cyclin-d1 and protocatechualdehyde

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 p27(KIP1) 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 p27(KIP1)-mediated activation of the cyclin-A/D1-Cdk2 signaling pathway and the mitochondrial apoptotic pathway.

Topics: Apoptosis; Benzaldehydes; Catechols; Cell Proliferation; Cyclin A1; Cyclin D1; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase Inhibitor p27; HT29 Cells; Humans; Mitochondria; S Phase Cell Cycle Checkpoints; Signal Transduction

Protocatechualdehyde (PCA) is a natural polyphenol compound isolated from the root of the herb S. miltiorrhiza and barley tea plants. PCA possesses antiproliferative and pro-apoptotic properties in human colorectal cancer cells. However, the cellular mechanism has not been fully understood. β-catenin and cyclin D1 are proto-oncogene that is overexpressed in many types of cancers and leads to cancer development. The present study was performed to elucidate the molecular mechanism by which PCA stimulates cell growth arrest and apoptosis in human breast cancer cells. PCA repressed cell proliferation and induced apoptosis in dose-dependent manner. PCA suppressed the expression of β-catenin and cyclin D1 with no changes in mRNA levels. Inhibition of proteosomal degradation using MG-132 and Ada-(Ahx)3-(Leu)3-vinyl sulfone ameliorates PCA-induced downregulation of β-catenin and cyclin D1. PCA treatment decreased the half-life of β-catenin and cyclin D1. PCA-mediated β-catenin downregulation depends on GSK3β. We further provide the evidence that PCA increased nuclear translocation of nuclear factor kappa-B (NF-κB) and the blockage of NF-κB using Bay11-7082 inhibited PCA-mediated β-catenin downregulation. The current study demonstrates that PCA suppress β-catenin expression through GSK3β- and NF-κB-mediated proteosomal degradation. In addition, PCA decreased cyclin D1 expression independent to β-catenin through proteosomal degradation.

Topics: Antineoplastic Agents; Apoptosis; Benzaldehydes; beta Catenin; Breast Neoplasms; Catechols; Cell Cycle; Cell Line, Tumor; Cyclin D1; Down-Regulation; Female; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; NF-kappa B; Proto-Oncogene Mas

Protocatechualdehyde (PCA) is a naturally occurring polyphenol found in barley, green cavendish bananas, and grapevine leaves. Although a few studies reported growth-inhibitory activity of PCA in breast and leukemia cancer cells, the underlying mechanisms are still poorly understood. Thus, we performed in vitro study to investigate if treatment of PCA affects cell proliferation and apoptosis in human colorectal cancer cells and define potential mechanisms by which PCA mediates growth arrest and apoptosis of cancer cells. Exposure of PCA to human colorectal cancer cells (HCT116 and SW480 cells) suppressed cell growth and induced apoptosis in dose-dependent manner. PCA decreased cyclin D1 expression in protein and mRNA level and suppressed luciferase activity of cyclin D1 promoter, indicating transcriptional downregulation of cyclin D1 gene by PCA. We also observed that PCA treatment attenuated enzyme activity of histone deacetylase (HDAC) and reduced expression of HDAC2, but not HDAC1. These findings suggest that cell growth inhibition and apoptosis by PCA may be a result of HDAC2-mediated cyclin D1 suppression.

Topics: Antineoplastic Agents; Apoptosis; Benzaldehydes; Catechols; Colorectal Neoplasms; Cyclin D1; Down-Regulation; HCT116 Cells; Histone Deacetylase 2; Histone Deacetylase Inhibitors; Humans