Emerging evidence indicates that intracellular calcium (Ca2+) levels and their regulatory proteins play essential roles in normal stem cell proliferation and differentiation. Cancer stem-like cells (CSCs) are subpopulations of cancer cells that retain characteristics similar to stem cells and play an essential role in cancer progression. Recent studies have reported that the Orai3 calcium channel plays an oncogenic role in human cancer. However, its role in CSC remains underexplored. In this study, we explored the effects of Orai3 in the progression and stemness of oral/oropharyngeal squamous cell carcinoma (OSCC). Orai3 expression was increased in a stepwise manner during the progression of OSCC. In addition, Orai3 was highly enriched in CSC populations of OSCC. Ectopic Orai3 expression in non-tumorigenic immortalized oral epithelial cells increased intracellular Ca2+ levels, acquiring malignant growth and CSC properties. Conversely, silencing of endogenous Orai3 in OSCC cells suppressed CSC phenotype, indicating a pivotal role of Orai3 in CSC regulation. Moreover, Orai3 markedly increased the expression of inhibitor of DNA binding 1 (ID1), a stemness transcription factor. Orai3 and ID1 were highly expressed in CSCs compared to non-CSCs, implying the functional importance of the Orai3/ID1 axis in CSC regulation. Furthermore, suppression of ID1 abrogated CSC phenotype in the cell with ectopic Orai3 overexpression and OSCC. Our study reveals that Orai3 is a novel functional CSC regulator in OSCC and further suggests that Orai3 plays an oncogenic role in OSCC by promoting cancer stemness via ID1 upregulation.

Oral cancer ranks sixth among Taiwan's top 10 cancers, and most patients with poor prognosis acquire metastases. The essential fatty acid alpha-linolenic acid (ALA) has been found to diminish many cancer properties. However, the anti-cancer activity of ALA in oral cancer has yet to be determined. Migration and invasion assays confirmed OSCC cells' EMT capabilities, whereas flow cytometry and Western blotting identified the molecular pathways. ALA dramatically reduced cell growth in a concentration dependent manner, according to the findings. Low concentrations of ALA (100 or 200 μM) inhibit colony formation, expression of Twist and EMT-related proteins, expression of MMP2/-9 proteins and enzyme activity, as well as cell migration and invasion. Treatment with high concentrations of ALA (200 or 400 μM) greatly increases JNK phosphorylation and c-jun nuclear accumulation, then upregulates the FasL/caspase8/caspase3 and Bid/cytochrome c/caspase9/caspase3 pathways, leading to cell death. Low concentrations of ALA inhibit SAS and GNM cell migration and invasion by suppressing Twist and downregulating EMT-related proteins, or by decreasing the protein expression and enzyme activity of MMP-2/-9, whereas high concentrations of ALA promote apoptosis by activating the JNK/FasL/caspase 8/caspase 3-extrinsic pathway and the Bid/cytochrome c/caspase 9 pathway. ALA demonstrates potential as a treatment for OSCC patients.

Background: PD1 and its ligand PD-L1 are related to the prognosis in many solid tumors, whether its role in oral squamous cell carcinoma (OSCC) remains unclear. Methods: Retrospective monocentric study including all patients with OSCC diagnosed and treated between 01/2020 and 05/2022. PD-L1 expression was assessed by combined positive score (CPS), considering CPS > or equal to 1 as positive (1-20 “low expression”, and ≥20 “high”). Descriptive analysis of patient cohort and tumors was performed, including tumor size, stage, lymph node involvement, recur-rence and survival. Results: 65 patients (65 tumors) were analyzed. 66.15% of tumors were ad-vanced stages (III-IV), of them, 97.67% PD-L1+ versus 71.42% within early stages (I-II). T4 tumors expressed PD-L1 in 100% of cases, compared with 54’54% in T1 tumors. 50.79 % of tumors showed lymph node involvement (pN+), 100% of them showing PD-L1+. Prevalence of pN+ was 59.38% for PD-L1 high expression versus 40.63% for low expression. Patients' follow-up ranged from 2 to 34.5 months. No significant difference was seen between overall survival (OS) and PD-L1 +/- (CPS ≥1 vs CPS <1) neither PD-L1 high (CPS ≥20) vs low CPS <20) (p 0.97 and 0.64, re-spectively). Conclusions: The method used to measure (laboratory test with Dako 22C3 an-ti-PD-L1 primary antibody) PD-L1 was reliable and accurate, with a correlation coefficient be-tween the PD-L1 expression in the biopsy and surgical piece of 0.83 (p 0.0001). CPS≥1 was ob-served in large tumors (p<0.001), and was correlated with of lymph node metastases (p<0.004). Further analysis of PD-L1 expression and its relevance in tumor biology and prognosis is needed.

Oral squamous cell carcinoma (OSCC) is one of the most prevalent human malignancies and a global health concern with a poor prognosis despite therapeutic advances, highlighting the need for a better understanding of its molecular background. The genomic landscape of OSCC is well-established and recent research has focused on miRNAs, which regulate gene expression and may be useful as non-invasive biomarkers. A plethora of findings regarding miRNA expression have been generated, posing challenges for their interpretation and identification of disease-specific molecules. Hence, we opted to identify the most important miRNA molecules by bridging genetics and epigenetics, focusing on the key genes implicated in OSCC development. Based on published reports, we have developed a custom panel of 15 major oncogenes and a second panel of 5 major tumor suppressor genes. Following a miRNA/target interaction analysis and a comprehensive study of the literature, we selected the miRNA molecules, which target the majority of each gene panel and are reported to be downregulated or upregulated in OSCC, respectively. As a result, miR-34a-5p, miR-155-5p, miR-124-3p, miR-1-3p and miR-16-5p appeared to be the most OSCC-specific. Their expressional patterns, their verified targets and the signaling pathways affected by their dysregulation in OSCC, are thoroughly discussed in this review.