MicroRNA-21 in Pancreatic Cancer: Correlation with Clinical Outcome and Pharmacologic Aspects Underlying Its Role in the Modulation of Gemcitabine Activity

Abstract

MicroRNA-21 (miR-21) was reported to be overexpressed and contributes to invasion and gemcitabine resistance in pancreatic ductal adenocarcinoma (PDAC). The aim of this study was to evaluate whether miR-21 expression was associated with the overall survival (OS) of PDAC patients treated with gemcitabine and to provide mechanistic insights for new therapeutic targets. miR-21 expression was evaluated in cells (including 7 PDAC cell lines, 7 primary cultures, fibroblasts, and a normal pancreatic ductal cell line) and tissues (neoplastic specimens from 81 PDAC patients and normal ductal samples) isolated by laser microdissection. The role of miR-21 on the pharmacologic effects of gemcitabine was studied with a specific miR-21 precursor (pre-miR-21). Patients with high miR-21 expression had a significantly shorter OS both in the metastatic and in the adjuvant setting. Multivariate analysis confirmed the prognostic significance of miR-21. miR-21 expression in primary cultures correlated with expression in their respective tissues and with gemcitabine resistance. Pre-miR-21 transfection significantly decreased antiproliferative effects and apoptosis induction by gemcitabine, whereas matrix metalloproteinase (MMP)-2/MMP-9 and vascular endothelial growth factor expression were upregulated. Addition of inhibitors of phosphoinositide 3-kinase and mammalian target of rapamycin resulted in decrease of phospho-Akt and prevented pre-miR-21-induced resistance to the proapoptotic effects of gemcitabine. miR-21 expression correlated with outcome in PDAC patients treated with gemcitabine. Modulation of apoptosis, Akt phosphorylation, and expression of genes involved in invasive behavior may contribute to the role of miR-21 in gemcitabine chemoresistance and to the rational development of new targeted combinations. Cancer Res; 70(11); 4528-38. ©2010 AACR.

Development of bioluminescent chick chorioallantoic membrane (CAM) models from primary pancreatic cancer cells: A platform for drug testing

“…Collection of samples was performed in accordance with the relevant guidelines and regulations. Following tissue acquisition, we utilized a modified protocol based on a previously validated method 46 . Non necrotic areas of the excised tumors were minced into 1-mm 3 cubes and subsequently rinsed in a solution (1 mg/ml) of type XI Collagenase (SigmaAldrich, Zwijndrecht, The Netherlands) in primary tissue culture plates (PRIMARIA TM Tissue Culture Flask, Becton Dickinson, NJ) and RPMI-1640 medium (Lonza, Verviers, Belgium), supplemented with 10% heat-inactivated fetal bovine serum (FBS) and 1% streptomycin/penicillin (Gibco, Gaithersburg, MD), and maintained at 37 °C in a humidified incubator.…”

“…Furthermore, we included in our analysis two miRNAs that have been commonly associated with PDAC pathogenesis and gemcitabine chemoresistance, namely miR-155 and miR-21 46,50 .…”

Epigenetic markers for chemosensitivity and chemoresistance in pancreatic cancer—A review

“…[102][103][104] Several publications have shown that inhibition of oncogenic miRNAs such as miRNA-21 or reactivation of tumor suppressive miRNAs such as miRNA-34 can sensitize PC cells to gemcitabine chemotherapy. [76][77][78][79][80][81] These results suggest that specific targeting of miRNAs by a variety of approaches could open new avenues for PC treatment by overcoming drug resistance and thus improving PCoutcome. [105][106][107][108] Conclusions Overall, these results are highly encouraging and outline various starting points for new treatment strategies.…”

“…Overexpression of miRNA-21 leads to downregulation of the tumor suppressor gene phosphatase and tensin homologue deleted on chromosome 10 (PTEN) through activation of the PI3K/Akt-dependent pathway, rendering the cancer cells less susceptible to apoptosis. 76 PTEN is an established negative regulator of the antiapoptotic proto-oncogene Akt, inducing downregulation of miRNA-21. Reciprocally, Akt-inducing upregulation of miRNA-21 inhibits PTEN.…”

150 MicroRNA-199a and 214 as potential therapeutic targets in pancreatic stellate cells in pancreatic tumor

“…Dysregulation of miRNA in stromal cells has received a huge attention for the potential therapeutic and diagnostic targets in cancer [26][27][28][29]. Several altered miRNAs such as miR-21, miR-143, and miR-210 have shown therapeutic significance on pancreatic tumor growth [30][31][32].…”