaps even replacing them in some instances . Detection of HPV70 DNA integrated into BCL11B and transcriptional activation of it, along with HPV E7 transcripts, strongly implicate HPV70 in this tumor.…”

“…These initiate at viral promoters and proceed into the host genes. Viral enhancers may also activate flanking oncogene promoters …”

“…Viral enhancers may also activate flanking oncogene promoters. [38][39][40] Approaches to detect integrated viral DNA have included RNA sequencing (RNAseq) to detect fusion transcripts, and DNA sequencing strategies including PCR or hybridization capture to identify the junctions between inserted HPV and human genome DNA. [20][21][22][23] However, in most instances only one of the two junctions between the linear HPV DNA fragment and human DNA was identified, and structural characterization of the inserted viral DNA was incomplete or inferred.…”

Insertional oncogenesis by HPV70 revealed by multiple genomic analyses in a clinically HPV-negative cervical cancer

“…Tumorigenesis by insertion of viral DNA near oncogenes is a thoroughly established oncogenic mechanism (31)(32)(33)(34)(35). The frequent detection of HPV DNA near oncogenes in virally induced human tumors indicates that insertional oncogenesis is a key mechanism in HPV-induced tumors, and that it may act in concert with HPV-encoded oncogenes, perhaps even replacing them in some instances (40). Detection of HPV70 DNA integrated into BCL11B and transcriptional activation of it, along with HPV E7 transcripts, strongly implicate HPV70 in this tumor.…”

“…These initiate at viral promoters and proceed into the host genes. Viral enhancers may also activate flanking oncogene promoters (38)(39)(40).…”