Betulinic acid selectively increases protein degradation and enhances prostate cancer-specific apoptosis.

PMID: 

PLoS One. 2013 ;8(2):e56234. Epub 2013 Feb 12. PMID: 23424652

Abstract Title: 

Betulinic acid selectively increases protein degradation and enhances prostate cancer-specific apoptosis: possible role for inhibition of deubiquitinase activity.

Abstract: 

Inhibition of the ubiquitin-proteasome system (UPS) of protein degradation is a valid anti-cancer strategy and has led to the approval of bortezomib for the treatment of multiple myeloma. However, the alternative approach of enhancing the degradation of oncoproteins that are frequently overexpressed in cancers is less developed. Betulinic acid (BA) is a plant-derived small molecule that can increase apoptosis specifically in cancer but not in normal cells, making it an attractive anti-cancer agent. Our results in prostate cancer suggested that BA inhibited multiple deubiquitinases (DUBs), which resulted in the accumulation of poly-ubiquitinated proteins, decreased levels of oncoproteins, and increased apoptotic cell death. In normal fibroblasts, however, BA did not inhibit DUB activity nor increased total poly-ubiquitinated proteins, which was associated with a lack of effect on cell death. In the TRAMP transgenic mouse model of prostate cancer, treatment with BA (10 mg/kg) inhibited primary tumors, increased apoptosis, decreased angiogenesis and proliferation, and lowered androgen receptor and cyclin D1 protein. BA treatment also inhibited DUB activity and increased ubiquitinated proteins in TRAMP prostate cancer but had no effect on apoptosis or ubiquitination in normal mouse tissues. Overall, our data suggests that BA-mediated inhibition of DUBs and induction of apoptotic cell death specifically in prostate cancer but not in normal cells and tissues may provide an effective non-toxic and clinically selective agent for chemotherapy.

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Betulinic acid and betulin ameliorate acute ethanol-induced fatty liver via TLR4 and STAT3 in vivo and in vitro.

PMID: 

Int Immunopharmacol. 2013 Oct ;17(2):184-90. Epub 2013 Jun 28. PMID: 23816536

Abstract Title: 

Betulinic acid and betulin ameliorate acute ethanol-induced fatty liver via TLR4 and STAT3 in vivo and in vitro.

Abstract: 

Ethanol consumption leads to many kinds of liver injury and suppresses innate immunity, but the molecular mechanisms have not been fully delineated. The present study was conducted to determine whether betulinic acid (BA) or betulin (BT) would ameliorate acute ethanol-induced fatty liver in mice, and to characterize whether Toll like receptor 4 (TLR4) and signal transducer and activator of transcription 3 (STAT3) were involved in ethanol-stimulated hepatic stellate cells (HSCs). EtOH (5mg/kg) and BA or BT (20 or 50mg/kg) were applied in vivo, while EtOH (50mM) and BA or BT (12.5 or 25μM) were applied in vitro. Administration of BA or BT significantly prevented the increases of serum ALT and AST caused by ethanol, as well as serum TG. Supplement of BA or BT prevented ethanol-induced acidophilic necrosis, increased hepatocyte nuclei and stromal inflammation infiltration as indicated by liver histopathological studies. Administration of BA or BT significantly decreased CYP2E1 activities and expression of SREBP-1caused by ethanol, however, lower dosage of BA or BT showed slight effects on CYP2E1 activity or expression of SREBP-1c. BA or BT administration significantly decreased the expression of TLR4, and increased the phosphorylation of STAT3. In vitro, BA or BT treatment reduced the expressions of α-SMA and collagen-I in ethanol-stimulated HSCs via regulation of TLR4 and STAT3, coincided with in vivo. All of these findings demonstrated that BA or BT might ameliorateacute ethanol-induced fatty liver via TLR4 and STAT3 in vivo and in vitro, promising agents for ethanol-induced fatty liver therapies.

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Wow! It’s been 10 Years — Let’s Celebrate GreenMedInfo together!

We are excited to announce our 10 Year Anniversary Celebration of GreenMedInfo! 

 

 

At GreenMedInfo, our passion is providing users expertly curated, up to the minute research on the science supporting natural healing. 

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Betulinic acid alleviates non-alcoholic fatty liver.

PMID: 

Biochem Pharmacol. 2013 May 1 ;85(9):1330-40. Epub 2013 Feb 19. PMID: 23435355

Abstract Title: 

Betulinic acid alleviates non-alcoholic fatty liver by inhibiting SREBP1 activity via the AMPK-mTOR-SREBP signaling pathway.

Abstract: 

Non-alcoholic fatty liver disease (NAFLD) is emerging as the most common liver disease in industrialized countries. The discovery of food components that can ameliorate NAFLD is therefore of interest. Betulinic acid (BA) is a triterpenoid with many pharmacological activities, but the effect of BA on fatty liver is as yet unknown. To explore the possible anti-fatty liver effects and their underlying mechanisms, we used insulin-resistant HepG2 cells, primary rat hepatocytes and liver tissue from ICR mice fed a high-fat diet (HFD). Oil Red O staining revealed that BA significantly suppressed excessive triglyceride accumulation in HepG2 cells and in the livers of mice fed a HFD. Ca(+2)-calmodulin dependent protein kinase kinase (CAMKK) and AMP-activated protein kinase (AMPK) were both activated by BA treatment. In contrast, the protein levels of sterol regulatory element-binding protein 1 (SREBP1), mammalian target of rapamycin (mTOR) and S6 kinase (S6K) were all reduced when hepatocytes were treated with BA for up to 24h. We found that BA activates AMPK via phosphorylation, suppresses SREBP1 mRNA expression, nuclear translocation and repressed SREBP1 target gene expression in HepG2 cells and primary hepatocytes, leading to reduced lipogenesis and lipid accumulation. These effects were completely abolished in the presence of STO-609 (a CAMKK inhibitor) or compound C (an AMPK inhibitor), indicating that the BA-induced reduction in hepatic steatosis was mediated via the CAMKK-AMPK-SREBP1 signaling pathway. Taken together, our results suggest that BA effectively ameliorates intracellular lipid accumulation in liver cells and thus is a potential therapeutic agent for the prevention of fatty liver disease.

