Cellular biology and gene expression in oral carcinoma-associated fibroblasts

Objectives: Oral carcinoma is one of the most common tumors in stomatological diseases. Oral fibroblasts stimulated invasion of oral-carcinoma cells into the collagen matrix. We studied cellular biology and carcinogenesis-associated gene expression of oral carcinoma-associated fibroblasts (CAFs) to investigate the role of CAFs in oral carcinoma. Methods: Invasive oral squamous cell carcinoma (OSCC) and their corresponding resection margins were obtained from 10 patients. The primary oral CAFs and normal mucosa fibroblasts (NMFs) from tissue culture were observed under light microscope and transmission electron microscope. α-SMA protein was detected by immunohistochemistry SP method on tissue slides. After 3-8 passages, Vimentin and Cytokeratin were measured by immunohistochemistry. VEGF, TGF-â1, MMP-9, Tenascin-C and IGFBP-3 mRNA were analyzed by semiquantitative RT-PCR. Results: The primary oral CAFs, haphazardly arranged and spindle-shaped, showed plump cigar-shaped nuclei and characteristic ‘tram-tracking' intracytoplasmic filament which mostly located in the vicinity of vessels. After 3 passages to purify oral CAFs and NMFs, different shape, haphazard growth style and higher growth rate was seen in CAFs compared to NMFs. Dentate nuclei, substantial rough endoplasmic reticulum and myofilament were observed in CAFs under the transmission electron microscope. Both á-SMA and Vimentin were detected in CAFs. In contrast, only Vimentin was seen in NMFs. Neither in CAFs nor in NMFs was cytokeratin detected. Moreover, VEGF, TGF-â1, MMP-9, Tenascin-C and IGFBP-3 mRNA were only detected in oral CAFs. Conclusions: CAFs showed different morphology and growth rate compared to NMFs. Moreover, carcinogenesis-associated genes were overexpressed in CAFs. It is likely that CAFs have some characteristics of tumor cells, which is supposed to be the result of interaction between oral CAFs and oral malignant epithelium cells. Oral CAFs produced more growth factores, cytokines, ECM and ECM modulators to form a favorable microenvironment for the survival and development of oral tumor cells.