Polysaccharides from Ganoderma Sinense - rice bran fermentation products and their anti-tumor activities on non-small-cell lung cancer

Abstract

Background: Non-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.

Method: Polysaccharides (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.

Result: All 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.

Conclusion: GSFPS-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.

Keywords: Anti-tumor activity; Ganoderma sinense fermentation; H1299 non-small-cell lung cancer; In vivo and in vitro; Rice bran polysaccharides.

Fig. 1

The HPGPC chromatograms of RBS and GSRBPs (a), their molecular weights (b) as well as the area percentage of GSFPS-1 and GSFPS-2 (c). Both RBS and GSRBPs are composed of two fractions, GSFPS-1 and GSFPS-1 respectively. The ratio of the two fractions and their Mws were also changed during fermentation

Fig. 2

In vitro effect of polysaccharides extracted in GS-FRB (a) and GS-DRB (b) at different concentrations on H1299 NSCLC cell viability by MTT assay. All the polysaccharides could inhibit the viability of H1299 NSCLC. Each value represents the mean ± SE (n = 6). ∗ P < 0.05, ∗∗ P < 0.01 as compared to 0 μg/mL

Fig. 3

In vivo effect of polysaccharides extracted in GS-FRB (a and b) and GS-DRB (c and d) on mice body weight (a and c) and tumor volume (b and d). The difference in body weight gain between the sample group and the control group increased with the time of administration prolonged. Sample groups had a good inhibitory effect on the growth of H1299 NSCLC. Each value represents the mean ± SE (n = 5). ∗ P < 0.05, ∗∗ P < 0.01 as compared to control group at the corresponding time

Fig. 4

Photographs of solid tumors (a) and their representative images of HE-stained sections. (b) from H1299 NSCLC bearing mice after the 6-week treatment trial. The tumors in the sample groups were much smaller than those in the control group. In the pathological sections of the control group, the tumor nuclei (dark purple) were large, while the tumor cells were apoptosis significantly in the sample group. ∗:P < 0.05, ∗∗:P < 0.01 of the tumor weight as compared to control group

Fig. 5

(a) H1299-NSCLC InRas at different body weights in nude mice. The InRa of H1299 NSCLC was positively correlated with the body weight of the tumor-bear mice. (b) IC50 at different GSFPS-1 areas (red circle) and GSFPS-2 areas (black squares). It was positive correlate between InRa of H1299 NSCLC and the GSFPS-1: GSFPS-2 ratio. (c) H1299-NSCLC InRa at different GSFPS-1 areas (black squares) and GSFPS-2 areas (black pentagram). The correlation between InRa of H1299 NSCLC and the GSFPS-1: GSFPS-2 ratio was negative