Abstract 3916: role of her3 v104l mutation on tumor growth and her3 stabilization

Abstract

Abstract We aimed to determine if naturally occurring HER3 mutations could drive oncogenic activity of HER2+ HCC1569 cells in which endogenous HER3 was knocked out using CRISPR-Cas9 technology. A series of HER3 mutations found in breast cancer patients (F94L, V104L, G284R, D297Y, T355I, and E928G) were introduced via lentiviral transduction and stable cell lines were generated in HER3 knock out (KO) HCC1569 cells and were maintained in 0.5 mg/mL puromycin. Our data indicated that cells stably transduced with HER3V104L mutation had significantly higher cell growth with higher p-HER3 expression versus wild-type (wt) and empty-vector (EV) HER3. We found that HCC1569HER3KO cells with WT and V104L were sensitive to increasing concentration of neratinib (0.1-0.5 µM) as indicated by crystal violet assay. Next we examined if V104L mutation rendered resistance to another FDA- approved irreversible HER2 tyrosine kinase inhibitor, tucatinib. Our results showed that V104L cells were sensitive to higher concentration of tucatinib compared to neratinib. In other experiments, we used COS7 cells to examine the signaling pathways of HER3V104L mutation. Our western blot data demonstrated that transient transfection of COS7 cells with HER3V104L mutant significantly upregulated p-HER3 and p-HER2 expression versus WT HER3 in a NRG- dependent manner. In addition, we found that the V104L mutation stabilizes HER3 protein expression independent of ligand stimulation. Our western blot data showed that V104L induced HER3 stabilization is independent on HER3 binding partners HER1, HER2 and HER4. Our cycloheximide chase data indicated that V104L mutation stabilizes HER3 expression in COS7 cells as well as low HER3 expressing colon cancer cell line, SNUC5. Our western blot data indicates that V104L mutation activates ERK signaling in NRG dependent manner over AKT pathway in COS7 cells. In addition, we are using various PDXs with different HER3 mutations (V104M and E928D) to determine the role of these driver HER3 mutations in cancer and how this can be targeted in the clinic using HER targeted therapy. Citation Format: Rosalin Mishra, Mary Kate Kilroy, Wasim Feroz, Hima Patel, Samar Alanazi, Joan T. Garrett. role of her3 v104l mutation on tumor growth and her3 stabilization. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3916.