CANCER ASSOCIATED fiBROBLASTS (CAFS) INflUENCE TISSUE INVASION ON SALIVARY GLAND MUCOEPIDERMOID CARCINOMA (MEC) CELLS

Abstract

Objectives MEC is the most common salivary gland malignancy. Although prognosis is mostly based on TNM status, histologic grade is also used as a parameter to determine treatment. CAFs have been reported to influence worse behavior in several malignancies including head and neck squamous cell carcinoma. We noticed the presence of CAF-like cells, displaying immunohistochemical positivity for alpha smooth muscle actin, in some MECs with bad outcome and we hypothesize that CAFs may influence MEC aggressiveness. Therefore, we investigated tissue invasion using the organotypic 3D human leiomyoma model and cell migration using the Incucyte® system with a gel derived from human leiomyomas (myogel). MEC cell lines HMC2 and UTMUC1, derived from high grade tumors, were cultivated alone or co-cultured with CAFs in order to evaluate if CAFs would influence MEC cells invasion and migration. Cells were cultivated on top of human leiomyoma discs for 14 days to allow invasion. Discs were fixed in 10% buffered formalin, processed and 3 micrometer tissue slices were prepared and submitted to immunohistochemical reaction with a pan-cytokeratin antibody (clone AE1/AE3). The number of invasive cells was determined by counting invasive cells under light microscope. Invasion was studied using a wound scratch assay coupled with a live camera and data obtained was analyzed using software provided by the manufacturer. Findings Both MEC cell lines (HMC2 and UTMUC1) displayed a significant increase in tissue invasion when co-cultured with CAFs compared to when they were cultured alone. Only HMC2 cell line presented a significant increase in migration when co-cultured with CAFs. Conclusion CAFs significantly increase MEC cell lines invasion and migration. The presence of CAFs deserves further investigation in MEC tumor samples and it may correlate with tumor behavior and clinical outcome.