BRAF V600E-mutant colorectal cancer (CRC) represents a distinct molecular subtype with considerable heterogeneity in tumor biology and therapeutic response. Although gene expression-based classifications (BM1/BM2 subtypes) provide valuable insights into underlying molecular and immune features, their clinical application is limited by the need for high-throughput sequencing. This study aims to establish an immunohistochemistry (IHC)-based classification system to enable practical subtype stratification and aid prognostic and therapeutic evaluation. Using two independent cohorts (public dataset, n = 218; institutional cohort, n = 122), we performed differential expression analysis, machine learning modeling, and clinical feasibility evaluation. Fourteen candidate markers were identified, and a decision tree algorithm selected CD8 and ARHGEF17 as optimal classifiers. Based on these markers, two IHC-based subtypes were established: iBM1 (CD8+/ARHGEF17−) and iBM2 (CD8− with any ARHGEF17 expression or CD8+/ARHGEF17+). The IHC-based subtypes showed concordance with transcriptomic BM subtypes (training: 82.69%, κ = 0.55; validation: 72.22%, κ = 0.44; prospective: 83.33%, κ = 0.57). Transcriptomic profiling revealed enrichment of immune activation and epithelial–mesenchymal transition in iBM1, and cell cycle-related pathways in iBM2. In clinical validation, iBM1 was associated with poorer survival but greater sensitivity to immune checkpoint inhibitors. This IHC-based classification provides a practical and accessible approach for BM subtype stratification, reflecting underlying molecular and immune characteristics, and may support prognostic assessment and therapeutic decision-making in BRAF V600E-mutant CRC.
{"title":"A Robust Immunohistochemistry-Based Classification for BRAF V600E-Mutant Colorectal Cancer With Clinical Implications","authors":"Chao Liu, Yuli Ruan, Tong Wu, Xindi Luan, Yue Ma, Hong Wang, Tianjiao Dang, Yiwen Ou, Bojun Wang, Chunhui Zhang, Hongxue Meng, Yanqiao Zhang","doi":"10.1111/cas.70231","DOIUrl":"10.1111/cas.70231","url":null,"abstract":"<p>BRAF V600E-mutant colorectal cancer (CRC) represents a distinct molecular subtype with considerable heterogeneity in tumor biology and therapeutic response. Although gene expression-based classifications (BM1/BM2 subtypes) provide valuable insights into underlying molecular and immune features, their clinical application is limited by the need for high-throughput sequencing. This study aims to establish an immunohistochemistry (IHC)-based classification system to enable practical subtype stratification and aid prognostic and therapeutic evaluation. Using two independent cohorts (public dataset, <i>n</i> = 218; institutional cohort, <i>n</i> = 122), we performed differential expression analysis, machine learning modeling, and clinical feasibility evaluation. Fourteen candidate markers were identified, and a decision tree algorithm selected CD8 and ARHGEF17 as optimal classifiers. Based on these markers, two IHC-based subtypes were established: iBM1 (CD8<sup>+</sup>/ARHGEF17<sup>−</sup>) and iBM2 (CD8<sup>−</sup> with any ARHGEF17 expression or CD8<sup>+</sup>/ARHGEF17<sup>+</sup>). The IHC-based subtypes showed concordance with transcriptomic BM subtypes (training: 82.69%, κ = 0.55; validation: 72.22%, κ = 0.44; prospective: 83.33%, κ = 0.57). Transcriptomic profiling revealed enrichment of immune activation and epithelial–mesenchymal transition in iBM1, and cell cycle-related pathways in iBM2. In clinical validation, iBM1 was associated with poorer survival but greater sensitivity to immune checkpoint inhibitors. This IHC-based classification provides a practical and accessible approach for BM subtype stratification, reflecting underlying molecular and immune characteristics, and may support prognostic assessment and therapeutic decision-making in BRAF V600E-mutant CRC.</p>","PeriodicalId":9580,"journal":{"name":"Cancer Science","volume":"117 1","pages":"246-256"},"PeriodicalIF":4.3,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/cas.70231","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145402496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Investigating the phenotypic contribution of gene-spliced isoforms to tumor cellular heterogeneity can facilitate the development of innovative strategies for precision medicine. Serine protease 3 (PRSS3), a trypsin-like protease with four spliced variants (PRSS3-SVs: PRSS3-V1 to V4), plays diverse biological roles in cancer progression. Herein, we systematically analyzed the expression patterns and functional