Lucidone inhibits autophagy and MDR1 via HMGB1/RAGE/PI3K/Akt signaling pathway in pancreatic cancer cells

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-2GEMR 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-2GEMR 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.

Lucidone suppresses dengue viral replication through the induction of heme oxygenase-1

Dengue virus (DENV) infection causes life-threatening diseases such as dengue hemorrhagic fever and dengue shock syndrome. Currently, there is no effective therapeutic agent or vaccine against DENV infection; hence, there is an urgent need to discover anti-DENV agents. The potential therapeutic efficacy of lucidone was first evaluated in vivo using a DENV-infected Institute of Cancer Research (ICR) suckling mouse model by monitoring body weight, clinical score, survival rate, and viral titer. We found that lucidone effectively protected mice from DENV infection by sustaining survival rate and reducing viral titers in DENV-infected ICR suckling mice. Then, the anti-DENV activity of lucidone was confirmed by western blotting and quantitative-reverse-transcription-polymerase chain reaction analysis, with an EC₅₀ value of 25 ± 3 μM. Lucidone significantly induced heme oxygenase-1 (HO-1) production against DENV replication by inhibiting DENV NS2B/3 protease activity to induce the DENV-suppressed antiviral interferon response. The inhibitory effect of lucidone on DENV replication was attenuated by silencing of HO-1 gene expression or blocking HO-1 activity. In addition, lucidone-stimulated nuclear factor erythroid 2-related factor 2 (Nrf2), which is involved in transactivation of HO-1 expression for its anti-DENV activity. Taken together, the mechanistic investigations revealed that lucidone exhibits significant anti-DENV activity in in vivo and in vitro by inducing Nrf2-mediated HO-1 expression, leading to blockage of viral protease activity to induce the anti-viral interferon (IFN) response. These results suggest that lucidone is a promising candidate for drug development.