Downregulation of IL-6 in tumor-associated endothelial cells reduces tumor cell proliferation and decreases intratumoral microvessel density.
A, immunohistochemical analysis for Ki67, indicating tumor cell proliferation in implants containing HeLa and HDMEC-shRNA-C, or HeLa and HDMEC-shRNA-IL-6. Top panels represent 100× and bottom panels represent 200×. B, quantification of tumor cell proliferation determined by scoring Ki67 immunostaining. Data represent mean values obtained in random microscopic fields (100×) from 12 tumors per condition. Asterisk depicts p < 0.05. C, immunohistochemistry for Factor VIII depicting blood vessels (100×). Left panel shows a representative tumor populated with HeLa and HDMEC-shRNA-C, and right panel shows a tumor containing HeLa and HDMEC-shRNA-IL-6. D, quantification of the microvessel density in these tumors. Data represent mean values obtained in 10 random microscopic fields per implant (100×) from 12 tumors per condition. Asterisk depicts p < 0.05. Red arrows point to blood vessels.