The introduction of preoperative concurrent chemoradiotherapy (CCRT) increases the rate of anal preservation and allows tumor downstaging for clinical stage T3/T4 or node-positive rectal cancer patients. However, there is no precise predictive tool to verify the presence of residual tumor apart from surgical resection. The gastrointestinal (GI) tract not only digests nutrients but also coordinates immune responses. As the outermost layer of the GI tract, mucus plays a key role in mediating the interaction between the digestive and immune systems, and aberrant mucus mesh formation may cause chemoresistance by impeding drug delivery. However, the correlations among digestion-related genes, mucin synthesis, and chemoresistance remain poorly understood. In the present study, we evaluated genes related to digestion (GO: 0007586) and identified cathepsin E (CTSE), which is involved in immune regulation, as the most significantly upregulated gene associated with CCRT resistance in rectal cancer in a public transcriptome dataset (GSE35452). We recovered 172 records of rectal cancer patients receiving CCRT followed by surgical resection from our biobank and evaluated the expression level of CTSE using immunohistochemistry. The results revealed that tumors with CTSE overexpression were significantly correlated with pre-CCRT and post-CCRT positive nodal status (both p < 0.001), advanced pre-CCRT and post-CCRT tumor status (p < 0.001 and p = 0.002), perineural invasion (p = 0.023), vascular invasion (p < 0.001), and a lesser degree of tumor regression (p = 0.003). At the univariate level, CTSE overexpression was an adverse prognostic factor for all three endpoints: disease-specific survival (DSS), metastasis-free survival (MeFS) (both p < 0.0001), and local recurrence-free survival (LRFS) (p = 0.0001). At the multivariate level, CTSE overexpression remained an independent prognostic factor for poor DSS, MeFS (both p = 0.005), and LRFS (p = 0.019). Through bioinformatics analysis, we speculated that CTSE overexpression may confer CCRT resistance by forming a defensive mucous barrier. Taken together, these results suggest that CTSE overexpression is related to CCRT resistance and inferior survival in rectal cancer patients, highlighting the potential predictive and prognostic value of CTSE expression.

Objective: To reduce the risk of locoregional recurrence, the addition of neoadjuvant concurrent chemoradiotherapy (CCRT) is recommended before surgical management for rectal cancer patients. However, despite identical tumor histology, individual patient response to neoadjuvant CCRT varies greatly. Accordingly, a comprehensive molecular characterization that is used to predict CCRT efficacy is instantly needed.Methods: Pearson’s chi-squared test was utilized to correlate dehydrogenase/reductase 9 (DHRS9) expression with clinicopathological features. Survival curves were created applying the Kaplan-Meier method, and the log-rank test was conducted to compare prognostic utility between high and low DHRS9 expression groups. Multivariate Cox proportional hazards regression analysis was applied to identify independent prognostic biomarkers based on variables with prognostic utility at the univariate level.Results: Utilizing a public transcriptome dataset, we identified that the DHRS9 gene is the most considerably upregulated gene related to epithelial cell differentiation (GO: 0030855) among rectal cancer patients with CCRT resistance. Employing immunohistochemical staining, we also demonstrated that high DHRS9 immunoexpression is considerably associated with an aggressive clinical course and CCRT resistance in our rectal cancer cohort. Among all variables with prognostic utility at the univariate level, only high DHRS9 immunoexpression was independently unfavorably prognostic of all three endpoints (all p ≤ 0.048) in the multivariate analysis. In addition, applying bioinformatic analysis, we also linked DHRS9 with unrevealed functions, such as keratan sulfate and mucin synthesis which may be implicated in CCRT resistance.Conclusion: Altogether, DHRS9 expression may serve as a helpful predictive and prognostic biomarker and assist decision-making for rectal cancer patients who underwent neoadjuvant CCRT.

For rectal cancer patients with stage T3-4 disease or positive lymph node, neoadjuvant concurrent chemoradiotherapy (CCRT) has become the standard treatment, but the clinical outcomes are still far from satisfactory. Accordingly, a more precise predictive tool such as genetic biomarkers is urgently required to optimize therapy decisions. Colorectal cancer (CRC) development has been considerably correlated with cellular metabolic process involving nucleotides, but the underlying molecular mechanisms remain unclear. In this study, we employed a transcriptome dataset comprising 46 rectal adenocarcinoma patients undergoing preoperative CCRT and focused on nucleobase-containing compound metabolic process (GO: 0055134) for data mining. We identified solute carrier family 28 member 2 (SLC28A2) as the most considerably upregulated gene among rectal cancer patients with CCRT resistance. Afterwards, there were a total of 172 rectal cancer tissue blocks procuring from our biobank, and the immunointensity of SLC28A2 was appraised utilizing immunohistochemical staining. Strong SLC28A2 immunointensity was significantly linked to female patients (p = 0.032), vascular invasion (p = 0.021), and post-CCRT tumor invasion and regional lymph node involvement (p < 0.001 and p = 0.005). Notably, patients with strong SLC28A2 immunointensity had no tumor downstaging (p < 0.001). Univariate analysis revealed that high SLC28A2 immunoexpression was considerably unfavorably linked to all three endpoints: local recurrence-free survival (LRFS), metastasis-free survival (MeFS), and disease-specific survival (DSS) (all p ≤ 0.0333). Moreover, both high SLC28A2 immunoexpression and low tumor regression grade were independently unfavorable prognostic factors for all three endpoints (all p ≤ 0.013) in the multivariate analysis. Utilizing function prediction analysis, SLC28A2 upregulation was more likely to be linked with stem cell homeostasis in rectal cancer. In brief, we demonstrated that high SLC28A2 immunoexpression is substantially linked to an advanced stage, poor response to CCRT, and worse patient survival. Consequently, SLC28A2 expression can be a valuable predictive and prognostic marker for rectal cancer patients and be an encouraging therapeutic target for those with CCRT resistance.

Despite neoadjuvant chemoradiotherapy (CRT) being the established standard for treating advanced rectal cancer, clinical outcomes remain suboptimal, necessitating the identification of predictive biomarkers for improved treatment decisions. Previous studies have hinted at the oncogenic properties of the Fc fragment of IgG binding protein (FCGBP) in various cancers; however, its clinical significance in rectal cancer remains unclear. In this study, we first conducted an analysis of a public transcriptome comprising 46 rectal cancer patients. Focusing on cell adhesion during data mining, we identified FCGBP as the most upregulated gene associated with CRT resistance. Subsequently, we assessed FCGBP immunointensity using immunohistochemical staining on 343 rectal cancer tissue blocks. Elevated FCGBP immunointensity correlated with lymph node involvement before treatment (p = 0.001), tumor invasion, and lymph node involvement after treatment (both p < 0.001), vascular invasion (p = 0.001), perineural invasion (p = 0.041), and reduced tumor regression (p < 0.001). Univariate analysis revealed a significant association between high FCGBP immunoexpression and inferior disease-specific survival, local recurrence-free survival, and metastasis-free survival (all p ≤ 0.0002). Furthermore, high FCGBP immunoexpression independently emerged as an unfavorable prognostic factor for all three survival outcomes in the multivariate analysis (all p ≤ 0.025). Enriched pathway analysis substantiated the role of FCGBP in conferring resistance to radiation. In summary, our findings suggest that elevated FCGBP immunoexpression in rectal cancer significantly correlates with a poor response to CRT and diminished patient survival. FCGBP holds promise as a valuable prognostic biomarker for rectal cancer patients undergoing CRT.