In vitro effect of Pleurotus ferulatus total triterpenoids, oleanolic acid and paclitaxel on colon cancer

Objective To investigate the effects of ethyl acetate phase of Pleurotus ferulatus triterpenoid component (PFTP-E), oleanolic acid (OA) and paclitaxel (PTX) on growth inhibition and possible regulation mechanisms of colon cancer cells HCT116 and CT26. Methods Ultraviolet and infrared spectroscopy was used to analyze the component of PFTP-E. MTT assay was used to detect the proliferation of HCT116 and CT26 cells by PFTP-E, OA and PTX in vitro. Apoptosis was observed by Hoechst 33258 staining. Flow cytometry was used to detect apoptosis, cell cycle, mitochondrial membrane potential and intracellular ROS. Western Blot were used to detect the expressions of apoptosis-related proteins B cell lymphoma-2 (Bcl-2), BCL2 associated X protein (Bax), poly(adenosine diphosphate-ribose) polymerase (PARP), Caspase-3, Caspase-9, cell cycle related proteinB1 (Cyclin B1), endoplasmic reticulum stress-related proteins glucose-regulated protein 78 (GRP78), protein kinase R-like ER kinase (PERK), eukaryotic initiation factor 2α (eIF2α), C/EBP-homologous protein (CHOP), and autophagy microtubule associated protein light chain 3A/B (LC3A/B). Results PFTP-E is mainly composed of steroids and triterpenoids. PFTP-E, OA and PTX can inhibit the proliferation of HCT116 and CT26 cells in a time- and dose-dependent manner, induce apoptosis, and block the cell cycle at G0/G1 and G2/M phases. PFTP-E can collapse mitochondrial membrane potential of HCT116 and CT26 cells and increase the content of intracellular reactive oxygen species, which is similar to the effect of PTX. PFTP-E and PTX can up-regulate CytC, Bax, GRP78, p-PERK, p-eIF2α and CHOP, down-regulate Bcl-2, significantly increase the content of cleaved PARP, Caspase3 and Caspase9, and induce endoplasmic reticulum stress response. OA can significantly increase the expression of LC3A/B in HCT116 cells and tend to induce autophagy and apoptosis. Conclusions PFTP-E and PTX have a similar effect on apoptosis, and that is related to mitochondrial injury pathway, cycle arrest, and endoplasmic reticulum stress response. The side effects of PFTP-E are significantly lower than PTX, which provides a meaningful reference for the screening and research of PFTP-E as an anticancer drug. Key words: Triterpenoid; Colonic neoplasms; Apoptosis; Pleurotus ferulatus; Endoplasmic reticulum stress