Zakir Hossain

Docosahexaenoic acid and eicosapentaenoic acid-enriched phosphatidylcholine liposomes enhance the permeability, transportation and uptake of phospholipids in Caco-2 cells

The influence of docosahexaenoic acid (DHA)- and eicosapentaenoic acid (EPA)-enriched phosphatidylcholine (PC) on the permeability, transport and uptake of phospholipids was evaluated in Caco-2 cells. The cells were grown on permeable polycarbonate transwell filters, thus allowing separate access to the apical and basolateral chambers. The monolayers of the cells were used to measure lucifer yellow permeability and transepithelial electrical resistance (TEER). Transcellular transportation of diphenylhexatriene (DPH) labeled-PC small unilamellar vesicles (SUV) from the apical to basolateral chamber, and uptake of the same SUV was monitored in the cell monolayers. Cell-membrane perturbation was evaluated to measure the release of lactate dehydrogenase and to determine the cell viability with sodium 2-(4-iodophenyl)-3-(4-nitrophenyl) -5-(2, 4-disulfophenyl)-2H-tetrazolium dye reduction assay. The lucifer yellow flux was 1.0 and 1.5 nmol/h/cm2 with 50 μM PC, and 17.0 and 23.0 nmol/h/cm2 with 100 μM PC when monolayers of Caco-2 cells were treated with DHA- and EPA-enriched PC, respectively. TEER decreased to 24 and 27% with 50 and 100 μM DHA-enriched PC, and to 25 and 30% with 50 and 100 μM EPA-enriched PC, respectively. Our results show that DHA- and EPA-enriched PC increases tight junction permeability across the Caco-2 cell monolayer whereas soy PC has no effect on tight junction permeability. Transportation and uptake of DHA- and EPA-enriched PC SUV differed significantly (P < 0.01) from those of soy PC SUV at all doses. We found that PC SUV transported across Caco-2 monolayer and was taken up by Caco-2 cells with very slight injury of the cell membrane up to 100 μM PC. Lactate dehydrogenase release and cell viability did not differ significantly between the treatment and control, emphasizing that injury was minimal. Our results suggest that DHA- and EPA-enriched PC enhance the permeability, transport and uptake of PC SUV across monolayers of Caco-2 cells. (Mol Cell Biochem xxx: 1–9, 2005)

Growth inhibition and induction of apoptosis of colon cancer cell lines by applying marine phospholipid.

Polyunsaturated fatty acids (PUFAs) exhibit beneficial biological functions in carcinogenic processes. We examined the effects of PUFAs in the acid and phospholipid forms on three colon cancer cell lines (HT-29, Caco-2, and DLD-1). Docosahexaenoic acid (DHA) and eicosapentaenoic (EPA) in both acid and phospholipid forms showed growth inhibition effects on experimental colon cancer cell lines. But these PUFAs had the strongest growth-inhibitory effect on HT-29 than Caco-2 and DLD-1. Combined application of PUFAs and sodium butyrate (NaBt) increased the growth inhibition. Growth inhibition was apparently caused by increased lipid peroxidation. DHA or EPA in combination with NaBt significantly increased caspase-3 activity compared to control. DHA and DHA-rich phosphatidylcholine decreased Bcl-2 level in HT-29 and Caco-2 cells.

GROWTH INHIBITION AND INDUCTION OF DIFFERENTIATION AND APOPTOSIS MEDIATED BY SODIUM BUTYRATE IN CACO-2 CELLS WITH ALGAL GLYCOLIPIDS

SummaryGlycolipids should have potential effects as antitumor agents. However, very few studies have examined this property of digalactosyl diacylglycerol (DGDG) and sulfoquinovosyl diacylglycerol (SQDG) on colon cancer cells. Cell viability was determined every 24 h with sodium 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2, 4-disulfophenyl)-2H-tetrazolium dye reduction assay up to 72 h. Alkaline phosphatase activity was measured for assessing cell differentiation. Apoptosis was tested with enzyme-linked immunosorbent assay analysis. Growth of Caco-2 cells was inhibited apparently at 48 h after addition of SQDG and at 72 h with DGDG. Alkaline phosphatase activity of Caco-2 cells obviously increased in combination with DGDG or SQDG and sodium butyrate (NaBT) at 72 h, indicating that DGDG and SQDG enhanced cell differentiation induced with NaBT. An increased enrichment factor was found when the cell was treated in combination with DGDG or SQDG and NaBT. These results strongly suggest that DGDG and SQDG should be considered as the leading compounds of potentially useful colon cancer chemotherapy agents when NaBT is combined.

Marine phosphatidylcholine suppresses 1,2-dimethylhydrazine-induced colon carcinogenesis in rats by inducing apoptosis

In vitro and animal studies indicate that n-3 polyunsaturated fatty acids (PUFAs) suppress carcinogenesis. This study presents a new insight on effectiveness of marine phospholipids for suppression of colon carcinogenesis. The purpose of this study was to investigate growth inhibition and apoptosis inducing effects of n-3 PUFA in the form of marine phosphatidylcholine (PC) on chemically induced (1,2-dimethylhydrazine) colon cancer in rats. Growth inhibition of Caco-2 cells was determined by colorimetric sodium 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-1) dye reduction assay. For animal studies, the rats were fed 5 different diets containing docosahexaenoic acid (DHA)-ethyl ester, eicosapentaenoic acid (EPA)-ethyl ester, squid meal PC (rich in DHA), starfish PC (rich in EPA), and corn oil. The 1,2-dimethylhydrazine (30 mg/kg) or saline was injected 48 hours before the experiment. Rats were anesthetized, and apoptotic as well as mitotic cells in crypt were counted based on morphological criteria in isolated crypts. Squid meal and starfish PC potently inhibited the growth of Caco-2 cells. The experimental diets containing n-3 PUFA suppressed colon cancer in rats. Rats that consumed diets containing DHA-ethyl ester, EPA-ethyl ester, squid meal PC, and starfish PC showed increased apoptosis (P < .01) and suppressed proliferation. These results suggest that marine PC-containing diets might be an effective dietary protective factor against colon cancer.