Improvement of gemcitabine sensitivity of p53-mutated pancreatic cancer MiaPaCa-2 cells by RUNX2 depletion-mediated augmentation of TAp73-dependent cell death.
Pancreatic cancer exhibits the worst prognostic outcome among human cancers. Recently, we have described that depletion of RUNX2 enhances gemcitabine (GEM) sensitivity of p53-deficient pancreatic cancer AsPC-1 cells through the activation of TAp63-mediated cell death pathway. These findings raised a question whether RUNX2 silencing could also improve GEM efficacy on pancreatic cancer cells bearing p53 mutation. In the present study, we have extended our study to p53-mutated pancreatic cancer MiaPaCa-2 cells. Based on our current results, MiaPaCa-2 cells were much more resistant to GEM as compared with p53-proficient pancreatic cancer SW1990 cells, and there existed a clear inverse relationship between the expression levels of TAp73 and RUNX2 in response to GEM. Forced expression of TAp73α in MiaPaCa-2 cells significantly promoted cell cycle arrest and/or cell death, indicating that a large amount of TAp73 might induce cell death even in the presence of mutant p53. Consistent with this notion, overexpression of TAp73α stimulated luciferase activity driven by p53/TAp73-target gene promoters in MiaPaCa-2 cells. Similar to AsPC-1 cells, small interfering RNA-mediated knockdown of RUNX2 remarkably enhanced GEM sensitivity of MiPaCa-2 cells. Under our experimental conditions, TAp73 further accumulated in RUNX2-depleted MiaPaCa-2 cells exposed to GEM relative to GEM-treated non-silencing control cells. As expected, silencing of p73 reduced GEM sensitivity of MiPaCa-2 cells. Moreover, GEM-mediated Tyr phosphorylation level of TAp73 was much more elevated in RUNX2-depleted MiaPaCa-2 cells. Collectively, our present findings strongly suggest that knockdown of RUNX2 contributes to a prominent enhancement of GEM sensitivity of p53-mutated pancreatic cancer cells through the activation of TAp73-mediated cell death pathway, and also provides a promising strategy for the treatment of patients with pancreatic cancer bearing p53 mutation.
Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, Chiba, Japan.
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Nakamura
Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, Chiba, Japan.
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Sugimoto
Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, Chiba, Japan.
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Ogata
Laboratory of Cancer Genetics, Chiba Cancer Center Research Institute, Chiba, Japan.
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Hiraoka
Laboratory of Cancer Genetics, Chiba Cancer Center Research Institute, Chiba, Japan.
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Yoda
Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, Chiba, Japan.|Department of Regenerative Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan.
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Sang
Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, Chiba, Japan.|Research Center, Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei province, P.R. China.
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Sang
Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, Chiba, Japan.|Department of Urology, First Hospital of China Medical University, Shenyang, Liaoning Sheng province, P.R. China.
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Zhu
Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, Chiba, Japan.|Department of Laboratory Animal of China Medical University, Shenyang, Liaoning Sheng province, P.R. China.
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Yu
Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, Chiba, Japan.
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Shimozato
Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, Chiba, Japan.
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http://orcid.org/0000-0002-1612-7394
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Ozaki