Anticancer Targets in the Glycolytic Metabolism of Tumors: A Comprehensive Review

Cancer is a metabolic disease and the solution of two metabolic equations: to produce energy with limited resources and to fulfill the biosynthetic needs of proliferating cells. Both equations are solved when glycolysis is uncoupled from oxidative phosphorylation in the tricarboxylic acid cycle, a process known as the glycolytic switch. This review addresses in a comprehensive manner the main molecular events accounting for high-rate glycolysis in cancer. It starts from modulation of the Pasteur Effect allowing short-term adaptation to hypoxia, highlights the key role exerted by the hypoxia-inducible transcription factor HIF-1 in long-term adaptation to hypoxia, and summarizes the current knowledge concerning the necessary involvement of aerobic glycolysis (the Warburg effect) in cancer cell proliferation. Based on the many observations positioning glycolysis as a central player in malignancy, the most advanced anticancer treatments targeting tumor glycolysis are briefly reviewed

A non-surgical approach for male germ cell mediated gene transmission through transgenesis

Microinjection of foreign DNA in male pronucleus by in-vitro embryo manipulation is difficult but remains the method of choice for generating transgenic animals. Other procedures, including retroviral and embryonic stem cell mediated transgenesis are equally complicated and have limitations. Although our previously reported technique of testicular transgenesis circumvented several limitations, it involved many steps, including surgery and hemicastration, which carried risk of infection and impotency. We improved this technique further, into a two step non-surgical electroporation procedure, for making transgenic mice. In this approach, transgene was delivered inside both testes by injection and modified parameters of electroporation were used for in-vivo gene integration in germ cells. Using variety of constructs, germ cell integration of the gene and its transmission in progeny was confirmed by PCR, slot blot and immunohistochemical analysis. This improved technique is efficient, requires substantially less time and can be easily adopted by various biomedical researchers

Targeting the Lactate Transporter MCT1 in Endothelial Cells Inhibits Lactate-Induced HIF-1 Activation and Tumor Angiogenesis

Switching to a glycolytic metabolism is a rapid adaptation of tumor cells to hypoxia. Although this metabolic conversion may primarily represent a rescue pathway to meet the bioenergetic and biosynthetic demands of proliferating tumor cells, it also creates a gradient of lactate that mirrors the gradient of oxygen in tumors. More than a metabolic waste, the lactate anion is known to participate to cancer aggressiveness, in part through activation of the hypoxia-inducible factor-1 (HIF-1) pathway in tumor cells. Whether lactate may also directly favor HIF-1 activation in endothelial cells (ECs) thereby offering a new druggable option to block angiogenesis is however an unanswered question. In this study, we therefore focused on the role in ECs of monocarboxylate transporter 1 (MCT1) that we previously identified to be the main facilitator of lactate uptake in cancer cells. We found that blockade of lactate influx into ECs led to inhibition of HIF-1-dependent angiogenesis. Our demonstration is based on the unprecedented characterization of lactate-induced HIF-1 activation in normoxic ECs and the consecutive increase in vascular endothelial growth factor receptor 2 (VEGFR2) and basic fibroblast growth factor (bFGF) expression. Furthermore, using a variety of functional assays including endothelial cell migration and tubulogenesis together with in vivo imaging of tumor angiogenesis through intravital microscopy and immunohistochemistry, we documented that MCT1 blockers could act as bona fide HIF-1 inhibitors leading to anti-angiogenic effects. Together with the previous demonstration of MCT1 being a key regulator of lactate exchange between tumor cells, the current study identifies MCT1 inhibition as a therapeutic modality combining antimetabolic and anti-angiogenic activities

Transgenesis via permanent integration of genes in repopulating spermatogonial cells in vivo

Current techniques for making transgenic mice are cumbersome, requiring trained personnel, costly infrastructure and collection of many zygotes from mice that are then killed. We developed a reproducible nonterminal technique for transfecting genes in undifferentiated spermatogonia through in vivo electroporation of the testis; about 94% of male mice electroporated with different transgenes successfully sired transgenic pups. Such electroporated males provide a valuable resource for continuous production of transgenic founders for more than a year

Multiple Biological Activities of Lactic Acid in Cancer: Influences on Tumor Growth, Angiogenesis and Metastasis

High rate of glycolysis is a metabolic hallmark of cancer. While anaerobic glycolysis promotes energy production under hypoxia, aerobic glycolysis, the Warburg effect, offers a proliferative advantage through redirecting carbohydrate fluxes from energy production to biosynthetic pathways. To fulfill tumor cell needs, the glycolytic switch is associated with elevated glucose uptake and lactic acid release. Altered glucose metabolism is the basis of positron emission tomography using the glucose analogue tracer [18F]-fluorodeoxyglucose, a widely used clinical application for tumor diagnosis and monitoring. On the other hand, high levels of lactate have been associated with poor clinical outcome in several types of human cancers. Although lactic acid was initially considered merely as an indicator of the glycolytic flux, many evidences originally from the study of normal tissue physiology and more recently transposed to the tumor situation indicate that lactic acid, i.e. the lactate anion and protons, directly contributes to tumor growth and progression. Here, we briefly review the current knowledge pertaining to lactic acidosis and metastasis, lactate shuttles, the influence of lactate on redox homeostasis, lactate signaling and lactate-induced angiogenesis in the cancer context. The monocarboxylate transporters MCT1 and MCT4 have now been confirmed as prominent facilitators of lactate exchanges between cancer cells with different metabolic behaviors and between cancer and stromal cells. We therefore address the function and regulation of MCTs, highlighting MCT1 as a novel anticancer target. MCT1 inhibition allows to simultaneously disrupt metabolic cooperativity and angiogenesis in cancer with a same agent, opening a new path for novel anticancer therapies

A method for rapid generation of transgenic animals to evaluate testis genes during sexual maturation

In certain forms of idiopathic infertility, there is failure of follicle stimulating hormone (FSH) and testosterone (T) to initiate spermatogenesis despite the presence of Sertoli cells and germ cells in the testis. In postnatal rats (up to 11 days of age) and infant monkeys (3–4 months old), robust division and differentiation of spermatogonial stem cells is not discerned, even though serum levels of FSH and T are similar to those found during adulthood. Lack of spermatogenesis together with normal hormone levels is a situation similar to that found in certain categories of male infertility. To investigate this intriguing situation, Sertoli cells were cultured from infant and pubertal rats and monkeys and differential gene expression by testicular Sertoli cells was evaluated by DNA microarray using the Agilent microarray system. To determine the role of candidate genes in regulation of spermatogenesis, transgenic animals over-expressing these genes must be generated. However, present techniques for generation of transgenic animals have limited utility for production of several transgenic animals within a short period of time. Therefore, we have developed a technique for making transgenic animals by the testicular route which is less labor intensive and less time consuming. This technique is also ethically superior since fewer mice are required than in existing alternative methods of transgenesis