Amber F. Gallanis, MD
Surgical Oncology Research Fellow
National Cancer Institute
Arlington, Virginia, United States
Yunhe Liu, PhD
MD Anderson Cancer Center
Houston, Texas, United States
Rachael E. Belcher, MD (she/her/hers)
Research Fellow
University of Maryland School of Medicine
Baltimore, Maryland, United States
Sun A Kim, MD, PhD
Faculty
National Institutes of Health
Bethesda, Maryland, United States
Donna Butcher, BS
National Institutes of Health
Frederick, Maryland, United States
Baktiar Karim, DVM PhD
National Institutes of Health
Frederick, Maryland, United States
Andrew M. Blakely, MD
Surgical Oncologist
Surgical Oncology Branch / National Cancer Institute / National Institute of Health
Bethesda, Maryland, United States
Jonathan Hernandez, MD
Principal Investigator
NIH
Bethesda, Maryland, United States
Linghua Wang, MD, PhD
MD Anderson Cancer Center
Houston, Texas, United States
Jeremy L. Davis, MD (he/him/his)
Professor of Surgery
Division of Surgical Oncology,
Department of Surgery,
University of Maryland School of Medicine
Baltimore, Maryland, United States
Amber F. Gallanis, MD
Surgical Oncology Research Fellow
National Cancer Institute
Arlington, Virginia, United States
Occult, gastric signet ring cell (SRC) lesions are ubiquitous in patients with germline CDH1 loss-of-function variants. Though SRC lesions typically exhibit a clinically indolent behavior, the drivers of progression to advanced diffuse gastric cancer remain unknown. We aimed to identify gene expression patterns associated with tumor cell invasion depth to determine potential biomarkers of SRC tumorigenesis.
Methods:
We employed a spatial transcriptomics platform (10X Genomics Xenium) with subcellular resolution of both early SRC lesions (pT1a) and advanced diffuse gastric cancers (≥T2) from 18 patients with germline CDH1 variants. A customized gastric cancer panel and the 10X Genomics Multi-Tissue and Cancer panel were used to investigate transcriptomic changes in 671 genes of interest. Spatially resolved gene expression readouts were analyzed according to depth of gastric wall invasion. Immunohistochemistry was performed to correlate protein expression with mRNA markers of interest.
Results:
Advanced hereditary diffuse gastric cancers exhibited three distinct transcriptomic clusters based on depth of tumor invasion into the mucosa, submucosa and muscularis propria layers and clustered distinctly from early signet ring cell lesions. Three differentially expressed genes demonstrated increased expression according to depth of tumor invasion: clusterin (CLU), eukaryotic translation initiation factor 3 (EIF3E), and annexin A2 (ANXA2). CLU, a known regulator of epithelial-to-mesenchymal transition and apoptosis, was over-expressed both in advanced SRC lesions (p< 0.05) compared to early SRC lesions and within SRC lesions compared to gastric epithelium (p=0.03). Clusterin protein expression was quantitatively increased in SRC lesions compared to unaffected gastric epithelium, with more intense staining demonstrated with deeper tumor invasion in advanced diffuse gastric cancers.
Conclusions:
Early SRC lesions are transcriptomically distinct from advanced diffuse gastric cancers, corroborating that SRC lesions are precancers. Clusterin appears to be a biomarker of SRC lesions that is correlated with cancer progression in germline CDH1 variant carriers. Thus, clusterin could be useful for early detection of SRC precancers that transform to a progressive phenotype.