PA‐MSHA inhibits proliferation and induces apoptosis through the up‐regulation and activation of caspases in the human breast cancer cell lines

Abstract

To investigate the effects of PA-MSHA (Pseudomonas aeruginosa-mannose sensitive hemagglutinin) on inhibiting proliferation of breast cancer cell lines and to explore its mechanisms of action in human breast cancer cells. MCF-10A, MCF-7, MDA-MB-468, and MDA-MB-231HM cells were treated with PA-MSHA or PA (Heat-killed P. aeruginosa) at different concentrations and different times. Changes of cell super-microstructure were observed by transmission electron microscopy. Cell cycle distribution and apoptosis induced by PA-MSHA were measured by flow cytometry (FCM) with PI staining, ANNEXIN V-FITC staining and Hoechst33258 staining under fluorescence microscopy. Western blot was used to evaluate the expression level of apoptosis-related molecules. A time-dependent and concentration-dependent cytotoxic effect of PA-MSHA was observed in MDA-MB-468 and MDA-MB-231HM cells but not in MCF-10A or MCF-7 cells. The advent of PA-MSHA changed cell morphology, that is to say, increases in autophagosomes, and vacuoles in the cytoplasm could also be observed. FCM with PI staining, ANNEXIN V-FITC and Hoechst33258 staining showed that the different concentrations of PA-MSHA could all induce the apoptosis and G(0)-G(1) cell cycle arrest of breast cancer cells. Cleaved caspase 3, 8, 9, and Fas protein expression levels were strongly associated with an increase in apoptosis of the breast cancer cells. There was a direct relationship with increased concentrations of PA-MSHA but not of PA. Completely different from PA, PA-MSHA may impart antiproliferative effects against breast cancer cells by inducing apoptosis mediated by at least a death receptor-related cell apoptosis signal pathway, and affecting the cell cycle regulation machinery.

Inhibition of EGFR pathway signaling and the metastatic potential of breast cancer cells by PA-MSHA mediated by type 1 fimbriae via a mannose-dependent manner

“…The human breast cancer cell lines MCF-7, MDA-MB-231HM, and MDA-MB-468 used were obtained in the same way and grown in the same medium as we have reported earlier (Liu et al, 2009c). The PA-MSHA and inactivated PA used in this study was the same as that used in our previous study.…”

“…Cytotoxic effects of PA-MSHA or PA on the cells were evaluated by the Cell Counting Kit-8 (CCK-8; Dojindo Molecular Technologies Inc., Gaithersburg, MD, USA) assays as mentioned in the previous study (Liu et al, 2009c). Cells were treated with several specified concentrations of PA-MSHA or PA cocultured with 100 mM mannose or 100 mM glucose and then incubated at 37 1C for another 24, 48, or 72 h. The IC 50 value was calculated using CalcuSyn Software (Biosoft, Ferguson, MO, USA).…”

“…Cells were treated with the mannose or glucose coculture test as mentioned above. Then, the wholecell lysates were collected following the standardized protocol as described in an earlier study (Liu et al, 2009c). A densitometry analysis was performed with Quantity One software (BioRad, Hercules, CA, USA).…”

“…PA-MSHA is a genetically established, engineered Pseudomonas aeruginosa (PA) strain characterized by the expression of mannosesensitive type 1 fimbriae on its surface. In our earlier study, we reported that the biological response to the treatment with PA-MSHA includes an inhibition of cell proliferation, cell cycle arrest, and induction of apoptosis in human breast cancer cells compared with PA (Liu et al, 2009c). This result suggests that the mannosesensitive type 1 fimbriae are responsible for the apoptosis and that a certain protein with high mannose expression that has a key role in mediating the growth of tumor cells might act as a potent ligand for those type 1 fimbriae.…”

The Pseudomonas aeruginosa Mannose Sensitive Hamemagglutination Strain (PA-MSHA) Induces a Th1-Polarizing Phenotype by Promoting Human Dendritic Cells Maturation

“…He adopted biological engineering technology to make the non-MSHA heat-inactivated P. aeruginosa strain have many tenuous and upright MSHA fimbriae around the mycelium, which is widely used for anti-infection and anti-inflammation purposes and even in anti-tumor therapies [1]. Recently, it was reported that PA-MSHA made Th2 differentiation index decreased, and shift Th1 cell increased in spleen cells of IgA nephropathy mouse model [2].…”