Targeting the survival kinase DYRK1B: A novel approach to overcome radiotherapy-related treatment resistance

Background: Cancer cell survival under stress conditions is a prerequisite for the development of treatment resistance. The survival kinase DYRK1B is a key regulator of stress survival pathways and might thereby also contribute to radiation resistance. Here we investigate the strategy of targeting DYRK1B in combination with ionizing radiation (IR) to enhance tumor cell killing under stress conditions.

Methods: DYRK1B expression, ROS formation and DNA damage were investigated under serum-starvation (0.1% FBS), hypoxia (0.2%, 1% O2) and IR. The combined treatment modality of IR and DYRK1B inhibition was investigated in 2D and in spheroids derived from the colorectal cancer cell line SW620, and in primary patient-derived colorectal carcinoma (CRC) organoids.

Results: Expression of DYRK1B was upregulated under starvation and hypoxia, but not in response to IR. The small molecule DYRK1B inhibitor AZ191 and shRNA-mediated DYRK1B knockdown significantly reduced proliferative activity and clonogenicity of SW620 tumor cells alone and in combination with IR under serum-starved conditions, which correlated with increased ROS levels and DNA damage. Furthermore, AZ191 successfully targeted the hypoxic core of tumor spheroids while IR preferentially targeted normoxic cells in the rim of the spheroids. A combined treatment effect was also observed in CRC-organoids but not in healthy tissue-derived organoids.

Conclusion: Combined treatment with the DYRK1B inhibitor AZ191 and IR resulted in (supra-) additive tumor cell killing in colorectal tumor cell systems and in primary CRC organoids. Mechanistic investigations support the rational to target the stress-enhanced survival kinase DYRK1B in combination with irradiation to overcome hypoxia- and starvation-induced treatment resistances.

 

Comments:

This study delves into targeting the survival kinase DYRK1B in conjunction with ionizing radiation (IR) to potentially boost tumor cell elimination under stressful conditions like serum-starvation and hypoxia. DYRK1B's increased expression under these stressors hints at its role in aiding cancer cells to survive these harsh environments and potentially develop resistance to treatment.

The methods employed examined DYRK1B expression, generation of reactive oxygen species (ROS), DNA damage, and the impact of inhibiting DYRK1B in combination with IR on various cancer cell models. These models included 2D cultures, spheroids derived from a colorectal cancer cell line, SW620, and primary patient-derived colorectal carcinoma (CRC) organoids.

The results demonstrated that DYRK1B expression escalated under serum-starvation and hypoxia but not in response to IR. However, inhibiting DYRK1B, either through the AZ191 inhibitor or shRNA-mediated knockdown, significantly reduced the proliferative capacity and clonogenicity of SW620 cells. This reduction was observed both individually and in combination with IR under serum-starved conditions, concomitant with heightened ROS levels and DNA damage.

Moreover, the study noted that AZ191 effectively targeted the hypoxic core of tumor spheroids, while IR primarily targeted normoxic cells on the spheroid periphery. The combined treatment exhibited an enhanced effect in CRC organoids but not in healthy tissue-derived organoids.

In conclusion, the combined approach of utilizing the DYRK1B inhibitor AZ191 with IR displayed a (supra-) additive effect in eliminating colorectal tumor cells and primary CRC organoids. These findings suggest a promising strategy to combat treatment resistances induced by stress conditions like hypoxia and starvation by targeting DYRK1B alongside irradiation.

Related Products

Cat.No.	Product Name	Information
S7338	AZ191	AZ191 is a potent and selective DYRK1B inhibitor with IC50 of 17 nM in a cell-free assay, about 5- and 110-fold selectivity over DYRK1A and DYRK2, respectively.

Related Targets

DYRK