S100P Emerges as a Prognostic and Immune-Linked Biomarker in Lung Adenocarcinoma

S100P is a member of the S100 calcium-binding protein family that has been implicated in the development of several human malignancies, but its clinical significance and potential role in the tumor immune microenvironment of lung adenocarcinoma (LUAD) remain incompletely understood. A new study published in Discover Oncology turns the spotlight on one such player: S100P, a member of the S100 family of calcium-binding proteins that has previously been implicated in the development of several human malignancies. Combining large-scale bioinformatics with single-cell sequencing, researchers Decai Li, Dawei Zhang and Yingjie Xu set out to determine whether S100P could serve as a meaningful marker of disease severity and immune status in patients with lung adenocarcinoma, a question the authors describe as incompletely understood until now.

The team assembled its evidence from two public repositories in cancer genomics. Transcriptomic data and clinical information for lung adenocarcinoma were downloaded from The Cancer Genome Atlas and the Gene Expression Omnibus, giving the investigators a broad patient base on which to test the behavior of S100P. They then ran a battery of standard but powerful analyses: differential expression testing to see whether the gene behaves differently in tumor versus normal tissue, survival analysis to probe its prognostic weight, clinicopathological correlation to link expression levels with disease stage, and functional enrichment analysis to infer which biological pathways the gene’s activity touches. Immune infiltration was evaluated with two complementary algorithms, ESTIMATE and ssGSEA, which estimate the composition of immune cells within a tumor sample from bulk gene expression data.

The study reported several central findings. S100P expression was significantly elevated in lung adenocarcinoma tissues compared with normal lung tissue, and patients whose tumors expressed higher levels of the gene fared worse in terms of overall survival. The association extended beyond prognosis into the clinicopathological realm: increased S100P expression correlated with more advanced T stage, a measure of the size and extent of the primary tumor, and with more advanced pathological stage overall. In the study's data, increased S100P expression was correlated with advanced T stage and pathological stage, and the authors suggest it may serve as a potential biomarker for evaluating disease progression in patients with LUAD.

What does the study indicate about S100P's associations within the tumor? Functional enrichment analysis of the genes whose expression patterns track with S100P pointed toward several cancer-related pathways, and one of them stands out for its growing prominence in tumor immunology: the formation of neutrophil extracellular traps, or NETs. Functional enrichment analysis indicated that S100P-related genes were involved in several cancer-related pathways, including neutrophil extracellular trap (NET) formation. This result places S100P-related genes in a pathway relevant to neutrophil biology, and it dovetails with the study's other observations about immune cell populations.

The immune analyses reported associations rather than strong relationships. Elevated S100P expression showed weak-to-moderate correlations with the infiltration levels of several immune cell subsets, as estimated by the ssGSEA and ESTIMATE algorithms. The study did not establish that S100P single-handedly orchestrates the immune landscape; the reported correlations indicate association with measurable shifts in the estimated cellular composition of the tumor microenvironment. The authors interpret these findings as evidence that S100P is associated with alterations in the immune microenvironment of lung adenocarcinoma, while noting that the weak-to-moderate correlations do not establish a causal role in immune regulation.

The single-cell sequencing arm of the study sharpened that picture considerably. By analyzing single-cell data, the researchers were able to move beyond bulk tissue averages and ask which specific cell types within the tumor microenvironment actually express S100P. The answer was striking: the gene was predominantly enriched in neutrophil-associated cell populations. This cellular distribution is consistent with the functional enrichment result pointing to NET formation, and it suggests that the signal detected in bulk tumor samples may be associated, at least in part, with neutrophil-associated cell populations within the tumor microenvironment.

Taken together, the study's results support a specific model that the authors describe as requiring further investigation. S100P is upregulated in lung adenocarcinoma, its expression level rises with advancing stage, patients with high expression have poorer overall survival, and the gene’s activity is concentrated in neutrophil-associated cells that are part of the tumor’s immune landscape. The authors conclude that S100P may serve as a potential biomarker for evaluating disease progression and immune status in patients with lung adenocarcinoma, a framing that is deliberately cautious: the study establishes association, not causation, and the correlations with immune infiltration are described as weak to moderate rather than strong.

The work exemplifies a broader trend in cancer research, in which publicly available genomic datasets are mined with computational tools to generate hypotheses that can later be tested experimentally. By combining bulk transcriptomic analysis with single-cell sequencing, the study bridges two scales of observation: population-level associations that link a gene to survival and stage, and cellular-level data indicating where in the tumor microenvironment S100P was predominantly enriched. This dual-scale approach is relevant for genes like S100P, whose observed associations may depend on which cells in the microenvironment are doing the expressing.

For researchers, the findings add S100P to the list of molecular markers under investigation for lung adenocarcinoma, and they highlight neutrophil-associated cell populations as a dimension of the tumor microenvironment warranting further study. The authors note that their results suggest S100P may be useful for evaluating disease progression and immune status, and the study’s open-access publication in Discover Oncology makes the full analysis available to the research community. As with any bioinformatics-driven study, further validation in independent cohorts would be needed to determine whether measuring S100P can genuinely improve the care of patients with this disease.

Subject of Research: The clinical and immunological significance of the calcium-binding protein S100P in lung adenocarcinoma

Article Title: Integrated bioinformatics and single-cell analyses reveal the clinical and immunological significance of S100P in lung adenocarcinoma

Article References: Li, D., Zhang, D., & Xu, Y. (2026). Integrated bioinformatics and single-cell analyses reveal the clinical and immunological significance of S100P in lung adenocarcinoma. Discover Oncology. https://doi.org/10.1007/s12672-026-06163-x

Image Credits: AI Generated

DOI: 10.1007/s12672-026-06163-x

Keywords: lung adenocarcinoma, S100P, bioinformatics, single-cell sequencing, tumor microenvironment, immune infiltration, prognosis, neutrophil extracellular traps, TCGA, biomarker, Integrated, single-cell