Double genetic disruption of lactate dehydrogenases A and B is required to ablate the “Warburg effect” restricting tumor growth to oxidative metabolism

Increased glucose consumption distinguishes cancer cells from normal cells and is known as the “Warburg effect” because of increased glycolysis. Lactate dehydrogenase A (LDHA) is a key glycolytic enzyme, a hallmark of aggressive cancers, and believed to be the major enzyme responsible for pyruvate-to-lactate conversion. To elucidate its role in tumor growth, we disrupted both the LDHA and LDHB genes in two cancer cell lines (human colon adenocarcinoma and murine melanoma cells). Surprisingly, neither LDHA nor LDHB knockout strongly reduced lactate secretion. In contrast, double knockout (LDHA/B-DKO) fully suppressed LDH activity and lactate secretion. Furthermore, under normoxia, LDHA/B-DKO cells survived the genetic block by shifting their metabolism to oxidative phosphorylation (OXPHOS), entailing a 2-fold reduction in proliferation rates in vitro and in vivo compared with their WT counterparts. Under hypoxia (1% oxygen), however, LDHA/B suppression completely abolished in vitro growth, consistent with the reliance on OXPHOS. Interestingly, activation of the respiratory capacity operated by the LDHA/B-DKO genetic block as well as the resilient growth were not consequences of long-term adaptation. They could be reproduced pharmacologically by treating WT cells with an LDHA/B-specific inhibitor (GNE-140). These findings demonstrate that the Warburg effect is not only based on high LDHA expression, as both LDHA and LDHB need to be deleted to suppress fermentative glycolysis. Finally, we demonstrate that the Warburg effect is dispensable even in aggressive tumors and that the metabolic shift to OXPHOS caused by LDHA/B genetic disruptions is responsible for the tumors' escape and growth.

Level of Arachidonic Acid and State of Peroxidation Processes in Patients with Aspirin-Intolerant Polypous Rhinosinusitis

The main peculiarity of aspirin-intolerant polypous rhinosinusitis pathogenesis is the presence of “genetic block” of constitutive cyclooxygenase being the key enzyme of the arachidonic acid metabolism. It justifies the necessity of studying its metabolic peculiarities.The objective of the research was to determine the level of arachidonic acid as well as the state of lipid and protein peroxidation processes in patients with aspirin-intolerant polypous rhinosinusitis.Materials and methods. The levels of arachidonic acid, malondialdehyde and oxidative modification of serum proteins were studied in 20 patients with aspirin-intolerant polypous rhinosinusitis and 7 healthy individuals.Results. Significantly elevated levels of arachidonic levels were observed. The search for alternative metabolic pathways stimulated lipid and protein peroxidation processes and led to the increase in the levels of malondialdehyde and oxidative modification of serum proteins. The peculiarities of biochemical changes indicated pro-inflammatory orientation of lipid metabolism.Conclusions. The obtained data confirmed the hypothesis of “genetic block” of the arachidonic acid metabolism as the main pathogenetic component of aspirin-intolerant polypous rhinosinusitis and allowed us to clearly interpret biochemical picture of the disease.

THE STATE OF LIPID METABOLISM IN PATIENTS WITH ASPIRIN ASSOCIATED POLYPOUS RHINOSINUSITIS

Nowadays it is observed the wide prevalence of polypous rhinosinusitis, associated with intolerance to aspirin. From today positions the main principle of pathogenesis is in presence of “genetic block” of constitutive cyclooxigenase – the node enzyme of metabolism of arachidonic acid that leads to its active accumulation. It leads to the disorder of lipid metabolism and conditions the necessity to study its biochemical features. Aim of research. To study biochemical parameters of the lipid exchange in patients with chronic polypous rhinosinusitis, associated with intolerance to acetylsalicylic acid by determination of the main metabolites. Materials and methods. The results of laboratory examination of 20 patients with aspirin associated polypous rhinosinusitis are presented in the article. The control group included 7 practically healthy donors. There were studied the level of arachidonic acid in condensate of exhaled air, arachidonic, linoleic, eicosapentaenoic acids, phospholipids, malonic dialdehyde and oxide modification of protein in the blood serum. Results. There were determined the changes of lipid exchange, which essence is in increase of the level of arachidonic acid in condensate of exhaled air and blood serum that leads to the decrease of the content of its main predecessors – linoleic and eicosapentaenoic acids and also phospholipids. The increase of arachidonic acid content stimulates the processes of peroxidation and leads to the increase of malonic dialdehyde content and oxide modifications of protein. The features of biochemical disorders testify to the proinflammatory direction of lipids metabolism. Conclusions. The received data confirm the hypothesis of “genetic block” of arachidonic acid metabolism as the main pathogenetic link of polypous rhinosinusitis, associated with intolerance to aspirin, and allow clearly interpret the clinical image and the features of clinical course.

Can Anopheles gambiae Be Infected with Wolbachia pipientis? Insights from an In Vitro System

ABSTRACT Wolbachia pipientis are maternally inherited endosymbionts associated with cytoplasmic incompatibility, a potential mechanism to drive transgenic traits into Anopheles populations for malaria control. W. pipientis infections are common in many mosquito genera but have never been observed in any Anopheles species, leading to the hypothesis that Anopheles mosquitoes are incapable of harboring infection. We used an in vitro system to evaluate the ability of Anopheles gambiae cells to harbor diverse W. pipientis infections. We successfully established W. pipientis infections (strains wRi and wAlbB) in the immunocompetent Anopheles gambiae cell line Sua5B. Infection was confirmed by PCR, antibiotic curing, DNA sequencing, and direct observation using fluorescence in situ hybridization. The infections were maintained at high passage rates for >30 passages. Our results indicate that there is no intrinsic genetic block to W. pipientis infection in A. gambiae cells, suggesting that establishment of in vivo W. pipientis infections in Anopheles mosquitoes may be feasible.