The MUC4 mucin mediates gemcitabine resistance of human pancreatic cancer cells via the Concentrative Nucleoside Transporter family

Abstract

The fluorinated analog of deoxycytidine, Gemcitabine (Gemzar), is the main chemotherapeutic drug in pancreatic cancer, but survival remains weak mainly because of the high resistance of tumors to the drug. Recent works have shown that the mucin MUC4 may confer an advantage to pancreatic tumor cells by modifying their susceptibility to drugs. However, the cellular mechanism(s) responsible for this MUC4-mediated resistance is unknown. The aim of this work was to identify the cellular mechanisms responsible for gemcitabine resistance linked to MUC4 expression. CAPAN-2 and CAPAN-1 adenocarcinomatous pancreatic cancer (PC) cell lines were used to establish stable MUC4-deficient clones (MUC4-KD) by shRNA interference. Measurement of the IC 50 index using tetrazolium salt test indicated that MUC4-deficient cells were more sensitive to gemcitabine. This was correlated with increased Bax/Bcl XL ratio and apoptotic cell number. Expression of Equilibrative/Concentrative Nucleoside Transporter (hENT1, hCNT1/3), deoxycytidine kinase (dCK), ribonucleotide reductase (RRM1/2) and Multidrug-Resistance Protein (MRP3/4/5) was evaluated by quantitative RT-PCR (qRT-PCR) and western blotting. Alteration of MRP3, MRP4, hCNT1 and hCNT3 expression was observed in MUC4-KD cells, but only hCNT1 alteration was correlated to MUC4 expression and sensitivity to gemcitabine. Decreased activation of MAPK, JNK and NF-kB pathways was observed in MUC4-deficient cells, in which the NF-kB pathway was found to have an important role in both sensitivity to gemcitabine and hCNT1 regulation. Finally, and in accordance with our in vitro data, we found that MUC4 expression was conversely correlated to that of hCNT1 in tissues from patients with pancreatic adenocarcinoma. This work describes a new mechanism of PC cell resistance to gemcitabine, in which the MUC4 mucin negatively regulates the hCNT1 transporter expression via the NF-kB pathway. Altogether, these data point out to MUC4 and hCNT1 as potential targets to ameliorate the response of pancreatic tumors to gemcitabine treatment.

Contribution of DUSP28 to Regulation of Mucins in Human Pancreatic Cancer Cells

“…The need for a more-effective pancreatic cancer treatment strategy is urgent and the link between DUSP28 and MUC5B and MUC16 expression may enhance understanding of the development of malignant pancreatic cancer. MUC16 has been reported previously to be a key factor in pancreatic cancer malignancy [27,28]. However, we suggest the importance of MUC5B in pancreatic cancer cells for the first time and that MUC5B and MUC16 are involved more closely in human pancreatic cancer malignancy than previously recognized.…”

“…Several studies have suggested that mucins regulate the ERK1/2, p38, mTOR and c-Myc intracellular signalling pathways in pancreatic cancer cells. The regulation of MUC5B and MUC16 expression by DUSP28 therefore might affect various MAPK signalling pathways [15,27,28]. Silencing of MUC5B and MUC16 caused reduction of phospho-ERK1/2 levels compared with those of phospho-FAK.…”

“…With emerging recognition of the role of mucins in malignancy of tumors, it is becoming evident that pancreatic cancer cells exploit the properties of mucins to interact with their microenvironment, survive in an inhospitable local environment, and metastasise to distant sites [25]. Numerous reports have suggested that MUC1 [26], MUC4 [27], MUC16 [28] and MUC20 [29] expression is increased in pancreatic cancers. In agreement with previous reports, our results revealed that transcriptional levels of MUC1, MUC4, MUC16 and MUC20 were enhanced in pancreatic cancers; moreover, we further demonstrated unique overexpression of MUC5B at both the mRNA and protein levels in pancreatic cancer cells.…”

Licochalcone A, a Natural Inhibitor of c-Jun N-Terminal Kinase 1

“…Epidemiologic and biologic data show a clear association between chronic inflammatory conditions and subsequent malignant transformation (31). Colorectal cancer is an inflammatory bowel disease (32), and several studies showed that JNK signaling is critical for pancreatic cancer development (33,34). Recently, many dietary compounds have been recognized as potential anticancer agents.…”

Overcoming tumor cell chemoresistance using nanoparticles: lysosomes are beneficial for (stearoyl) gemcitabine-incorporated solid lipid nanoparticles

“…Chen et al that contribute to gemcitabine resistance include NF-κB, 114 heat shock proteins, and the presence of highly resistant tumor stem cells.…”