Defining sodium channel isoforms in oral squamous cell carcinoma in vitro

Overview: Sodium channels overexpression contributes to invasion and metastatic behavior and plays a functional role in cancer progression. Many knowledge gaps remain in voltage-gated sodium channels (VGSC's) subtype's role in metastasis, as well as distinguishing the difference of cancer progression of Oral Squamous Cell Carcinoma (OSCC) HPV(-) and HPV(+). Defining isoform-specific regulatory roles in OSCC may serve as potential targets for novel therapeutic treatments. The purpose of the study was to define VGSC isoforms regulating the cell growth, motility, and invasiveness in OSCC. Methods: To access sodium channel expression patterns and comparisons of components of metastasis, we used two OSCC cell lines, Cal-27 HPV(-) and SCC-090 HPV(+). We measured motility in wound healing, area progression of invasiveness, cell proliferation over time treated with TNF-alpha, and compared VGSC isoforms and organelle expression patterns using microscopy. Results: Motility rate for Cal-27 was significantly higher than SCC-090. When treated with TNF-alpha there was no significant difference relative to controls for either cell line. Invasiveness of Cal-27 exhibited significantly greater migration compared to SCC-090. Under low-glucose conditions, Cal-27 demonstrated a significant decrease in migration, whereas SCC-090 had no significant change. At 24 hours, there was no significant difference in cell growth of either cell line; however, by 48 hours, Cal-27 had a significantly higher growth. Both cell lines treated with TNF-alpha, demonstrated a concentration-dependent response, with SCC-090 showing a significant reduction in proliferation at higher concentrations. Immunofluorescence was performed for all VGCS isoforms (NaV1.1 - 1.9) and centrosome marker, anti-PCM-1. NaV1.6 and NaV1.7 display distinct expression patterns as punctate signals in both cell lines. In SCC-090 cells, PCM-1 expression closely resembled the NaV1.6/NaV1.7 localization. Conclusion: Cal-27 cells exhibited greater migratory and proliferative capacity than SCC-090, particularly evident through higher motility at 24 hours, increased migration, and proliferation by 48 hours. While TNF-alpha did not alter migration in either cell line, it produced a concentration-dependent decrease in proliferation, most notably in SCC-090. Metabolic stress further differentiated between the two lines: low glucose significantly impaired migration in Cal-27 but had no effect on SCC-090. Immunofluorescence revealed that NaV1.6 and NaV1.7 exhibited distinct punctate localization patterns in both cell lines. In SCC-090, this pattern closely aligned with PCM-1 staining. Together, these findings highlight functional and phenotypic differences between Cal-27 and SCC-090.