Oleanolic acid arrests cell cycle and induces apoptosis via ROS‐mediated mitochondrial depolarization and lysosomal membrane permeabilization in human pancreatic cancer cells

Abstract

Oleanolic acid (OA), a pentacyclic triterpenoid, exhibits potential anti-tumor activity against many tumor cell lines. This study aims to examine the anti-tumor activity of OA on pancreatic cancer cells and its potential molecular mechanism. The results showed that the proliferation of Panc-28 cells was inhibited by OA in a concentration-dependent manner, with an IC50 (The half maximal inhibitory concentration) value of 46.35 µg ml(-1) , as determined by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The cell cycle was arrested in S phase and G2/M phase by OA. The study also showed that OA could induce remarkable apoptosis, evidenced by an increased percentage of early/late apoptotic cells, DNA ladder and nuclear morphology change. Further study revealed that OA could induce Reactive Oxygen Species (ROS) generation, mitochondrial depolarization, release of cytochrome C, lysosomal membrane permeabilization and leakage of cathepin B. The expression of apoptosis-correlated proteins was also affected in cells treated with OA, including activation of caspases-3/9 and cleavage of PARP. Further study confirmed that ROS scavenger vitamin C could reverse the apoptosis induced by OA in Panc-28 cells. Our results provide evidence that OA arrests the cell cycle and induces apoptosis, possibly via ROS-mediated mitochondrial and a lysosomal pathway in Panc-28 cells.

p38 MAPK Signaling Mediates Mitochondrial Apoptosis in Cancer Cells Induced by Oleanolic Acid

“…These events mediated the proapoptotic activity of OA on cancer cells ( Figure 4C and 4D). Although the enhanced expression of Bax has been demonstrated to be associated with apoptosis in cancer cells treated with OA for 24 hr (Wei et al, 2012), translocation of Bax and Bim and suppression of Bcl-2 anti-apoptotic function that were dependent on phosphorylation events was more likely to account for the quick detection of apoptosis in cancer cells treated with OA.…”

“…Considering its pleiotropic function and nontoxicity, researchers have been increasingly focused on OA and making efforts to improve its activity and drugability in recent decades (Liby Since that cancer-related deaths keep rising both in developed and developing countries in recent years, the anti-tumor property of OA receives more and more attention. Apoptosis induction has been well known as one of the major mechanisms underlying OA anti-tumor activity on various types of cancer cells (Juan et al, 2006;Martin et al, 2007;Zhang et al, 2007;Shyu et al, 2010;Yan et al, 2010;Feng et al, 2011b;Lucio et al, 2011;Pratheeshkumar et al, 2011;Zhou et al, 2011;Chakravarti et al, 2012;George et al, 2012;Gu et al, 2012;Struh et al, 2012;Wei et al, 2012;Wang et al, 2013). Mechanistically, OA treatment increases the ratio of proapoptotic protein, Bax, to anti-apoptotic protein, Bcl-2, in the outer mitochondrial membrane, facilitates the formation of Bax oligomer, increases the permeability of mitochondrial membrane, releases cytochrome C from inner membrane into cytosol, triggers the caspase pathway through activating Apaf-1, cleaves multiple cellular target molecules including Poly ADP ribose polymerase (PARP) and DNA, and eventually leads to cell death (Martin et al, 2007;Zhang et al, 2007;Shyu et al, 2010;Yan et al, 2010;Zhou et al, 2011;Chakravarti et al, 2012;Wei et al, 2012;Wang et al, 2013).…”

“…Although it is well recognized that OA induces mitochondria-mediated apoptosis in a broad range of cancer cells, the mechanism by which it initiates this pathway is largely unknown. In addition, the generation of reactive oxygen species (ROS) were frequently observed in cancer cells under OA administration (Martin et al, 2007;Chakravarti et al, 2012;Wei et al, 2012;Wang et al, 2013). This event is required for OA induction of mitochondria-mediated apoptosis (Martin et al, 2007;Wei et al, 2012).…”

“…In addition, the generation of reactive oxygen species (ROS) were frequently observed in cancer cells under OA administration (Martin et al, 2007;Chakravarti et al, 2012;Wei et al, 2012;Wang et al, 2013). This event is required for OA induction of mitochondria-mediated apoptosis (Martin et al, 2007;Wei et al, 2012). However, it is still not clear how OA-induced ROS accumulation causes the activation of apoptotic pathway in cancer cells.…”

Oleanolic acid inhibits colorectal cancer angiogenesis in vivo and in vitro via suppression of STAT3 and Hedgehog pathways

“…Oleanolic acid (3β-hydroxy-olea-12-en-28-oic acid, OA) is the principal active compound present in various traditional Chinese medicinal herbs (including Hedyotis diffusa and Patrinia scabiosaefolia) that have been used to clinically treat various types of human malignancies (24)(25)(26)(27). Previous studies have reported that OA may suppress tumor growth via inhibition of proliferation and promotion of apoptosis of cancer cells (28)(29)(30). To further elucidate the underlying mechanism of anti-cancer activity, the present study used a colorectal cancer (CRC) mouse xenograft model and human umbilical vein endothelial cells (HUVECs) to evaluate the effect of OA on tumor angiogenesis and the activation of the STAT3 and SHH signaling pathways.…”