Role of NRF2 cascade in determining the differential response of cervical cancer cells to anticancer drugs: an in vitro study.

BACKGROUND: Cervical cancers are usually treatable if detected in early stages by a combination of therapies. However, the prognosis of cervical cancer patients with metastasis remains unfavorable due to the fact that most of the cervical carcinomas are either resistant to anticancer drugs or show signs of relapse after initial treatment. Therefore, it is important to control the chemoresistance as it is the key to develop effective treatment options for cervical cancer. OBJECTIVE: The current study aimed at evaluating the differential responses of cervical cancer cells to anti-cancer drugs and assessed whether the differences in the expression profiles of antioxidant genes regulated by nuclear factor erythroid-2-related factor 2 (NRF2), led to the variations in the sensitivities of the cancer cells to treatment. METHODOLOGY: Three cervical cancer cell lines were investigated for their differences in NRF2 pathway by measuring the gene expression and enzyme activity. The differences in the sensitivity to anti-cancer drugs and variation in ROS profile was also evaluated. The addition of exogenous drugs to manipulate the intracellular ROS and its effect on NRF2 pathway genes was also investigated. RESULTS: HeLa and SiHa cells were more sensitive to cisplatin and oxaliplatin treatment than C33A cells. HeLa and SiHa cells had significantly lower NRF2 gene levels, NQO1 enzyme activity and basal GSH levels than C33A cells. Levels of ROS induced were higher in HeLa than C33A cells. CONCLUSION: Overall, the differences in the cellular levels of antioxidant regulatory genes led to the differential response of cervical cancer cells to anti-cancer drugs.

Prevalence of Epstein Barr Virus and Herpes Simplex Virus Among Human Papillomavirus Negative Oral Cancer Patients: A Cross-Sectional Study from South India.

The high incidence of oral carcinomas is due to its multifactorial etiology and the presence of various risk factors. Human Papillomavirus (HPV) has a proven role in the pathogenesis of oral carcinomas, but in the recent times there has been an increasing incidence of oral cancers who are negative for HPV infection. Also, these patients are non-smokers and non-drinkers so it could be speculated that these oral cancers are due to some other etiological factor probably of other viral infections. Therefore, this study examined the prevalence of Epstein Barr Virus (EBV) and Herpes Simplex Virus (HSV) among oral cancer patients. This cross-sectional study was conducted from January 2019 to June 2020. Biopsy samples from 47 newly diagnosed untreated patients with oral malignancies were collected along with their demographic and clinicopathological information. DNA extracted from the biopsies was processed for nested PCR for the detection of EBV and HSV. All the samples tested negative for HPV and HSV infection. Nested PCR detected 29 cases (70.7%) to be positive for EBV. The non-cancerous adjacent tissues also were negative for HPV, EBV and HSV. The prevalence of EBV was found to be more in males (62.1%) and the highest number of cases was of the left buccal mucosa compromising 34% of the total cases. From the present study it can be concluded that EBV but not HSV infection is associated with an increased risk of developing oral cancers. Although, 70.7% of the patients were found to be positive for EBV whether the viral infection played any role in the driving the malignancy needs to be further elucidated.

Oncogenic viruses as etiological risk factors for head and neck cancers: An overview on prevalence, mechanism of infection and clinical relevance.

OBJECTIVE: This review article aims to discuss the role of oncogenic viruses in the development of head and neck cancers including the prevalence, mode of infection and the clinical relevance of these viral infections associated with tumours. DESIGN: A detailed review of scientific literature was performed relevant to oncogenic viruses associated with head and neck cancers. RESULTS: The incidence of head and neck cancers associated with traditional risk factors such as smoking, chewing tobacco and alcohol consumption have reduced gradually. With the emergence of oncogenic viruses, the viral infection has become a major etiological contributor to the global cancer burden. Viral infection in the etiology of cancer opens up an opportunity for viral gene specific targets in diagnosis and biomarkers to evaluate prognosis. Infection with high-risk HPVs in the oropharynx is already proving to be beneficial as a subset of HPV-positive oropharyngeal cancer patients tend to have better prognosis in terms of treatment responses and overall survival. CONCLUSIONS: Large multi-center clinical trials exploring the implications of modifying viral infections in cancers are further warranted and the results hold the key to the management of patients suffering from cancers driven by viral infections.

DNA extraction from archived hematoxylin and eosin-stained tissue slides for downstream molecular analysis.

BACKGROUND: Histopathologically stained archived tissue slides are stored in hospital archives for years to decades. They are the largest available source of biological materials and are a potentially useful resource that can be used for retrospective epidemiological studies. DNA recovered from the slides can be used for several downstream molecular processes including polymerase chain reaction, single nucleotide polymorphism analysis, and whole genome sequencing. The DNA from these slides can be utilized to compare gene signatures of normal and diseased tissues. However, extraction of high-quality DNA from archived stained hematoxylin and eosin (H&E) slides remains challenging. AIM: To standardize a new protocol for extracting DNA from archived H&E-stained tissue slides for further molecular assays. METHODS: A total of 100 archived H&E-stained cancer slides were subjected to a total of five methods of DNA extraction. Methods were varied in the deparaffinization step, tissue rehydration, duration of lysis, and presence or absence of proteinase K. The extracted DNA was quantified using a NanoDrop spectrophometer and the quality was analyzed by agarose gel electrophoresis. Then each sample was subjected to polymerase chain reaction (PCR) to amplify the internal control gene GAPDH, thereby confirming the DNA intactness, which could be further utilized for other downstream applications. RESULTS: Of the five different methods tested, the third method wherein xylene was used for tissue deparaffinization followed by 72 h of digestion and without proteinase K inactivation yielded the highest amount of DNA with good purity. The yield was significantly higher when compared to other methods. In addition, 90% of the extracted DNA showed amplifiable GAPDH gene. CONCLUSION: Here we present a step-by-step, cost-effective, and reproducible protocol for the extraction of PCR-friendly DNA from archived H&E-stained cancer tissue slides that can be used for further downstream molecular applications.