ABSTRACT
BACKGROUND/AIMS: Combination therapy utilizing tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) in conjunction with other anticancer agents, is a promising strategy to overcome TRAIL resistance in malignant cells. Recently, parthenolide (PT) has proved to be a promising anticancer agent, and several studies have explored its use in combination therapy. Here, we investigated the molecular mechanisms by which PT sensitizes colorectal cancer (CRC) cells to TRAIL-induced apoptosis. METHODS: HT-29 cells (TRAIL-resistant) were treated with PT and/or TRAIL for 24 hours. The inhibitory effect on proliferation was detected using the 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Annexin V staining, cell cycle analysis, and Hoechst 33258 staining were used to assess apoptotic cell death. Activation of an apoptotic pathway was confirmed by Western blot. RESULTS: Treatment with TRAIL alone inhibited the proliferation of HCT 116 cells in a dose-dependent manner, whereas proliferation was not affected in HT-29 cells. Combination PT and TRAIL treatment significantly inhibited cell growth and induced apoptosis of HT-29 cells. We observed that the synergistic effect was associated with misregulation of B-cell lymphoma 2 (Bcl-2) family members, release of cytochrome C to the cytosol, activation of caspases, and increased levels of p53. CONCLUSION: Combination therapy using PT and TRAIL might offer an effetive strategy to overcome TRAIL resistance in certain CRC cells.
ABSTRACT
Parthenolide (PT) is responsible for the bioactivities of feverfew (Tanacetum parthenium). Apart from its potent anti-inflammatory effects, this compound has been reported to induce apoptosis in various cancer cells. However, little is known about its role in the process of tumor angiogenesis. In the present study, we investigated the effects and potential mechanisms of action of PT on angiogenesis in human colorectal cancer (CRC). The anti-angiogenic effects of PT were evaluated in cultured human umbilical vein endothelial cells (HUVECs) and in the human CRC cell lines, HT-29, SW620 and HCT116. PT markedly inhibited vascular cell migration and capillary-like structure formation even at a dose which had not effects on cell viability. PT also suppressed the expression of angiogenic biomarker proteins [vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR)1 and VEGFR2] in both the HUVECs and CRC cells. Additionally, PT effectively inhibited tumor neovascularization in a HT-29 xenograft model. These results indicate that PT suppresses angiogenesis by reducing the expression of VEGF and its receptors and may be a viable drug candidate in anti-angiogenesis therapies for human CRC.
Subject(s)
Colorectal Neoplasms/metabolism , Neovascularization, Pathologic/metabolism , Receptors, Vascular Endothelial Growth Factor/metabolism , Sesquiterpenes/pharmacology , Vascular Endothelial Growth Factor A/metabolism , Cell Movement/drug effects , Cell Movement/genetics , Cell Survival/drug effects , Cell Survival/genetics , Colorectal Neoplasms/genetics , HCT116 Cells , HT29 Cells , Human Umbilical Vein Endothelial Cells , Humans , Receptors, Vascular Endothelial Growth Factor/genetics , Vascular Endothelial Growth Factor A/geneticsABSTRACT
Parthenolide (PT), a NF-κB inhibitor, has recently been demonstrated as a promising anticancer agent that promotes apoptosis of cancer cells. 5-fluorouracil (5-FU) has been a drug of choice for treatment of colorectal cancer (CRC). Unfortunately, many of the therapies that use 5-FU alone or in combination with other agents are likely to become ineffective due to drug resistance. In the present study, we investigated the antitumor effect of PT combined with 5-FU on a human CRC cell line, SW620. The results demonstrated that combination of PT and 5-FU induced apoptosis which was determined using MTT, cell cycle analysis, annexin-V assay, and Hoechst 33258 staining. Apoptosis through the mitochondrial pathway was confirmed by detecting regulation of Bcl-2 family members, cytochrome C release, and activation of caspase 3 and 9. Moreover, intra-peritoneal injection of PT and 5-FU showed significant inhibition of tumor growth in the xenograft model. These results demonstrate that PT exhibits anticancer activity in human colorectal cancer in vitro and in vivo. These findings provide an efficacious strategy to overcome 5-FU resistance in certain CRC.
