Abstract 6274: Integrated multi-omics revealed the involvement of MYC and mTOR pathways in radiation resistance of adrenocortical cancer
Authors: Ramamoorthy Bhavishya , Mishra Prachi , Boufraqech Myriem , Michael Nicholas , Cam Margaret , Finney Richard , Meyer Thomas , Holewinski Ronald , Andresson Thorkell , Wong Madeline , Shema Steven , Tillo Desiree , Nilubol Naris 
Published: March 2024

The morbidity and mortality of patients with adrenocortical cancer (ACC) are commonly due to locoregional postoperative recurrence and progressive systemic metastasis. Surgical resection remains the only curative treatment option, but even with complete resection, locoregional recurrence rates remain high. Adjuvant radiation therapy (RT) has been shown to reduce recurrence rates and may improve overall survival in selected patients. However, half of the patients receiving postoperative RT still develop locoregional recurrence, clearly demonstrating the heterogeneous nature of ACC. Minimal investigation into the mechanisms underlying radiation response and resistance in ACC has been performed, but elucidating this information is critical to improving outcomes. To address this knowledge gap, NCI-H295R cells were treated with fractionated radiation at 1 Gray (Gy) per day for 5 consecutive days for two consecutive weeks, cumulating in a total radiation dose of 10 Gy. Treated and control ACC cells were harvested on days 7 and 14 for bulk RNA-sequencing (RNA-Seq) and total proteomics by liquid chromatography and tandem mass spectrometry. Significantly differentially expressed genes (DEGs) and proteomes (adj. p. value &lt;0.05) that overlapped between day 7 and day 14 were selected for further analysis and comparison with publicly available gene expression data sets in ACC (The Cancer Genome Atlas (TCGA); Gene Expression Omnibus: GSE12368, GSE33371, GSE75415, GSE90713).

There were 3993 DEGs and 423 proteomes identified, respectively. Of these, there were 139 overlapping DEGs with respective proteomes found, 72 of which were differentially expressed in the 4 GEO data sets comparing normal adrenal cortex to ACC. RNA-Seq pathway analysis demonstrated enrichment of E2F targets, G2M checkpoint, mTORC1 signaling, and MYC targets v1, while total proteomics pathway analysis revealed enrichment of cell cycle, transcriptional regulation, cellular stress and injury, alterations of RNA metabolism, and metabolism proteomes. Given that MYC and mTOR are both involved in transcriptional regulation and cell cycle regulation, and mTORC1 in particular is associated with cellular metabolism, the RNA-Seq and proteomics pathway analyses show general consistency with each other.

TCGA gene expression analysis showed that overexpression of MYC or mTOR was correlated with shorter overall survival (OS) and disease-free survival (DFS) in the entire ACC cohort (p&lt;0.05). Together, the combination of in vitro pathway analysis and TCGA analysis suggests a potential involvement of the MYC and mTOR pathways in radiation resistance in ACC. Further in vitro and in vivo studies are warranted to identify specific molecular compounds that target MYC and mTOR pathways and improve radiation response in ACC.

Citation Format: Bhavishya Ramamoorthy, Prachi Mishra, Myriem Boufraqech, Nicholas Michael, Margaret Cam, Richard Finney, Thomas Meyer, Ronald Holewinski, Thorkell Andresson, Madeline Wong, Steven Shema, Desiree Tillo, Naris Nilubol. Integrated multi-omics revealed the involvement of MYC and mTOR pathways in radiation resistance of adrenocortical 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 6274.