Abstract 4328: Erlotinib suppresses autophagy in colorectal cancer
Authors: Siegman Alexander , Shaykevich Aaron , Silverman Isaac , Goel Sanjay , Maitra Radhashree 
Published: March 2024

Introduction: Oncogenic KRAS mutation is prevalent in approximately 45% of colorectal cancer (CRC) patients. Limited targeted therapies are available to inhibit the detrimental effects of KRAS mutation primarily pertaining to its unique structural intricacies. Erlotinib is an EGFR inhibitor which inducing autophagy in lung cancer cells. In this study, we followed the effects of Erlotinib treatment in mutant and wild-type colorectal cancer (CRC) cells. We report that Erlotinib exhibits selectivity between mutated KRAS and wild type, significantly modulating the expression of autophagy proteins ATG5, ULK1, Beclin1, and LC3A.

Methodology: The 2 cell lines used in this study were HCT116 (KRAS mutant) and Hke3 (KRAS wild type). These cells were treated with Erlotinib for 24 hours and 48 hours, A cell viability assay was performed and subsequently followed by protein extraction. The expression of autophagy proteins ATG5, ULK1, Beclin1, and LC3A was determined. The TCGA COAD-READ patient dataset was utilized using GEPIA 2 software. A correlation was found between the autophagy proteins and the KRAS gene expression.

Results: The cell viability assays showed that there was significantly more cell death in KRAS wild-type cells compared with KRAS mutant at time points ranging from 24 to 48 hours (p = 0.036). The experiment also showed that treatment of Erlotinib with concentrations of 20 uM, 35 uM, and 50 uM and significant down regulatory fold changes (p &lt; 0.05). Both KRAS mutated and wild-type cells treated with Erlotinib expressed significant downregulation of ATG5, ULK1, Beclin1, and LC3A proteins at 48 hours (p &lt; 0.05). The 20 uM treatment demonstrated a significance of p &lt; 0.05 for all proteins. The 20 uM treatment resulted in fold changes of the KRAS mutated cells for ATG5, ULK1, Beclin1, and LC3A to be 1.42, 1.42, 1.81, and 2.09 respectively. A strong KRAS correlation was found with ATG5, ULK1, Beclin1, and LC3A using COAD & READ tumor and COAD & READ normal (R &gt; 0.75, p &lt; 0.05).

Conclusion: This study highlights the effects of Erlotinib as a treatment for KRAS mutated CRC. Our results confirmed that Erlotinib had the opposite effect on CRC cells in relation to the expression of the autophagy proteins when compared to lung cancer cells. There were distinct effects of Erlotinib between KRAS wild-type and mutant cells in both cell viability and the expression of autophagy-related proteins. In both KRAS cell types, there was significant downregulation of autophagy proteins, however, the KRAS wild type had significantly more downregulation than the KRAS mutant. This data suggests that there is a relationship between KRAS mutation and the expression of the autophagy proteins. Our analysis of the patient datasets confirmed the strong correlation between KRAS mutation and the expression of autophagy proteins. These findings emphasize the need to explore further how Erlotinib can be augmented into the current treatment regimen as a benefit to CRC patients.

Citation Format: Alexander Siegman, Aaron Shaykevich, Isaac Silverman, Sanjay Goel, Radhashree Maitra. Erlotinib suppresses autophagy in colorectal cancer [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 4328.