Modulator of the PI3K/Akt oncogenic pathway affects mTOR complex 2 in human adenocarcinoma cells

The strategic roles of four enzymes in the interconnection between metabolism and oncogene activation in non-small cell lung cancer: Therapeutic implications

NSCLC is the leading cause of cancer mortality and represents a major challenge in cancer therapy. Intrinsic and acquired anticancer drug resistance are promoted by hypoxia and HIF-1α. Moreover, chemoresistance is sustained by the activation of key signaling pathways (such as RAS and its well-known downstream targets PI3K/AKT and MAPK) and several mutated oncogenes (including KRAS and EGFR among others). In this review, we highlight how these oncogenic factors are interconnected with cell metabolism (aerobic glycolysis, glutaminolysis and lipid synthesis). Also, we stress the key role of four metabolic enzymes (PFK1, dimeric-PKM2, GLS1 and ACLY), which promote the activation of these oncogenic pathways in a positive feedback loop. These four tenors orchestrating the coordination of metabolism and oncogenic pathways could be key druggable targets for specific inhibition. Since PFK1 appears as the first tenor of this orchestra, its inhibition (and/or that of its main activator PFK2/PFKFB3) could be an efficacious strategy against NSCLC. Citrate is a potent physiologic inhibitor of both PFK1 and PFKFB3, and NSCLC cells seem to maintain a low citrate level to sustain aerobic glycolysis and the PFK1/PI3K/EGFR axis. Awaiting the development of specific non-toxic inhibitors of PFK1 and PFK2/PFKFB3, we propose to test strategies increasing citrate levels in NSCLC tumors to disrupt this interconnection. This could be attempted by evaluating inhibitors of the citrate-consuming enzyme ACLY and/or by direct administration of citrate at high doses. In preclinical models, this "citrate strategy" efficiently inhibits PFK1/PFK2, HIF-1α, and IGFR/PI3K/AKT axes. It also blocks tumor growth in RAS-driven lung cancer models, reversing dedifferentiation, promoting T lymphocytes tumor infiltration, and increasing sensitivity to cytotoxic drugs.

Inositol Polyphosphate 4-Phosphatase Type II Is a Tumor Suppressor in Multiple Myeloma

Inositol polyphosphate-4-phosphatase type II (INPP4B) has been identified as a tumor suppressor, while little is known about its expression and function in multiple myeloma (MM). In this study, we evaluated the expression of INPP4B in 28 cases of newly diagnosed MM patients and 42 cases of extramedullary plasmacytoma (EMP) patients compared with normal plasma cells and found that low INPP4B expression was correlated with poor outcomes in MM patients. Moreover, expression of INPP4B in seven MM cell lines was all lower than that in normal plasma cells. In addition, loss of function of INPP4B promoted cell proliferation in MM cells; however, gain of function suppressed MM cells proliferation and arrested the cell cycle at G0/G1 phage. Meanwhile, knockdown of INPP4B enhanced resistance, but overexpression promoted sensitivity to bortezomib treatment in MM cells. Mechanistically, we found that INPP4B exerted its role via inhibiting the phosphorylation of Akt at lysine 473 but not threonine 308, which attenuated the activation of the PI3K/Akt/mammalian target of rapamycin (mTOR) signaling pathway. Therefore, we identified an inhibitory effect of INPP4B in MM, and our findings suggested that loss of INPP4B expression is a risk factor of aggressive MM.

Galectin-3 mediates cardiac remodeling caused by impaired glucose and lipid metabolism through inhibiting two pathways of activating Akt

Pathological cardiac remodeling is a leading cause of mortality in patients with diabetes. Given the glucose and lipid metabolism disorders (GLDs) in patients with diabetes, it is urgent to conduct a comprehensive study of the myocardial damage under GLDs and find key mechanisms. Apolipoprotein E knockout (ApoE-/-) mice, low-density lipoprotein receptor heterozygote (Ldlr+/-) Syrian golden hamsters, or H9C2 cells were used to construct GLDs models. GLDs significantly promoted cardiomyocyte fibrosis, apoptosis, and hypertrophy in vivo and in vitro, but inhibition of galectin-3 (Gal-3) could significantly reverse this process. Then, the signal transmission pathways were determined. It was found that GLDs considerably inhibited the phosphorylation of Akt at Thr308/Ser473, whereas the silencing of Gal-3 could reverse the inhibition of Akt activity through phosphoinositide 3-kinase-AktThr308 (PI3K-AktThr308) and AMP-activated protein kinase-mammalian target of rapamycin complex 2-AktSer473 (AMPK-mTOR2-AktSer473) pathways. Finally, the PI3K, mTOR, AMPK inhibitor, and Akt activator were used to investigate the role of pathways in regulating cardiac remodeling. Phospho-AktThr308 could mediate myocardial fibrosis, whereas myocardial apoptosis and hypertrophy were regulated by both phospho-AktThr308 and phospho-AktSer473. In conclusion, Gal-3 was an important regulatory factor in GLDs-induced cardiac remodeling, and Gal-3 could suppress the phosphorylation of Akt at different sites in mediating cardiomyocyte fibrosis, apoptosis, and hypertrophy.NEW & NOTEWORTHY Studies on the pathogenesis of diabetic cardiac remodeling are highly desired. Glucose and lipid metabolism are both disordered in diabetes. Glucose and lipid metabolism disturbances promote myocardial fibrosis, apoptosis, and hypertrophy through galectin-3. Galectin-3 promotes cardiac remodeling by inhibiting phosphorylation of AktThr308 or AktSer473. The present study finds that glucose and lipid metabolism disorders are important causes for myocardial damage and provides novel ideas for the prevention and treatment of diabetic cardiac remodeling.

Bioactivities and Future Perspectives of Chaetoglobosins

Chaetoglobosins belonging to cytochalasan alkaloids represent a large class of fungal secondary metabolites. To date, around 100 chaetoglobosins and their analogues have been isolated and identified over the years from a variety of fungi, mainly from the fungus Chaetomium globosum. Studies have found that chaetoglobosins possess a broad range of biological activities, including antitumor, antifungal, phytotoxic, fibrinolytic, antibacterial, nematicidal, anti-inflammatory, and anti-HIV activities. This review will comprehensively summarize the biological activities and mechanisms of action of nature-derived chaetoglobosins.

Pyruvate Kinase M2: a Metabolic Bug in Re-Wiring the Tumor Microenvironment

Metabolic reprogramming is a newly emerged hallmark of cancer attaining a recent consideration as an essential factor for the progression and endurance of cancer cells. A prime event of this altered metabolism is increased glucose uptake and discharge of lactate into the cells surrounding constructing a favorable tumor niche. Several oncogenic factors help in promoting this consequence including, pyruvate kinase M2 (PKM2) a rate-limiting enzyme of glycolysis in tumor metabolism via exhibiting its low pyruvate kinase activity and nuclear moon-lightening functions to increase the synthesis of lactate and macromolecules for tumor proliferation. Not only its role in cancer cells but also its role in the tumor microenvironment cells has to be understood for developing the small molecules against it which is lacking with the literature till date. Therefore, in this present review, the role of PKM2 with respect to various tumor niche cells will be clarified. Further, it highlights the updated list of therapeutics targeting PKM2 pre-clinically and clinically with their added limitations. This upgraded understanding of PKM2 may provide a pace for the reader in developing chemotherapeutic strategies for better clinical survival with limited resistance.