OBJECTIVE: To examine the effect of trastuzumab on cell proliferation, colony formation and changes of HER-2 proteins in human breast cancer cell line SKBR3 and human ovarian cancer cell line SKOV3 cells which overexpress p185 HER-2 but shed high or low HER-2 extracellular domain (ECD) levels. METHODS: SKBR3 cells and SKOV3 cells were treated with or without trastuzumab. Cell number and the rate of colony formation were calculated. Western blot analysis was used to detect p185 HER-2, HER-2 ECD and phospho-HER-2. Two-site ELISA assay was used for the detection of HER-2 ECD. RESULTS: Trastuzumab inhibited cell proliferation, colony formation, and decreased or eliminated the levels of two uncharacterized phospho-proteins (molar weight about 90 000 and 40 000) in SKBR3 cells shedding high level of HER-2 ECD expression. These responses were not observed in SKOV3 cells shedding low level of HER-2 ECD expression. But total p185, phospho-p185 and phospho-p95 proteins did not appear to change in SKBR3 and SKOV3 cells after treatment with trastuzumab. Trastuzumab reacts not only with proteolytic cleavage HER-2 ECD containing HER-2 ECD I , II , III and IV subdomains of p185 HER-2 extracellular domain, but also with the secreted autoinhibitor p68/ECD III a specifying 340 residues, identical to subdomains I and II from the extracellular domain of p185 HER-2, followed by a unique C-terminal sequence of 79 aa encoded by intron 8, which suggested that there may be a trastuzumab binding site on p68/ECD III a protein. Comparing with HER-2 ECD levels of the same number of SKBR3 cells, there was no significant decrease of HER-2 ECD shedding level after treatment with or without trastuzumab for 4 days in serum-free medium. CONCLUSION: Antitumor effects of trastuzumab may be related to the two uncharacterized phospho-p90 and/or phospho-p40 proteins. There is probably a trastuzumab epitope on p68/ECD III a. The decrease of HER-2 ECD levels may be positively correlated with the number of SKBR3 cells.
OBJECTIVE: To examine the effect of trastuzumab on cell proliferation, colony formation and changes of HER-2 proteins in humanbreast cancer cell line SKBR3 and humanovarian cancer cell line SKOV3 cells which overexpress p185HER-2 but shed high or low HER-2 extracellular domain (ECD) levels. METHODS: SKBR3 cells and SKOV3 cells were treated with or without trastuzumab. Cell number and the rate of colony formation were calculated. Western blot analysis was used to detect p185HER-2, HER-2ECD and phospho-HER-2. Two-site ELISA assay was used for the detection of HER-2ECD. RESULTS:Trastuzumab inhibited cell proliferation, colony formation, and decreased or eliminated the levels of two uncharacterized phospho-proteins (molar weight about 90 000 and 40 000) in SKBR3 cells shedding high level of HER-2ECD expression. These responses were not observed in SKOV3 cells shedding low level of HER-2ECD expression. But total p185, phospho-p185 and phospho-p95 proteins did not appear to change in SKBR3 and SKOV3 cells after treatment with trastuzumab. Trastuzumab reacts not only with proteolytic cleavage HER-2ECD containing HER-2ECD I , II , III and IV subdomains of p185HER-2 extracellular domain, but also with the secreted autoinhibitor p68/ECD III a specifying 340 residues, identical to subdomains I and II from the extracellular domain of p185HER-2, followed by a unique C-terminal sequence of 79 aa encoded by intron 8, which suggested that there may be a trastuzumab binding site on p68/ECD III a protein. Comparing with HER-2ECD levels of the same number of SKBR3 cells, there was no significant decrease of HER-2ECD shedding level after treatment with or without trastuzumab for 4 days in serum-free medium. CONCLUSION: Antitumor effects of trastuzumab may be related to the two uncharacterized phospho-p90 and/or phospho-p40 proteins. There is probably a trastuzumab epitope on p68/ECD III a. The decrease of HER-2ECD levels may be positively correlated with the number of SKBR3 cells.
Authors: Jason A Wilken; Tayf Badri; Sarah Cross; Rhoda Raji; Alessandro D Santin; Peter Schwartz; Adam J Branscum; Andre T Baron; Adam I Sakhitab; Nita J Maihle Journal: Future Med Chem Date: 2012-03 Impact factor: 3.808
Authors: Mothaffar F Rimawi; Ingrid A Mayer; Andres Forero; Rita Nanda; Matthew P Goetz; Angel A Rodriguez; Anne C Pavlick; Tao Wang; Susan G Hilsenbeck; Carolina Gutierrez; Rachel Schiff; C Kent Osborne; Jenny C Chang Journal: J Clin Oncol Date: 2013-04-08 Impact factor: 44.544
Authors: Galatea Kallergi; Sofia Agelaki; Maria A Papadaki; Dimitris Nasias; Alexios Matikas; Dimitris Mavroudis; Vassilis Georgoulias Journal: Breast Cancer Res Date: 2015-08-19 Impact factor: 6.466