Fungal 7-epi-10-deacetyltaxol produced by an endophytic Pestalotiopsis microspora induces apoptosis in human hepatocellular carcinoma cell line (HepG2)

Kamalraj Subban,Ramesh Subramani,Jayabaskaran Chelliah,Muthumary Johnpaul,Satpal Singh

doi:10.1186/s12906-017-1993-8

Abstract

BackgroundPaclitaxel (taxol) is a potent anticancer drug that is used in the treatment of a wide variety of cancerous. In the present study, we identified a taxol derivative named 7-epi-10-deacetyltaxol (EDT) from the culture of an endophytic fungus Pestalotiopsis microspora isolated from the bark of Taxodium mucronatum. This study was carried out to investigate the effects of fungal EDT on cell proliferation, the induction of apoptosis and the molecular mechanisms of apoptosis in human hepatoma HepG2 cells in vitro.MethodsThe endophytic fungus was identified by traditional and molecular taxonomical characterization and the fungal EDT was purified using column chromatography and confirmed by various spectroscopic and chromatographic comparisons with authentic paclitaxel. We studied the in vitro effects of EDT on HepG2 cells for parameters such as cell cycle distribution, DNA fragmentation, reactive oxygen species (ROS) generation and nuclear morphology. Further, western blot analysis was used to evaluate Bcl-2-associated X protein (Bax), B-cell lymphoma 2 (Bcl-2), p38-mitogen activated protein kinase (MAPK) and poly [ADP-ribose] polymerase (PARP) expression.ResultsWe demonstrate that the fungal EDT exhibited significant in vitro cytotoxicity in HepG2 cells. We investigated cytotoxicity mechanism of EDT in HepG2 cells. The results showed nuclear condensation and DNA fragmentation were observed in cells treated with fungal EDT. Besides, the fungal EDT arrested HepG2 cells at G2/M phase of cell cycle. Furthermore, fungal EDT induced apoptosis in HepG2 cells in a dose-dependent manner associated with ROS generation and increased Bax/Bcl-2 ratio, p38 MAPKs and PARP cleavage.ConclusionsOur data show that EDT induced apoptotic cell death in HepG2 cells occurs through intrinsic pathway by generation of ROS mediated and activation of MAPK pathway. This is the first report for 7-epi-10-deacetyltaxol (EDT) isolated from a microbial source.

Highlights

Paclitaxel is a potent anticancer drug that is used in the treatment of a wide variety of cancerous
It was noted that P. microspora are in different subclades sequences for which were collected from Genbank database except HM802304
They are from different places, conclusive relationships based on host associations of P. microspora is unwise as there are a number of isolates that have been isolated from different places

Summary

Introduction

Paclitaxel (taxol) is a potent anticancer drug that is used in the treatment of a wide variety of cancerous. We identified a taxol derivative named 7-epi-10-deacetyltaxol (EDT) from the culture of an endophytic fungus Pestalotiopsis microspora isolated from the bark of Taxodium mucronatum. Known as paclitaxel, is a complex diterpenoid compound originally reported from bark of the Pacific yew tree, Taxus brevifolia [1] and later reported in other yew species [2]. Taxol was first reported from an endophytic fungus Taxomyces andreanae isolated from the inner bark of Taxus brevifolia [14]. Several reports have shown that non-Taxus plants harbour taxol-producing endophytic fungi such as Periconia sp., Bartalinia robilldoides and Pestalotiopsis guepinii [21,22,23]. A total of 100 reports of endophytic fungi belonging to 72 fungal species from 32 different host plants have been reported so far for taxol production [24]

Methods

Results

Discussion

Conclusion