In vitro sequence-dependent synergism between paclitaxel and gefitinib in human lung cancer cell lines

[Sequence-dependent effect of docetaxel with gefitinib on the proliferation and apoptosis of lung adenocarcinoma cell H1975]

BACKGROUND AND OBJECTIVE

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib show promising therapeutic effects in patients with advanced non-small cell lung cancer (NSCLC). However, despite an initial response to EGFR-TKIs treatment among responsive patients, most inevitably acquire resistance after a progression-free period of about 10 months. The percentage of T790M in TKI acquired-resistant patients in most studies is around 50%. The aim of this study is to assess the effects of the sequential administration of docetaxel and gefitinib on cell proliferation and apoptosis of lung adenocarcinoma cell H1975.

METHODS

An MTT assay was used to measure cell proliferation. The potency of the sequential administration of docetaxel and gefitinib were determined by isobolograms and combination index (CI). Cell apoptosis and cycle distribution were determined by flow cytometry. The Hoechst 33258 method was used to observe the apoptotic morphology. Chemical colorimetric luminescence was used to measure the caspase activity.

RESULTS

The isobolograms and CI showed that the sequential administration of docetaxel following gefitinib remarkably inhibits cell proliferation and cell apoptosis compared with other sequential administration models. The cycle distribution results indicate that sequential docetaxel administration following gefitinib blocked the cells in the G₂/M phase but not in the G0/G1. The activation of the Caspase-8/Caspase-3 cascade is mainly involved in the apoptotic pathway of lung adenocarcinoma cell H1975 in all sequential administration models.

CONCLUSIONS

The docetaxel administration following gefitinib might be a new stratagy for lung cancer with T790M mutation after having EGFR-TKIs resistance.

Synergistic inhibitory effects by the combination of gefitinib and genistein on NSCLC with acquired drug-resistance in vitro and in vivo

In clinical practice, most patients with non small cell lung cancer (NSCLC) who respond to tyrosine kinase inhibitors eventually progress because of an acquired resistance mutation, T790M, in epidermal growth factor receptor (EGFR). Thus, it is important to identify a new drug to reduce resistance. The aim of this study was to test whether genistein combined with gefitinib is effective against NSCLC in a cell line carrying T790M, and to clarify the underlying mechanisms. The human lung cancer cell line H1975 was used as an in vitro and in vivo model. Cells were treated with gefitinib, genistein, or a combination at a range of concentrations. Cell proliferation was calculated to assess the anticancer effects of the compounds in vitro. Flow cytometry and Western blotting were employed to determine the inhibitory effects on proliferation and the induction of apoptosis. The in vivo effects of the compounds were examined using a xenografted nude mouse model for validation. Gefitinib together with genistein enhanced both growth inhibition and apoptosis; however, the greatest synergistic effect was observed at low concentrations. p-EGFR, p-Akt, and p-mTOR expressions in vitro were reduced more by the combined use of the drugs, whereas caspase-3 and PARP activities were increased. Significantly more tumor growth inhibition was detected following combination treatment in the in vivo model. These findings suggest that genistein enhanced the antitumor effects of gefitinib in a NSCLC cell line carrying the T790M mutation. This synergistic activity may be due to increased inhibition of the downstream molecular and pro-apoptotic effects of EGFR.

Synergistic interaction between sunitinib and docetaxel is sequence dependent in human non-small lung cancer with EGFR TKIs-resistant mutation

PURPOSE

Previous studies have demonstrated that sunitinib has the anti-tumor activity in human non-small cell lung cancer (NSCLC). This study was aimed to investigate the efficacy of single use of sunitinib and that of concurrent or sequential administration of sunitinib and docetaxel in NSCLC cell lines that are resistant to EGFR TKIs.

METHODS

NSCLC cell lines with EGFR T790M mutation and K-ras mutation were exposed to either sunitinib or docetaxel or both based on various sequential administrations. After exposure, the cell viability was measured by MTT assay, cell cycle distribution was analyzed by flow cytometry, and alterations in signaling pathway were determined by immunoblotting.

RESULTS

Sunitinib exhibited dose-dependent growth inhibition in NSCLC cell lines and arrested cell cycle at G1 phase, whereas docetaxel arrested at S phase. Although single or concurrent use of sunitinib and docetaxel has some anti-proliferative effects, the sequential administrations of both drugs remarkably enhanced anti-tumor activity. When cells were exposed to docetaxel followed by sunitinib, synergism was observed. The molecular basis of this synergism is that the signaling pathways that were initially activated by docetaxel exposure were efficiently suppressed by the subsequent exposure to sunitinib. In contrast, the reverse of this sequential administration resulted in antagonism, which may be due to differential effects on cell cycle arrest.

