Extrinsic and Intrinsic Apoptotic Responses Induced by Shiitake Culinary-Medicinal Mushroom Lentinus edodes (Agaricomycetes) Aqueous Extract against a Larynx Carcinoma Cell Line.

Cumulative evidence from research studies has shown that the shiitake culinary-medicinal mushroom, Lentinus edodes, is an excellent source of natural antitumor agents and is capable of inhibiting cancer cell growth. However, the cell signaling pathway that leads tumor cells to apoptosis is not well understood because many chemical compounds may be acting. This study investigated the chemopreventive effects of an L. edodes aqueous extract on human HEp-2 epithelial larynx carcinoma cells and normal human MRC-5 lung fibroblasts by identifying proliferative and apoptotic pathways. The chemical characterization of the dry powder was assessed by high-performance liquid chromatography. Antiproliferative and proapoptotic effects induced by the extract were evaluated by assessing proliferative markers, cell sorting through flow cytometry, and expression levels of apoptotic proteins with Western blotting. The results suggest that inhibition of cell proliferation was more prominent in HEp-2 than in MRC-5 cells. Cell death analysis showed the appearance of cell populations in the sub-G1 phase, with late apoptotic signal increased in a dose-dependent manner. In addition, the aqueous extract induced depolarization of mitochondria, activating the generation of intracellular reactive oxygen species in HEp-2 cells. These observations suggest that L. edodes extract may exert a chemopreventive effect, regulating mitotic induction of apoptogenic signals. These findings highlight the mushroom's pharmacological potential in cancer treatment.

Lentinan depresses 3T3-L1 fat cell formation by inhibiting PPARγ/AKT signaling pathway.

We investigated the mechanism of the effect of lentinan on 3T3-L1 fat cell formation by inhibiting the peroxisome proliferator-activated receptor gamma (PPARγ)/protein kinase B (AKT) signaling pathway. 3T3-L1 fat cells were treated with 80 mM lentinan with or without the PPARγ activator, 100 mM rosiglitazone for 24 h. Reverse transcription-polymerase chain reaction was applied to detect PPARγ and AKT mRNA expression levels. Western blotting was used to detect AKT protein expression level. Compared with the control group, 80 mM lentinan increased PPARγ mRNA expression and downregulated AKT mRNA expression. After treatment with rosiglitazone, PPARγ mRNA expression increased by 78% (P < 0.05), while AKT mRNA expression decreased by 71% (P < 0.05). Lentinan treatment decreased AKT protein expression by 33%, and AKT protein expression in the lentinan and rosiglitazone co-treatment group was reduced by 28% compared with the lentinan treatment group. We found that 80 mM lentinan increased PPARγ mRNA expression and reduced AKT mRNA. Combination treatment with rosiglitazone increased this effect. This suggests that lentinan can depress 3T3-L1 fat cell formation by inhibiting the PPARγ/AKT signaling pathway.

Properties of aqueous solutions of lentinan in the absence and presence of zwitterionic surfactants.

Morphological and conformational transitions of lentinan (LT), a ß-glucan extracted from Shiitake mushrooms (Lentinula edodes), were investigated at different concentrations of aqueous NaOH, using Small Angle X-ray Scattering (SAXS) technique. At low NaOH(aq) concentration LT chains are self-associated and adopt the triple helix form where as at higher NaOH concentrations the polymer chains undergo a transition to random coil chains. Also, the presence of fractal dimensions was observed through analysis of the exponential decay of the scattering intensity as a function of the scattering angle. In addition, the lateral radius of gyration was determined for LT in different concentrations of NaOH solution, indicating a rigid triple helix present as a small rod-like structure. Interactions of LT with two zwitterionic surfactants were investigated by surface tension, fluorescence, and static light scattering measurements. Experimental data showed that the formation of LT-(surfactant) complexes occurred through a cooperative process.