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Background:@#Colorectal cancer is the third most common cancer worldwide and still lack of effective therapy so far. Petasin, a natural product found in plants of the genus Petasites, has been reported to possess anticancer activity. The present study aimed to investigate the anticolon cancer activity of petasin both in vitro and in vivo. The molecular mechanism of petasin was also further explored.@*Methods:@#Caco-2, LoVo, SW-620, and HT-29 cell lines were used to detect the inhibitory effect of petasin on colon cancer proliferation. Cell viability was determined using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. Cell apoptosis was analyzed by flow cytometry. Hoechst 33258 staining was used to visualize morphological changes. Cell migration was assessed using a wound-healing migration assay, and cell invasion was investigated using Transwell chambers. Western blotting assays were employed to evaluate the expression levels of proteins in the protein kinase B/mammalian target of rapamycin (Akt/mTOR) signaling pathway. Finally, in vivo activity of petasin was evaluated using the SW-620 subcutaneous tumor model established in Balb/c nude mice. Twelve rats were randomly divided into control group and 10 mg/kg petasin group. The tumor volume was calculated every 7 days for 28 days. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay was performed to assess the apoptotic effect of petasin. Differences between two groups were assessed by analysis of independent-sample t tests.@*Results:@#Petasin significantly inhibited the proliferation of human colon carcinoma cell lines, induced apoptosis, and suppressed migration and invasion in SW-620 cells. Western blotting results showed that petasin decreased the phosphorylation of Akt (1.01 ± 0.16 vs. 0.74 ± 0.06, P = 0.042), mTOR (0.71 ± 0.12 vs. 0.32 ± 0.11, P = 0.013), and P70S6K (1.23 ± 0.21 vs. 0.85 ± 0.14, P = 0.008), elevated the expression of caspase-3 (0.41 ± 0.09 vs. 0.74 ± 0.12, P = 0.018) and caspase-9 (1.10 ± 0.27 vs. 1.98 ± 0.22, P = 0.009), decreased the Bcl-2 protein (2.75 ± 0.47 vs. 1.51 ± 0.36, P = 0.008), downregulated the expression of matrix metalloproteinase (MMP)-3 (1.51 ± 0.31 vs. 0.82 ± 0.11, P = 0.021) and MMP-9 (1.56 ± 0.32 vs. 0.94 ± 0.15, P = 0.039) in SW-620 cell. In vivo, 10 mg/kg petasin inhibited tumor growth in Balb/c nude mice (924.18 ± 101.23 vs. 577.67 ± 75.12 mm3 at day 28, P = 0.001) and induced apoptosis (3.6 ± 0.7% vs. 36.0 ± 4.9%, P = 0.001) in tumor tissues.@*Conclusions:@#Petasin inhibits the proliferation of colon cancer SW-620 cells via inactivating the Akt/mTOR pathway. Our findings suggest petasin as a potential candidate for colon cancer therapy.
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Objective To investigate the apoptotic effect of petasin on myeloma RPMI 8226 cells and the mechanisms.Methods The inhibition of petasin on the proliferation of myeloma RPMI 8226 cells was tested by trypan blue assay.Apoptosis of RPMI 8226 cells was measured by terminal-deoxynueleotidyl transferase mediated dUTP nick end labeling (TUNEL)assay and Hoechst 33258 staining assay.Effects of petasin on caspase-3,8 and 9 expressions,phosphorylation of ERK1/2,MEK(p-ERK1/2 ;p-MEK)and p38MAPK(p-p38MAPK)protein were analyzed by Western blot.Results Incubation by petasin for 24 h,48 h or 72 h could significantly inhibit the pro-liferation of myeloma RPMI 8226 cells (P <0.01,P <0.01,P <0.01).Petasin induced the apoptosis of myeloma RPMI 8226 cells in time-and concentration-dependent manners (P <0.05,P <0.05).Caspase inhibitor pretreat-ment could significantly inhibit the apoptosis of myeloma cells.After cultured with petasin for 72 h,the expressions of caspase-3,8 and 9 were obviously enhanced (P <0.05,P <0.01,P <0.05)and phosphorylation of p-p38MAPK of RPMI8226 cells was significantly increased (P <0.01).However,phosphorylation of p-ERK1/2 and p-MEK was decreased significantly (P <0.01,P <0.05).Conclusion Petasin can inhibit the proliferation of myeloma RPMI 8226 cells and induce apoptosis.The mechanism may be related to the activation of caspase-3,8 and 9 proteins and the changes in phosphorylation of p38MAPK,ERK1/2 and MEK.
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To explore the anti-allergic and anti-inflammatory effects of extracts of Petasites genus, we studied the effects of s-petasin, a major sesquiterpene from Petasites formosanus (a butterbur species) on asthma and peritonitis models. In an ovalbumin-induced mouse asthma model, s-petasin significantly inhibited the accumulations of eosinophils, macrophages, and lymphocytes in bronchoalveolar fluids. S-petasin inhibited the antigen-induced degranulation of beta-hexosamidase but did not inhibit intracellular Ca2+ increase in RBL-2H3 mast cells. S-petasin inhibited the LPS induction of iNOS at the RNA and protein levels in mouse peritoneal macrophages. Furthermore, s-petasin inhibited the production of NO (the product of iNOS) in a concentration-dependent manner in the macrophages. Furthermore, in an LPS-induced mouse model of peritonitis, s-petasin significantly inhibited the accumulation of polymorpho nuclear and mononuclear leukocytes in peritoneal cavity. This study shows that s-petasin in Petasites genus has therapeutic effects on allergic and inflammatory diseases, such as, asthma and peritonitis through degranulation inhibition in mast cells, suppression of iNOS induction and production of NO in macrophages, and suppression of inflammatory cell accumulation.