The role of AMPK in pancreatic cancer: from carcinogenesis to treatment

Pancreatic cancer has doubled over the previous two decades. Routine therapies are becoming incredibly resistant and failing to compensate for the burden caused by this aggressive neoplasm. As genetic susceptibility has always been a highlighted concern for this disease, identifying the molecular pathways involved in the survival and function of pancreatic cancer cells provides insight into its variant etiologies, one of which is the role of AMPK. This regulating factor of cell metabolism is crucial in the homeostasis and growth of the cell. Herein, we review the possible role of AMPK in pancreatic cancer while considering its leading effects on glycolysis and autophagy. Then, we assess the probable therapeutic agents that have resulted from the suggested pathways. Studying the underlying genetic changes in pancreatic cancer provides a chance to detect and treat patients suffering from advanced stages of the disease, and those who have given up their hope on conventional therapies can gain an opportunity to combat this cancer.

Inhibiting CDK4/6 in pancreatic ductal adenocarcinoma via microRNA-21

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies, with a 5-year survival rate of 5-10 %. The high mortality rate is due to the asymptomatic progression of clinical features in metastatic stages of the disease, which renders standard therapeutic options futile. PDAC is characterised by alterations in several genes that drive carcinogenesis and limit therapeutic response. The two most common genetic aberrations in PDAC are the mutational activation of KRAS and loss of the tumour suppressor CDK inhibitor 2A (CDKN2A), which culminate the activation of the cyclin-dependent kinase 4 and 6 (CDK4/6), that promote G1 cell cycle progression. Therapeutic strategies focusing on the CDK4/6 inhibitors such as palbociclib (PD-0332991) may potentially improve outcomes in this malignancy. MicroRNAs (miRs/miRNAs) are small endogenous non-coding RNA molecules associated with cellular proliferation, invasion, apoptosis, and cell cycle. Primarily, miR-21 promotes cell proliferation and a higher proportion of PDAC cells in the S phase, while knockdown of miR-21 has been linked to cell cycle arrest at the G2/M phase and inhibition of cell proliferation. In this study, using a CRISPR/Cas9 loss-of-function screen, we individually silenced the expression of miR-21 in two PDAC cell lines and in combination with PD-0332991 treatment, we examined the synergetic mechanisms of CDK4/6 inhibitors and miR-21 knockouts (KOs) on cell survival and death. This combination reduced cell proliferation, cell viability, increased apoptosis and G1 arrest in vitro. We further analysed the mitochondrial respiration and glycolysis of PDAC cells; then assessed the protein content of these cells and revealed numerous Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with PD-0332991 treatment and miR-21 knocking out. Our results demonstrate that combined targeting of CDK4/6 and silencing of miR-21 represents a novel therapeutic strategy in PDAC.

Cellulose nanofibers as Scaffold-forming materials for thin film drug delivery systems

We explored the potential of cellulose nanofiber (CNF) for designing prolonged-release, thin-film drug delivery systems (TF-DDS). These delivery systems can be used as locally deployable drug-releasing scaffolds for achieving spatial and temporal control over therapeutic concentration in target tissues. Using doxorubicin (DOX) as a model anticancer drug, CNF-based TF-DDS were prepared using different film-formation processes, such as solvent casting and lyophilization. Formulations were prepared with or without the incorporation of additional macromolecular additives, such as gelatin, to include further biomechanical functionality. We studied the films for their mechanical properties, thermal stability, wettability, porosity and in vitro drug release properties. Our experimental results showed that CNF-based films, when prepared via solvent casting method, showed optimized performance in terms of DOX loading, and prolonged-release than those prepared via lyophilization-based fabrication processes. Scanning electron microscopy (SEM) analysis of the CNF-based films showed uniform distribution of fiber entanglement, which provided the scaffolds with sufficient porosity and tortuosity contributing to the sustained release of the drug from the delivery system. We also observed that surface layering of gelatin on CNF films via dip-coating significantly increased the mechanical strength and reduced the wettability of the films, and as such, affected drug release kinetics. The performance of the TF-DDS was evaluated in-vitro against two pancreatic cancer cell lines, i.e. MIA PaCa-2 and PANC-1. We observed that, along with the enhancement of mean dissolution time (MDT) of DOX, CNF-based TF-DDS were able to suppress the proliferation of pancreatic cancer cells in a time-dependent fashion, indicating that the drug liberated from the films were therapeutically active against cancer cells. Additionally, TF-DDS were also tested ex-vivo on patient-derived xenograft (PDX) model of pancreatic ductal adenocarcinoma (PDAC). We observed that DOX released from the TF-DDS was able to reduce Ki-67 positive, pancreatic cancer cells in these models.