A co-regulatory network of SPIB, AQP8, and GUCA2B related to immune infiltration for early-stage colorectal cancer in silico and in vitro

In early-stage colorectal cancer (CRC), AQP8, GUCA2B, and SPIB were important suppressor genes and frequently co-expressed. However, the underlying co-regulation effect remains unknown and need to be elucidated. We aimed to investigate the co-regulatory network of AQP8, GUCA2B, and SPIB in CRC using in vitro and in silico methods. Q-PCR, western blot, and immunohistochemistry were used to assess the co-regulatory network of the target genes in the HCT-116 cell line and fresh tumor tissues. Bioinformatical methods were used to validate the findings using the Cancer Genome Atlas COlon ADenocarcinoma and REctum ADenocarcinoma datasets, as well as large scale integrated data sets from Gene Expression Omnibus. In clinical CRC tissues, SPIB, AQP8, and GUCA2B were barely expressed compared to normal mucosa. When compared to 22 well-known genetic biomarkers, they are independent predictors of CRC identification with near 100% accuracy. In the co-regulatory network, they were coupregulated at the mRNA and protein expression levels. AQP8, GUCA2B and SPIB were linked to immune cell infiltration and GUCA2B and SPIB were negatively associated with tumor purity. The co-regulatory network in miRNA-mRNA analysis was mediated by cancer-related microRNAs miR-182-5p and miR-27a-3. The functional analysis of the coregulatory network's protein-protein interaction networks reveals three clusters and three major functions: complex interactions of transcription factors in mediating cytokine biology in T cells (SPIB cluster), guanylin, and Intestinal infectious diseases (GUCA2B cluster), and water channel activity balance (AQP8 cluster). The co-regulatory network of SPIB, AQP8, and GUCA2B was confirmed. MiR-27a-3p and miR-182-5p were two possible mediators. The mechanisms of SPIB, AQP8, GUCA2B, miR-182-5p, and miR-27a-3p in CRC merit further investigation.