TIMP1 down-regulation enhances gemcitabine sensitivity and reverses chemoresistance in pancreatic cancer

The therapeutic effect of gemcitabine (GEM) in pancreatic ductal adenocarcinoma (PDAC) is limited due to low drug sensitivity and high drug resistance. Tissue inhibitor of matrix metalloprotease 1 (TIMP1) is reportedly associated with GEM resistance in PDAC. However, the effect of TIMP1 down-regulation in combination with GEM treatment is unknown. We analyzed the expression of TIMP1 in human PDAC tissue using western blot, quantitative real-time polymerase chain reaction (qRT-PCR), and immunohistochemistry. TIMP1 was highly expressed in PDAC specimens. Kaplan-Meier survival analysis suggested that a higher level of TIMP1 was correlated with poorer overall survival in 103 PDAC patients. The mRNA and protein expression profiles of TIMP1 were explored in the HTERT-HPNE human pancreatic ductal epithelium cell line, five PDAC cell lines (MIA PaCa-2, PANC-1, BxPC-3, Capan2, and SW1990), and two GEM-resistant PDAC cell lines (MIA PaCa-2^R and PANC-1^R). Compared with HTERT-HPNE, TIMP1 was highly expressed in the PDAC cell lines. In addition, TIMP1 was upregulated in GEM-resistant PDAC cell lines compared with their parental cells. When TIMP1 was knocked-down using short hairpin RNA, GEM-induced cytotoxicity and Apoptosis were increased, while colony formation was repressed in MIA PaCa-2, PANC-1, and their GEM-resistant cells. When Bax was activated by BAM7 or Bcl-2 was inhibited by venetoclax, CCK-8 assays demonstrated that GEM sensitivity was restored in GEM-resistant cells. When Bax was down-regulated by siRNA, CCK-8 assays verified that GEM sensitivity was decreased in PDAC cells. The observations that TIMP1 knockdown enhanced GEM sensitivity and reversed chemoresistance by inducing cells Apoptosis indicated cooperative antitumor effects of shTIMP1 and GEM therapy on PDAC cells. The combination may be a potential strategy for PDAC therapy.