Longan flower extract inhibits the growth of colorectal carcinoma.
Longan flower extract (LFE) has been shown to exhibit free radical scavenging ability and anti-inflammatory effects. However, the effect of LFE treatment on the growth of colorectal cancer cells has not been evaluated. This study investigated the effect of LFE on two colorectal cancer cell lines, SW-480 and Colo 320DM, and the possible mechanisms involved. LFE-treated cells were assessed for viability by trypan blue exclusion, for in vitro tumorigenesis by seeding cells in soft agar to allow anchorage independent growth, for cell cycle distribution by flow cytometry, for loss of mitochondrial membrane potential by rhodamine 123 staining, for increased apoptosis by DNA fragmentation assay, and for changes in the levels of proteins involved in cell cycle control and apoptosis by immunoblotting. LFE (25-400 microg/ml) could inhibit proliferation in a dose- and time-dependent manner. The cell cycle of both LFE-treated cell lines showed obvious S phase block. Western blotting further showed the S phase block in these two cell lines was mainly due to cyclin E accumulation and cyclin A decrease. LFE treatment increased rhodamine 123-negative cells and DNA fragmentation in Colo 320DM cells but not in SW480 cells. Increased levels of the apoptosis activation protein, caspase 3, were also found in Colo 320DM cells. The activation of caspase 3 in LFE-treated SW480 cells was not significant. The caspase 3 activation in Colo 320DM cells by LFE was mediated by the suppression of Bcl-2 protein levels. LFE treatment could inhibit the proliferation and malignancy of colorectal cancer cell lines and was associated with S phase block of the cell cycle. An apoptotic mechanism induced by LFE involving a loss of mitochondrial membrane potential and caspase 3 activation was found in Colo 320DM cells but not in SW480 cells. The results of this study indicate that LFE has potential to be developed as a novel functional food or chemopreventive agent for colorectal cancer.
Hsu
Chih-Ping
CP
Yuanpei University, Taiwan, Republic of China 300.
Lin
Ying-Hsi
YH
Zhou
Shi-Ping
SP
Chung
Yuan-Chiang
YC
Lin
Chih-Cheng
CC
Wang
Shao-Cheng
SC
D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000032:analysis; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000737:chemistry / Q000473:pathology*; D019925:Cyclin A / Q000032:analysis; D019927:Cyclin E / Q000032:analysis; D053938:DNA Fragmentation; D035264:Flowers / Q000737:chemistry*; D005456:Fluorescent Dyes; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D020112:Rhodamine 123; D016196:S Phase / Q000187:drug effects; D029631:Sapindaceae / Q000737:chemistry*
D019925:Cyclin A; D019927:Cyclin E; D005456:Fluorescent Dyes; D010936:Plant Extracts; D020112:Rhodamine 123; D053148:Caspase 3