American Association for Cancer Research
10780432ccr170696-sup-180267_2_supp_4197829_hh5nzc.docx (15.67 kB)

Supplementary Figure legend from Defective Cyclin B1 Induction in Trastuzumab-emtansine (T-DM1) Acquired Resistance in HER2-positive Breast Cancer

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posted on 2023-03-31, 19:33 authored by MohammadA Sabbaghi, Gabriel Gil-Gómez, Cristina Guardia, Sonia Servitja, Oriol Arpí, Sara García-Alonso, Silvia Menendez, Montserrat Arumi-Uria, Laia Serrano, Marta Salido, Aura Muntasell, Maria Martínez-García, Sandra Zazo, Cristina Chamizo, Paula González-Alonso, Juan Madoz-Gúrpide, Pilar Eroles, Joaquin Arribas, Ignasi Tusquets, Ana Lluch, Atanasio Pandiella, Federico Rojo, Ana Rovira, Joan Albanell

Supplementary Figure legend



Generalitat de Catalunya




Purpose: Trastuzumab-emtansine (T-DM1) is a standard treatment in advanced HER2-positive breast cancer. However, resistance inevitably occurs. We aimed to identify mechanisms of acquired T-DM1 resistance.Experimental Design: HER2-positive breast cancer cells (HCC1954, HCC1419, SKBR3, and BT474) were treated in a pulse-fashion with T-DM1 to induce a resistant phenotype. Cellular and molecular effects of T-DM1 in parental versus resistant cells were compared. CDK1 kinase activity and cyclin B1 expression were assayed under various conditions. Genetic modifications to up- or downregulate cyclin B1 were conducted. Effects of T-DM1 on cyclin B1 levels, proliferation, and apoptosis were assayed in human HER2-positive breast cancer explants.Results: We obtained three cell lines with different levels of acquired T-DM1 resistance (HCC1954/TDR, HCC1419/TDR, and SKBR3/TDR cells). HER2 remained amplified in the resistant cells. Binding to HER2 and intracellular uptake of T-DM1 were maintained in resistant cells. T-DM1 induced cyclin B1 accumulation in sensitive but not resistant cells. Cyclin B1 knockdown by siRNA in parental cells induced T-DM1 resistance, while increased levels of cyclin B1 by silencing cdc20 partially sensitized resistant cells. In a series of 18 HER2-positive breast cancer fresh explants, T-DM1 effects on proliferation and apoptosis paralleled cyclin B1 accumulation.Conclusions: Defective cyclin B1 induction by T-DM1 mediates acquired resistance in HER2-positive breast cancer cells. These results support the testing of cyclin B1 induction upon T-DM1 treatment as a pharmacodynamic predictor in HER2-positive breast cancer. Clin Cancer Res; 23(22); 7006–19. ©2017 AACR.

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