Effects of bone marrow-derived mesenchymal stem cells on doxorubicin-induced liver injury in rats.

Doxorubicin (DOX) is a potent chemotherapeutic agent and has toxic effects on various organs, including the liver. In the current study, we aimed to investigate the effects of bone-marrow-derived mesenchymal stem cell (BM-MSC) administration on DOX-induced hepatotoxicity in rats. 24 Wistar-albino rats were divided into three groups: Control, DOX, and DOX+MSC. DOX (20 mg/kg) was administered to the DOX group. In the DOX + MSC group, BM-MSCs (2 × 106 ) were given through the tail vein following DOX administration. DOX administration led to significant structural liver injury. Besides this, oxidative balance in the liver was impaired following DOX administration. DOX administration also led to an increase in apoptotic cell death in the liver. Structural and oxidative changes were significantly alleviated with the administration of BM-MSCs. Furthermore, BM-MSC administration suppressed excessive apoptotic cell death. Our findings revealed that BM-MSC administration may alleviate DOX-induced liver injury via improving the oxidative status and limiting apoptotic cell death in the liver tissue.

Oncogenic WIP1 phosphatase attenuates the DNA damage response and sensitizes p53 mutant Jurkat cells to apoptosis.

Wild-type (wt) p53-induced phosphatase 1 (Wip1), encoded by the protein phosphatase, Mg2+/Mn2+ dependent 1D (PPM1D) gene, is a serine/threonine phosphatase induced upon genotoxic stress in a p53-dependent manner. Wip1/PPM1D is frequently overexpressed, amplified and mutated in human solid tumors harboring wt p53 and is thus currently recognized as an oncogene. Oncogenic Wip1 dampens cellular stress responses, such as cell cycle checkpoints, apoptosis and senescence, and consequently increases resistance to anticancer therapeutics. Targeting Wip1 has emerged as a therapeutic strategy for tumors harboring wt p53. However, little is known about the efficacy of Wip1-targeted therapies in tumors lacking p53. The present study aimed to investigate the potential role of oncogenic Wip1 in p53 mutant (mt) Jurkat cells. In the present study, it was demonstrated that p53 mt Jurkat cells exhibited PPM1D/Wip1 gene amplification and expressed relatively high levels of Wip1, as confirmed by gene copy number and RNA expression analysis. In addition, Jurkat cells underwent G2 cell cycle arrest, apoptotic cell death and senescence in response to etoposide and doxorubicin, although the phosphorylation levels of DNA damage response (DDR) elements, including ataxia-telangiectasia mutated, ataxia-telangiestasia and Rad3-related, checkpoint kinase (Chk)1 and Chk2 were significantly low. Accordingly, the targeting of Wip1 phosphatase by RNA interference increased the phosphorylation of DDR elements, but decreased the rate of apoptosis in response to etoposide or doxorubicin in Jurkat cells. The induction of senescence or cell cycle arrest was not affected by the knockdown of Wip1. The results suggest that increased Wip1 expression enhances the apoptotic sensitivity of Jurkat cells in response to chemotherapeutic agents by attenuating DDR signaling. The present study highlights the possible pro-apoptotic role of Wip1 in a p53 mt T-cell acute lymphoblastic leukemia cell line. The data suggest the careful consideration of future treatment strategies aiming to manipulate or target Wip1 in human cancers lacking p53.