No abstract

Gemcitabine (GEM) drug resistance causes high mortality rates and poor outcomes in pancreatic ductal adenocarcinoma (PDAC) patients. Receptor for advanced glycation end products (RAGE) involvement in the GEM resistance process has been demonstrated. Therefore, finding a safe and effective way to inhibit receptors for RAGE-initiated GEM resistance is urgent. Pterostilbene (PTE), a natural methoxylated analogue derived from resveratrol and found in grapes and blueberries, has diverse bioactivities, such as antioxidative, anti-inflammatory, and anticancer qualities. The overall research objective was to determine the potential of PTE to enhance tumor cytotoxicity and chemosensitivity in PDAC cells. Our results have demonstrated that PTE induced S-phase cell cycle arrest, apoptosis, and autophagic cell death and inhibited multidrug resistance protein 1 (MDR1) expression by downregulating RAGE/PI3K/Akt signaling in both MIA PaCa-2 and MIA PaCa-2 GEMR cells (GEM-resistant cells). Remarkably, convincing evidence was established by RAGE small interfering RNA transfection. Taken together, our study demonstrated that PTE promoted chemosensitivity by inhibiting cell proliferation and MDR1 expression via the RAGE/PI3K/Akt axis in PDAC cells. The observations in these experiments indicate that PTE may play a crucial role in MDR1 modulation for PDAC treatment.

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Gemcitabine (GEM) drug resistance remains a difficult challenge in pancreatic ductal adenocarcinoma (PDAC) treatment. Therefore, identifying a safe and effective treatment strategy for PDAC is urgent. Lucidone is a natural compound extracted from the fruits of Lindera erythrocarpa Makino. However, the role of lucidone in PDAC inhibition remains unclear. In addition, high-mobility group box 1 (HMGB1) and receptor for advanced glycation end products (RAGE) are involved in multidrug resistance protein 1 (MDR1) regulation and GEM resistance. Thus, this study aimed to explore the function of lucidone in tumor cytotoxicity and chemosensitivity through the suppression of RAGE-initiated signaling in PDAC cells. The data showed that lucidone significantly promoted apoptotic cell death and inhibited the expression of autophagic proteins (Atg5, Beclin-1, LC3-II, and Vps34) and MDR1 by inhibiting the HMGB1/RAGE/PI3K/Akt axis in both MIA Paca-2 cells and MIA Paca-2 GEMR cells (GEM-resistant cells). Notably, convincing data were also obtained in experiments involving RAGE-specific siRNA transfection. In addition, remarkable cell proliferation was observed after treatment with lucidone combined with GEM, particularly in MIA Paca-2 GEMR cells, indicating that lucidone treatment enhanced chemosensitivity. Collectively, this study provided the underlying mechanism by which lucidone treatment inhibited HMGB1/RAGE-initiated PI3K/Akt/MDR1 signaling and consequently enhanced chemosensitivity in PDAC.