OBJECTIVETo investigate the role of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in regulating both angiogenesis and the expressions of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and vascular endothelial growth factor (VEGF)/Flk-1 expression in human proximal tubular epithelial cells (HKC).

METHODSHKC cells were transfected with two recombinant plasmids containing sense and antisense full-length TIMP-1 cDNA (TIMP-1S-pcDNA3.0 and TIMP-1AS-pcDNA3.0, respectively) constructed previously, or treated with 100 µmol/L MMP-2/MMP-9 inhibitor III (with similar cellular enzyme suppression activity with sense TIMP-1 plasmid). The mRNA expression of TIMP-1, MMP-2, MMP-9, PTEN, VEGF and Flk-1 were examined by RT-PCR. In each group, the expression of PTEN, VEGF and Flk-1 were also detected using an indirect immunofluorescence assay.

RESULTSCompared with non-transfected cells and cells transfected with the empty vector, sense TIMP-1-transfected cells showed obviously upregulated PTEN expression (P<0.05) and significantly lowered gelatinase activity (P<0.05) and VEGF and Flk-1 expressions (P<0.05). Transfection with the antisense TIMP-1 plasmid produced the reverse results (P<0.05). MMP-2/MMP-9 inhibitor III did not obviously affected the expression of PTEN, VEGF or Flk-1 as compared with the non-transfected or empty vector-transfected cells.

CONCLUSIONIn the aging progress, the renal tissues express high levels of TIMP-1 to upregulate PTEN expression via a MMP-independent pathway, and subsequently down-regulates the expression of VEGF and Flk-1 to cause aging-related impairment of renal angiogenesis. These findings provide new evidence for understanding the role of TIMP-1 in renal aging.