The role of PKM2 in cancer progression and its structural and biological basis.

Pyruvate kinase M2 (PKM2), a subtype of pyruvate kinase (PK), has been shown to play an important role in the development of cancer. It regulates the last step of glycolytic pathway. PKM2 has both pyruvate kinase and protein kinase activity, and the conversion of these two functions of PKM2 depends on the mutual change of dimer and tetramer. The dimerization of PKM2 can promote the proliferation and growth of tumor cells, so inhibiting the dimerization of PKM2 is essential to curing cancer. The aggregation of PKM2 is regulated by both endogenous and exogenous cofactors as well as post-translational modification (PTM). Although there are many studies on the different aggregation of PKM2 in the process of tumor development, there are few summaries in recent years. In this review, we first introduce the role of PKM2 in various biological processes of tumor growth. Then, we summarize the aggregation regulation mechanism of PKM2 by various endogenous cofactors such as Fructose-1, 6-diphosphate (FBP), various amino acids, and post-translational modification (PTMs). Finally, the related inhibitors and agonists of PKM2 are summarized to provide reference for regulating PKM2 aggregation in the treatment of cancer in the future.

Salvianolic acid F suppresses KRAS-dependent lung cancer cell growth through the PI3K/AKT signaling pathway.

BACKGROUND: KRAS mutation is a common driver of NSCLC, and there is a high proportion of lung cancer patients with KRAS G12C and G12D mutation. KRAS was previously considered an "undruggable" target, but the first KRAS G12C mutation-targeted drug AMG510, entered the market in 2021. However, treatments for G12D mutant tumors remain to be discovered. Salvianolic acid F (SalF), a monomer derived from the traditional Chinese medicine Salvia miltiorrhiza (SM), and KRAS had high binding affinity, especially for KRAS G12D. There is an urgent need to investigate effective and safe novel targeted therapies against KRAS G12D-driven NSCLC. METHODS: To evaluate the anticancer effect of SalF, we used KRAS-overexpressing lung cancer cells in vitro, a subcutaneous transplant tumor model, and KRAS G12D mice model in vivo. Then, the binding effect of SalF and KRAS was investigated using molecular docking, proteolytic assays and protein thermal shift assays. More critically, the PI3K/AKT signaling pathway in the lung was investigated utilizing RT-qPCR and Western Blotting. RESULTS: This is the first study to evaluate the anticancer effect of SalF on KRAS-overexpressing lung cancer cells or KRAS G12D lung tumors in vivo. We demonstrated that SalF inhibits OE-KRAS A549 cell migration, proliferation and promotes apoptosis in vitro. In addition, we used a subcutaneous transplant tumor model to show that SalF suppresses the growth of lung cancer cells in vivo. Interestingly, our group found that SalF was strongly bound to G12D and could decrease the stability and promoted the degradation of the KRAS G12D mutant through molecular docking, proteolytic assays and protein thermal shift assays. Further research demonstrated that in the KrasG12D mice model, after SalF treatment, the number and size of mouse lung tumors were significantly reduced. More importantly, SalF can promote apoptosis by inhibiting downstream PI3K/AKT signaling pathway activation. CONCLUSION: SalF activated apoptosis signaling pathways, suppressed anti-apoptotic genes, and inhibited lung cancer cell growth. These datas suggested that SalF could effectively inhibit the growth of lung tumors with KRAS G12D mutation. SalF may be a novel inhibitor against KRAS G12D, providing a strong theoretical basis for the clinical treatment of lung cancer with KRAS mutations.

Insight into the mechanism of Xiao-Chai-Hu-Tang alleviates irinotecan-induced diarrhea based on regulating the gut microbiota and inhibiting Gut ß-GUS.

BACKGROUND: Irinotecan (CPT-11, Camptosar@) is a first-line drug for metastatic colorectal cancer. CPT-11-induced diarrhea, which is closely related to the concentrations of ß-glucuronidase (ß-GUS) and SN-38 in the gut, largely limits its clinical application. PURPOSE: Herein, Xiao-Chai-Hu-Tang (XCHT), a traditional Chinese formula, was applied to mitigate CPT-11-induced toxicity. This study initially explored the mechanism by which XCHT alleviated diarrhea, especially for ß-GUS from the gut microbiota. METHODS: First, we examined the levels of the proinflammatory cytokines and the anti-inflammatory cytokines in the intestine. Furthermore, we researched the community abundances of the gut microbiota in the CPT-11 and XCHT-treated mice based on 16S rRNA high-throughput sequencing technology. Meanwhile, the level of SN-38 and the concentrations of ß-GUS in intestine were examined. We also resolved the 3D structure of ß-GUS from gut microbiota by X-ray crystallography technology. Moreover, we used virtual screening, SPR analysis, and enzyme activity assays to confirm whether the main active ingredients from XCHT could selectively inhibit ß-GUS. RESULTS: In XCHT-treated mice, the levels of the proinflammatory cytokines decreased, the anti-inflammatory cytokines increased, and the community abundances of beneficial Firmicutes and Bacteroidota improved in the gut microbiota. We also found that the concentrations of ß-GUS and the level of SN-38, the major ingredient that induces diarrhea in the gut, significantly decreased after coadministration of XCHT with CPT-11 in the intestine. Additionally, we revealed the structural differences of ß-GUS from different gut microbiota. Finally, we found that EcGUS had good affinity with baicalein and meanwhile could be selectively inhibited by baicalein from XCHT. CONCLUSIONS: Overall, XCHT could relieve the delayed diarrhea induced by CPT-11 through improving the abundance of beneficial gut microbiota and reduced inflammation. Furthermore, based on the three-dimensional structure, baicalein, especially, could be used as a candidate EcGUS inhibitor to alleviate CPT-11-induced diarrhea.