Sunwang Xu

miR-145 sensitizes gallbladder cancer to cisplatin by regulating multidrug resistance associated protein 1

Gallbladder cancer (GBC) is the most common malignancy in biliary tract with poor prognosis. Due to its high chemoresistance, systemic chemotherapies have had limited success in treating GBC patients. MicroRNAs (miRNAs) are emerging novel regulators of chemoresistance, which modulate the expression of drug resistance-related genes. In this study, we investigated the association between miR-145 expression and cisplatin sensitivity by both in vivo and in vitro analysis. Quantitative PCR (q-PCR) analysis indicated an increased miR-145 expression in GBC tissues. In addition, studies on GBC cell lines suggested an increased cisplatin efficacy with miR-145 overexpression, whereas decreasing miR-145 expression reduced cisplatin sensitivity. Further, we found that miR-145 accelerated MRP1 mRNA degradation by directly targeting its 3′-UTR and therefore caused increased cisplatin toxicity in GBC cells. Moreover, lower miR-145 and higher MRP1 expression levels predicted poor prognosis in GBC patients who received chemotherapy. Collectively, our findings established a rationale for using miR-145 expression as a biomarker to identify cisplatin-resistant GBC patients and propose that treatment strategies increasing the expression of miR-145 could be a new therapeutic approach for GBC patients.

miR-125b-5p enhances chemotherapy sensitivity to cisplatin by down-regulating Bcl2 in gallbladder cancer

Gallbladder cancer represents the most common malignancy of the biliary tract and is highly lethal with less than 5% overall 5-year survival rate. Chemotherapy remains the major treatment for late-stage patients. However, insensitivity to these chemotherapeutic agents including cisplatin is common. MicroRNAs (miRNAs) have been shown as modulators of drug resistance in many cancer types. We used genome-wide gene expression analysis in clinical samples to identify miR-125b-5p down-regulated in gallbladder cancer. miR-125b-5p up-regulation promoted cell death in gallbladder cancer cells in the presence of cisplatin. In contrast, knockdown of miR-125b-5p reduced cell death in gallbladder cancer cells treated with cisplatin. Up-regulation of miR-125b-5p significantly decreased tumor growth in combination with cisplatin in a mouse model. We identified Bcl2 as a direct target of miR-125b-5p which mediates the function of miR-125b-5p in gallbladder cancer. In clinical samples, miR-125b-5p was down-regulated in gallbladder cancer whereas Bcl2 was up-regulated and their expression was inversely correlated. Moreover, low miR-125b-5p expression or high expression of Bcl2 is correlated with poor prognosis in gallbladder cancer. Taken together, our findings indicate that miR-125b-5p is a potent chemotherapy sensitizer and may function as a new biomarker for the prognosis of gallbladder cancer patients.

miR-92b-3p acts as a tumor suppressor by targeting Gabra3 in pancreatic cancer

BackgroundMicroRNAs (miRNAs) can act as oncogenes or tumor suppressors by controlling cell proliferation, differentiation, metastasis and apoptosis, and miRNA dysregulation is involved in the development of pancreatic cancer (PC). Our previous study demonstrated that Gabra3 plays critical roles in cancer progression. However, whether Gabra3 is regulated by miRNAs in PC remains unknown.MethodsThe expression levels of miR-92b-3p and Gabra3 were measured by quantitative PCR (qPCR), immunoblotting, in situ hybridization (ISH) and immunohistochemistry (IHC). The proliferation rate of PC cells was detected by MTS assay. Wound-healing and transwell assays were used to examine the invasive abilities of PC cells. Dual-luciferase reporter assays were used to determine how miR-92b-3p regulates Gabra3. Xenograft mouse models were used to assess the role of miR-92b-3p in PC tumor formation in vivo.ResultsHere, we provide evidence that miR-92b-3p acted as a tumor suppressor in PC by regulating Gabra3 expression. MiR-92b-3p expression levels were lower in PC tissues than corresponding noncancerous pancreatic (CNP) tissues and were associated with a poor prognosis in PC patients. MiR-92b-3p overexpression suppressed the proliferation and invasion of PC cells in both in vivo and in vitro models. Conversely, miR-92b-3p knockdown induced an aggressive phenotype in PC cells. Mechanistically, miR-92b-3p overexpression suppressed Gabra3 expression, which then led to the inactivation of important oncogenic pathways, including the AKT/mTOR and JNK pathways.ConclusionOur results suggest that miR-92b-3p acted as a tumor suppressor by targeting Gabra3-associated oncogenic pathways; these results provide novel insight into future treatments for PC patients.

