The membrane cluster hypothesis of mitogenesis and carcinogenesis

Malignant breast tumor phospholipid profiles using (31)P magnetic resonance

Biochemical markers improve the classification and staging of breast cancer and may refine management decisions if it can be shown that they correlate with accepted prognostic factors or patient outcome. Using phosphorus-31 magnetic resonance spectroscopy ((31)P MRS), we determined the phospholipid content of 43 malignant breast tumors, correlating the profiles with specific histopathologic and clinical features and hormone receptor status. Among the 14 phospholipids identified, the mean mole percentage of sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidic acid, phosphatidylglycerol, and alkylacylphosphatidylcholine predicted cellular infiltration, infiltration type, elastosis, lymphatic invasion, perineural invasion, necrosis, and estrogen receptor positivity. (31)P MRS phospholipid profile data provide statistical correlations among histologic features and molecules known to play important roles in cellular communication, regulation, and processes unique to malignant tissues.

Esophageal cancer phospholipids correlated with histopathologic findings: a 31P NMR study

We analyzed 36 esophageal tumor specimens for phospholipid content using phosphorus nuclear magnetic resonance spectroscopy (31P NMR) and correlated the individual phospholipid profiles with specific clinical and histopathologic features. Among the 18 phospholipids identified in the esophageal tumor specimens, the mean mole percentage concentration of dimethylphosphatidylethanolamine, lysoalkylacylphosphatidylcholine, lysophosphatidic acid, lysophosphatidylcholine (deacylated at the glycerol-1 carbon), and lysoethanolamine plasmalogen correlated with pathologic T stage, nuclear grade, or the presence of lymphatic invasion. 31P NMR produces well-dispersed phospholipid spectra and a precise determination of phospholipid relative mole percentages. These data provide a statistical correlation between histopathologic features and molecules known to play an important role in cellular activities and processes unique to malignant tissues.

Carcinogenesis and initiation of cell cycling by charge-induced membrane clusters may be due to mitogen receptors and Na+/H+ antiports

The membrane cluster hypothesis of mitogenesis and carcinogenesis is extended by proposing that much of the Na+ ingress across a cell's plasma membrane at surface charge-induced (SCI) aggregates is due to mitogen-induced activation of Na+/H+ antiports. Intrinsic proteins (including mitogen receptors and antiports) are electrostatically attracted to and become part of the aggregate. In this location, close proximity facilitates antiport activation. Resulting Na+ ingress may cause sustained partial depolarization, cytoplasmic alkalinization, and initiation of cell cycling. Chronic phosphorylation-dephosphorylation at SCI aggregates too weak to induce cycling, may slowly form polyionic bonds between adjacent proteins at the inner lipid layer. These bonds convert the SCI aggregates to 'permanent' clusters that pass to a daughter cell with parental plasma membrane at mitosis, and are associated with malignancy. EGF and PDGF growth factors are used to develop the hypothesis, which is also applied to steroid and dioxin receptors and to oncogene products.