CCL5-CCR5 interactions modulate metabolic events during tumor onset to promote tumorigenesis

Background: In earlier studies we have shown that CCL5 activation of CCR5 induces the proliferation and survival of breast cancer cells in a mechanistic target of rapamycin (mTOR)-dependent manner and that this is in part due to CCR5-mediated increases in glycolytic metabolism. Methods: Using the MDA-MB-231 triple negative human breast cancer cell line and mouse mammary tumor virus -polyomavirus middle T-antigen (MMTV-PyMT) mouse primary breast cancer cells, we conducted in vivo tumor transplant experiments to examine the effects of CCL5-CCR5 interactions in the context of regulating tumor metabolism. Additionally, we employed Matrix-Assisted Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry imaging (MALDI-FTICR-MSI) to evaluate tumor utilization of cellular metabolites. Results: We provide evidence that, in the absence of CCR5, the early events associated with rapid tumor growth in the MMTV-PyMT mouse model of spontaneous breast cancer development, are diminished, as demonstrated by a delay in tumor onset. In tumor transplant studies into immunocompromised mice we identify a direct correlation between reduced tumor proliferation and decreased metabolic activity, specifically associated with tumor expression of CCR5. The reduction in tumorigenesis is accompanied by decreases in glucose uptake, glucose transporter-1 (GLUT-1) cell surface expression, intracellular ATP and lactate levels, as well as reduced CCL5 production. Using MALDI-FTICR-MS, we show that the rapid early tumor growth of CCR5(+/+) triple negative breast cancer cells in vivo is attributable to increased levels of glycolytic intermediates required for anabolic processes, in contrast to the slower growth rate of their corresponding CCR5(-/-)cells, that exhibit reduced glycolytic metabolism. Conclusions: These findings suggest that CCL5-CCR5 interactions in the tumor microenvironment modulate metabolic events during tumor onset to promote tumorigenesis.