Pseudolaric Acid B Induces Caspase-Dependent and Caspase-Independent Apoptosis in U87 Glioblastoma Cells

Abstract

Pseudolaric acid B (PLAB) is one of the major bioactive components of Pseudolarix kaempferi. It has been reported to exhibit inhibitory effect on cell proliferation in several types of cancer cells. However, there is no report elucidating its effect on glioma cells and organ toxicity in vivo. In the present study, we found that PLAB inhibited growth of U87 glioblastoma cells in a dose-dependent manner with IC50 ~10 μM. Flow cytometry analysis showed that apoptotic cell death mediated by PLAB was accompanied with cell cycle arrest at G2/M phase. Using Western blot, we found that PLAB induced G2/M phase arrest by inhibiting tubulin polymerization in U87 cells. Apoptotic cell death was only partially inhibited by pancaspase inhibitor, z-VAD-fmk, which suggested that PLAB-induced apoptosis in U87 cells is partially caspase-independent. Further mechanistic study demonstrated that PLAB induced caspase-dependent apoptosis via upregulation of p53, increased level of proapoptotic protein Bax, decreased level of antiapoptotic protein Bcl-2, release of cytochrome c from mitochondria, activation of caspase-3 and proteolytic cleavage of poly (ADP-ribose) polymerase (PARP) and caspase-independent apoptosis through apoptosis inducing factor (AIF). Furthermore, in vivo toxicity study demonstrated that PLAB did not induce significant structural and biochemical changes in mouse liver and kidneys at a dose of 25 mg/kg. Therefore, PLAB may become a potential lead compound for future development of antiglioma therapy.

Tubeimoside-1 induces oxidative stress-mediated apoptosis and G0/G1 phase arrest in human prostate carcinoma cells in vitro

“…Many chemotherapeutic agents inhibit cell proliferation through activation of various intracellular signaling pathways to arrest the cell cycle at G 0 / G 1 , S, or G 2 /M phase [22] . p53, "the guardian of the genome," has been shown to induce cell cycle arrest at both G 0 /G 1 and G 2 /M phase by activating its direct downstream effector p21 [37,38] .…”

“…After harvesting and fixing with 70% ice-cold ethanol overnight, the cells were washed twice with PBS. The cell pellets were then resuspended in a solution containing 50 µg/mL PI and 100 µg/mL RNase A for 30 min in the dark at room temperature as described previously [22] . The DNA contents were analyzed by flow cytometry (Beckman Coulter, Epics XL) using Cell Quest software.…”

Role of pseudolaric acid B in A549 lung cancer cell proliferation and apoptosis

“…PAB is a diterpene acid isolated from the root and trunk bark of Pseudolarix kaempferi and possesses multiple biological and pharmacological activities, including antifungal, antimicrobial, antifertility and antiangiogenic properties (10)(11)(12)(13)(14)(15). It has been previously confirmed that PAB exhibits an antitumor effect by inducing apoptosis in various types of cancer (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). Apoptosis is important in homeostasis maintenance through a balance between cell proliferation and cell death (28).…”

“…In DU145 hormone-refractory prostate cancer cells, PAB induced apoptosis by activating caspase-3 and -9 and downregulating Bcl-2 (26). In U87 glioblastoma cells, PAB inhibits proliferation and induces apoptosis by arresting cell cycle at the G2/M phase, activating caspase-3, upregulating P53 and Bax protein and downregulating Bcl-2 (27).…”

Periostin as a promising target of therapeutical intervention for colorectal cancer

“…SW480 cells were incubated with the siRNAs in 6-well plates for 48 hours and cell cycle profile was analyzed as described previously (Khan et al, 2012). Briefly, the cells were collected and washed with PBS 3 times.…”