Abstract 5970: Carbamazepine mediated SMARCA4 inhibition as a therapeutic target for KRAS-mutated CRC
Authors: Shaykevich Aaron , Chae Danbee , Silverman Isaac , Bassali Jeremy , Louloueian Netanel , Siegman Alexander , Bandyopadhyaya Gargi , Goel Sanjay , Maitra Radhashree 
Published: March 2024

Introduction: Carbamazepine (CBZ) is an autophagy inducer along with its other therapeutic properties. KRAS-mutated CRC has a worse prognosis and limited treatment options when compared to KRAS wild-type CRC. In this study, we followed the effects of CBZ treatment in the mutant and wild-type CRC cells. We herein report that CBZ exhibits mutant selectivity in efficacy and significantly modulates SMARCA4 levels, a protein heavily implicated in both tumor suppression and proliferation, presenting a promising method for KRAS-mutated CRC treatment.

Methodology: 2 cell lines, HCT116 (KRAS mutant) and Hke3 (KRAS wild-type), were used in this study. These cells were treated with Carbamazepine (CBZ) for either 6 or 24 hours. Subsequently, RNA and protein extractions were performed to assess the expression levels of SMARCA4 through quantitative polymerase chain reaction (qPCR) and Western blot analysis, respectively. Furthermore, the TCGA COAD-READ patient dataset was accessed using Xena. The data is used to assess the correlation of KRAS and SMARCA4 wt-tumor vs. mutant-tumor. The dataset was also used to visualize the effect of high SMARCA4 mRNA on the different patient cohorts.

Results: Basal levels of SMARCA4 are higher in CRC patients than control (p = 1.81e-16). Patients with a KRAS mutation has higher levels than KRAS-wt (p = 0.000005). KRAS mutated cells treated with CBZ expressed less BRG1 (SMARCA4 protein) at 24 hours (Fold Change = 0.68, p= 0.041). KRAS wildtype cells treated with CBZ expressed more BRG1 at 6 hours (Fold Change = 1.23, p= 0.006). The fold change of BRG1 in KRAS-mutant was significantly lower than in KRAS-wildtype at both 6 and 24 hours (p= 0.013 and p= 0.002). KRAS mutated cells treated with CBZ expressed less SMARCA4 mRNA at 24 hours (Fold Change = 0.69, p= 0.008). KRAS wildtype cells treated with CBZ expressed more SMARCA4 at 6 hours (Fold Change = 1.62, p= 0.006) and 24 hours (Fold Change = 1.31, p= 0.06). The fold change of SMARCA4 in KRAS-mutant was significantly lower than in KRAS-wildtype at both 6 and 24 hours (p= 0.0032 and p= 0.00009). BRG1 expression affected overall survival for the first 1500 days - only in patients with a KRAS-mutant (p= 0.015).

Conclusion: This study sheds light on the potential therapeutic role of CBZ in colorectal cancer, particularly in the context of KRAS-mutated CRC. Our findings indicate that CBZ treatment has distinct effects on SMARCA4 expression in CRC depending on KRAS mutation status. In KRAS-mutated cells, CBZ reduced SMARCA4 protein and mRNA levels. Conversely, in KRAS wild-type cells, CBZ resulted in an increase in SMARCA4 expression. Furthermore, our analysis of patient datasets reaffirmed the association between elevated SMARCA4 and KRAS, since high SMARCA4 expression led to worse overall survival rates, specifically in KRAS-mutant CRC patients. These findings emphasize the need for further exploration of CBZ as a potential treatment strategy for CRC.

Citation Format: Aaron Shaykevich, Danbee Chae, Isaac Silverman, Jeremy Bassali, Netanel Louloueian, Alexander Siegman, Gargi Bandyopadhyaya, Sanjay Goel, Radhashree Maitra. Carbamazepine mediated SMARCA4 inhibition as a therapeutic target for KRAS-mutated CRC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5970.