Regulation of metabolism in pancreatic ductal adenocarcinoma via nanotechnology-enabled strategies

Pirfenidone Antagonizes TGF-β1-Mediated Gabapentin Resistance via Reversal of Desmoplasia and the 'Cold' Microenvironment in Pancreatic Cancer

Owing to the desmoplastic stroma constituted by cancer-associated fibroblasts (CAFs), few immune cells infiltrate the pancreatic ductal adenocarcinoma (PDAC). Gabapentin can impede the production of ketoacids by CAFs to support cancer cells. However, in our study, we discovered a dose-dependent increase in transforming growth factor β1 (TGF-β1) levels in cancer cells in response to gabapentin. This reverse increase of TGF-β1 contributes to 'Gabapentin-resistance', leading to the antitumor effects on PDAC cell lines are negatively negotiated in the presence of pancreatic stellate cells. Pirfenidone synergistically inhibited the growth and apoptosis resistance of PDAC when combined with Gabapentin. In a mouse orthotopic PDAC model, Fe3+-mediated coordination nanodrugs, which contain gabapentin, pirfenidone and the natural polyphenol (EGCG), efficiently promoted the infiltration of naïve CD8+ T cells (CD44lowCD62Lhigh) and the accumulation of inflammatory CAFs (α-SMAlowIL-6high). This led to a nearly two-fold increase in survival compared to the control. Furthermore, we identified a new subpopulation as Hmox1highiCAFs following treatment with our nanodrugs. Hmox1highiCAFs overexpressed the Cxcl10 receptor (Sdc4) and facilitated functional CD8+ T-cell infiltration through the Tnfsf9-Tnfrsf9 axis. Overall, our nanodrugs reshape the phenotype of CAFs and enhance functional CD8+ T-cell infiltration into tumors, holding the potential to be a safe and promising therapy for PDAC.

The new era of pancreatic cancer treatment: Application of nanotechnology breaking through bottlenecks

Since the advent of nanomedicine, physicians have harnessed these approaches for the prophylaxis, detection, and therapy of life-threatening diseases, particularly cancer. Nanoparticles have demonstrated notable efficacy in cancer therapy, showcasing the primary application of nanotechnology in targeted drug delivery. Pancreatic cancer stands out as the most lethal solid tumour in humans. The low survival rate is attributed to its highly aggressive nature, intrinsic resistance to chemotherapeutics, and the lack of successful therapies, compounded by delayed diagnosis due to nonspecific symptoms and the absence of rapid diagnostic strategies. Despite these challenges, nanotechnology-based carrier methods have been successfully employed in imaging and therapy approaches. Overcoming drug resistance in pancreatic cancer necessitates a comprehensive understanding of the microenvironment associated with the disease, paving the way for innovative nanocarriers. Hindered chemotherapy infiltration, attributed to inadequate vascularization and a dense tumour stroma, is a major hurdle that nanotechnology addresses. Intelligent delivery techniques, based on the Enhanced Permeability and Retention effect, form the basis of recently developed anticancer nanocarriers. These advancements aim to enhance drug accumulation in tumour locations, offering a potential solution to the treatment-resistant nature of cancer. Addressing the challenges in pancreatic cancer treatment demands innovative therapies, and the emergence of active nanocarriers presents a promising avenue for enhancing outcomes. This review specifically delves into the latest advancements in nanotechnology for the treatment of pancreatic cancer.

Fatty acids abrogate the growth-suppressive effects induced by inhibition of cholesterol flux in pancreatic cancer cells

BACKGROUND

Despite therapeutic advances, the prognosis of pancreatic ductal adenocarcinoma (PDAC) remains extremely poor. Metabolic reprogramming is increasingly recognized as a key contributor to tumor progression and therapy resistance in PDAC. One of the main metabolic changes essential for tumor growth is altered cholesterol flux. Targeting cholesterol flux appears an attractive therapeutic approach, however, the complex regulation of cholesterol balance in PDAC cells remains poorly understood.

METHODS

The lipid content in human pancreatic duct epithelial (HPDE) cells and human PDAC cell lines (BxPC-3, MIA PaCa-2, and PANC-1) was determined. Cells exposed to eight different inhibitors targeting different regulators of lipid flux, in the presence or absence of oleic acid (OA) stimulation were assessed for changes in viability, proliferation, migration, and invasion. Intracellular content and distribution of cholesterol was assessed. Lastly, proteome profiling of PANC-1 exposed to the sterol O-acyltransferase 1 (SOAT1) inhibitor avasimibe, in presence or absence of OA, was performed.

RESULTS

PDAC cells contain more free cholesterol but less cholesteryl esters and lipid droplets than HPDE cells. Exposure to different lipid flux inhibitors increased cell death and suppressed proliferation, with different efficiency in the tested PDAC cell lines. Avasimibe had the strongest ability to suppress proliferation across the three PDAC cell lines. All inhibitors showing cell suppressive effect disturbed intracellular cholesterol flux and increased cholesterol aggregation. OA improved overall cholesterol balance, reduced free cholesterol aggregation, and reversed cell death induced by the inhibitors. Treatment with avasimibe changed the cellular proteome substantially, mainly for proteins related to biosynthesis and metabolism of lipids and fatty acids, apoptosis, and cell adhesion. Most of these changes were restored by OA.

CONCLUSIONS

The study reveals that disturbing the cholesterol flux by inhibiting the actions of its key regulators can yield growth suppressive effects on PDAC cells. The presence of fatty acids restores intracellular cholesterol balance and abrogates the alternations induced by cholesterol flux inhibitors. Taken together, targeting cholesterol flux might be an attractive strategy to develop new therapeutics against PDAC. However, the impact of fatty acids in the tumor microenvironment must be taken into consideration.