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Betulinic acid has apoptotic activity against head and neck squamous cell carcinoma.

PMID: 

Head Neck. 2003 Sep ;25(9):732-40. PMID: 12953308

Abstract Title: 

Betulinic acid: a new cytotoxic compound against malignant head and neck cancer cells.

Abstract: 

BACKGROUND: A new compound, betulinic acid, has been found to be cytotoxic against a variety of tumor cells originating from the neural crest. Its efficacy against head and neck squamous cellular carcinoma cell lines has so far not been tested.METHODS: Cell numbers were assayed by automated counting; caspase activation and programmed cell death were determined using an antibody specific for an apoptosis-associated epitope in epithelial cells. The expression pattern of Bcl-2 family members was assessed by Western blotting.RESULTS: In two HNSCC cell lines betulinic acid induced apoptosis, which was characterized by a dose-dependent reduction in cell numbers, emergence of apoptotic cells, and an increase in caspase activity. Western blot analysis of the expression of various Bcl-2 family members in betulinic acid-treated cells showed, surprisingly, a suppression of the expression of the proapoptotic protein Bax but no changes in Mcl-1 or Bcl-2 expression.CONCLUSION: These data clearly demonstrate for the first time that betulinic acid has apoptotic activity against HNSCC cells.

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Beneficial effect of betulinic acid on hyperglycemia via suppression of hepatic glucose production.

PMID: 

J Agric Food Chem. 2014 Jan 15 ;62(2):434-42. Epub 2013 Dec 30. PMID: 24354358

Abstract Title: 

Beneficial effect of betulinic acid on hyperglycemia via suppression of hepatic glucose production.

Abstract: 

The inhibitory effect of betulinic acid (BA) on hepatic glucose production was examined in HepG2 cells and high fat diet (HFD)-fed ICR mice. BA significantly inhibited the hepatic glucose production (HGP) and gene expression levels of PGC-1α, PEPCK, and G6Pase. BA activated AMPK and suppressed the expression level of phosphorylated CREB. These effects were all abolished in the presence of compound C (an AMPK inhibitor). Moreover, inhibition of AMPK by overexpression of dominant negative AMPK prevented BA from suppression of HGP, indicating that the inhibitory effect of BA on HGP is AMPK-dependent. In addition, BA markedly phosphorylated CAMKK, and phosphorylation of AMPK and ACC, and suppression of HGP were all reversed in the presence of STO-609 (a CAMKK inhibitor), suggesting that CAMKK is an upstream kinase for AMPK. In an animal study, HFD-fed ICR mice were orally administered with 5 or 10 mg of BA per kg (B5 and B10) for three weeks. Plasma glucose, triglyceride, and the insulin resistance index of the B10 group were decreased by 34%, 59%, and 38%, respectively. In a pyruvate tolerance test, pyruvate-induced glucoseexcursion was decreased by 27% when mice were pretreated with 10 mg/kg of BA. In summary, BA effectively ameliorates hyperglycemia through inhibition of hepatic gluconeogenesis via modulating the CAMKK-AMPK-CREB signaling pathway.

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Betulinic acid protects against cerebral ischemia-reperfusion injury.

PMID: 

Nitric Oxide. 2011 Apr 30 ;24(3):132-8. Epub 2011 Feb 1. PMID: 21292018

Abstract Title: 

Betulinic acid protects against cerebral ischemia-reperfusion injury in mice by reducing oxidative and nitrosative stress.

Abstract: 

Increased production of reactive oxygen and nitrogen species following cerebral ischemia-reperfusion is a major cause for neuronal injury. In hypercholesterolemic apolipoprotein E knockout (ApoE-KO) mice, 2h of middle cerebral artery (MCA) occlusion followed by 22h of reperfusion led to an enhanced expression of NADPH oxidase subunits (NOX2, NOX4 and p22phox) and isoforms of nitric oxide synthase (neuronal nNOS and inducible iNOS) in the ischemic hemisphere compared with the non-ischemic contralateral hemisphere. This was associated with elevated levels of 3-nitrotyrosine, an indicator of peroxynitrite-mediated oxidative protein modification. Pre-treatment with betulinic acid (50mg/kg/day for 7days via gavage) prior MCA occlusion prevented the ischemia reperfusion-induced upregulation of NOX2, nNOS and iNOS. In parallel, betulinic acid reduced the levels of 3-nitrotyrosine. In addition, treatment with betulinic acid enhanced the expression of endothelial eNOS in the non-ischemic hemispheres. Finally, betulinic acid reduced infarct volume and ameliorated the neurological deficit in this mouse stroke model. In conclusion, betulinic acid protects against cerebral ischemia-reperfusion injury in mice. This is likely to result from a reduction of oxidative stress (by downregulation of NOX2) and nitrosative stress (by reduction of nNOS and iNOS), and an enhancement of blood flow (by upregulation of eNOS).

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