Multidrug resistance protein 5 affects cell proliferation, migration and gemcitabine sensitivity in pancreatic cancer MIA Paca‑2 and PANC‑1 cells

Gemcitabine‑based chemotherapy has been widely adopted as the standard and preferred chemotherapy regimen for treating advanced pancreatic cancer. However, the contribution of multidrug resistance protein 5 (MRP5) to gemcitabine resistance and pancreatic cancer progression remains controversial. In the present study, the effect of silencing MRP5 on gemcitabine resistance and cell proliferation and migration of human pancreatic cancer MIA Paca‑2 and PANC‑1 cells was investigated by using short‑hairpin RNA delivered by lentiviral vector transduction. The knockdown of MRP5 was confirmed on both mRNA and protein levels using qPCR and surface staining assays, respectively. MRP5‑regulated gemcitabine sensitivity was assessed by MTT, PrestoBlue and apoptosis assays. The effect of MRP5 on pancreatic cancer cell proliferation and migration was determined using colony‑formation, wound‑healing and Transwell migration assays. The interaction of gemcitabine and cyclic guanosine monophosphate (cGMP) with MRP5 protein was explored using molecular docking. The results indicated that the MRP5 mRNA and protein levels were significantly reduced in all the MIA Paca‑2 and PANC‑1 clones. MRP5 affected gemcitabine cytotoxicity and the rate of gemcitabine‑induced apoptosis. Silencing MRP5 decreased cell proliferation and migration in both MIA Paca‑2 and PANC‑1 cells. Docking studies showed high binding affinity of cGMP towards MRP5, indicating the potential of MRP5‑mediated cGMP accumulation in the microenvironment. In conclusion, MRP5 has an important role in cancer proliferation and migration in addition to its drug efflux functions in two widely available pancreatic tumour cell lines (MIA Paca‑2 and PANC‑1).

Application of CRISPR-Cas9 System to Study Biological Barriers to Drug Delivery

In recent years, sequence-specific clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) systems have been widely used in genome editing of various cell types and organisms. The most developed and broadly used CRISPR-Cas system, CRISPR-Cas9, has benefited from the proof-of-principle studies for a better understanding of the function of genes associated with drug absorption and disposition. Genome-scale CRISPR-Cas9 knockout (KO) screen study also facilitates the identification of novel genes in which loss alters drug permeability across biological membranes and thus modulates the efficacy and safety of drugs. Compared with conventional heterogeneous expression models or other genome editing technologies, CRISPR-Cas9 gene manipulation techniques possess significant advantages, including ease of design, cost-effectiveness, greater on-target DNA cleavage activity and multiplexing capabilities, which makes it possible to study the interactions between membrane proteins and drugs more accurately and efficiently. However, many mechanistic questions and challenges regarding CRISPR-Cas9 gene editing are yet to be addressed, ranging from off-target effects to large-scale genetic alterations. In this review, an overview of the mechanisms of CRISPR-Cas9 in mammalian genome editing will be introduced, as well as the application of CRISPR-Cas9 in studying the barriers to drug delivery.