Investigation of the synergistic effects of paclitaxel and herbal substances and endemic plant extracts on cell cycle and apoptosis signal pathways in prostate cancer cell lines.

Paclitaxel, which isolated from Taxus brevifolia, is recently started to be used against prostate cancer treatment and it is a very effective compound against cancer. In this study, we aimed to test the synergistic effect of two plant active compounds (sulphoraphane (SFN) and silymarin (SILY)) and several endemic plant species from Turkey (such as Phlomis leucophracta, Rubia davisiana, Alkanna tinctoria), which are known to have anticarcinogenic effect on androgen-independent PC3 and DU145, and androgen-dependent VCaP prostate cancer cell lines, with paclitaxel on the expression of cell cycle signaling and apoptosis regulator genes. Herbal substances and endemic herbal extracts were combined with Paclitaxel drug. IC50 doses were identified as real-time online. The most effective synergistic doses were determined according to isobologram analysis. The apoptotic effects of effective combined doses were evaluated by TUNEL, Annexin V, and JC-1 methods. Apoptotic and/or cell cycle arrest effects of confirmed combined doses on the expression of genes in these pathways were assessed by real-time online. Endemic plant extracts (Alkanna tinctoria, Phlomis leucophracta and Rubia davisiana, IC50 < 220 µg/ml) and herbal substances (SILY, and SFN IC50 < 130 µM) indicated antiproliferative and apoptotic effects in prostate cancer cell lines. They testified to the synergistic effect of paclitaxel with endemic plant extracts (Combination Index CI, ED50 < 0.41). The combinations, which indicate the synergistic effect was increased to the Bax/Bcl­2 ratio by suppressing Bcl­2 gene expression into the prostate cancer cell lines. Besides, they increased the expression of TNFRSF10A, TNFRSF1A, CHEK1, CDKN1A, CDKN2B, CDK8, CDKN3 and CASP14 and decreased BAD, CDK5RAP1, CDC20, cyclin H, CDK5RAP1, CDC20. The effective doses of paclitaxel were reduced and G2/M arrest was induced by the endemic plant extracts and herbal substances that indicate a synergistic effect with paclitaxel. By using different combination of herbal extracts or active substances with paclitaxel, more economical and efficient treatment strategies can be developed.

Antileukemic effect of paclitaxel in combination with metformin in HL-60 cell line.

Acute promyelocytic leukemia (APL) is a subtype of AML that is a mixture of hematological malignancy, characterized by a specific translocation t(15;17). The using of all-trans retinoic acid (ATRA) with arsenic trioxide (ATO) or chemotherapeutic agents or both of these agents, composes main treatment strategy of APL. While it is possible to achieve success in treatment of low-risk APL with current treatment regimens, such success is not mentioned in high-risk APL. So, it may develop new approaches for treatment regimens for high-risk APL. In the present study, we aimed to investigate the effects of combinational of a classic anticancer agent paclitaxel and antidiabetic agent metformin on HL-60 APL cell line. The combination dose of paclitaxel and metformin was determined by WST-1 analysis. The effect of combinational dose on apoptosis was assessed in fluorescence microscope after using AnnexinV-EGFP Apoptosis and JC-1 Assay Kit. The effect of combinational dose on cell cycle, apoptosis and differentiation, and signaling pathways were determined investigating gene expression changes by using real time qRT-PCR. The combinational dose of paclitaxel and metformin was determined as 4.8nM and 398.7µM for 72h, respectively. The combination dose significantly increased apoptosis for 48h. In expression changes of genes associated cell cycle, apoptosis, cytokines, co-stimulator molecules, NF-kB and MAP/MAPK pathways, TLRs (Toll-like receptors) were found to be decreased or increased to provide apoptosis or differentiation. Consequently, we suggest that the combination of paclitaxel and metformin can be used as an option assessable for development of new treatment strategies for APL.

Effect of Extracts of the Endemic Plants Centaurea lydia and Phlomis nissolii on Toxoplasma gondii.

OBJECTIVE: This study aimed to investigate the potential antitoxoplasma activities of extracts of the endemic plants Centaurea lydia and Phlomis nissolii in a fibroblast cell culture infected with T. gondii trophozoites. METHODS: WI-38 cell lines treated with plant extracts (55 µg/mL each) and an untreated control were infected with 5×105 T. gondii trophozoites, and the number of parasites in the medium was determined on days 7, 14, and 24. RESULTS: No cytotoxic effects of C. lydia and P. nissolii extracts were detected at concentrations of 0.86-55 µg/mL in the WI-38 cell line, and the absence of the cytotoxicity of these extracts on the fibroblast cell line was considered as a positive effect. C. lydia extract at 55 µg/mL had marked activity against T. gondii trophozoites. A 47.5-fold increase was observed in the number of trophozoites in the control group, while a 84-fold decrease was found in the C. lydia extract group. However, a 36-fold increase was detected in the P. nissolii extract group, indicating no antitoxoplasma activity. CONCLUSION: The extract of C. lydia, an endemic plant, was found to be a good drug candidate for treating toxoplasmosis. The in vitro activity of the extract of this endemic plant should be further investigated in animal models in vivo.