Ozaki et al. BMC Cancer (2018) 18:309 https://doi.org/10.1186/s12885-018-4217-9 REVIEWARTICLE Open Access Impact of RUNX2 on drug-resistant human pancreatic cancer cells with p53 mutations Toshinori Ozaki1*†, Meng Yu2†, Danjing Yin3, Dan Sun4, Yuyan Zhu4, Youquan Bu5 and Meixiang Sang3 Abstract Background: Despite the remarkable advances in the early diagnosis and treatment, overall 5-year survival rate of patients with pancreatic cancer is less than 10%. Gemcitabine (GEM), a cytidine nucleoside analogue and ribonucleotide reductase inhibitor, is a primary option for patients with advanced pancreatic cancer; however, its clinical efficacy is extremely limited. This unfavorable clinical outcome of pancreatic cancer patients is at least in part attributable to their poor response to anti-cancer drugs such as GEM. Thus, it is urgent to understand the precise molecular basis behind the drug-resistant property of pancreatic cancer and also to develop a novel strategy to overcome this deadly disease. Review: Accumulating evidence strongly suggests that p53 mutations contribute to the acquisition and/or maintenance of drug-resistant property of pancreatic cancer. Indeed, certain p53 mutants render pancreatic cancer cells much more resistant to GEM, implying that p53 mutation is one of the critical determinants of GEM sensitivity. Intriguingly, runt-related transcription factor 2 (RUNX2) is expressed at higher level in numerous human cancers such as pancreatic cancer andosteosarcoma,indicatingthat,inadditiontoits pro-osteogenic role, RUNX2 has a pro-oncogenic potential. Moreover, a growing body of evidence implies that a variety of miRNAs suppress malignant phenotypes of pancreatic cancer cells including drug resistance through the down-regulation of RUNX2. Recently, we have found for the first time that forced depletion of RUNX2 significantly increases GEM sensitivity of p53-null as well as p53-mutated pancreatic cancer cells through the stimulation of p53 family TAp63/TAp73-dependent cell death pathway. Conclusions: Together, it is likely that RUNX2 is one of the promising molecular targets for the treatment of the patients with pancreatic cancer regardless of their p53 status. In this review article, we will discuss how to overcome the serious drug-resistant phenotype of pancreatic cancer. Keywords: Gemcitabine, Mutant p53, p53 family, RUNX2 Background the treatment of patients with advanced pancreatic can- Pancreatic cancer which is highly metastatic to lymph cer [3]. Unfortunately, its clinical efficacy is extremely nodes, liver and the other distal sites, is one of the most limited and the extensive efforts to develop the combin- lethal malignancies among human cancers with 5-year ation regimes with GEM have resulted in only a minor survival rate less than 10%, and its incidence is gradually improvement over the conventional therapies [4]. There- increasing worldwide [1]. Although 20% of patients re- fore, it is urgent to develop novel treatment options ceive surgical resection at diagnosis, the remaining 80% against pancreatic cancer, and also to understand the of patients are identified as unresectable due to their late precise molecular mechanisms how pancreatic cancer diagnosis [2]. Gemcitabine (GEM), a deoxycytidine cells could acquire and maintain GEM-resistant analogue, has become a standard chemotherapeutic for phenotype. As mentioned above, GEM resistance is a critical * Correspondence: [email protected] issue to be adequately addressed for the better treat- †Equal contributors ment of pancreatic cancer patients. Accumulating evi- 1 Laboratory of DNA Damage Signaling, Chiba Cancer Center Research dence strongly suggests that the alterations within Institute, Chiba 260-8717, Japan KRAS p53 CDKN2A SMAD4 Full list of author information is available at the end of the article , , and are frequently © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Ozaki et al. BMC Cancer (2018) 18:309 Page 2 of 15 detected in pancreatic cancer tissues, and contribute Main text to the genesis and/or maintenance of their advanced Pancreatic cancer phenotypes including GEM resistance [5]. Among Pancreatic cancer is ranked as the fourth leading cause these genetic aberrations, p53 mutations (around of cancer-related death in the world (both in industrial 75%) appear in the later stages of pancreatic cancer countries as well as nonindustrial ones), and is known to genesis and development [6, 7]. Since p53, which exhibit the worst prognosis among cancers (5-year sur- monitors and ensures the genomic integrity, is an es- vival rate is less than 10%) [24, 25]. Its mortality rate is sential molecular barrier against carcinogenesis [8, 9], nearly equal to its incidence. Up to 80% of pancreatic it is possible that loss of function mutation of p53 cancer deaths take place within the first year of diagno- leads to the accumulation of genetic damage within sis. Although surgical resection is the only potentially pancreatic cancer cells, and thus they might acquire curative approach against pancreatic cancer, greater than GEM-resistant property as well as metastatic 80% of cases are judged as unresectable at the time of potential. diagnosis due to its locally advanced property and/or RUNX2 (also called Osf2/Cbfa1, AML-3 or Peb- metastasis. A highly invasive and metastatic nature of p2αA), a member of RUNX (runt-related transcription the advanced pancreatic cancer is often responsible for factor) family, has been shown to be one of the major its extremely poor clinical outcome. Therefore, it is ur- determinants of osteoblast differentiation and bone gently required to identify the reliable diagnostic and/or formation [10]. As expected, RUNX2 transactivates prognostic markers. These biomarkers could be helpful number of pro-osteogenic target genes such as colla- to the accurate detection of pancreatic cancer in the gen type I, bone alkaline phosphatase, osteopontin early stage, and the prediction of its biological behavior. and osteocalcin [11]. In addition to its pro-osteogenic Because of the low chance of successful surgery, role,agrowingbodyofevidencestronglysuggests chemotherapy is the most common approach to ex- that RUNX2 plays a vital role in tumor initiation, tend the survival time of pancreatic cancer patients. progression, invasion and metastasis. From the clinical For advanced pancreatic cancer patients, a deoxycyti- point of view, the elevated expression level of RUNX2 dine analogue termed gemcitabine (GEM) (2′,2′- has been shown to correlate to poor prognosis of pa- difluorodeoxycytidine) has been considered to be the tients with pancreatic cancer or with thyroid cancer first choice as a front-line chemotherapy based on the [12, 13]. In support of these observations, it has been results of the Phase III trial [26, 27]. The cytotoxicity described that RUNX2 regulates numerous genes im- of GEM relies on its ability to promote cancer cell plicated in carcinogenesis including MMP9 death. Similar to the related nucleoside analog termed (matrixmetalloproteinase-9), MMP13 (matrixmetallo- cytarabine (Ara-C) [28], GEM is taken up within pan- proteinase-13),VEGF (vascular endothelial growth fac- creatic cancer cells through equilibrative nucleoside tor) and survivin [14–16]. Furthermore, Pratap et al. transporter-1 (hENT1) [29], and subjected to deoxycy- found that RUNX2 promotes invasion of bone tidine kinase (dCK)-mediated phosphorylation to be- metastatic cancer cells through the induction of come an active form (dFdCTP). dFdCTP is then MMP9, and also stimulates the early events of breast incorporated at the end of the elongating DNA cancer progression [17, 18]. Recently, we have de- strand, terminates DNA replication process, and scribed for the first time that siRNA-mediated knock- thereby inducing DNA fragmentation (cancer cell down of RUNX2 increases adriamycin (ADR) death) [30]. In addition to the advanced pancreatic sensitivity of p53-wild-type osteosarcoma cells cancer, GEM is also utilized to treat patients with the through the activation of p53 family-dependent cell other serious diseases such as non-small-lung cell, death pathway [19, 20]. Our subsequent studies breast, bladder, gastric and ovarian cancers. However, revealed that depletion of RUNX2 improves GEM theresponserateofGEMmonotherapyislowand sensitivity of pancreatic cancer cells regardless of their the improvement of 5-year survival rate is unsatisfied p53 status [21–23]. (less than 6 months) [31].TheefficacyofGEMisless In this review article, we provide a brief overview of than 20% of treated patients, and almost all the pa- the molecular basis behind drug-resistant phenotype of tients eventually become resistant to GEM [31]. pancreatic cancer cells, and also describe p53 family- Subsequently, the extensive studies to improve the un- dependent cell death pathway in response to DNA dam- favorable clinical outcome of the advanced pancreatic age. Subsequently, we summarize the current under- cancer patients by GEM-based combination