High-dose vitamin C suppresses the invasion and metastasis of breast cancer cells via inhibiting epithelial-mesenchymal transition.

PURPOSE: Vitamin C (VC) is a kind of essential nutrient in the body regarded as a canonical antioxidant during the past hundred years. However, the anti-cancer effect of VC is controversial. Our study is trying to clarify the relationship between VC dosage and breast cancer metastasis. METHODS: Human breast cancer cell lines Bcap37 and MDA-MB-453 were treated with VC at three different concentrations (low-dose, 0.01 mM; medium-dose, 0.1 mM; high-dose, 2 mM). Wound healing assays were conducted for migration assay; transwell tests were performed to detect the ability of cell invasion. The protein levels were evaluated by Western blot analysis or immunohistochemistry. Tumor xenografts in nude mice were built to test the effects of VC on breast cancer cell proliferation and metastasis. RESULTS: 0.01 and 0.1 mM VC promoted cell migration and invasion when compared with the control group, but 2 mM VC significantly suppressed cell migration and invasion of breast cancer cell lines. High-dose VC increased E-cadherin and reduced Vimentin, indicating that high-dose VC suppressed epithelial-mesenchymal transition (EMT) in breast cancer cells. Besides, high-dose VC inhibited cell invasion promoted by TGF-ß1 in breast cancer cells. Meanwhile, high-dose VC reversed the suppression of E-cadherin and enhancement of Vimentin induced by TGF-ß1 in breast cancer cells. Furthermore, high-dose VC significantly inhibited breast cancer metastasis in vivo. CONCLUSION: High-dose VC inhibits cell migration and invasion of breast cancer cell lines through suppressing EMT. Thus, it may be considered as an anticancer drug candidate for breast cancer patients.

[High dose vitamin C inhibits proliferation of breast cancer cells through reducing glycolysis and protein synthesis].

OBJECTIVE: To investigate the effects of high dose vitamin C (VC) on proliferation of breast cancer cells and to explore its mechanisms. METHODS: Human breast cancer cells Bcap37 and MDA-MB-453 were treated with VC at low dose (0.01 mmol/L), medium dose (0.10 mmol/L) and high dose (2.00 mmol/L). Cell proliferation was determined with CCK-8 assay, protein expression was evaluated by Western blot, and the secretion of lactic acid in tumor cells was detected by colorimetric method. Bcap37 cells were inoculated in nude mice, and tumor baring nude mice were intraperitoneally injected with high VC(4 g/kg, VC group, n=5)or normal saline (control group, n=5) for 24 d. Tumor weight and body weight were calculated. RESULTS: In vitro experiments demonstrated that high dose VC significantly inhibited cell proliferation in Bcap37 and MDA-MB-453 cells (all P<0.01); the expressions of Glut1 and mTOR signaling pathway-related proteins were decreased (all P<0.05); and the secretion of lactic acid was also markedly reduced (all P<0.05). In vivo experiment showed that the tumor weight was decreased in mice treated with high-dose VC as compared with control group (P<0.05), but no difference in body weights between two groups was observed. CONCLUSIONS: High dose VC may inhibit proliferation of breast cancer cells both in vitro and in vivo through reducing glycolysis and protein synthesis.

[Rapamycin treatment starting at 24 h after cerebral ischemia/reperfusion exhibits protective effect on brain injury in rats].

OBJECTIVE: To investigate whether rapamycin treatment starting at 24 h after cerebral ischemia/reperfusion(I/R) has protective effect on brain injury in rats. METHODS: The rat I/R model was established by middle cerebral artery occlusion according to Longa's method. A total of 104 Sprague Dawley rats were randomly divided into sham group, model group, and rapamycin-treated groups (6 h or 24 h after modeling). Neurological function was assessed with neurological severity score (NSS). Triphenyl tetrazolium chloride (TTC) staining and Fluoro-Jade B (FJB) staining were used to examine the infarct volume and neuronal apoptosis, respectively. The expression of p-S6 protein in mTOR signaling pathway was detected by Western blot analysis. RESULTS: Compared with sham group, NSS of the model group was significantly increased and TTC staining indicated obvious infarct area (all P<0.01). Furthermore, significantly increased number of FJB-positive cells and p-S6 expression in the penumbra area were shown in the model group (all P<0.01). Compared with the model group, both rapamycin-treated groups demonstrated decreased NSS, infarction volume and FJB positive cells as well as p-S6 expression in the penumbra area (P<0.05 or P<0.01). There was no significant difference between the groups of rapamycin administrated 6 h and 24 h after modeling (all P>0.05). CONCLUSIONS: Rapamycin treatment starting at 24 h after I/R exhibits protective effect on brain injury in rats.