Fractal analysis and ionic dependence of endocytotic membrane activity of human breast cancer cells.
The endocytic membrane activities of two human breast cancer cell lines (MDA-MB-231 and MCF-7) of strong and weak metastatic potential, respectively, were studied in a comparative approach. Uptake of horseradish peroxidase was used to follow endocytosis. Dependence on ionic conditions and voltage-gated sodium channel (VGSC) activity were characterized. Fractal methods were used to analyze quantitative differences in vesicular patterning. Digital quantification showed that MDA-MB-231 cells took up more tracer (i.e., were more endocytic) than MCF-7 cells. For the former, uptake was totally dependent on extracellular Na(+) and partially dependent on extracellular and intracellular Ca(2+) and protein kinase activity. Analyzing the generalized fractal dimension (D(q )) and its Legendre transform f(alpha) revealed that under control conditions, all multifractal parameters determined had values greater for MDA-MB-231 compared with MCF-7 cells, consistent with endocytic/vesicular activity being more developed in the strongly metastatic cells. All fractal parameters studied were sensitive to the VGSC blocker tetrodotoxin (TTX). Some of the parameters had a "simple" dependence on VGSC activity, if present, whereby pretreatment with TTX reduced the values for the MDA-MB-231 cells and eliminated the differences between the two cell lines. For other parameters, however, there was a "complex" dependence on VGSC activity. The possible physical/physiological meaning of the mathematical parameters studied and the nature of involvement of VGSC activity in control of endocytosis/secretion are discussed.
Krasowska
Monika
M
Division of Cell and Molecular Biology, Neuroscience Solutions to Cancer Research Group, Imperial College London, Sir Alexander Fleming Building, South Kensington Campus, London SW7 2AZ, UK. Monika.Krasowska@polsl.pl
Grzywna
Zbigniew J
ZJ
Mycielska
Maria E
ME
Djamgoz
Mustafa B A
MB
D001943:Breast Neoplasms / Q000473:pathology / Q000503:physiopathology*; D045744:Cell Line, Tumor; D002462:Cell Membrane; D004705:Endocytosis; D017709:Fractals; D006801:Humans; D015640:Ion Channel Gating; D015222:Sodium Channels / Q000378:metabolism*
D015222:Sodium Channels