Kaurene diterpene induces apoptosis in U87 human malignant glioblastoma cells by suppression of anti-apoptotic signals and activation of cysteine proteases

Abstract

Gliomas are the most common and malignant primary brain tumors in humans. Studies have shown that classes of kaurene diterpene have anti-tumor activity related to their ability to induce apoptosis. We investigated the response of the human glioblastoma cell line U87 to treatment with ent-kaur-16-en-19-oic acid (kaurenoic acid, KA). We analyzed cell survival and the induction of apoptosis using flow cytometry and annexin V staining. Additionally, the expression of anti-apoptotic (c-FLIP and miR-21) and apoptotic (Fas, caspase-3 and caspase-8) genes was analyzed by relative quantification (real-time PCR) of mRNA levels in U87 cells that were either untreated or treated with KA (30, 50, or 70 µM) for 24, 48, and 72 h. U87 cells treated with KA demonstrated reduced viability, and an increase in annexin V- and annexin V/PI-positive cells was observed. The percentage of apoptotic cells was 9% for control cells, 26% for cells submitted to 48 h of treatment with 50 µM KA, and 31% for cells submitted to 48 h of treatment with 70 µM KA. Similarly, in U87 cells treated with KA for 48 h, we observed an increase in the expression of apoptotic genes (caspase-8, -3) and a decrease in the expression of anti-apoptotic genes (miR-21 and c-FLIP). KA possesses several interesting properties and induces apoptosis through a unique mechanism. Further experiments will be necessary to determine if KA may be used as a lead compound for the development of new chemotherapeutic drugs for the treatment of primary brain tumors.

Pharmacokinetic Profile of Kaurenoic Acid after Oral Administration of Araliae Continentalis Radix Extract Powder to Humans

“…The calibration curve for KAU in human plasma exhibited a good linearity over the concentration range of 0.2–100 ng/mL for KAU, with correlation coefficients exceeding 0.997 at each batch (n = 5). Typical linear regression equation of the calibration curve was y = (0.15222 ± 0.01135)x + (0.00614 ± 0.00122) for KAU by plotting peak area ratio (y) of KAU to IS versus nominal concentration (x) of KAU that was weighted [9]. The developed UPLC-MS/MS analysis in our study provided LLOQ that was sufficient for further PK study after oral administration of Araliae continentalis Radix extract powder in humans.…”

“…Kaurenoic acid (KAU) is one of the representative diterpenes isolated from Aralia continentalis . It possesses various biological activities, including anticonvulsant [8], tumor suppression [9], leukemia apoptosis [10], and anti-inflammatory. It also have antibacterial [11], antifungal [12], anti-leishmanial [13], anti-plasmodial [14], anti-syphiliticus [15], and anti-cariogenic [16] activities.…”

Diterpenes and Their Derivatives as Potential Anticancer Agents

“…targeted pro‐apoptotic proteins in U937 cell lysate and caused an apoptotic cell death (Faiella et al , ). The ent ‐kaur‐16‐en‐19‐oic acid (30, 50 or 70 μM) was reported to increase the expression of apoptotic genes (caspase‐8 and caspase‐3) and decrease the expression of antiapoptotic genes (miR‐21 and c‐FLIP) in U87 cells (Lizarte Neto et al , ). Xu et al () suggested that the jolkinolide B from E. fischeriana in MCF‐7 human breast cancer cells exerted an apoptotic cell via PI3K/Akt signalling pathway.…”

Impact of ethanolic extract of Mikania glomerata on human breast cancer (MCF 7) cell line

“…According to Mukherjee et al [27], ethanolic leaf extract of Thuja occidentalis blocks proliferation of A549 cells (lung carcinoma cells) and induces apoptosis in vitro. Anti-cancer potential study of plant extracts adopting Annexin V on Ziziphus mauritiana in vitro against HL-60, Molt-4, and HeLa cancer cell lines [28], algal extract on the AML cell lines HL-60 and MV-4-11 [29], Sutherlandia frutescens (cancer bush) extract on SNO oesophageal cancer cell line [30], Chaetoceros calcitrans extract on human breast cell line (MCF-7) [31], Mikania hirsutissima leaf extract fraction on U87 human glioblastoma cell line [32] and Melilotus officinalis (sweet clover) extract fraction on human TK6 lymphoblastoid cell line [33] were studied and their apoptotic property has been recorded.…”