Human papillomavirus prevalence in lung carcinomas in Bulgaria

The emerging role of human papillomavirus in lung cancer

Lung cancer stands as one of the most lethal diseases and is the foremost cause of cancer-related mortalities worldwide. The pathophysiology of lung cancer is multifaceted, and it includes multiple cell signaling pathways and other complex factors such as oxidative stress and genetics. The association of HPV with lung carcinogenesis was first proposed in 1979, and since then, scientists worldwide have been putting forward several hypotheses to establish a relationship between this virus and lung cancer. Although studies have reported the presence of HPV in lung cancer, the exact mechanism of entry and the route of transmission have not been elucidated clearly till date. Numerous studies across the globe have detected differentially expressed HPV oncoproteins in lung cancer patients and found their association with the critical cell signaling pathways that leads to the development and progression of lung cancer. Many reports have also provided evidence stating the involvement of HPV in determining the survival status of lung cancer patients. The present review recapitulates the studies evincing the association of HPV and lung cancer, its route of transmission and mechanism of action; the detection of the virus and treatment opportunities for HPV-positive lung cancer; and the severity associated with this disease. Therefore, this will provide an explicit idea and would help to develop preventive measures and specific as well as effective treatment for HPV-associated lung carcinogenesis.

High-Risk Human Papillomavirus Infection in Lung Cancer: Mechanisms and Perspectives

Lung cancer is a very prevalent and heterogeneous group of malignancies, and most of them are etiologically associated with tobacco smoking. However, viral infections have been detected in lung carcinomas, with high-risk human papillomaviruses (HR-HPVs) being among them. The role of HR-HPVs in lung cancer has been considered to be controversial. This issue is due to the highly variable presence of this virus in lung carcinomas worldwide, and the low viral load frequently that is detected. In this review, we address the epidemiological and mechanistic findings regarding the role of HR-HPVs in lung cancer. Some mechanisms of HR-HPV-mediated lung carcinogenesis have been proposed, including (i) HPV works as an independent carcinogen in non-smoker subjects; (ii) HPV cooperates with carcinogenic compounds present in tobacco smoke; (iii) HPV promotes initial alterations being after cleared by the immune system through a "hit and run" mechanism. Additional research is warranted to clarify the role of HPV in lung cancer.

Evaluation of microRNAs as potential biomarkers in circulating HPV-DNA-positive non-small cell lung cancer patients

The aim of the present study was to identify the potential risk of circulating-HPV-DNA in non-small cell lung cancer (NSCLC) and to analyze abnormally expressed miRNAs in circulating HPV-DNA-positive NSCLC. HPV universal primers were used to detect the presence of HPV-DNA in the peripheral blood of 100 patients with NSCLC. The relationship between circulating-HPV-DNA and NSCLC patients characteristics was analyzed. Then, eight differentially expressed miRNAs in NSCLC were screened based on the TCGA database. The levels of miRNAs in circulating HPV-DNA-positive NSCLC patients were detected by real-time quantitative PCR. ROC curves were generated to evaluate the diagnostic performance. Circulating-HPV-DNA was found in 16 patients. The proportion of HPV-DNA-positive patients with poorly differentiated NSCLC, advanced lung cancer and lymph node metastasis was higher than that of HPV-DNA-negative patients. The levels of miR-183, miR-210 and miR-182 were significantly higher and miR-144 was significantly lower in HPV-DNA-positive NSCLC than those in HPV-DNA-negative NSCLC patients. When using a single miRNA to identify circulating HPV-DNA-positive NSCLC patients, miR-210 had a higher area under the ROC curve (AUC) than other miRNAs, and its sensitivity and specificity were also higher. In addition, the combination of two miRNAs was more effective than a single miRNA. Among them, miR-210+ miR-144 had the highest AUC value and showed the best prediction performance. Circulating-HPV-DNA may serve as a risk factor in NSCLC. Plasma miR-183, miR-210, miR-182 and miR-144 can be used as reliable biomarkers to identify circulating HPV-DNA-positive NSCLC.

Papillomavirus can be transmitted through the blood and produce infections in blood recipients: Evidence from two animal models

Human papillomaviruses (HPV) contribute to most cervical cancers and are considered to be sexually transmitted. However, papillomaviruses are often found in cancers of internal organs, including the stomach, raising the question as to how the viruses gain access to these sites. A possible connection between blood transfusion and HPV-associated disease has not received much attention. Here we show, in rabbit and mouse models, that blood infected with papillomavirus yields infections at permissive sites with detectable viral DNA, RNA transcripts, and protein products. The rabbit skin tumours induced via blood infection displayed decreased expression of SLN, TAC1, MYH8, PGAM2, and APOBEC2 and increased expression of SDRC7, KRT16, S100A9, IL36G, and FABP9, as seen in tumours induced by local infections. Furthermore, we demonstrate that blood from infected mice can transmit the infection to uninfected animals. Finally, we demonstrate the presence of papillomavirus infections and virus-induced hyperplasia in the stomach tissues of animals infected via the blood. These results indicate that blood transmission could be another route for papillomavirus infection, implying that the human blood supply, which is not screened for papillomaviruses, could be a potential source of HPV infection as well as subsequent cancers in tissues not normally associated with the viruses.