Ginsenosides synergize with mitomycin C in combating human non-small cell lung cancer by repressing Rad51-mediated DNA repair.

The use of ginseng extract as an adjuvant for cancer treatment has been reported in both animal models and clinical applications, but its molecular mechanisms have not been fully elucidated. Mitomycin C (MMC), an anticancer antibiotic used as a first- or second-line regimen in the treatment for non-small cell lung carcinoma (NSCLC), causes serious adverse reactions when used alone. Here, by using both in vitro and in vivo experiments, we provide evidence for an optimal therapy for NSCLC with total ginsenosides extract (TGS), which significantly enhanced the MMC-induced cytotoxicity against NSCLC A549 and PC-9 cells in vitro when used in combination with relatively low concentrations of MMC. A NSCLC xenograft mouse model was used to confirm the in vivo synergistic effects of the combination of TGS with MMC. Further investigation revealed that TGS could significantly reverse MMC-induced S-phase cell cycle arrest and inhibit Rad51-mediated DNA damage repair, which was evidenced by the inhibitory effects of TGS on the levels of phospho-MEK1/2, phospho-ERK1/2 and Rad51 protein and the translocation of Rad51 from the cytoplasm to the nucleus in response to MMC. In summary, our results demonstrate that TGS could effectively enhance the cytotoxicity of MMC against NSCLC cells in vitro and in vivo, thereby revealing a novel adjuvant anticancer mechanism of TGS. Combined treatment with TGS and MMC can significantly lower the required concentration of MMC and can further reduce the risk of side effects, suggesting a better treatment option for NSCLC patients.

Shenmai injection enhances the cytotoxicity of chemotherapeutic drugs against colorectal cancers via improving their subcellular distribution.

Shenmai injection (SMI) is a Chinese patent-protected injection, which was mainly made of Red Ginseng and Radix Ophiopogonis and widely used for treating coronary heart disease and tumors by boosting Qi and nourishing Yin. In this study we examined whether SMI could produce direct synergetic effects on the cytoxicity of adriamycin (ADR) and paclitaxel (PTX) in colorectal cancers in vivo and in vitro, and explored the underlying pharmacokinetic mechanisms. BALB/c nude mice with LoVo colon cancer xenografts were intraperitoneally injected with ADR (2 mg·kg-1·3d-1) or PTX (7.5 mg·kg-1·3d-1) with or without SMI (0.01 mL·g-1·d-1) for 13 d. Co-administration of SMI significantly enhanced the chemotherapeutic efficacy of ADR and PTX, whereas administration of SMI alone at the given dosage did not produce visible anti-cancer effects, The chemosensitizing action of SMI was associated with increased concentrations of ADR and PTX in the plasma and tumors. In Caco-2 and LoVo cells in vitro, co-treatment with SMI (2 µL/mL) significantly enhanced the cytotoxicity of ADR and PTX, and resulted in some favorable pharmacokinetic changes in the subcellular distribution of ADR and PTX. In addition, SMI-induced intracellular accumulation of ADR was closely correlated with the increased expression levels of P-glycoprotein in 4 colon cancer cell lines (r2=+0.8558). SMI enhances the anti-cancer effects of ADR and PTX in colon cancers in vivo and in vitro by improving the subcellular distributions of ADR and PTX.

NAMPT inhibition synergizes with NQO1-targeting agents in inducing apoptotic cell death in non-small cell lung cancer cells.

Nicotinamide phosphoribosyltransferase (NAMPT) catalyzes the first rate-limiting step in converting nicotinamide to NAD(+), essential for a number of enzymes and regulatory proteins involved in a variety of cellular processes, including deacetylation enzyme SIRT1 which modulates several tumor suppressors such as p53 and FOXO. Herein we report that NQO1 substrates Tanshione IIA (TSA) and ß-lapachone (ß-lap) induced a rapid depletion of NAD(+) pool but adaptively a significant upregulation of NAMPT. NAMPT inhibition by FK866 at a nontoxic dose significantly enhanced NQO1-targeting agent-induced apoptotic cell death. Compared with TSA or ß-lap treatment alone, co-treatment with FK866 induced a more dramatic depletion of NAD(+), repression of SIRT1 activity, and thereby the increased accumulation of acetylated FOXO1 and the activation of apoptotic pathway. In conclusion, the results from the present study support that NAMPT inhibition can synergize with NQO1 activation to induce apoptotic cell death, thereby providing a new rationale for the development of combinative therapeutic drugs in combating non-small lung cancer.