(P26-048-25) Impact of Flavonoids on the Therapeutic Efficacy of Chemotherapeutics on 3D Bioprinted Colorectal Cells

Objectives: Colorectal cancer (CRC) is the second leading cause of all cancer-related deaths worldwide. Its increasing incidence, chemotherapy resistance and the hypoxic tumor environment require further research to avoid the lack of drug response. 3D bioprinted models represent reliable platforms for drug testing including natural products.

The soy isoflavone daidzein is a precursor of equol which exhibits estrogen-like activity and has an anti-inflammatory potential. Because of its lipophilic structure and high bioavailability, equol is associated with higher anticancer activity then its precursor. There are no published reports so far on the effect of Equol on 3D bioprinted CRC models.

Methods:

Aim: To investigate the efficacy of therapeutic regimens consisting of the standart chemotherapeutic (5-FU), Equol, and of both substances in combination, on 3D bioprinted HCT-116 CRC cells under normoxic and hypoxic conditions.

The HCT-116 CRC cell line was grown as 2D and 3D cultures, each of them in conditions of normoxia and hypoxia. The cells were 3D bioprinted and the spheroids were cultured for 10 days. Drug testing was carried out from day 10 to day 13. The MTT assay was used to determine IC50 values. The IC50 concentration for 5FU was 5,5 µM and for Equol it was 19,28 µg/mL. Additionally, fluorescence assessment of cell viability was performed. All results were compared to untreated control cells.

Results: HCT-116 cells were treated with 5FU - 5,5µM, Equol - 19,28µg/mL, and with a combination of both substances under normoxic and hypoxic conditions. A higher inhibitory effect of Equol and 5-FU in hypoxia was detected for both 2D and 3D cultures compared to normoxia. When a combination ot 5-FU +Equol was applied on hypoxic 3D cultures, the additive effect of Equol in terms of inhibition of cell proliferation was more pronounced. The results of MTT test were confirmed by fluorescence analysis of cell viability.

Conclusions: In conclusion, our data demonstrate that the application of Equol in combination with 5-FU results in higher cytotoxicity on 3D CRC cell models and gives grounds for subsequent tailoring of anticancer treatment regimens.

Therefore, Equol has the potential to be employed as an alternative supplement in the adjuvant therapy of CRC.

Funding Sources: Acknowledgments: to  the Ministry of Education and Science of the Republic of Bulgaria. Project Д01-165/28.07.2022.