implications of PRSS3-SVs in gastric cancer (GC) using an integrative approach that combined bioinformatic analyses, CpG site-specific methylation detection, splice-specific qPCR, isoform-based methodologies, and multiple functional assays. Our findings revealed that differentially expressed PRSS3 isoforms, predominantly PRSS3-V1 and PRSS3-V2, are regulated by intragenic methylation and exert pleiotropic roles in GC. Overexpression of PRSS3 transcripts suppressed GC cell proliferation via the NF-κB signaling pathway, while exerting distinct effects on matrix metalloproteinase-associated cell migration and invasion. Clinically, patients with low PRSS3-V1 or high PRSS3-V2 expression exhibited poorer survival outcomes, and the expression difference between these two transcripts was identified as an independent prognostic indicator for GC patients. Epigenetically, differential methylation patterns within PRSS3 enabled stratification of GC patients into subgroups characterized by either high-methylation with low-expressed PRSS3-SVs or low-methylation with high-expressed PRSS3-SVs. The UHRF1/DNMT1 complex was found to mediate CpG site methylation and regulate PRSS3 transcripts, particularly silencing PRSS3-V1 through intragenic CpG methylation. This methylation pattern was associated with reduced survival rates and further validated its correlation with tumor metastasis in an independent cohort (n = 243). Our study elucidates that methylation-regulated alternative splicing contributes to phenotypic heterogeneity in GC, highlighting its potential advantage over differentially expressed genes in improving stratification strategies for precision oncology.
{"title":"CpG Methylation-Driven Pleiotropic Spliced Isoforms of PRSS3 Facilitate Gastric Intratumor Heterogeneity and Metastasis","authors":"Mengdi Pang, Hanli Xu, Duoduo Li, Meiying Zhang, Daichuan Chen, Rongmeng Tian, Jie Gu, Nafisa Alimu, EnKai Wang, Ziyun Zhou, Xinyi Li, Qihang Peng, Yuqi He, Shuye Lin, Mingzhou Guo, Jiaqiang Huang","doi":"10.1111/cas.70227","DOIUrl":"10.1111/cas.70227","url":null,"abstract":"<p>Investigating the phenotypic contribution of gene-spliced isoforms to tumor cellular heterogeneity can facilitate the development of innovative strategies for precision medicine. Serine protease 3 (PRSS3), a trypsin-like protease with four spliced variants (<i>PRSS3-SVs</i>: <i>PRSS3-V1</i> to <i>V4</i>), plays diverse biological roles in cancer progression. Herein, we systematically analyzed the expression patterns and functional implications of <i>PRSS3-SVs</i> in gastric cancer (GC) using an integrative approach that combined bioinformatic analyses, CpG site-specific methylation detection, splice-specific qPCR, isoform-based methodologies, and multiple functional assays. Our findings revealed that differentially expressed <i>PRSS3</i> isoforms, predominantly PRSS3-V1 and PRSS3-V2, are regulated by intragenic methylation and exert pleiotropic roles in GC. Overexpression of <i>PRSS3</i> transcripts suppressed GC cell proliferation via the NF-κB signaling pathway, while exerting distinct effects on matrix metalloproteinase-associated cell migration and invasion. Clinically, patients with low <i>PRSS3-V1</i> or high <i>PRSS3-V2</i> expression exhibited poorer survival outcomes, and the expression difference between these two transcripts was identified as an independent prognostic indicator for GC patients. Epigenetically, differential methylation patterns within <i>PRSS3</i> enabled stratification of GC patients into subgroups characterized by either high-methylation with low-expressed <i>PRSS3-SVs</i> or low-methylation with high-expressed <i>PRSS3-SVs</i>. The UHRF1/DNMT1 complex was found to mediate CpG site methylation and regulate <i>PRSS3</i> transcripts, particularly silencing <i>PRSS3-V1</i> through intragenic CpG methylation. This methylation pattern was associated with reduced survival rates and further validated its correlation with tumor metastasis in an independent cohort (<i>n</i> = 243). Our study elucidates that methylation-regulated alternative splicing contributes to phenotypic heterogeneity in GC, highlighting its potential advantage over differentially expressed genes in improving stratification strategies for precision oncology.</p>","PeriodicalId":9580,"journal":{"name":"Cancer Science","volume":"117 1","pages":"33-49"},"PeriodicalIF":4.3,"publicationDate":"2025-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/cas.70227","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145402437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}