Genes related to suppression of malignant phenotype induced by Maitake D-Fraction in breast cancer cells

Abstract

It is already known that the Maitake (D-Fraction) mushroom is involved in stimulating the immune system and activating certain cells that attack cancer, including macrophages, T-cells, and natural killer cells. According to the U.S. National Cancer Institute, polysaccharide complexes present in Maitake mushrooms appear to have significant anticancer activity. However, the exact molecular mechanism of the Maitake antitumoral effect is still unclear. Previously, we have reported that Maitake (D-Fraction) induces apoptosis in breast cancer cells by activation of BCL2-antagonist/killer 1 (BAK1) gene expression. At the present work, we are identifying which genes are responsible for the suppression of the tumoral phenotype mechanism induced by Maitake (D-Fraction) in breast cancer cells. Human breast cancer MCF-7 cells were treated with and without increased concentrations of Maitake D-Fraction (36, 91, 183, 367 μg/mL) for 24 h. Total RNA were isolated and cDNA microarrays were hybridized containing 25,000 human genes. Employing the cDNA microarray analysis, we found that Maitake D-Fraction modified the expression of 4068 genes (2420 were upmodulated and 1648 were downmodulated) in MCF-7 breast cancer cells in a dose-dependent manner during 24 h of treatment. The present data shows that Maitake D-Fraction suppresses the breast tumoral phenotype through a putative molecular mechanism modifying the expression of certain genes (such as IGFBP-7, ITGA2, ICAM3, SOD2, CAV-1, Cul-3, NRF2, Cycline E, ST7, and SPARC) that are involved in apoptosis stimulation, inhibition of cell growth and proliferation, cell cycle arrest, blocking migration and metastasis of tumoral cells, and inducing multidrug sensitivity. Altogether, these results suggest that Maitake D-Fraction could be a potential new target for breast cancer chemoprevention and treatment.

FIG. 1.

Gene expression profile of upmodulated genes induced by Maitake D-Fraction in MCF-7 cells. Human breast cancer MCF-7 cells were treated with and without (control) increased concentrations of Maitake D-Fraction for 24 h, namely, 36, 91, 187, or 367 μg/mL. Genomic analysis using complementary DNA (cDNA) microarrays was used to monitor expression levels of 25,000 human known genes. The resulting array images were analyzed and normalized employing the Nexus Expression Software (Biodiscovery). Color images available online at www.liebertpub.com/jmf

FIG. 2.

Gene expression profile of downmodulated genes induced by Maitake D-Fraction in MCF-7 cells. Human breast cancer MCF-7 cells were treated with and without (control) increased concentrations of Maitake D-Fraction for 24 h, namely, 36, 91, 187, or 367 μg/mL. Genomic analysis using complementary DNA (cDNA) microarrays was used to monitor expression levels of 25,000 human known genes. The resulting array images were analyzed and normalized employing the Nexus Expression Software (Biodiscovery). Color images available online at www.liebertpub.com/jmf

FIG. 3.

Maitake D-Fraction induces apoptosis mediated by BAK1 stimulation and blocks tumor cells growth and proliferation in MCF-7 cells through activation of p27/Kip1 and RASSF2 genes. The putative molecular mechanism of apoptosis and anti-tumoral cell proliferation induced by Maitake D-Fraction in breast cancer MCF7 cells is shown, with red lines indicating stimulated pathways, green lines indicating inhibitory pathways, and discontinuous gray lines representing the genes whose expression has not been changed after Maitake treatment. Color images available online at www.liebertpub.com/jmf

FIG. 4.

Maitake D-Fraction blocks the malignant phenotype, cell invasion, and metastasis in MCF-7 cells through activation of PTEN and MTSS1. The putative molecular mechanism of cell cycle arrest and blocking of malignant phenotype induced by activation of PTEN gene expression after Maitake D-Fraction treatment is depicted. As shown, MTSS1 blocks cell migration, invasion, and metastasis in MCF-7 cells. Stimulated (red) and inhibitory (green) pathways are indicated. Discontinuous gray lines represent the genes whose expression has not been changed after Maitake treatment. Color images available online at www.liebertpub.com/jmf

FIG. 5.

Maitake D-Fraction blocks tumor cells growth and proliferation in MCF-7 cells through activation of p27/Kip1 gene expression. The putative molecular mechanism of cell growth and proliferation inhibition by activation of p27/Kip1 gene expression is shown; this process is stimulated by SMAD3 and SMAD7 proteins, which are activated after TGFBRII interaction. Stimulated (red) and inhibitory (green) pathways are indicated. Discontinuous gray lines represent the genes whose expression has not been changed after Maitake treatment. Color images available online at www.liebertpub.com/jmf

FIG. 6.

Maitake D-fraction blocks malignant phenotype through activation of SPARC gene expression, and in collaboration with CUL3, they promote multi-drug sensitivity. The putative molecular mechanism of inhibition of malignant phenotype through activation of SPARC gene expression in MCF-7 cells is depicted. Also shown are the means by which SOD2 blocks the oxidative stress in tumoral cells and CUL3 participates in multi-drug sensitivity, blocking the output drug in those cells. Stimulated (red) and inhibitory (green) pathways are indicated. Discontinuous gray lines represent the genes whose expression has not been changed after Maitake treatment. Color images available online at www.liebertpub.com/jmf