Internalization of the E-cadherin/catenin complex and scattering of human mammary carcinoma cells MCF-7/AZ after treatment with conditioned medium from human skin squamous carcinoma cells COLO 16.
Cytokines and other paracrine or autocrine factors functionally modulate the invasion-suppressor and signal-transducing E-cadherin/catenin complex. We have used conditioned medium from human squamous carcinoma COLO 16 cells (CM COLO 16) as a source of such factors to modulate the E-cadherin/catenin complex in human breast carcinoma MCF-7 cells. CM COLO 16 induces scattering of MCF-7/AZ, but not of MCF-7/6 cells on tissue culture plastic substratum, and reduces aggregation of MCF-7/AZ cells in suspension. Insulin-like growth factor I counteracts this reduction of aggregation. Confocal laser scanning microscopy of immunocytochemical stainings shows loss of the honeycomb pattern of E-cadherin, alpha-catenin and beta-catenin, and internalization of those elements. Cell surface biotinylation shows a decrease in membrane-bound E-cadherin. Immunoprecipitation and cell fractionation show that the composition of the complex is maintained. Interleukin-1, interleukin-6, granulocyte-monocyte colony stimulating factor, stem cell factor, scatter factor/hepatocyte growth factor and transforming growth factor-beta, added separately to MCF-7/AZ cells, could not mimic the effects of CM COLO 16. Neither could we find evidence that the 80 kDa extracellular fragment of E-cadherin is implicated in scattering of MCF-7/AZ cells. This fragment is present in CM COLO 16, but it is also produced by the MCF-7/AZ cells themselves, even at higher levels. Our data point toward cytoplasmic internalization induced by paracrine factors as one of the downregulating mechanisms for the E-cadherin/catenin complex.
Boterberg
T
T
Department of Radiotherapy, Nuclear Medicine and Experimental Cancerology, University Hospital Gent, Belgium.
Vennekens
K M
KM
Thienpont
M
M
Mareel
M M
MM
Bracke
M E
ME
D019921:Biotinylation; D015153:Blotting, Western; D001943:Breast Neoplasms; D015820:Cadherins / Q000032:analysis / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell; D002449:Cell Aggregation / Q000187:drug effects / Q000502:physiology; D002458:Cell Fractionation; D017077:Culture Media, Conditioned / Q000494:pharmacology*; D003598:Cytoskeletal Proteins / Q000032:analysis / Q000378:metabolism*; D051180:Desmoplakins; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D008858:Microscopy, Phase-Contrast; D011233:Precipitin Tests; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D012878:Skin Neoplasms; D015534:Trans-Activators; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051178:alpha Catenin; D051176:beta Catenin
D015820:Cadherins; D017077:Culture Media, Conditioned; D003598:Cytoskeletal Proteins; D051180:Desmoplakins; D017228:Hepatocyte Growth Factor; D007334:Insulin-Like Growth Factor I; D007375:Interleukin-1; D015847:Interleukin-4; D015850:Interleukin-6; D008565:Membrane Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D051178:alpha Catenin; D051176:beta Catenin; C495273:CTNNA1 protein, human; C495270:CTNNB1 protein, human