Caveolin-1 Dependent Endocytosis Enhances the Chemosensitivity of HER-2 Positive Breast Cancer Cells to Trastuzumab Emtansine T-DM1Reportar como inadecuado




Caveolin-1 Dependent Endocytosis Enhances the Chemosensitivity of HER-2 Positive Breast Cancer Cells to Trastuzumab Emtansine T-DM1 - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

The humanized monoclonal antibody-drug conjugate trastuzumab emtansine T-DM1, Kadcyla has been approved by the U.S. FDA to treat human epidermal growth factor receptor 2 HER-2-positive metastatic breast cancer. Despite its effectiveness in most patients, some are initially resistant or develop resistance. No biomarker of drug resistance to T-DM1 has been identified. Antibody-drug efficacy is associated with antibody internalization in the cell; therefore, cellular sensitivity of cells to the drug may be linked to cellular vesicle trafficking systems. Caveolin-1 is a 22 KD protein required for caveolae formation and endocytic membrane transport. In this study, the relationship between caveolin-1 expression and the chemosensitivity of HER-2-positive breast cancer cells to T-DM1 was investigated. Samples from 32 human breast cancer biopsy and normal tissue specimens were evaluated immunohistochemically for caveolin-1 expression. Caveolin-1 was shown to be expressed in 68% 22-32 of the breast cancer specimens. In addition, eight 72.7%, 8-11 HER-2 positive breast cancer specimens had a higher caveolin-1 expression than normal tissues. HER-2-positive BT-474 and SKBR-3 breast cancer cells that express low and moderate levels of caveolin-1, respectively, were treated with trastuzumab or its conjugate T-DM1. Cell viability and molecular localizations of caveolin-1, antibody and its conjugate were examined. Confocal microscopy showed that T-DM1 and caveolin-1 colocalized in SKBR-3 cells, which also were five times more sensitive to the conjugate in terms of cell survival than BT-474 cells, although T-DM1 also showed improved drug efficacy in BT-474 cells than trastuzumab treatment. Caveolin-1 expression in these lines was manipulated by transfection of GFP-tagged caveolin-1 or caveolin-1 siRNA. BT-474 cells overexpressing caveolin-1 were more sensitive to T-DM1 treatment than mock-transfected cells, whereas the siRNA-transfected SKBR-3 cells had decreased sensitivity to T-DM1 than mock-transfected SKBR-3 cells. The expression of caveolin-1 could mediate endocytosis and promote the internalization of T-DM1 into HER-2 positive cancer cells. Thus, caveolin-1 protein may be an effective predictor for determining the outcome of T-DM1 treatment in breast cancer patients.



Autor: Yuan-Chiang Chung, Jang-Fang Kuo, Wan-Chen Wei, King-Jen Chang, Wei-Ting Chao

Fuente: http://plos.srce.hr/



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