Spatial profiles of markers of glycolysis, mitochondria, and proton pumps in a rat glioma suggest coordinated programming for proliferation.

Abstract

BACKGROUND:

In cancer cells in vitro, the glycolytic pathway and the mitochondrial tricarboxylic acid (TCA) cycle are programmed to produce more precursor molecules, and relatively less ATP, than in differentiated cells. We address the questions of whether and where these changes occur in vivo in glioblastomas grown from C6 cells in rat brain. These gliomas show some spatial organization, notably in the upregulation of membrane proton transporters near the rim.

RESULTS:

We immunolabeled pairs of proteins (as well as DNA) on sections of rat brains containing gliomas, measured the profiles of fluorescence intensity on strips 200 µm wide and at least 3 mm long running perpendicular to the tumor rim, and expressed the intensity in the glioma relative to that outside. On averaged profiles, labeling of a marker of the glycolytic pathway, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), was, as expected, greater in the glioma. Over distances up to 2.5 mm into the glioma, expression of a marker of the TCA cycle, Tom20, a pre-protein receptor on the translocation complex of the mitochondrial outer membrane, was also upregulated. The ratio of upregulation of Tom20 to upregulation of GAPDH was, on average, slightly greater than one. Near the rim (0.4-0.8 mm), GAPDH was expressed less and there was a peak in the mean ratio of 1.16, SEM = 0.001, N = 16 pairs of profiles. An antibody to V-ATPase, which, by pumping protons into vacuoles contributes to cell growth, also indicated upregulation by about 40%. When compared directly with GAPDH, upregulation of V-ATPase was only 0.764, SD = 0.016 of GAPDH upregulation.

CONCLUSIONS:

Although there was considerable variation between individual measured profiles, on average, markers of the glycolytic pathway, of mitochondria, and of cell proliferation showed coherent upregulation in C6 gliomas. There is a zone, close to the rim, where mitochondrial presence is upregulated more than the glycolytic pathway, in agreement with earlier suggestions that lactate is taken up by cells near the rim.

• Authors: Emmanuelle Grillon, Régine Farion, Moshe Reuveni, Andrew Glidle, Chantal Rémy, Jonathan A Coles
• Journal: BMC research notes (BMC Res Notes) Vol. 8 Pg. 207 (Jun 02 2015) ISSN: 1756-0500 [Electronic] England
• PMID: 26032618 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Membrane Transport Proteins
• Mitochondrial Precursor Protein Import Complex Proteins
• Mitochondrial Proteins
• Proton Pumps
• Receptors, Cell Surface
• Receptors, Cytoplasmic and Nuclear
• Tomm20 protein, rat
• Glyceraldehyde-3-Phosphate Dehydrogenases
• Vacuolar Proton-Translocating ATPases

Topics

• Animals
• Brain Neoplasms (metabolism, pathology)
• Cell Line, Tumor
• Cell Proliferation
• Glioma (metabolism, pathology)
• Glyceraldehyde-3-Phosphate Dehydrogenases (metabolism)
• Glycolysis
• Male
• Membrane Transport Proteins
• Mitochondria (metabolism)
• Mitochondrial Precursor Protein Import Complex Proteins
• Mitochondrial Proteins (metabolism)
• Proton Pumps (metabolism)
• Rats, Wistar
• Receptors, Cell Surface
• Receptors, Cytoplasmic and Nuclear (metabolism)
• Up-Regulation
• Vacuolar Proton-Translocating ATPases (metabolism)