# Spermidine and Eugenol Modulate Tight Junction and Stemness Markers in Colorectal Cancer Spheroids

## TL;DR

This study shows that spermidine and eugenol reduce the growth and stemness of colorectal cancer spheroids, with mixed effects on tight junction and stem cell markers at the RNA and protein levels.

## Contribution

The study introduces combined spermidine and eugenol treatment effects on 3D CRC spheroids, emphasizing the importance of multi-level molecular analysis.

## Key findings

- SPD+EUG reduced spheroid area and self-renewal in both Caco-2 and SW620 CRC models.
- Transcript and protein levels of TJ and CSC markers showed inconsistent changes, suggesting post-transcriptional regulation.
- 3D spheroid models proved valuable for evaluating bioactive compounds in CRC research.

## Abstract

Alterations in tight junction (TJ) organization and dysregulation of cancer stem cell (CSC)-associated markers are increasingly recognized as molecular features linked to colorectal cancer (CRC) progression, heterogeneity and clinical outcome. Bioactive dietary compounds such as spermidine (SPD) and eugenol (EUG) have been proposed as modulators of cancer-related molecular pathways; however, their combined effects on CRC spheroid models relevant to molecular characterization remain insufficiently defined. In the present study, the molecular impact of SPD and EUG, administered individually or in combination, was evaluated in primary and metastatic CRC spheroids. First-generation spheroids derived from Caco-2 and SW620 cells were exposed to SPD, EUG, or SPD+EUG at the time of seeding, and spheroid growth and self-renewal capacity were monitored across successive generations. The expression of TJ- and CSC-associated markers was assessed at both the transcript and protein levels using reverse transcription–quantitative polymerase chain reaction (RT-qPCR), Western blotting and immunohistochemistry. The combined SPD+EUG treatment was associated with a marked reduction in spheroid area and self-renewal capacity in both CRC models. Baseline molecular profiling revealed higher TJ marker expression in Caco-2 spheroids and enrichment of CSC-associated markers in SW620 spheroids. Treatment-induced modulation of CSC- and TJ-related transcripts was observed; however, transcript-level changes were not consistently mirrored at the protein level, indicating the involvement of post-transcriptional regulatory mechanisms. In particular, Occludin (OCLN), Zonula occludens-1 (ZO-1), CD133, ALDH1A1, SOX2 and VE-cadherin exhibited divergent RNA and protein expression patterns depending on cell type and treatment condition. Collectively, these findings underscore the relevance of three-dimensional CRC spheroid models for molecular profiling studies and highlight the importance of integrating transcript- and protein-level analyses when evaluating bioactive compounds with potential diagnostic and translational relevance in colorectal cancer.