CONCLUSIONS

Sunitinib as a single agent exhibits anti-proliferative effects in vitro in NSCLC cell lines with EGFR T790M and K-ras mutations but the sequential administration of docetaxel followed by sunitinib is superior to sunitinib followed by docetaxel and concurrent administration.

[Sequence-dependent effect of docetaxel with gefitinib on the proliferation and signal protein expression of human lung adenocarcinoma cell SPC-A1]

BACKGROUND AND OBJECTIVE

It has been proven that chemotherapy combined with epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) could not increase response for advanced non-small cell lung cancer (NSCLC), but its cellular mechanism was not well known. The aim of this study is to assess the effects of sequential administration of docetaxel and gefitinib on the cell proliferation and signal pathway of lung adenocarcinoma cell SPC-A1 and its cellular mechanism.

METHODS

The mutation of EGFR and K-ras gene were examined by qPCR-HRM. MTT assay was used to measure the cell proliferation. The expression and phosphorylation of EGFR, ERK, AKT and IGF-1R were determined by Western blot.

RESULTS

No EGFR or K-ras gene mutation was found in SPC-A1 cells. Compared with docetaxel or gefitinib alone, no synergistic effects on the cell proliferation were observed in cells treated with docetaxel and gefitinib concomitantly or gefitinib followed by docetaxel. However, sequential administration of gefitinib following docetaxel could remarkably increase the inhibition of docetaxel on cell proliferation. Docetaxel increased, and gefitinib decreased, the phosphorylation of EGFR and ERK respectively. The suppression of pEGFR and pERK induced by gefitinib could not be activated by docetaxel, whether simultaneously or subsequently. No significant effects on the expression of AKT and p-AKT were found when docetaxel and gefitinib were administered simultaneously or sequentially. Docetaxel decreased the expression of IGF-1R.

CONCLUSION

The phosphorylation of both EGFR and ERK, not the phosphorylation of AKT or the expression of IGFR, may contribute to the synergistic effects of EFGR-TKI following chemotherapy on the cell proliferation of NSCLC.

Molecular mechanism of the schedule-dependent synergistic interaction in EGFR-mutant non-small cell lung cancer cell lines treated with paclitaxel and gefitinib

Background

Chemotherapy combined concurrently with TKIs produced a negative interaction and failed to improve survival when compared with chemotherapy or TKIs alone in the treatment of non-small cell lung cancer (NSCLC). The present study investigated the sequence-dependent interaction between paclitaxel and gefitinib and clarified the underlying mechanism.

Methods

The effects on cell proliferation, EGFR signaling pathway, and TGFα expression were evaluated in a panel of human NSCLC cell lines harboring EGFR mutations with three different combination sequences: sequential treatment with paclitaxel followed by gefitinib (T→G), sequential treatment with gefitinib followed by paclitaxel (G→T), or concomitant treatment (T + G).

Results

The sequence-dependent anti-proliferative effects differed between EGFR-TKI-sensitive and -resistant cell lines carrying EGFR mutations. A synergistic anti-proliferative activity was obtained with paclitaxel treatment followed by gefitinib in all cell lines, with mean CI values of 0.63 in Hcc827, 0.54 in PC-9, 0.81 in PC-9/GR, and 0.77 in H1650 cells for the T→G sequence. The mean CI values for the G→T sequence were 1.29 in Hcc827, 1.16 in PC-9, 1.52 in PC-9/GR, and 1.5 in H1650 cells. The mean CI values for T+G concomitant treatment were 0.88 in Hcc827, 0.91 in PC-9, 1.05 in PC-9/GR, and 1.18 in H1650 cells. Paclitaxel produced a dose-dependent increase in EGFR phosphorylation. Paclitaxel significantly increased EGFR phosphorylation compared with that in untreated controls (mean differences: +50% in Hcc827, + 56% in PC-9, + 39% in PC-9/GR, and + 69% in H1650 cells; p < 0.05). The T→G sequence produced significantly greater inhibition of EGFR phosphorylation compared with the opposite sequence (mean differences: -58% in Hcc827, -38% in PC-9, -35% in PC-9/GR, and -30% in H1650 cells; p < 0.05). Addition of a neutralizing anti-TGFα antibody abolished paclitaxel-induced activation of the EGFR pathway in PC-9 and H1650 cells. Sequence-dependent TGFα expression and release are responsible for the sequence-dependent EGFR pathway modulation.

Conclusion

The data suggest that the sequence of paclitaxel followed by gefitinib is an appropriate treatment combination for NSCLC cell lines harboring EGFR mutations. Our results provide molecular evidence to support clinical treatment strategies for patients with lung cancer.