[The inhibition effects of apatinib on cell proliferation, migration and apoptosis in esophageal carcinoma via Ras/Raf/MEK/ERK and JAK2/STAT3 pathways]

Abstract

Objective: To investigate the in vitro and in vivo effects of apatinib in esophageal squamous cell carcinoma and the underlying mechanisms. Methods: The esophageal cancer cells, KYSE-150 and ECA-109, were divided into control group and apatinib treatment group at the concentrations of 2.5, 5, 10, 20 and 40 μmol/L respectively. All of experiments were performed in triplicate. MTT and colony formation assays were used to measure cell proliferation. Transwell assay was used to determine the migration capacity. The effect of apatinib on cell cycle and apoptosis was analyzed by flow cytometry. The expression of VEGF and VEGFR-2 was measured by real-time quantitative PCR (qRT-PCR). The concentration of VEGF in the cell supernatant was assessed by enzyme-linked immunosorbent assay (ELISA). The expression levels of MEK, ERK, p-MEK, p-ERK, JAK2, STAT3 and p-STAT3 after VEGF stimulation were detected by Western blot. Furthermore, the nude mice xenograft model was established. The tumor-bearing mice were randomly divided into control group, apatinib low dose treatment group (250 mg) and apatinib high dose treatment group (500 mg), respectively. Tumor inhibition rates of different groups were calculated. And then the expressions of VEGF and VEGFR2 were detected in xenograft tissues by immunohistochemical staining. Results: In the presence of 20 μmol/L and 40 μmol/L of apatinib for 24 hours, the migration cell numbers of KYSE-150 and ECA-109 were 428.67±4.16 and 286.67±1.53 as well as 1 123.67±70.00 and 477.33±26.84, respectively, that were significantly lower than control group (P<0.05 for all). In addition, after treatment with 10 μmol/L, 20 μmol/L and 40 μmol/L of apatinib for 7 days on KYSE-150 and ECA-109, the colony formation rates were (65.12±25.48)%, (58.19±24.73)% and (29.10±22.40)% as well as (70.61±15.14)%, (61.12±17.21)% and (43.09±11.13)%, respectively. The colony formation rates of 20 μmol/L and 40 μmol/L of apatinib treatment groups were significantly lower than control group (100.00±0.00, P<0.05). The cell cycle ratio of G(2)/M phase and apoptosis rate of control group and 20 μmol/L apatinib group in KYSE-150 cells were (12.14±2.13)% and (3.49±0.74)% as well as (26.27±3.30)% and (15.65±1.54)%, respectively. The corresponding ratios in ECA-109 cells were (3.44±0.57)% and (6.31±1.43)% as well as (22.64±2.36)% and (49.26±1.62)%, respectively. The results show that apatinib suppressed cell cycle progression at G(2)/M phase and induced cell apoptosis in both KYSE-150 and ECA-109 cells (P<0.05 for all). In the presence of 20 μmol/L and 40 μmol/L of apatinib in KYSE-150 cells, the relative levels of VEGF mRNA were (42.57±10.43)% and (25.69±1.24)%, and those of VEGF-2 mRNA were (36.09±10.82)% and (13.99±6.54)%, which were all significantly decreased compared to control group (100.00±0.00, P<0.05 for all). For ECA-109 cells, the relative expression of VEGF and VEGFR2 showed similar tendency (P<0.05 for all). Moreover, after treatment with 20 μmol/L and 40 μmol/L of apatinib in KYSE-150 cells, the VEGF concentrations were (766.48±114.27) pg/ml and (497.40±102.18)pg/ml, which were significantly decreased compared to control group [(967.41±57.75) pg/ml, P<0.05)]. The results in ECA-109 were consistent (P<0.05). Furthermore, after treatment with 40 μmol/L of apatinib in KYSE-150 and ECA-109, the relative expression of p-MEK and p-ERK were 0.49±0.05 and 0.28±0.03 as well as 0.63±0.03 and 1.22±0.15, which were significantly lower than control group (1.23±0.19 and 0.66±0.07 as well as 1.03±0.20 and 1.76±0.20; P<0.05). The relative expression of STAT3, p-STAT3 in control group and experimental group were 0.96±0.15 and 0.85±0.16 as well as 0.62±0.09 and 0.36±0.13, respectively. The results showed that the protein levels of STAT3 and p-STAT3 were significantly lower than the control group (P<0.05 for all). The inhibition rates of apatinib in xenograft nude mice were 29.25% and 19.96% for 250 mg and 500 mg treatment groups. The concentration of VEGF were (25.11±4.12) pg/ml, (16.40±2.81) pg/ml and (15.04±4.88)pg/ml for control, 250 mg and 500 mg treatment groups, respectively. Conclusions: Apatinib can inhibit cell proliferation, induce apoptosis and suppress migration of esophageal cancer cells in vitro and in vivo. This effect was mainly mediated via the alterations of Ras/Raf/MEK/ERK pathway and JAK2/STAT3 pathway.

Keywords: Apatinib; Apoptosis; Esophageal neoplasms; Nude mice; Vascular endothelial growth factor.