Abstract 6466: Multi-omics analysis of molecular characteristics and transformation mechanisms of stage I-III micropapillary lung adenocarcinoma
Authors: Shao Kang , Gao Shugeng , Tan Fengwei , Shao Anqi , Feng Xiaoli , Xue Qi , Qu Yang , Zheng Bo , Zheng Wei , Chen Hanlin , Ou Qiuxiang , Tang Haimeng 
Published: March 2024

Abstract
Background: The micropapillary pattern (MIP) is recognized as a high-grade histological subtype in lung adenocarcinoma (LUAD), with its presence often indicative of a poorer prognosis. Despite distinctive molecular characteristics of MIP, there is a research gap regarding the molecular mechanisms underlying micropapillary transformation and prognosis factors for micropapillary LUAD.
Methods: Surgically resected tumor samples from 101 patients with stage I-III LUAD and MIP components exceeding 30% were collected. The tumor samples were microdissected to separate MIP components from non-MIP components, and both fractions underwent RNA and DNA whole-exome sequencing (WES). The molecular profiles between MIP and non-MIP components, along with MIP-naïve LUAD tissues from an external cohort, were compared. Associations between molecular characteristics and recurrence-free survival were also assessed.
Results: The genomic landscapes of MIP and non-MIP components within tumor tissues featuring MIP patterns exhibited remarkable similarity. At the transcriptomic level, MIP components displayed elevated PRB4 expression (FDR &lt; 0.001), an up-regulated cell cycle pathway (P = 0.004), and reduced natural killer cell-mediated cytotoxicity (P = 0.066). Nevertheless, in comparison to MIP-naïve LUAD tissues, the MIP components showed higher chromosomal instability (P &lt; 0.001) and revealed eighteen enriched somatic alterations, encompassing EGFR mutations, EGFR amplifications, and CDKN2A/CDKN2B deletions, all linked to up-regulations in cell proliferation pathways and down-regulated immune pathways. In the context of MIP transformation, shared mutations were observed in 97.8% (91/93) of patients between MIP and non-MIP components within the same tissues, suggesting a common origin. The subclonal fractions were comparable between paired MIP and non-MIP components, while a significant co-occurrence of EGFR amplification, CDKN2A deletion, and CDKN2B deletion was identified in MIP components. A comprehensive analysis combining differential gene expression and Cox analysis, employing a both-direction stepwise Akaike Information Criteria selection, identified the high expressions of five genes (GALNT4, MIAT, FOSL1, LAT2, SMN2) as adverse factors associated with the recurrence of micropapillary LUAD.
Conclusions: We conducted an in-depth analysis of the molecular characteristics and transformation mechanisms of micropapillary lung adenocarcinoma, employing microdissection techniques to investigate at both genomic and transcriptomic levels within a substantial cohort, providing insights for the precision medicine of this aggressive cancer subtype.
Citation Format: Kang Shao, Shugeng Gao, Fengwei Tan, Anqi Shao, Xiaoli Feng, Qi Xue, Yang Qu, Bo Zheng, Wei Zheng, Hanlin Chen, Qiuxiang Ou, Haimeng Tang. Multi-omics analysis of molecular characteristics and transformation mechanisms of stage I-III micropapillary lung adenocarcinoma [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 6466.