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Old 01-04-2015, 07:21 PM
gdpawel gdpawel is offline
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Default The Case for the Metabolic Basis of Cancer Gains Traction

Robert A. Nagourney, M.D.

Researchers from the Huntsman Cancer Institute at the University of Utah reported an interesting finding with far-reaching implications.

In their study of the rare tumor known as alveolar soft part sarcoma (ASPS), they examined the well-established chromosomal translocation that occurs between chromosomes 17 and X. This results in the production of a fusion protein dubbed ASPSCR1-TFE3. Like other fusion proteins described in malignancies such as lymphoma, acute pro-myelocytic leukemia and chronic myelogenous leukemia, a novel function occurs when two disparate genomic elements are spliced together.

In this instance, the ASPSCR1-TFE3 gene product functions as a lactate transporter. Strikingly, every mouse in which the gene was up regulated developed a tumor. The locations of tumor, in the skull and near the eye, both represented areas of high lactate concentration. In humans, this tumor occurs in skeletal muscle, also associated with high lactate production.

Since 1930, when Otto Warburg first described increased glycolysis (preferential use of sugars) in tumor cells, investigators have pondered the implication of inefficient glucose metabolism in the face of adequate oxygenation.

Human metabolism relies upon mitochondrial function to efficiently liberate the maximum amount of energy in the form of ATP from each glucose molecule. Glycolysis occurring in the cell cytoplasm is highly inefficient and produces only 1/18 of the amount of ATP that a full molecule of glucose can produce through mitochondrial oxidative phosphorylation. Recent molecular biological studies have established that the preferential use of glycolysis may represent the cells need to direct glucose away from energy production and toward the creation of essential structures like amino acids, lipids, and nucleic acids. With the rapid turnover of glucose, cells produce an overwhelming amount of lactate, which is then transported out of the cell. At least this has been the working hypothesis over many years.

More recently, investigators have begun to examine how lactate metabolism may represent the interplay between stromal fibroblast cells and tumor cells. Indeed, many tumor cells are now known to increase lactate uptake reflecting increased lactate production by fibroblasts that have been commandeered in the tumor microenvironment.

Lactate uptake is under the control of a family of transporters known as monocarboxylate transporters, of which nine have been described. These are expressed differently in various tissues, have different affinities for lactate and transport in one direction or another. These processes appear to be under the control of the major regulator of oxygen metabolism known as HIF-1 alpha. As cancer cells adapt to a high lactate environment, they can survive in low oxygen tension.

The preferential use of lactate as a source of energy is contrary to many dictates of current metabolic research that suggest that tumor cells preferentially use glucose and have limited capacity to utilize non-glucose energy sources like the ketone bodies acetoacetate and beta-hydroxybutyrate. Substantial literature on ketogenic diets suggests that these ketone bodies deprive cancer cells of needed nutrition and energy. The current discovery by the Utah investigators, as well as interesting work conducted by researchers in Italy on the prostate cancer, provide a new angle on some of these principles of cancer metabolism.

As the investigators from Utah note, the alveolar soft part sarcoma is a rare tumor, but the implications of these findings could be profound, as they force us to re-think tumorigenesis and the metabolic basis of cancer.

Thomas Seyfried: Cancer: A Metabolic Disease With Metabolic Solutions

[url]https://www.youtube.com/watch?v=SEE-oU8_NSU&feature=youtu.be
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Last edited by gdpawel : 05-29-2015 at 03:35 PM. Reason: Additional info
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Old 01-04-2015, 07:34 PM
gdpawel gdpawel is offline
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Default Toward A 100% Response Rate in Human Cancer?

Robert A. Nagourney, M.D.

Oncologists confront numerous hurdles as they attempt to apply the new cancer prognostic and predictive tests. Among them are the complexities of gene arrays that introduce practicing physicians to an entirely new lexicon of terms like “splice variant, gene-rearrangement, amplification and SNP.”

Although these phrases may roll of the tongue of the average molecular biologists (mostly PhDs), they are foreign and opaque to the average oncologist (mostly MDs). To address this communication shortfall laboratory service providers provide written addenda (some quite verbose) to clarify and illuminate the material. Some institutions have taken to convening “molecular tumor boards” where physicians most adept at genomics serve as “translators.” Increasingly, organizations like ASCO offer symposia on modern gene science to the rank and file, a sort of Cancer Genomics for Dummies. If we continue down this path, oncologists may soon know more but understand less than any other medical sub-specialists.

However well intended these educational efforts may be, none of them are prepared to address the more fundamental question: How well do genomic profiles actually predict response? This broader issue lays bare our tendency to confuse data with results and big data with big results. To wit, we must remember that our DNA, originally provided to each of us in the form of a single cell (the fertilized ovum) carries all of the genetic information that makes us, us. From the hair follicles on our heads to the acid secreting cells in our stomach, every cell in our body carries exactly the same genetic data neatly scripted onto our nuclear hard-drives.

