[Mechanism of total flavonoids from Smilacis Glabrae Rhizoma against obesity-associated colorectal cancer via regulation of fatty acid oxidation].

Authors

Jian-Qin Xu, Zhao-Wei Cai, Zi-Yao Pang, Wen-Jing Chen, Jia-Yan Chen, De-Jun Wang, Jue Tu

Published in

Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica. Volume 51. Issue 13. Pages 3818-3829.

Abstract

This study aimed to investigate the mechanism of total flavonoids from Smilacis Glabrae Rhizoma(SGF) against obesity-associated colorectal cancer(CRC) via regulation of fatty acid oxidation(FAO). In vivo, syngeneic subcutaneous and orthotopic xenograft models of CRC cells MC38 were established in obese mice induced by high fat diet(HFD), which was followed by the administration with SGF. The tumor volume and tumor weight were measured in the CRC subcutaneous model. The growth of CRC orthotopic tumors was monitored by a small animal in vivo imaging system. Hematoxylin-eosin(HE) staining was used to observe the pathological changes in tumors and peritumoral adipose tissues. Immunohistochemistry, TdT-mediated dUTP nick end labeling(TUNEL), and oil red O staining were separately conducted to detect Ki67 expression, apoptosis, and lipid accumulation in tumors. Western blot was used to detect the phosphorylation levels of adenosine monophosphate-activated protein kinase(AMPK) and acetyl-CoA carboxylase(ACC), as well as the expression of FAO-related proteins and cell death-related proteins in tumor tissues. In vitro, MC38 cells cultured under low-glucose and high-oleic acid conditions were taken as the research object and treated with varying concentrations of SGF for 48 h. Apoptosis rates were assessed by flow cytometry, and the expression of FAO-related and cell death-related proteins was analyzed by Western blot. Further, the prolyl hydroxylase domain-containing protein 3(PHD3) expression was subjected to RNA interference(RNAi), and the viability and apoptosis of PHD3-knockdown MC38 cells following SGF treatment were assessed by MTT assay and flow cytometry, respectively. The results showed that both high and low doses of SGF significantly inhibited tumor growth in two obese mouse xenograft models. The SGF-treated groups exhibited extensive, scattered necrotic areas within the tumor tissue, with marked destruction of tissue structure. Compared with the HFD group, the SGF-treated groups showed a significant reduction in the rate of Ki67-positive cells and a significant increase in the proportion of TUNEL-staining-positive apoptotic cells. In obese mice, subcutaneous tumors showed significantly enhanced oil red O staining, with large lipid droplets visible. The SGF-treated groups markedly reduced lipid deposition. In both models, peritumoral adipocytes were significantly enlarged after SGF treatment. The tumor tissues of obese mice exhibited significantly increased expression of FAO-related proteins cluster of differentiation 36(CD36), carnitine palmitoyltransferase 1(CPT1), and acyl-CoA dehydrogenase long chain(ACADL), as well as elevated adenosine triphosphate(ATP) content. The phosphorylation levels of upstream regulatory proteins AMPK and ACC were significantly increased, while the expression of the energy switch protein PHD3 was significantly decreased. SGF significantly reduced the protein expression of CD36, CPT1, and ACADL, decreased ATP content, inhibited AMPK and ACC phosphorylation, and increased PHD3 protein levels. This was accompanied by a significant increase in the apoptotic protein cysteine-dependent aspartate-specific protease-3(caspase-3) and significant decreases in the anti-apoptotic protein B-cell lymphoma-2(Bcl-2) and the cell cycle protein cyclin D1. In MC38 cells cultured under low-glucose and high-oleic acid conditions, SGF significantly induced apoptosis and inhibited lipid uptake. FAO-related protein expression was significantly suppressed. Caspase-3 expression was significantly increased, while Bcl-2 and cyclin D1 expression was significantly decreased. PHD3 expression was significantly elevated. In MC38 cells transfected with siPHD3, the inhibitory effect of SGF on cell viability and its pro-apoptotic effect were both significantly enhanced. In summary, SGF effectively reduces lipid transfer between adipose tissue and tumors under obese conditions, regulates the AMPK/ACC signaling pathway, and targetedly inhibits tumor FAO, thereby exerting potent antitumor effects against obesity-associated CRC.

PMID:
42543372
Bibliographic data and abstract were imported from PubMed on 03 Aug 2026.

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