Abstract
Protocatechualdehyde (PCA) extracted from Phellinus gilvus exhibits anti-cancer activity in human colorectal carcinoma cells (HT-29). However, the underlying mechanisms remain poorly understood. We performed an in vitro study involving MTT, flow cytometry, RT-PCR, and western blot analyses to investigate the effects of PCA treatment on cell proliferation, cell cycle distribution, apoptosis, and expression of several cell cycle-related genes in HT-29 cells. The treatment enhanced S-phase cell cycle and apoptosis in HT-29 cells in a dose-dependent manner. Western blot results showed that PCA treatment decreased the expression levels of cyclin A, cyclin D1, and p27KIP1 but increased those of cyclin-dependent kinase 2 (CDK2) in HT-29 cells. Furthermore, the expression levels of B-cell lymphoma/leukemia-2 (Bcl-2) and B-cell lymphoma/leukemia-xL (Bcl-xL) were down-regulated, whereas the levels of BH3-interacting domain death agonist (Bid), Bcl-2 homologous antagonist/killer (Bak), and cytosolic cytochrome c were significantly upregulated. Thus, the enzymes caspases-9, -3, -8, and -6 were found to be activated in HT-29 cells with PCA treatment. These results indicate that PCA-induced S-phase cell cycle arrest and apoptosis involve p27KIP1-mediated activation of the cyclin-A/D1-Cdk2 signaling pathway and the mitochondrial apoptotic pathway.
Highlights
Phytochemicals from natural resources exhibit strong potential for use in cancer treatment.Phellinus spp (Mesima) is a basidomycota fungus that is rich in polysaccharides and polyphenol compounds
To study the mechanismsthe underlying theproperties therapeuticPCA, properties of PCA, the effects effects of of this this compound compound on on cell cell cycle cycle distribution, distribution, apoptosis, apoptosis, and and expression expression of of several several regulatory regulatory the we examined the effects of this compound on cell cycle distribution, apoptosis, and expression of proteins and and signaling signaling molecules molecules in in HT-29
These results suggested that PCA induced S-phase arrest in HT-29 cells (Figure 3)
Summary
Phytochemicals from natural resources exhibit strong potential for use in cancer treatment. PCA exhibits anti-cancer activities in human breast cancer cells [9] and leukemia cells by inhibiting casein kinase II activity [10]. It downregulates cyclin D1 and HDAC2, and activates ATF3 expression in human colorectal cancer cell lines, namely, HCT116 and SW480 cells [11,12]. Many natural agents can cause cell cycle arrest at different phases and induce apoptosis [16]. Natural agents can cause arrest different phases and induce apoptosis growth Many. PCA attenuates cyclin D1 expression, resultingof in cell inhibition cell apoptosis in in HCT116.
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