Figure 6
Erythropoietin increases xenograft tumor growth of human 786-O renal cell carcinoma cells. Xenograft tumors were established by subcutaneous injection of Caki-1 and 786-O cells into athymic nude mice (nu/nu). One day after cell injection, administration of rhEPO was initiated as described in Material and Methods. A, The tumor size was monitored over 10 wks and plotted as mean ± SEM from the two treatment groups per cell line (n = 10 per group). Treatment with rhEPO was associated with an increase in tumor burden among 786-O xenograft tumors. B, Representative pictures of 786-O tumors of H&E staining and IHC staining for EPO, phospho-EPOR, cyclin D1, p21cip1 and p27kip1 are shown. Original magnification, 200 ×. Scale bars, 100 μm. C, Proliferative index (%) was quantified based on Ki-67 staining of tumor xenografts of Caki-1 and 786-O. *, p < 0.05. D, Immunohistochemical localization of pimonidazole hydrochloride (Hypoxyprobe-1) adducts in subcutaneous tumors of Caki-1 and 786-O. Original magnification in right panels, 50 ×. Scale bars, 500 μm.