Immune checkpoint inhibitor therapy has proven efficacy in a subset of colon cancer patients featuring a deficient DNA mismatch repair system or a high microsatellite instability profile. However, there is high demand for more effective biomarkers to expand the colon cancer population responding to ICI therapy. PBK/TOPK, a serine/threonine kinase, plays a role in cell cycle regulation and mitotic progression. Here, we investigated the correlation between PBK/TOPK expression and tumor immunity and its prognostic value in colon cancer. Based on large-scale bioinformatics analysis, we discovered that elevated PBK/TOPK expression predicted a favorable outcome in patients with colon cancer and was positively associated with immune infiltration levels of CD8+ T cells, CD4+ T cells, natural killer cells, and M1 macrophages. In contrast, a negative correlation was found between PBK/TOPK expression and immune suppressor cells, including regulatory T cells and M2 macrophages. Furthermore, the expression of PBK/TOPK was correlated with the expression of T-cell cytotoxicity genes in colon cancer. Additionally, high PBK/TOPK expression was associated with mutations in DNA damage repair genes, and thus with increased tumor mutation and neoantigen burden. These findings suggest that PBK/TOPK may serve as a prognostic and predictive biomarker for immunotherapy in colon cancer.

Background: Hospital drainage systems represent an important interface between healthcare facilities and urban wastewater networks and may contribute distinct microbial inputs to downstream aquatic environments. This issue is particularly relevant in Seoul, Republic of Korea, where urban wastewater discharges into receiving waters within the Han River watershed. Methods: In this study, we characterized hospital drain microbiomes to evaluate their microbial and environmental signatures, using residential drains as a non-clinical comparison. Results: Hospital drains exhibited a distinct taxonomic profile, with greater relative abundances of Bacteroidota and Firmicutes and several genera of environmental or potential public health relevance, including Mycobacterium, Legionella, and Pseudomonas. Although microbial richness was comparable between the two environments, Simpson diversity was significantly lower in hospital drains, indicating reduced community evenness. Bray–Curtis and Jaccard analyses showed clear separation between hospital and residential microbial communities, and hierarchical clustering further supported environment-associated community structuring. LEfSe analysis identified distinct hospital-associated taxonomic biomarkers, and predicted functional profiling revealed substantial metabolic differentiation, with 19 of the 25 most significantly differentiated pathways enriched in hospital samples. Conclusions: These microbial and functional differences underscore the ecological uniqueness of hospital drains and support their inclusion in future wastewater-based microbial surveillance strategies. Collectively, these findings establish hospital drains as distinct microbial ecosystems within urban wastewater networks and provide a baseline for future studies examining the persistence of hospital-associated microbial signatures within the Han River watershed.