Fig. 5

High EREG expression in fibroblasts promotes tumor growth in vivo. a, Photographs of tumor formation in nude mice and tumor xenografts 4 weeks after inoculation. b & c, Tumor growth curves measured after injection of HSC3 cells or conditioned fibroblasts as indicated. The tumor volume was calculated every 7 days until termination. d-g, RT-PCR analysis of Ereg, Jak2, Stat3 and Il6 expression in tissues of resected tumors, revealing successful overexpression/interference of Ereg and associated upregulation or downregulation of Jak2, Stat3 and Il6. h, Immunohistochemical staining showed that tumors that developed from EREG-overexpressing NFs had a higher level of EREG, phospho-JAK2, phospho-STAT3, and IL-6 protein expression than tumors that developed from control NFs. Tumors that developed from siEREG-transfected CAFs showed a lower level of EREG, phospho-JAK2, phospho-STAT3, and IL-6 protein expression than tumors developed from siNC-transfected CAFs. S: stroma, T: tumor. Magnification: 200×. i & j, Western blotting showed that CAFs significantly promote EMT in vivo compared with NFs, with decreased E-cadherin expression and increased N-cadherin and vimentin expression. This EMT-promoting ability was attenuated after EREG knockdown. On the other hand, EREG overexpression in NFs gave NFs a CAF-like EMT-promoting ability. k, Increased EREG expression in NFs led to acquisition of the CAF phenotype in a JAK2-STAT3-dependent way and supported OSCC invasion through the promotion of EMT in tumor cells