What makes this all work, however, isn’t the DNA on the hard drive, but instead the software that judiciously extracts exactly what it needs, exactly when it needs it. It’s this next level of complexity that makes us who we are. While it is true that you can’t grow hair or secrete stomach acid without the requisite DNA, simply having that DNA does not mean you will grow hair or make acid. Our growing reliance upon informatics has created a “forest for the trees” scenario, focusing our gaze upon nearby details at the expense of larger trends and insights.

What is desperately needed is a better approximation of the next level of complexity. In biology that moves us from the genotype (informatics) to the phenotype (function). To achieve this, our group now regularly combines genomic, transcriptomic or proteomic information with functional analyses. This enables us to interrogate whether the presence or absence of a gene, transcript or protein will actually confer that behavior or response at the system level.

I firmly believe that the future of cancer therapeutics will combine genomic, transcriptomic and/or proteomic analyses with functional (phenotypic) analyses.

Recent experiences come to mind. A charming patient in her 50s underwent a genomic analysis that identified a PI3K mutation. She sought an opinion. We conducted an EVA-PCD assay on biopsied tissue that confirmed sensitivity to the drugs that target PI3K. Armed with this information, we administered Everolimus at a fraction of the normal dose. The response was prompt and dramatic with resolution of liver function abnormalities, normalization of her performance status and a quick return to normal activities. A related case occurred in a young man with metastatic colorectal cancer. He had received conventional chemotherapies but at approximately two years out, his disease again began to progress.

A biopsy revealed that despite prior exposure to Cetuximab (the antibody against EGFR) there was persistent activity for the small molecule inhibitor, Erlotinib. Consistent with prior work that we had reported years earlier, we combined Cetuximab with Erlotinib, and the patient responded immediately.

Each of these patients reflects the intelligent application of available technologies. Rather than treat individuals based on the presence of a target, we can now treat based on the presence of a response. The identification of targets and confirmation of response has the potential to achieve ever higher levels of clinical benefit. It may ultimately be possible to find effective treatments for every patient if we employ multi-dimensional analyses that incorporate the results of both genomic and phenotypic platforms.
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Old 01-14-2015, 09:18 PM
gdpawel gdpawel is offline
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Default Breakthroughs In Cancer?

Robert A. Nagourney, M.D.

Coco Chanel, the icon of 20th century fashion once said, “Only those with no memory insist on their originality.” I am reminded of this quote as I review recent discoveries in cancer, among them, the recognition that cancer represents a dysregulation of cellular metabolism.

The field of metabolomics (the systematic study of cellular energy production), explored by investigators over the last decade is little more than the rediscovery of enzymology (a branch of biochemistry that deals with the properties, activity, and significance of enzymes), biochemistry (the science dealing with the chemistry of living matter) and stoichiometry (the part of chemistry that studies amounts of substances that are involved in reactions), pioneered by investigators like Albert Lehninger, Hans Krebs, Otto Warburg, and Albert Szent-Gyorgyi. These innovators used crude tools to explore the basis of human metabolism as they crafted an understanding of bioenergetics (the study of the transformation of energy in living organisms) and oxidative phosphorylation (processes occurring in the cell’s mitochondrion that produce energy through the synthesis of ATP (energy carrier of the body).

More recently, scientists wedded to genomics have slowly come to recognize the limitations of their approach and have returned to the field of phenotypic (the observable physical or biochemical characteristics of an organism analysis).

While newcomers to the field claim to be the first to recognize the role of cellular biology in tumor biology, a cadre of dedicated investigators had already charted these waters decades earlier. Beginning with the earliest studies by Siminovitch, McCulloch and Till, subsequent investigations by Sydney Salmon and Anne Hamburger, developed the earliest iteration of cellular studies for the examination of cancer biology in primary culture.

The work of Black and Spear, published in the 1950s similarly explored the study of human cellular behavior for the study of cancer research. While Larry Weisenthal, Andrew Bosanquet and others established useful predictive methodologies to study cellular phenotype, their seminal contributions have gone largely unrecognized.

Today, start-up companies are examining cellular biology to predict cancer outcomes, each claiming to be the first to recognize the importance of cell death events in primary culture. The most recent and widely touted in the literature is the use of mouse avatars. Implanting biopsied explants of tissue from patients into nude mice, they grow the cancers to desired size and then inject the drugs of interest to show tumor shrinkage. To the discerning eye however, it obvious that this represents little more than an expensive, inefficient, and extremely slow way to achieve that, which can be done more easily, inexpensively, and quickly in a tissue culture environment.

When I read the promotional material of some of the new entrants to this field, I am reminded of another quote, that of Marie Antoinette, who said, “There is nothing new except what has been forgotten.”
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