miR-3656 expression enhances the chemosensitivity of pancreatic cancer to gemcitabine through modulation of the RHOF/EMT axis

The highly refractory nature of pancreatic cancer (PC) to chemotherapeutic drugs is one of the key reasons contributing to the poor prognosis of this disease. MicroRNAs (miRNAs) are key regulators of gene expression and have been implicated in a variety of processes from cancer development through to drug resistance. Herein, through miRNA profiling of gemcitabine-resistant (GR) and parental PANC-1 cell lines, we found a consistent reduction of miR-3656 in GR PANC-1 cells. miR-3656 overexpression enhanced the antitumor effect of gemcitabine, whereas silencing of miR-3656 resulted in the opposite effect. By performing mechanistic studies using both in vitro and in vivo models, we found that miR-3656 could target RHOF, a member of the Rho subfamily of small GTPases, and regulate the EMT process. Moreover, enforced EMT progression via TWIST1 overexpression compromised the chemotherapy-enhancing effects of miR-3656. Finally, we found significantly lower levels of miR-3656 and higher levels of RHOF in PC tissues compared with adjacent noncancerous pancreatic tissues, and this was also associated with poor PC patients’ prognosis. Taken together, our results suggest that the miR-3656/RHOF/EMT axis is an important factor involved in regulating GR in PC, and highlights the potential of novel miR-3656-based clinical modalities as a therapeutic approach in PC patients.

Epithelial-to-mesenchymal transition in gallbladder cancer: from clinical evidence to cellular regulatory networks

Gallbladder cancer (GBC), with late diagnosis, rapid disease progression and early metastasis, is a highly aggressive malignant tumor found worldwide. Patients with GBC have poor survival, low curative resection rates and early recurrence. For such a lethal tumor, uncovering the mechanisms and exploring new strategies to prevent tumor progression and metastasis are critically important. Epithelial-to-mesenchymal transition (EMT) has a prominent role in the early steps of tumor progression and metastasis by initiating polarized epithelial cell transition into motile mesenchymal cells. Accumulating evidence suggests that EMT can be modulated by the cooperation of multiple mechanisms affecting common targets. Signaling pathways, transcriptional and post-transcriptional regulation and epigenetic alterations are involved in the stepwise EMT regulatory network in GBC. Loss of epithelial markers, acquisition of mesenchymal markers and dysregulation of EMT-inducing transcription factors (EMT-TFs) have been observed and are associated with the clinicopathology and prognosis of GBC patients. Therefore, EMT may be a detectable and predictable event for predicting GBC progression and metastasis in the clinic. In this review, we will provide an overview of EMT from the clinical evidence to cellular regulatory networks that have been studied thus far in clinical and basic GBC studies.

PLZF inhibits proliferation and metastasis of gallbladder cancer by regulating IFIT2

Gallbladder cancer (GBC) is a malignant cancer with very poor prognosis. Although promyelocytic leukemia zinc-finger protein (PLZF) was reported to be deregulated in numerous cancers and also relevant to clinical prognosis, its role in GBC progression has been little known. In this study, we found PLZF expression was decreased in GBC, correlating to advanced TNM stage, distant metastasis, and shorter overall survival. Moreover, ectopic PLZF expression in GBC cells (NOZ and GBC-SD) significantly reduced the cell proliferation, migration, and invasion. Consistently, overexpression of PLZF in xenograft mice model could suppress tumor growth and liver metastasis. Mechanical investigations verified PLZF could regulate the expression of cell cycle arrest-associated gene p21 and epithelial–mesenchymal transition (EMT)-related genes (E-cadherin and N-cadherin) in GBC cell lines. Importantly, PLZF remarkably increased the mRNA transcription of interferon-induced protein with tetratricopeptide repeat 2 (IFIT2) by increasing STAT1 protein level, a known factor involved in tumor progression. Furthermore, ablation of IFIT2 in PLZF overexpression cells abrogated the tumor-suppressive function of PLZF, at least partially, leading to impaired tumor growth and EMT program. These studies indicated PLZF inhibited the proliferation and metastasis via regulation of IFIT2. In conclusion, our study demonstrated PLZF could be a promising tumor biomarker for GBC, and also be a potential therapeutic target.