Putative Role of Circulating Human Papillomavirus DNA in the Development of Primary Squamous Cell Carcinoma of the Middle Rectum: A Case Report

Abstract

Here we present the case of a patient affected by rectal squamous cell carcinoma in which we demonstrated the presence of Human Papillomavirus (HPV) by a variety of techniques. Collectively, the virus was detected not only in the tumor but also in some regional lymph nodes and in non-neoplastic mucosa of the upper tract of large bowel. By contrast, it was not identifiable in its common sites of entry, namely oral and ano-genital region. We also found HPV DNA in the plasma-derived exosome. Next, by in vitro studies, we confirmed the capability of HPV DNA-positive exosomes, isolated from the supernatant of a HPV DNA positive cell line (CaSki), to transfer its DNA to human colon cancer and normal cell lines. In the stroma nearby the tumor mass we were able to demonstrate the presence of virus DNA in the stromal compartment, supporting its potential to be transferred from epithelial cells to the stromal ones. Thus, this case report favors the notion that human papillomavirus DNA can be vehiculated by exosomes in the blood of neoplastic patients and that it can be transferred, at least in vitro , to normal and neoplastic cells. Furthermore, we showed the presence of viral DNA and RNA in pluripotent stem cells of non-tumor tissue, suggesting that after viral integration (as demonstrated by p16 and RNA in situ hybridization positivity), stem cells might have been activated into cancer stem cells inducing neoplastic transformation of normal tissue through the inactivation of p53, p21, and Rb. It is conceivable that the virus has elicited its oncogenic effect in this specific site and not elsewhere, despite its wide anatomical distribution in the patient, for a local condition of immune suppression, as demonstrated by the increase of T-regulatory (CD4/CD25/FOXP3 positive) and T-exhausted (CD8/PD-1positive) lymphocytes and the M2 polarization (high CD163/CD68 ratio) of macrophages in the neoplastic microenvironment. It is noteworthy that our findings depicted a static picture of a long-lasting dynamic process that might evolve in the development of tumors in other anatomical sites.

HPV DNA Associates With Breast Cancer Malignancy and It Is Transferred to Breast Cancer Stromal Cells by Extracellular Vesicles

“…At this regard, some authors reported circulating HPV DNA in the serum of patients with HPV-associated invasive cancer (10) and as marker for disease extent and recurrence (14). We also found HPV DNA in the serum derived-extracellular vesicles (EVs) of breast pathologies affected women as well as in patient with HPV DNA positive squamous cell carcinoma of the middle rectum (15, 16). EVs are a heterogeneous population of vesicles, which includes exosomes, microvesicles, and apoptotic bodies that differ in size and biophysical properties (17).…”

“…We previously demonstrated that circulating HPV DNA can be found in serum derived-extracellular vesicles (EVs) in women with breast pathologies as well as in patient with HPV DNA positive squamous cell carcinoma of the middle rectum (15, 16). Here, as described in the first part of the study approved by the local ethics committee (145/2015/U/Sper), we enrolled 59 BC affected-patients and we searched for the presence of HPV DNA in the serum derived-EVs.…”

Exosomal cargoes in OSCC: current findings and potential functions

“…There are some evidence demonstrating that HPV DNA in exosomes participated in the process of cancer. HPV DNA in plasma-derived exosomes was detected in rectal squamous cell carcinoma patients (Ambrosio et al, 2019). Ambrosio et al isolated exosomes from the HPV DNA-positive cell line CaSki, which can transfer DNA to normal cell lines.…”

Diagnostically challenging human papillomavirus-associated primary squamous cell carcinoma of the rectum with metastasis in both ovaries: a case report

“…While there is a clear association of anal SCC with the most common subclasses of high risk HPVs, including types 16, 18, 31, and 33, a correlation to rectal SCC has not been clearly established yet [16,17]. One possible explanation for HPV-associated SCC in the rectum is circulating HPV DNA as discussed by Ambrosio et al [8]. An alternative pathogenetic pathway may be a misplacement of HPV-infected neoplastic epithelial cells from the anal canal with subsequent implantation of these tumor cells into the rectal mucosa.…”

“…In contrast, in the higher rectum there is no clear evidence for an association with HPV infections but an association with human immunodeficiency virus (HIV) [5][6][7]. One possible explanation of HPV infection in the higher rectum is circulating HPV deoxiribonucleic acid (DNA) [8]. Anal SCC affects more women than men and typically appears in the sixth decade of life, mostly with pelvic pain and bleeding [4,9,10].…”