STAT1 upregulates glutaminase and modulates amino acids and glutathione metabolism

Linking ABC transporters to the hallmarks of cancer

Human ATP-binding cassette (ABC) transporters are ubiquitously expressed and transport a broad range of endogenous and xenobiotic substrates across extra- and intracellular membranes. Mutations in ABC genes cause 21 monogenic diseases, and polymorphisms in these genes are associated with susceptibility to complex diseases. ABC transporters also play a major role in drug bioavailability, and they mediate multidrug resistance in cancer. At least 13 ABC transporters were shown to be involved in drug resistance in vitro. In the past decade, efforts have been made to elucidate their roles in tumor biology. Herein, we explore their involvement in tumorigenesis, focusing on the hallmarks of cells as they make their way from normalcy to neoplastic growth states.

T cell immunoglobulin and mucin domain protein 3 inhibits glycolysis in RAW 264.7 macrophages through Hexokinase 2

T cell immunoglobulin and mucin domain-3 (Tim-3), an immune checkpoint molecule, plays critical roles in maintaining innate immune homeostasis; however, the mechanisms underlying these roles remain to be determined. Here, we determined that Tim-3 controls glycolysis in macrophages and thus contributes to phenotype shifting. Tim-3 signal blockade significantly increases lactate production by macrophages, but does not influence cell proliferation or apoptosis. Tim-3 attenuates glucose uptake by inhibiting hexokinase 2 (HK2) expression in macrophages. Tim-3-mediated inhibition of macrophage glycolysis and the expression of proinflammatory cytokines, tumour necrosis factor (TNF)-α and interleukin (IL)-1β are reversed by HK2 silencing. Finally, we demonstrated that Tim-3 inhibits HK2 expression via the STAT1 pathway. We have thus discovered a new way by which Tim-3 modulates macrophage function.

Effect of TNIK upregulation on JQ1-resistant human colorectal cancer HCT116 cells

JQ1 disrupts the binding of bromodomain and extra-terminal (BET) family of proteins to acetylated histones, modulates the expression of various genes, and inhibits the proliferation of cancer cells. We established two JQ1-resistant sublines from human colorectal cancer HCT116 cells. These resistant cells showed an 8- to 9-fold higher resistance to JQ1, and a 2- to 4-fold higher resistance to various anti-cancer agents, such as doxorubicin, etoposide, mitoxantrone, SN-38, cisplatin, and methotrexate than the parental HCT116 cells. The JQ1-resistant cells expressed higher levels of TRAF2 and NCK-interacting protein kinase (TNIK), cyclin D1 (CCND1), cyclin E1 (CCNE1), and their corresponding mRNAs than the parental cells. TNIK is a regulator of Wnt/β-catenin signaling and is known to transactivate CCND1. Transient transfection of HCT116 cells with a TNIK expression plasmid resulted in the upregulation of cyclin D1, cyclin E1, and their corresponding mRNAs, as well as an increase in CCNE1 promoter activity. Furthermore, luciferase assay revealed that the JQ1-resistant cells showed high CCNE1 promoter activity. These results suggest that TNIK also transactivates CCNE1. Three stable TNIK transfectant clones of HEK293 cells expressed 1.5- to 2-fold higher levels of TNIK, cyclin D1, and cyclin E1 than the parental cells. The 293/TNIK-6 cells, which expressed the highest level of TNIK among the transfectants, showed a 2.3-fold higher resistance to JQ1 than the parental cells. These results suggest the possible involvement of TNIK in cellular resistance to JQ1.