Enhancement of gefitinib-induced growth inhibition by Marsdenia tenacissima extract in non-small cell lung cancer cells expressing wild or mutant EGFR

Abstract

BackgroundNon-small cell lung cancer (NSCLC) expressed high levels of epidermal growth factor receptor (EGFR). Gefitinib (Iressa) has demonstrated clinical efficacy in NSCLC patients harboring EGFR mutations or refractory to chemotherapy. However, most of NSCLC patients are with wild type EGFR, and showed limited response to gefitinib. Therefore, to develop new effective therapeutic interventions for NSCLC is still required. Our previous study showed Marsdenia tenacissima extract (MTE) restored gefitinib efficacy in the resistant NSCLC cells, but whether MTE acts in the gefitinib-sensitive NSCLC cells is the same as it in the resistant one is unknown.MethodsDose response curves for gefitinib and MTE were generated for two sensitive NSCLC cell lines with mutant or wild type EGFR status. Three different sequential combinations of MTE and gefitinib on cell growth were evaluated using IC50 and Combination Index approaches. The flow cytometric method was used to detect cell apoptosis and cell cycle profile. The impact of MTE combined with gefitinib on cell molecular network response was studied by Western blotting.ResultsUnlike in the resistant NSCLC cells, our results revealed that low cytotoxic dose of MTE (8 mg/ml) combined gefitinib with three different schedules synergistically or additively enhanced the growth inhibition of gefitinib. Among which, MTE → MTE + gefitinib treatment was the most effective one. MTE markedly prompted cell cycle arrest and apoptosis caused by gefitinib both in EGFR mutant (HCC827) and wild type of NSCLC cells (H292). The Western blotting results showed that MTE → MTE + gefitinib treatment further enhanced the suppression of gefitinib on cell growth and apoptosis pathway such as ERK1/2 and PI3K/Akt/mTOR. This combination also blocked the activation of EGFR and c-Met which have cross-talk with each other. Unlike in gefitinib-resistant NSCLC cells, MTE alone also demonstrated certain unexpected modulation on EGFR related cell signal pathways in the sensitive cells.ConclusionOur results suggest that MTE is a promising herbal medicine to improve gefitinib efficacy in NSCLC regardless of EGFR status. However, why MTE acted differently between gefitinib-sensitive and -resistant NSCLC cells needs a further research.

C21 steroid-enriched fraction refined from Marsdenia tenacissima inhibits hepatocellular carcinoma through the coordination of Hippo-Yap and PTEN-PI3K/AKT signaling pathways

“…Previous studies had verified the anti-tumor effect of MTE on human acute T cell leukemia cells [ 9 ], and non-small cell lung cancer cell line [ 14 ]. In our study, the Bel7402 and HepG2 cells were used to evaluate the anti-cancer activity of FR5 in the in vitro and in vivo experiments.…”

“…PI3K inhibitors impair the proliferation and survival of HCC cells [ 25 ]. It has been reported the inhibition of PI3K/AKT/mTOR pathway by MTE decreased the growth of gefitinib resistant non-small lung cancer cells [ 14 ]. The present study investigated the effect of FR5 on the PTEN/PI3K/AKT pathway.…”

“…Although the anti-tumor effect has been identified, the underlying molecular mechanism of MTE in HCC has not been fully understood. Han et al [ 14 ] had showed that MTE inhibited the growth of gefitinib resistant non-small lung cancer cell through blocking PI3K/AKT/mTOR pathway. Our previous study had proved MTE inhibits human acute T cell leukemia cells through enhancing PTEN pathway [ 9 ].…”

The Antitumor Activities of Marsdenia tenacissima

“…Studies have demonstrated that MTE administration could restore the gefitinib sensitivity in gefitinib-resistant NSCLC cells H460 and H1975 in vivo and in vitro through downregulating the ERK1/2, c-Met, and PI3K/AKT/mTOR pathways ( 19 , 20 ). Moreover, MTE could also improve gefitinib efficacy in NSCLC cells regardless of EGFR status ( 21 ). Tenacigenin D, a compound identified from MT, strengthened the activity of erlotinib and gefitinib in two resistant NSCLC cell lines H292 and H460, through reversing both K-Ras mutation and P-glycoprotein (P-gp) overexpression mediated multidrug resistance (MDR) mechanisms ( 18 ).…”

Marsdeniae tenacissima extract-induced growth inhibition and apoptosis in hepatoma carcinoma cells is mediated through the p53/nuclear factor-κB signaling pathway

“…M. tenacissima extract (MTE) injection has been used for the treatment of cancer in China for decades due to the bioactive constituents of polyoxypregnane glycosides ( 9 , 10 ). Both in vivo and in vitro studies have reported that MTE enhances the sensitivity of various tumors to gefitinib, paclitaxel and doxorubicin, and also inhibited gefitinib metabolism by interfering with hepatic cytochrome P450 (CYP) 3A4 and CYP2D6 enzymes ( 10 – 15 ). Furthermore, M. tenacissima or MTE alone have been demonstrated to repress the proliferation and promote apoptosis of human esophageal carcinoma cells, hematologic neoplasm cell line cells and Burkitt's lymphoma cells ( 16 – 19 ).…”