Adjuvant and neoadjuvant therapy for gastric cancer

Heparin-functionalized Pluronic nanoparticles to enhance the antitumor efficacy of sorafenib in gastric cancers

In this study, chitosan/heparin immobilized delivery system was developed for the delivery of sorafenib in gastric cancers. The SRF NP was nanosized with spherical outfit and present in the amorphous form. The SRF NP exhibited a sustained release of drug at pH 7.4 conditions and enhanced drug released at pH 5.5 conditions. Flow cytometer analysis showed that cellular uptake of NP increased two-fold after 4h of incubation compared to 1h incubation. The SRF NP showed superior anticancer effect compared to that of free SRF in BGC-823 cancer cells. SRF NP induced a remarkable apoptosis of cancer cells consistent with the cytotoxicity assay. Approximately, ∼ 50% of cell fractions were observed in early apoptosis phase with ∼ 15% of cells in the late apoptosis stage. Consistently, SRF NP exhibited a strong band for caspase-3 and P-53 than compared to free SRF in MGC-823 cancer cells. Importantly, SRF NP showed superior anticancer effect in xenograft tumor model making it a promising delivery vehicle in the treatment of gastric cancers.

Oridonin induces apoptosis in gastric cancer through Apaf-1, cytochrome c and caspase-3 signaling pathway

AIM: To investigate the effect and mechanism of oridonin on the gastric cancer cell line HGC-27 in vitro.

METHODS: The inhibitory effect of oridonin on HGC-27 cells was detected using the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. After treatment with 10 μg/mL oridonin for 24 h and 48 h, the cells were stained with acridine orange/ethidium bromide. The morphologic changes were observed under an inverted fluorescence microscope. DNA fragmentation (a hallmark of apoptosis) and lactate dehydrogenase activity were examined using DNA ladder assay and lactate dehydrogenase-release assay. After treated with oridonin (0, 1.25, 2.5, 5 and 10 μg/mL), HGC-27 cells were collected for anexin V-phycoerythrin and 7-amino-actinomycin D double staining and tested by flow cytometric analysis, and oridonin- induced apoptosis in HGC-27 cells was detected. After treatment with oridonin for 24 h, the effects of oridonin on expression of Apaf-1, Bcl-2, Bax, caspase-3 and cytochrome c were also analyzed using reverse-transcript polymerase chain reaction (RT-PCR) and Western blotting.

RESULTS: Oridonin significantly inhibited the proliferation of HGC-27 cells in a dose- and time-dependent manner. The inhibition rates of HGC-27 treated with four different concentrations of oridonin for 24 h (1.25, 2.5, 5 and 10 μg/mL) were 1.78% ± 0.36%, 4.96% ± 1.59%, 10.35% ± 2.76% and 41.6% ± 4.29%, respectively, which showed a significant difference (P < 0.05). The inhibition rates of HGC-27 treated with oridonin at the four concentrations for 48 h were 14.77% ± 4.21%, 21.57% ± 3.75%, 30.31% ± 4.91% and 61.19% ± 5.81%, with a significant difference (P < 0.05). The inhibition rates of HGC-27 treated with oridonin for 72 h at the four concentrations were 25.77% ± 4.85%, 31.86% ± 3.86%, 48.30% ± 4.16% and 81.80% ± 6.72%, with a significant difference (P < 0.05). Cells treated with oridonin showed typical apoptotic features with acridine orange/ethidium bromide staining. After treatment with oridonin, the cells became round, shrank, and developed small buds around the nuclear membrane while forming apoptotic bodies. Lactate dehydrogenase (LDH) release assay showed that after treated with 1.25 μg/mL and 20 μg/mL oridonin for 24 h, LDH release of HGC-27 caused by apoptosis increased from 22.94% ± 3.8% to 52.68% ± 2.4% (P < 0.001). However, the change in the release of LDH caused by necrosis was insignificant, suggesting that the major cause of oridonin-induced HGC-27 cell death was apoptosis. Flow cytometric analysis also revealed that oridonin induced significant apoptosis compared with the controls (P < 0.05). And the apoptosis rates of HGC-27 induced by the four different concentrations of oridonin were 5.3% ± 1.02%, 12.8% ± 2.53%, 28.5% ± 4.23% and 49.6% ± 3.76%, which were in a dose-dependent manner (P < 0.05). After treatment for 24 h, DNA ladder showed that oridonin induced a significant increase in DNA fragmentation in a dose-dependent manner. RT-PCR revealed that mRNA expression levels were up-regulated compared with the controls in caspase-3 (0.917 ± 0.103 vs 0.357 ± 0.019, P < 0.05), cytochrome c (1.429 ± 0.111 vs 1.002 ± 0.014, P < 0.05), Apaf-1 (0.688 ± 0.101 vs 0.242 ± 0.037, P < 0.05) and Bax (0.856 ± 0.101 vs 0.278 ± 0.027, P < 0.05) (P < 0.05), whereas down-regulated in Bcl-2 (0.085 ± 0.012 vs 0.175 ± 0.030, P < 0.05). Western blotting analysis also confirmed this result.

