cytochrome-c-t and Aberrant-Crypt-Foci

Annona muricata has been used in folk medicine for the treatment of cancer and tumors. This study evaluated the chemopreventive properties of an ethyl acetate extract of A. muricata leaves (EEAML) on azoxymethane-induced colonic aberrant crypt foci (ACF) in rats. Moreover, the cytotoxic compound of EEAML (Annomuricin E) was isolated, and its apoptosis-inducing effect was investigated against HT-29 colon cancer cell line using a bioassay-guided approach. This experiment was performed on five groups of rats: negative control, cancer control, EEAML (250 mg/kg), EEAML (500 mg/kg) and positive control (5-fluorouracil). Methylene blue staining of colorectal specimens showed that application of EEAML at both doses significantly reduced the colonic ACF formation compared with the cancer control group. Immunohistochemistry analysis showed the down-regulation of PCNA and Bcl-2 proteins and the up-regulation of Bax protein after administration of EEAML compared with the cancer control group. In addition, an increase in the levels of enzymatic antioxidants and a decrease in the malondialdehyde level of the colon tissue homogenates were observed, suggesting the suppression of lipid peroxidation. Annomuricin E inhibited the growth of HT-29 cells with an IC50 value of 1.62 ± 0.24 μg/ml after 48 h. The cytotoxic effect of annomuricin E was further substantiated by G1 cell cycle arrest and early apoptosis induction in HT-29 cells. Annomuricin E triggered mitochondria-initiated events, including the dissipation of the mitochondrial membrane potential and the leakage of cytochrome c from the mitochondria. Prior to these events, annomuricin E activated caspase 3/7 and caspase 9. Upstream, annomuricin E induced a time-dependent upregulation of Bax and downregulation of Bcl-2 at the mRNA and protein levels. In conclusion, these findings substantiate the usage of A. muricata leaves in ethnomedicine against cancer and highlight annomuricin E as one of the contributing compounds in the anticancer activity of A. muricata leaves.

Topics: Aberrant Crypt Foci; Animals; Annona; Apoptosis; Azoxymethane; bcl-2-Associated X Protein; Caspase 3; Caspase 7; Caspase 9; Cell Proliferation; Colon; Cytochromes c; Down-Regulation; Furans; G1 Phase Cell Cycle Checkpoints; HT29 Cells; Humans; Immunohistochemistry; Lactones; Lipid Peroxidation; Male; Malondialdehyde; Membrane Potential, Mitochondrial; Mitochondria; Plant Extracts; Plant Leaves; Proliferating Cell Nuclear Antigen; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Up-Regulation

Apoptosis is a highly regulated mechanism of cell death where pro-apoptotic proteins and caspases play an important role. Activation of pro-caspases at a definite time is essential to control the whole caspase cascade. Mitochondrion contains some pro-apoptotic proteins, which need to come out in cytoplasm for apoptotic function such as Cytochrome c (Cyt c), while the Bcl-2 protein family works as the guard of mitochondrial membrane and prevents the escape of Cyt c. Once Cyt c is out in cytoplasm, it binds with Apaf-1 (another pro-apoptotic protein also essential for proper cell differentiation) and pro-caspase-9, forming the Apoptosome complex. In this study, the role of two non-steroidal anti-inflammatory drugs (NSAIDs), Diclofenac and Celecoxib, in experimentally induced early neoplasm of colon via apoptosome mechanism had been studied. It has been recognized that the prolonged use of NSAIDs has its effect on reducing the risk of colorectal cancer through apoptotic pathways. However, the role of NSAIDs in respect of apoptosome is not clear.. Western blotting and immunohistochemistry were performed, along with morphological and histological analysis.. According to the expression levels of Cytochrome c, Apaf-1, Caspases, and Bcl-2, it was observed that NSAIDs do follow the mitochondrial or intrinsic pathway of apoptosis.. The effects of Diclofenac and Celecoxib on the expression of pro- and anti-apoptotic proteins have been observed, which may constitute the mechanism by which the NSAIDs are efficient in controlling the proliferation of neoplasm in the colon.

Topics: 1,2-Dimethylhydrazine; Aberrant Crypt Foci; Animals; Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Apoptosomes; Blotting, Western; Carcinogens; Celecoxib; Colorectal Neoplasms; Cyclooxygenase 2 Inhibitors; Cytochromes c; Diclofenac; Immunoenzyme Techniques; Male; Mitochondria; Pyrazoles; Rats; Rats, Sprague-Dawley; Sulfonamides