Deepening Cisplatin sensitivity on Oral Squamous cell Carcinoma cell lines after PON2 knockdown: A FTIRM investigation

Cisplatin is a platinum-based chemotherapy drug with antimicrobial and antitumoral activity, largely used for a long time in the treatment of several cancers, including the Oral Squamous Cell Carcinoma (OSCC), which is one of the most frequent neoplasms of the oral cavity. Due to its aggressiveness and metastatic invasion, OSCC is characterized by poor outcome, often related also to chemoresistance mechanisms. The intracellular enzyme paraoxonase-2 (PON2) normally acts defending cells from the damages induced by Reactive Oxygen Species. Hence, in cancer cells, this enzyme can shield the potential of cisplatin, triggering a resistance mechanism. Based on this evidence, PON2 knockdown seems to be a valuable way to enhance the effects of chemotherapy, escaping this resistance. In this study, HOC621 and HSC-3 OSCC cell lines submitted to PON2 silencing were analyzed by Fourier Transform Infrared Microspectroscopy to evaluate the time-dependent changes occurring in these cells after cisplatin treatment. Spectral data were statistically analyzed by multivariate and univariate analyses and compared with MTT results. Positive feedback on cisplatin efficacy was found in both cell lines submitted to PON2 knockdown, even if with a different response. In particular, a less growth was found in PON2 silenced HOC 621 cells, respect to HSC-3 ones. Moreover, specific spectral markers (A₁₁₇₂/A_TOT, A₁₀₅₃/A_TOT, A₉₆₇/A₁₀₈₀, and A₉₉₂/A_TOT band area ratios) were identified and statistically analyzed (p < 0.05): cellular alterations mainly in nucleic acids and carbohydrates were found in both cell lines, although more evident in HOC 621 ones, which therefore appeared to be more affected by chemotherapy treatment.