Isolation of Taxol-Producing Endophytic Fungi from Iranian Yew Through Novel Molecular Approach and Their Effects on Human Breast Cancer Cell Line

Taxol or paclitaxel, an approved drug by the Food and Drug Administration, is being used for the treatment of human cancers. This study aimed to isolate and determine different species of native endophytic fungi from Iranian Taxus baccata (yew) plants located in the northern forests of Iran. To do so, a novel molecular screening approach was performed for 50 isolated endophytic fungi through amplification of exon No. 1 of taxadine synthase as a key gene in taxol production pathway. We used effective colony-polymerase chain reaction technique for rapid screening of potent taxol-producing fungi instead of genomic DNA extraction. Production of taxol was performed in batch culture by selected fungi individually and produced taxol was assayed quantitatively by high-performance liquid chromatography using standard taxanes. We found that only six fungi could produce taxol and baccatin III. Interestingly, after 7 days of incubation, the highest level of taxol was found to be 129 and that of baccatin 139.2 mg/kg dw for two native isolated Cladosporium sp. named F1 and F3. The fungal taxols could decrease cell viability in MTT assay same as commercial taxol. The fungal taxols semi-quantitatively showed antimitotic effects on MCF-7 cells as human breast cancer cell line. The expression of bcl-2 anti-apoptotic gene, in contrast to bax pro-apoptotic gene, significantly decreased after treatment by standard and fungal taxols. As fungal taxol was produced simpler than other methods and could significantly affect viability and specific genes expression profile, it is recommended that using of taxol-producing fungi from Iranian yew could be a safe and confident procedure to overcome challenges of using other methods.