Related Experiment Video
Updated: Apr 24, 2026
Colorectal Cancer Cell Surface Protein Profiling Using an Antibody Microarray and Fluorescence Multiplexing
Published on: September 25, 2011
Integrated transcriptomic and proteomic validation identifies SLC35D3 as a tumor-selective surface antigen for
Shunsuke Someya1, Tatsuya Inoue1, Reimi Kawaida1
1Daiichi Sankyo Co., Ltd., 1-2-58 Hiromachi, Shinagawa-ku, Tokyo, 140-8710, Japan.
Abstract:
Antibody-drug conjugates (ADCs), bispecific T-cell engagers (TCEs), and chimeric antigen receptor (CAR)-T cells require truly tumor-restricted surface antigens to minimize on-target/off-tumor toxicity. To identify such antigens, we interrogated two complementary RNA-seq resources: (i) the Genotype-Tissue Expression (GTEx) atlas spanning diverse normal tissues and (ii) the Cancer Genome Atlas colon adenocarcinoma cohort (TCGA-COAD). Candidate membrane-protein transcripts were defined by low median GTEx expression (<1 RPKM across all normal tissues) and marked upregulation (≥10-fold) in TCGA colon tumors. Only two genes met these stringent criteria, with the little-studied nucleotide-sugar transporter SLC35D3 emerging as the leading candidate. Pan-cancer analysis of the TCGA datasets confirmed its selective enrichment in colorectal carcinoma and in pheochromocytoma/paraganglioma, while GTEx data showed near-background expression in essential organs including brain, heart, liver, lung, and kidney. Protein-level validation with immunohistochemistry on > 250 tissue-microarray cores revealed SLC35D3 positivity in 53% of colorectal cancers, 40% of small-cell lung cancers, and 24% of pancreatic neuroendocrine tumors, whereas vital normal organs were uniformly negative. Although SLC35D3 has been annotated as mainly localized to the endoplasmic reticulum and early endosomes, our analyses revealed its presence on the plasma membrane, which was corroborated by flow cytometry in SLC35D3 mRNA-positive cancer cell lines but not in negative control. Taken together, these transcriptomic and proteomic findings establish SLC35D3 as a tumor-selective surface antigen broadly represented in aggressive malignancies yet virtually absent from critical normal tissues, highlighting it as a promising new candidate for next-generation ADCs, TCEs, and CAR-T therapies in colorectal and neuroendocrine carcinomas.
Insights
Researchers identified SLC35D3 as a promising tumor-specific surface antigen for cancer therapies like antibody-drug conjugates (ADCs) and CAR-T cells. This antigen is present on various aggressive cancers but not vital normal organs, minimizing potential side effects.
Area of Science:
- Oncology
- Molecular Biology
- Immunotherapy
Background:
- Targeted cancer therapies such as antibody-drug conjugates (ADCs), bispecific T-cell engagers (TCEs), and chimeric antigen receptor (CAR)-T cells rely on tumor-specific surface antigens to prevent on-target, off-tumor toxicity.
- Identifying antigens with high tumor expression and minimal normal tissue presence is crucial for developing effective and safe immunotherapies.
Purpose of the Study:
- To identify novel, truly tumor-restricted surface antigens for next-generation immunotherapies.
- To evaluate SLC35D3 as a potential therapeutic target for antibody-drug conjugates (ADCs), bispecific T-cell engagers (TCEs), and chimeric antigen receptor (CAR)-T cell therapies.
Main Methods:
- Utilized RNA-sequencing data from the Genotype-Tissue Expression (GTEx) atlas and The Cancer Genome Atlas (TCGA) colon adenocarcinoma cohort (TCGA-COAD).
- Screened for membrane-protein transcripts with low normal tissue expression (<1 RPKM in GTEx) and high tumor upregulation (≥10-fold in TCGA-COAD).
- Validated candidate antigen SLC35D3 expression using immunohistochemistry and flow cytometry across various cancer types and normal tissues.
Main Results:
- Identified SLC35D3 as a leading candidate tumor-selective antigen, showing low expression in normal tissues (brain, heart, liver, lung, kidney) and significant upregulation in colon tumors.
- Protein-level validation confirmed SLC35D3 expression in 53% of colorectal cancers, 40% of small-cell lung cancers, and 24% of pancreatic neuroendocrine tumors, with uniform negativity in vital organs.
- Demonstrated plasma membrane localization of SLC35D3 via flow cytometry, despite previous annotations suggesting endoplasmic reticulum/endosome localization.
Conclusions:
- SLC35D3 is a tumor-selective surface antigen broadly expressed in aggressive malignancies like colorectal and neuroendocrine carcinomas, but virtually absent from critical normal tissues.
- SLC35D3 represents a promising novel target for developing next-generation antibody-drug conjugates (ADCs), bispecific T-cell engagers (TCEs), and CAR-T cell therapies.
