Changes in cell surface charge and transmembrane potential accompanying neoplastic transformation of rat kidney cells.

Free flow electrophoresis measurements have been used to determine the surface charge density of normal rat kidney (NRK) cells and a clone of NRK, designated as 6m2, that exhibit a transformed phenotype at 33 degrees C and a non-transformed phenotype at 39 degrees C. A clone of 6m2, designated 54-5A4, which is transformed at both 33 degrees C and 39 degrees C was also studied. A surface charge density of -1.42 microC/cm2 was obtained for the NRK and non-transformed 6m2 cells at 39 degrees C, whereas at 33 degrees C values of -1.85 and -1.78 microC/cm2 were determined for the transformed 6m2 and 54-5A4 cells, respectively. It was found that 72% of the increased charge that appeared on the transformed 6m2 cells compared with the non-transformed 6m2 cells was RNAase sensitive. The time-dependent decrease in surface charge that accompanied the shift of the 6m2 cells from their transformed to non-transformed state was found to mirror the increase in transmembrane potential previously reported using a fluorescent dye technique, and was also comparable to the reported temporal changes in their morphology and virally-coded protein content.      http://www.ncbi.nlm.nih.gov/sites/entrez?Db=PubMed&Cmd=ShowDetailView&TermToSearch=3828335&ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

PMID: 3828335 [PubMed - indexed for MEDLINE]

Electropotential measurements as a new diagnostic modality for breast cancer

Imperial Cancer Research Fund, London, UK. j.cuzick@icrf.icnet.uk

BACKGROUND: Proliferative changes in breast epithelium are an intrinsic aspect in the development of breast cancer, and result in regions of epithelial electrical depolarisation within the breast parenchyma, which can extend to the skin surface. Diagnostic information might be obtained from a non-imaging and non-invasive test based on skin-surface electropotentials. METHODS: In 661 women, scheduled for open biopsy at eight European centres, we studied whether measurements of breast electrical activity with surface sensors could distinguish benign from malignant breast disease. A depolarisation index was developed. RESULTS: We found a highly significant trend of progressive electrical changes according to the proliferative characteristics of the biopsied tissue. Discriminatory information was obtained in both premenopausal and postmenopausal women, and the index was not related to age. The best test performances were for women with palpable lesions. The median index was 0.398 for non-proliferative benign lesions, 0.531 for proliferative benign lesions, and 0.644 for cancer (ductal carcinoma-in-situ and invasive). A specificity of 55% was obtained at 90% sensitivity for women with palpable lesions when a discriminant based on age and the depolarisation index was used. INTERPRETATION: This new modality may have diagnostic value, especially in reducing the number of unnecessary diagnostic tests among women with inconclusive findings on physical examination. Understanding and control of the biological variability of these electrical phenomena will be important in the improvement of this test. Studies in populations with a lower cancer prevalence are needed to assess further the diagnostic value of this approach.           http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=9717923&dopt=AbstractPlus

PMID: 9717923 [PubMed - indexed for MEDLINE]