Targeting the DYRK1A kinase prevents cancer progression and metastasis and promotes cancer cells response to G1/S targeting chemotherapy drugs.

Metastatic cancer remains incurable as patients eventually loose sensitivity to targeted therapies and chemotherapies, further leading to poor clinical outcome. Thus, there is a clear medical gap and urgent need to develop efficient and improved targeted therapies for cancer patients. In this study, we investigated the role of DYRK1A kinase in regulating cancer progression and evaluated the therapeutic potential of DYRK1A inhibition in invasive solid tumors, including colon and triple-negative breast cancers. We uncovered new roles played by the DYRK1A kinase. We found that blocking DYRK1A gene expression or pharmacological inhibition of its kinase activity via harmine efficiently blocked primary tumor formation and the metastatic tumor spread in preclinical models of breast and colon cancers. Further assessing the underlying molecular mechanisms, we found that DYRK1A inhibition resulted in increased expression of the G1/S cell cycle regulators while decreasing expression of the G2/M regulators. Combined, these effects release cancer cells from quiescence, leading to their accumulation in G1/S and further delaying/preventing their progression toward G2/M, ultimately leading to growth arrest and tumor growth inhibition. Furthermore, we show that accumulation of cancer cells in G1/S upon DYRK1A inhibition led to significant potentiation of G1/S targeting chemotherapy drug responses in vitro and in vivo. This study underscores the potential for developing novel DYRK1A-targeting therapies in colon and breast cancers and, at the same time, further defines DYRK1A pharmacological inhibition as a viable and powerful combinatorial treatment approach for improving G1/S targeting chemotherapy drugs treatments in solid tumors.