Abstract
BackgroundNon-small-cell lung cancer (NSCLC) accounts more than 80% of the lung cancer cases. Polysaccharides in rice bran and its fermentation products have been proven to suppress many cancers. However, the report on inhibiting NSCLC is few. In this paper, the polysaccharides with suppression activity to H1299 NSCLC in the fermentation products of full-fat rice bran and defatted rice bran were studied in vitro and in vivo.MethodPolysaccharides (GSRBPs) were extracted from Ganoderma sinense – full-fat rice bran (GS-FRB) and Ganoderma sinense – defatted rice bran (GS-DRB) fermentation products. The structure information of the GSRBPs was studied using HPLC analysis. The anti-tumor activities on H1299 NSCLC of GSRBPs in vitro study was performed using MTT method. The in vivo studies use BALB/c-nu nude mice as H1299 NSCLC bearing mice.ResultAll the polysaccharides contained two fractions, GSFPS-1 and GSFPS-2. The molecular weight and the ratio of GSFPS-1 and GSFPS-2 were different in GS-FRB and GS-DRB. At the earlier state of fermentation, all polysaccharides were composed of D-glu, D-man, D-xyl and L-ara with certain molar ratios. But at the latter stage, polysaccharides in GS-FRB were composed of D-glu, D-man, D-xyl, L-ara and D-fru, while these in GS-DRB only composed of D-glu and D-man. In the in vitro study, the IC50 of RBS and GSRBPs was as GS-DRB-11 (40.62 μg/mL), GS-FRB-9 (43.82 μg/mL), GS-DRB-7 (48.08 μg/mL), RBS (49.56 μg/mL), GS-DRB-9 (49.91 μg/mL), GS-DRB-13 (51.89 μg/mL), GS-FRB-11 (53.75 μg/mL), GS-FRB-7 (56.84 μg/mL), GS-DRB-13 (60.63 μg/mL) from small to large. In the in vivo study, the H1299 NSCLC inhibition rate (InRa) of RBS and GSRBPs were GS-DRB-11 (86.81%) > GS-DRB-9 (86.01%) > GS-FRB-9 (84.88%) > GS-DRB-7 (82.21%) > GS-DRB-13 (78.04%) > RBS (76.06%) > GS-FRB-13 (65.44%) > GS-FRB-11 (64.70%) > GS-FRB-7 (27.87%). The GSFPS-2 area percent was negatively correlated to the IC50 and was positively correlated to the InRa. This means the GSFPS-2 had much higher anti-tumor activity than GSFPS-1.ConclusionGSFPS-2 had higher anti-tumor activities, and the lipid in the rice bran has a decisive effect on the structures of polysaccharides produced by fermentation. Therefore, GSRBPs could be considered as potential novel agents to suppress H1299 non-small-cell lung cancer.
Highlights
Non-small-cell lung cancer (NSCLC) accounts more than 80% of the lung cancer cases
Ganoderma sinense –rice bran polysaccharide (GSRBP) could be considered as potential novel agents to suppress H1299 non-small-cell lung cancer
In the Ganoderma sinense (GS)-defatted rice bran (DRB) fermentation product, the order of GSRBP yield was as follows: Ganoderma sinense – defatted rice bran (GS-DRB)-11 (9.67% ± 0.18%), GS-DRB-13 (9.44% ± 0.12%), GS-DRB-7 (8.33% ± 0.30%) and GS-DRB-9 (6.33% ± 0.12%). Both rice bran polysaccharides (RBS) and GSRBPs were composed of two polysaccharide fractions, GSFPS-1 with a larger molecular weight (Mw) and GSFPS-2 with a smaller Mw (Fig. 1a)
Summary
Polysaccharides in rice bran and its fermentation products have been proven to suppress many cancers. Among the lung cancer cases, more than 80% are identified as non-small-cell lung cancer (NSCLC) and it is responsible for over one million mortalities worldwide each year [2, 3]. The chemotherapy and radiotherapy are used in curing cancer patients, they often show serious side effects [4] Many natural products such as polysaccharides and some secondary metabolites have been proven to be effective in inhibiting the growth of NSCLC lines [5,6,7]. H1299 cells lack the tumor suppressor P53 protein which is expressed by the TP53 gene. It makes H1299 (p53-null) cell more sensitive to some compounds [9]
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