Evaluation of Galanin Expression in Colorectal Cancer: An Immunohistochemical and Transcriptomic Study

Abstract

Colorectal cancer (CRC) represents around 10% of all cancers, with an increasing incidence in the younger age group. The gut is considered a unique organ with its distinctive neuronal supply. The neuropeptide, human galanin, is widely distributed in the colon and expressed in many cancers, including the CRC. The current study aimed to explore the role of galanin at different stages of CRC. Eighty-one CRC cases (TNM stages I – IV) were recruited, and formalin-fixed paraffin-embedded samples were analyzed for the expression of galanin and galanin receptor 1 (GALR1) by immunohistochemistry (IHC). Galanin intensity was significantly lower in stage IV (n= 6) in comparison to other stages (p= 0.037 using the Mann-Whitney U test). Whole transcriptomics analysis using NGS was performed for selected samples based on the galanin expression by IHC [early (n=5) with high galanin expression and late (n=6) with low galanin expression]. Five differentially regulated pathways (using Absolute GSEA) were identified as drivers for tumor progression and associated with higher galanin expression, namely, cell cycle, cell division, autophagy, transcriptional regulation of TP53, and immune system process. The top shared genes among the upregulated pathways are AURKA, BIRC5, CCNA1, CCNA2, CDC25C, CDK2, CDK6, EREG, LIG3, PIN1, TGFB1, TPX2. The results were validated using real-time PCR carried out on four cell lines [two primaries (HCT116 and HT29) and two metastatic (LoVo and SK-Co-1)]. The current study shows galanin as a potential negative biomarker. Galanin downregulation is correlated with advanced CRC staging and linked to cell cycle and division, autophagy, transcriptional regulation of TP53 and immune system response.

The Galaninergic System: A Target for Cancer Treatment

“…The data show that the expression of GAL is related to CRC aggressive behavior and it seems that CRC cells showing a high GAL expression are more malignant and are also involved in the recurrence of the tumor [ 180 ]. However, a recent study has shown that GAL downregulation is correlated with advanced CRC stages in northern African individuals and it is linked to autophagy, cell cycle and division, immune system response and the transcriptional regulation of TP53 [ 183 ]. Compared to epithelial cells of the large intestine, a stronger immunoreactivity for GAL 1 R/GAL 3 R was observed in CRC cells and it has been reported that the high expression of GAL 3 R in CRC tissue was associated with a better prognosis and longer survival of CRC patients; this means that GAL 3 R is a prognostic factor for these patients [ 184 ].…”

Integrating Transcriptomics and Metabolomics to Explore the Novel Pathway of Fusobacterium nucleatum Invading Colon Cancer Cells

“…We found that differentially expressed mRNAs are involved in positive regulation of the cell proliferation process. Upregulated genes such as DHRS2, ID2 [ 32 ], CCNA1 [ 33 ], EGR2 [ 34 ], WNT4 [ 35 ], RIPK4 [ 36 ], PDK4 [ 37 ], IL-11 [ 38 ], and MAPK4 play a role in promoting the development of colon cancer and various malignancies [ 39 ]. IL-16 plays a role in promoting cellular inflammation [ 40 ]; BCl-6 plays a role in inhibiting apoptosis in colon cancer cells [ 41 ]; and NFKBIZ plays a role in promoting the expression of the IL-17 inflammatory signaling pathway [ 42 ].…”

Elucidation of the mechanism of action of ailanthone in the treatment of colorectal cancer: integration of network pharmacology, bioinformatics analysis and experimental validation

“…The inhibition of CCNB1 expression has also been reported to inactivate PI3K/AKT signaling and induce G2/M arrest ( Meng et al, 2023 ). Moreover, elevated CCNA1 and CCNA2 expression levels activates the PI3K/AKT pathway, promoting tumor growth and cell survival ( Talaat et al, 2022 ). MCM5 is a chromatin-binding protein that serves as a diagnostic marker for CRC, regulating tumor cell proliferation and cell cycle progression ( Dai et al, 2017 ; Huang et al, 2018 ).…”