Study On Differences In Regulation Of Angiogenesis Between Renal Adenocarcinoma Cells And Renal Tubular Epithelial Cells Under Hypoxia

Aims:Renal cell carcinoma(RCC)is characterized by excessive angiogenesis,while chronic kidney disease(CKD)suffers from the opposite problem-failure of reparative angiogenesis and a progressive loss of peritubular capillary.The difference in angiogenesis can be due to the different responses of renal carcinoma cells and renal tubular epithelial cells to their located hypoxic environment.But the specific molecular regulators are still unclear.Human RECK(Reversion-inducing cysteine-rich protein with Kazal motifs)may have a role because it regulates angiogenesis and inhibits cancer invasion.This study is aimed to explore the influence of human renal cell cancer cells(786-0)and human renal tubular epithelial cells(HK2)on RECK expression,proliferation and angiogenesis of adjacent microvascular endothelial cells(HMEC-1).Methods:Cobalt chloride(CoCl2)treatment was used to simulate the hypoxia environment in 786-0,HK2 and HMEC-1 cells.Co-culture,cell proliferation assay and tube formation assay were used to evaluate the influence of 786-0 or HK2 cells on proliferation and angiogenesis of adjacent HMEC-1 cells.Effects of different environments on RECK expressions in 786-0,HK2 or HMEC-1 cells were determined by western blot.Gelatin zymograpHy also be used to evaluate the activity of MMP2 and MMP9 in different co-culture systems.Results:We found that the effects of hypoxia on the endogenous expression of RECK and MMP2 are dramatically different depending on the considered cell type.The RECK expression was significantly decreased in 786-0 cells under hypoxia,while it was slightly increased in HK2 and HMEC-1 cells.The MMP2 expression was significantly increased in HMEC-1 cells under hypoxia,while it was slightly decreased in HK2 and 786-0 cells.In co-culture system,both 786-0 cells and HK2 cells can up-regulate RECK expression of adjacent HMEC-1 cells under normoxic conditions.However,under hypoxia,the HMEC-1 cells co-cultured with 786-0 significantly reduced RECK expression and there was no significant change in HMEC-1 cells co-cultured with HK2 cells.We also found that 786-0 significantly enhanced the proliferation and angiogenesis of adjacent HMEC-1 cells.The activity of MMP2 and MMP9 in the supernatant of co-culture system of 786-0 and HMEC-1 were significantly higher than that in the single culture of 786-0 or HMEC-1 cells.Conclusions:Our results showed that the mechanism of RECK modulation within 786-0 and HK2 cells may be different though they receive the same hypoxic signal.Some paracrine substances produced by 786-0 cells may reduce RECK expression of adjacent HMEC-1 cells and enhance their proliferation and in vitro angiogenic capacity.