Investigating the role of cancer-associated and normal fibroblasts in Nasopharyngeal Carcinoma (NPC) pathogenesis through modulation of Fibroblasts Growth Factor Receptor 4 (FGFR4)

• Main Author: Yap, Hooi Yeen *
• Format: Thesis
• Published: 2022
• Subjects: RC Internal medicine
• Online Access: http://eprints.sunway.edu.my/2449/
• Institution: Sunway University

NPC is a malignant arises from the epithelial cells of the nasopharynx, with higher prevalence concentrated around countries located in Southern China and Southeast Asia. In Malaysia, NPC is the fifth most common cancer overall, with higher incidence rate among men compared to women. NPC is separated into keratinising and non-keratinising epithelial carcinoma, with non-keratinising NPC being highly associated with Epstein-Barr virus (EBV) infection and is the most common type of NPC found in endemic areas. Tumour microenvironment in different cancer types have been previously studied and have shown to play an important role in modulating oncogenesis of cancer cells. Fibroblasts, specifically cancer-associated fibroblasts, are important component present in tumour microenvironment, playing a role in enhancing cancer cell pathogenesis by secreting soluble molecules and activating various signalling pathways. However, the role of fibroblasts in modulating NPC cells were not studied previously. This study aims to investigate the role of fibroblast in NPC pathogenesis through in vitro experiments. To investigate the role of fibroblasts on modulating NPC cell lines’ pathogenesis, conditioned media was collected from patient-derived fibroblasts to culture NPC cell line HONE1, and proliferation, migration, and invasion activities were measured. mRNA was then collected from HONE1 that were cultured in fibroblasts conditioned media and analysed to identify any potential genes that were significantly modulated by fibroblasts conditioned media. NPC cell lines were selected to study their FGFR4 expression in complete medium, and cell lines expressing FGFR4 were then selected to study their FGFR4 expression profile in various media, as well as inhibiting FGFR4 using siRNA. Cells treated with FGFR4 siRNA were then cultured again in fibroblasts conditioned media and their proliferation, migration, and invasion activities were determined.Experiments using fibroblasts conditioned media showed that NPC cell line HONE1 had elevated proliferation (~10x increase), migration (~2x increase), and significant increase in invasive marker expression, as well as higher metastatic activities (~2x increase). mRNA analysis of cells cultured in fibroblasts conditioned media demonstrated several significantly regulated genes, which point towards FGFR4 being a potential receptor that is playing a role in modulating NPC cell line’s pathogenesis. Experiments carried out on NPC cell lines showed that not all tested NPC cell lines expressed FGFR4, and cell lines such as HONE1 and C666-1 showed different FGFR4 expression profile when cultured in complete medium. Culturing both cell lines in various media including fibroblasts conditioned media resulted in HONE1 cells having similar FGFR4 expression profile compared to when cultured in complete medium, while C666-1 cells’ FGFR4 expression when cultured in conditioned media was comparable to those cultured in serum-free medium. HONE1 cells treated with FGFR4 siRNA showed reduced proliferation (~80% inhibition), migration, and significantly reduced invasive marker expression when both cells were cultured in fibroblasts conditioned media. Overall, the results from the present study suggest that fibroblasts could possibly secrete factors that modulated FGFR4, leading to enhanced NPC cell line HONE1’s proliferation, migration activity, and increased expression of invasion-associated proteins in HONE1. Further studies should be carried out to investigate the complete sequence of action for fibroblasts to promote NPC pathogenesis through FGFR4 modulation in vivo, as well as studying FGFR4 as a potential therapeutic target for treating NPC.