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RENAL PROGENITOR CELLS PROTECT TUBULAR EPITHELIAL CELLS FROM CISPLATIN-INDUCED DAMAGE BY OVER-EXPRESSING THE CYP1B1 GENE Free

INTRODUCTION: Acute renal failure (ARF) is emerging as a public health problem worldwide and many studies recently focused their attention on the possibility of using human adult renal stem/progenitor cells (ARPCs) to improve regeneration in ARF. We previously found that tubular ARPCs (tARPCs) provided a protective effect on renal proximal tubular epithelial cells (RPTECs) by promoting proliferation and inhibiting apoptosis caused by cisplatin. Here we show an additional mechanism by which ARPCs can stop the cisplatin damaging effect.

METHODS: Gene expression profile was obtained from tARPCs and RPTECs by Agilent SurePrint G3 Human Gene Expression Microarrays. Genespring and R software were used for the analysis. Gene expression data were validated by Real-time PCR. Cell proliferation was determined using a BrdU assay. Immunohistochemical expression of activated caspase-3 was used as a marker of apoptosis in RPTECs.

RESULTS: With the aim to identify new genes involved in the ARPC protective and reparative effect, we performed a whole-genome gene expression analysis comparing RPTECs alone, RPTEC damaged by cisplatin and RPTEC damaged by cisplatin in co-culture with ARPCs. We identified 107 genes specifically modulated by RPTECs in response to cisplatin and, among these, 30 genes induced by ARPCs following the cisplatin damage. In particular, we found a strong upregulation of the CYP1B1 gene (false discovery rate corrected p value <0.05; fold change=4,1). This gene encodes a member of the cytochrome P450 superfamily of enzymes and the produced enzyme metabolizes procarcinogens, such as polycyclic aromatic hydrocarbons. CYP1B1 has been shown to be active within tumors and is also capable of metabolizing a structurally diverse range of anticancer drugs. It is responsible for the resistance to docetaxel, cisplatin, tamoxifen and nucleoside analogues. We found that It was expressed at low levels in RPTECs and in cisplatin damaged RPTECs. Moreover, four days after 2.5 µM exposure to cisplatin 2, RPTECs reduced the proliferation and undergo in apoptosis, as showed by caspase 3. However, in co-culture with ARPCs, CYP1B1 expression significantly increased, the apoptotic process was stopped and RPTECs increased their proliferation rate.

CONCLUSIONS: This is the first evidence of a cisplatin-induced overexpression of CYP1b1 in renal epithelial cells as a defense mechanism against cisplatin toxicity. This is consistent with our previous data showing that renal progenitors are resistant to cisplatin. The findings may have biological and clinical significance in terms of their implications in cellular communications and potential use of CYP1B1 as biomarkers for AKI induced by cisplatin or as protective agent.