https://www.cell.com/molecular-cell/pdf/S1097-2765(12)00003-2.pdf

Pyruvate Kinase M2 Regulates Gene Transcription by Acting as a Protein Kinase

https://www.cell.com/structure/pdf/S0969-2126(98)00021-5.pdf

The allosteric regulation of pyruvate kinase by fructose-1,6-bisphosphate.

Protein-protein interactions (PPIs) are critical regulatory events in physiology and pathology, and they represent an important target space for pharmacological intervention. However, targeting PPIs with small molecules is challenging owing to the large surface area involved in protein-protein binding and the lack of obvious small-molecule-binding pockets at many protein-protein interfaces. Nonetheless, successful examples of small-molecule modulators of PPIs have been growing in recent years. This article reviews some of the recent advances in the discovery of small-molecule regulators of PPIs that involve key oncogenic proteins. Our discussion focuses on the three key modes of action for these small-molecule modulators: orthosteric inhibition, allosteric regulation, and interfacial binding/stabilization. Understanding the opportunities and challenges of these diverse mechanisms will help guide future efforts in developing small-molecule modulators against PPIs.

Targeting protein-protein interaction by small molecules.

Pancreatic cancer is a highly deadly disease: almost all patients develop metastases and conventional treatments have little impact on survival. Therapeutically, this tumor is poorly responsive, largely due to drug resistance. Accumulating evidence suggest that this chemoresistance is intimately linked to specific metabolic aberrations of pancreatic cancer cells, notably an increased use of glucose and the amino acid glutamine fueling anabolic processes. Altered metabolism contributes also to modulation of apoptosis, angiogenesis and drug targets, conferring a resistant phenotype. As a modality to overcome chemoresistance, a variety of experimental compounds inhibiting key metabolic pathways emerged as a promising approach to potentiate the standard treatments for pancreatic cancer in preclinical studies. These results warrant confirmation in clinical trials. Thus, this review summarizes the impact of metabolic aberrations from the perspective of drug resistance and discusses possible novel applications of metabolic inhibition for the development of more effective drugs against pancreatic cancer.

Drug resistance in pancreatic cancer: Impact of altered energy metabolism.

6-Phosphofructokinase (PFK) plays a central role in the regulation of glycolysis in both normal and neoplastic cells. Since PFK also mediates the Pasteur effect, it coordinates the two modes of energy production in most cell systems, i.e., glycolysis and respiration. The energy production in the cancer cell is characterized by a predominance of aerobic glycolysis (the Warburg effect) and a diminution or lack of the Pasteur effect. Previous studies from this laboratory have demonstrated that PFK in humans and in the rat exists in multiple tetrameric isozymic forms consisting of three unique subunits under separate genetic controls, M, L, and P types. These isozymes are distinguishable from one another by ion-exchange chromatography and subunit-specific antibodies. Various organs exhibit unique isozyme distribution patterns which essentially reflect the preferred mode of carbohydrate metabolism utilized, i.e., glycolysis or gluconeogenesis or both. In order to investigate whether the high aerobic glycolysis of the cancer cell can be explained on the basis of a lack of the regulatory function of PFK due to an altered isozyme distribution pattern, we compared the activity and isozymic profile of the enzyme from malignant cells of human leukemias, lymphomas, virus-transformed cell lines, and established malignant cell lines of lymphoid, myeloid, erythroid, and fibroblastic origin and their normal counterparts. The myeloid and erythroid cell lines were also investigated after in vitro differentiation induced by dimethyl sulfoxide, sodium butyrate, hemin, etc. Our results show that, as is the case with hexokinase and pyruvate kinase, the other two rate-limiting enzymes of glycolysis, PFK shows both quantitative increases and isozymic alterations secondary to altered gene expression during neoplastic transformation, both in vivo and in vitro. In contradistinction to the isozymic alteration in hexokinase and pyruvate kinase, where highly regulated liver-type isozymes decrease or disappear and are replaced by the nonregulated ones, in the case of PFK, the highly regulated liver-type isozyme not only persists but actually increases, followed by an increase in the platelet-type isozyme. These isozymic alterations closely parallel the quantitative increases in total PFK activity, which in turn is closely related to the rate of replication of cancer cells and hence an increase in metabolism. Thus, human PFK is both a transformation- and a progression-linked discriminant of malignancy (For definitions of these terms, see Weber et al., N. Engl. J. Med., 296: 486-493, 1977.).(ABSTRACT TRUNCATED AT 400 WORDS)

https://cancerres.aacrjournals.org/content/canres/45/7/2993.full.pdf

Alterations in the activity and isozymic profile of human phosphofructokinase during malignant transformation in vivo and in vitro: transformation- and progression-linked discriminants of malignancy.

Pyruvate kinase isozymes were studied in normal brain tissue (both fetal and adult) and in meningiomas and malignant gliomas. In fetal brain five different forms could be detected by electrophoresis (K4, K3M, K2M2, KM3, and M4). In adult brain the M4-type, K3M hybrid, and K4-type are present; the M isozyme is largely predominant. Alanine inhibition of pyruvate kinase is in agreement with the electrophoretic pattern. Pyruvate kinase from fetal brain and brain of a newborn is more inhibited compared with pyruvate kinase from adult brain. The Lineweaver-Burk plots for pyruvate kinase from fetal brain and brain of the newborn are nonlinear due to the presence of hybrids. Pyruvate kinase from meningiomas and malignant gliomas is strongly inhibited by alanine. Electrophoresis proved the presence of mainly K4 type and the hybrid K3M, which is in agreement with the alanine inhibition. Determination of the Km's for phosphoenolpyruvate supports this conclusion. The determination of the alanine inhibition of pyruvate kinase may be a diagnostic tool in surgery for gliomas.

https://cancerres.aacrjournals.org/content/canres/38/12/4681.full.pdf

G E Staal

Papers

Isozymes of Pyruvate Kinase from Human Brain, Meningiomas, and Malignant Gliomas