PD-L1 has been widely demonstrated to contribute to failed antitumor immunity. Blockade of PD-L1 with monoclonal antibody could modulate the tumor immune environment to augment immunotherapy. PD-L1 expression is also detected in several types of cancer and is associated with poor prognosis. However, the prognostic role of PD-L1 in oral squamous cell carcinoma (OSCC) is still controversial. Our aim was to determine the role of PD-L1 in the prognosis of OSCC patients to identify its potential therapeutic relevance. PD-L1 immunoreactivity was analyzed by immunohistochemistry in 305 cancer specimens from primary OSCC patients. The medium follow-up time after surgery was 3.8 years (range from 0.1 to 11.1 years). The prognostic value of PD-L1 on overall survival was determined by Kaplan-Meier analysis and Cox proportional hazard models. Higher PD-L1 expression is more likely in tumor tissues of female than male OSCC patients (P = 0.0062). Patients with distant metastasis also had high PD-L1 expression (P = 0.0103). Multivariate analysis identified high PD-L1 expression as an independent risk factor in males and smokers (males: hazard ratio = 1.556, P = 0.0077; smokers: hazard ratio = 2.058, P = 0.0004). We suggest that PD-L1 expression, determined by IHC staining, could be an independent prognostic marker for OSCC patients who are male or who have a smoking habit.

Oxaliplatin (OXA), is a third generation platinum drug used as first-line chemotherapy in colorectal cancer (CRC). Cancer cells acquires resistance to anti-cancer drug and develops resistance. ATP-binding cassette (ABC) drug transporter ABCG2, one of multidrug resistance (MDR) protein which can effectively discharge a wide spectrum of chemotherapeutic agents out of cancer cells and subsequently reduce the intracellular concentration of these drugs. Role of ABCG2 and plausible molecular signaling pathways involved in Oxaliplatin-Resistant (OXA-R) colon cancer cells was evaluated in the present study. OXA resistant LoVo cells was developed by exposing the colon cells to OXA in a dose-dependent manner. Development of multi drug resistance in OXA-R cells was confirmed by exposing the resistance cells to oxaliplatin, 5-FU, and doxorubicin. OXA treatment resulted in G2 phase arrest in parental LoVo cells, which was overcome by OXA-R LoVo cells. mRNA and protein expression of ABCG2 and phosphorylation of NF-κB was significantly higher in OXA-R than parental cells. Levels of ER stress markers were downregulated in OXA-R than parental cells. OXA-R LoVo cells exposed to NF-κB inhibitor QNZ effectively reduced the ABCG2 and p-NF-κB expression and increased ER stress marker expression. On other hand, invasion and migratory effect of OXA-R cells were found to be decreased, when compared to parental cells. Metastasis marker proteins also downregulated in OXA-R cells. ABCG2 inhibitor verapamil, downregulate ABCG2, induce ER stress markers and induces apoptosis. In vivo studies in nude mice also confirms the same.