Exposure of Human Breast Cancer Cells to the Anti-inflammatory Agent Indomethacin Alters Choline Phospholipid Metabolites and Nm23 Expression

We previously observed that changes in choline phospholipids of two malignant human mammary epithelial cells (HMECs) following treatment with a high dose of the cyclooxygenase (COX) inhibitor, indomethacin, mimicked changes following transfection with a metastasis suppressor gene, nm23. The similarity between response to indomethacin and nm23 transfection led us to 1) expand our (1)H NMR spectroscopy study of indomethacin treatment by determining the response at two doses for two nonmalignant and three malignant HMECs, 2) investigate COX-1 and COX-2 levels in HMECs and their relationship with choline phosholipid metabolites, and 3) determine changes in Nm23 expression following treatment with indomethacin. All HMECs exhibited a significant change in choline phospholipids following treatment with 300 µM indomethacin. At the lower dose of 50 µM, only nonmalignant HMECs and the estrogen-dependent malignant cell line, MCF-7, responded. COX-1 levels were significantly higher in malignant HMECs than in nonmalignant HMECs. A significant increase in Nm23 expression following 300 µM indomethacin was detected in MCF-12A and MCF-7 cells but not in MDA-MB-231 and MDAMB-435 cells. These results suggest that COX-1 expression and its inhibition play a role in the choline phospholipid metabolism of HMECs, and the effect of indomethacin on HMECs may be mediated, in part, through upregulation of nm23

Vascular Differences Detected by MRI for Metastatic Versus Nonmetastatic Breast and Prostate Cancer Xenografts

Several studies have linked vascular density, identified in histologic sections, to “metastatic risk.” Functional information of the vasculature, not readily available from histologic sections, can be obtained with contrast-enhanced MRI to exploit for therapy or metastasis prevention. Our aims were to determine if human breast and prostate cancer xenografts preselected for differences in invasive and metastatic characteristics established correspondingly different vascular volume and permeability, quantified here with noninvasive MRI of the intravascular contrast agent albumin-GdDTPA. Tumor vascular volume and permeability of human breast and prostate cancer xenografts were characterized using MRI. Parallel studies confirmed the invasive behavior of these cell lines. Vascular endothelial growth factor (VEGF) expression in the cell lines was measured using ELISA and Western blots. Metastasis to the lungs was evaluated with spontaneous as well as experimental assay. Metastatic tumors formed vasculature with significantly higher permeability or vascular volume (P<.05, two-sided unpaired t test). The permeability profile matched VEGF expression. Within tumors, regions of high vascular volume usually exhibited low permeability whereas regions of low vascular volume exhibited high permeability. We observed that although invasion was necessary, without adequate vascularization it was not sufficient for metastasis to occur

Choline Phospholipid Metabolites of Human Vascular Endothelial Cells Altered by Cyclooxygenase Inhibition, Growth Factor Depletion, and Paracrine Factors Secreted by Cancer Cells

Magnetic resonance studies have previously shown that solid tumors and cancer cells in culture typically exhibit high phosphocholine and total choline. Treatment of cancer cells with the anti-inflammatory agent, indomethacin (INDO), reverted the phenotype of choline phospholipid metabolites in cancer cells towards a less malignant phenotype. Since endothelial cells form a key component of tumor vasculature, in this study, we used MR spectroscopy to characterize the phenotype of choline phospholipid metabolites in human umbilical vein endothelial cells (HUVECs). We determined the effect of growth factors, the anti-inflammatory agent INDO, and conditioned media obtained from a malignant cell line, on choline phospholipid metabolites. Growth factor depletion or treatment with INDO induced similar changes in the choline phospholipid metabolites of HUVECs. Treatment with conditioned medium obtained from MDA-MB-231 cancer cells induced changes similar to the presence of growth factor supplements. These results suggest that cancer cells secrete growth factors and/or other molecules that influence the choline phospholipid metabolism of HUVECs. The ability of INDO to alter choline phospholipid metabolism in the presence of growth factor supplements suggests that the inflammatory response pathways of HUVECs may play a role in cancer cell-HUVEC interaction and in the response of HUVECs to growth factors

Loss of P53 Function in Colon Cancer Cells Results in Increased Phosphocholine and Total Choline

Mutations in the p53 gene are the most frequently observed genetic lesions in human cancers. Human cancers that contain a p53 mutation are more aggressive, more apt to metastasize, and more often fatal. p53 controls numerous downstream targets that can influence various outcomes such as apoptosis, growth arrest, and DNA repair. Based on previous observations using 1 H magnetic resonance spectroscopy (MRS), we have identified choline phospholipid metabolite intensities typical of increased malignancy. Here we have used 1 H MRS to characterize the choline phospholipid metabolite levels of p53 +/+ and p53 −/– cells, and demonstrated that loss of p53 function results in increased phosphocholine and total choline. These data suggest that the increased malignancy of cancer cells resulting from loss of p53 may be mediated, in part, through the choline phospholipid pathway