CONCLUSION: Apoptosis of HGC-27 induced by oridonin may be associated with differential expression of Apaf-1, caspase-3 and cytochrome c, which are highly dependent upon the mitochondrial pathway.

Inducible nitric oxide synthase expression correlates with angiogenesis, lymphangiogenesis, and poor prognosis in gastric cancer patients

Increased nitric oxide synthase expression plays a key role in tumor progression. To examine inducible nitric oxide synthase expression and its correlation with clinical variables, such as tumor progression, angiogenesis, lymphangiogenesis, and prognosis in gastric cancer, we studied inducible nitric oxide synthase expression in gastric cancer samples from 211 patients with 5-year follow-up. CD105 and D2-40 were adopted as biomarkers for tumor angiogenesis and lymphangiogenesis, respectively. Inducible nitric oxide synthase staining was mainly found in the cytoplasm of gastric cancer tumor cells. Positive inducible nitric oxide synthase immunoreactivity was seen in 54.03% of gastric cancer specimens, which was correlated with lymph node metastasis, vascular invasion, distant metastasis, and TNM stage. Compared with inducible nitric oxide synthase negative patients, inducible nitric oxide synthase-positive patients had significantly shorter survival times and higher microvessel density and lymphatic vessel density. Intratumor and peritumor blood microvessel density and lymphatic vessel density correlated with inducible nitric oxide synthase expression (Spearman ρ test, P < .05). We conclude that inducible nitric oxide synthase expression correlates with lymph node metastasis, vascular invasion, distant metastasis, TNM stage, and poor survival rate in gastric cancer. We propose that synthesized inducible nitric oxide synthase increases angiogenesis, and lymphangiogenesis thus promotes tumor progression. Inducible nitric oxide synthase expression may be a good biomarker for poor prognosis in gastric cancer.

Effects of Stat5 antisense oligonucleotide combined with 5-fluorouracil on proliferation and apoptosis of gastric cancer cells

AIM: To investigate the mechanism of Stat5 antisense oligonucleotide (Stat5 AS-ON) combined with 5-fluorouracil (5-FU) in the treatment of gastric cancer.

METHODS: Human gastric cancer cell line BGC823 was treated with Stat5 AS-ON and 5-FU, respectively, or in combination. The expression of Stat5, p-Stat5, cyclin D1 and Bcl-xL in the cells were detected by Western blot, and the cell cycle and apoptosis were detected by flow cytometry.

RESULTS: After treatment with Stat5 AS-ON and 5-FU for 72 h, the ratio of G₁-phase cells was up-regulated from 65.7% to 78.2%, and that of S-phase cells was down-regulated from 18.6% to 10.5%; the percentage of apoptotic cells was increased from 7.4% to 21.6%. Stat5 AS-ON and 5-FU synergically inhibited the growth of gastric cancer cells, induced significant apoptosis of the cancer cells, and they reduced the expression and phosphorylation of Stat5, as well as the expression of cyclin D1 and Bcl-xL.

CONCLUSION: Selective inhibition of specific signaling pathway in the cells may provide a new approach in the treatment of gastric cancer.