Analysis of the response of in vitro proliferating CLL patient cells to CK1 inhibition

Casein kinase 1 (CK1) has been proved as an efficient approach in the treatment of chronic lymphocytic leukemia (CLL), as this therapeutic strategy led to longer overall survival and scarcer relapse in Eµ-TCL1 adoptive transfer (AT) mouse model. In this study, we aimed to further characterize what mechanism makes CK1 inhibition efficient in counteracting the CLL progression. In particular, we performed bulk RNA sequencing on splenic CLL cells from in vivo treated Eµ-TCL1 AT mice which led us to a hypothesis that CK1 inhibition delays the cell cycle progression of the CLL cells by accumulation of cells at the S/G2 interface. To be able to test whether this mechanism might lead to actual attenuation of primary CLL cells, we utilized an established protocol that uses CD40L-expressing HS5 stromal cells in combination with soluble interleukin (IL-) 4 and IL-21 where we (at the same time) tested the efficacy of CK1 inhibition in suppression of the in vitro stimulated proliferation boost. This helped us to test intrinsic and microenvironmental aspect of the mechanism-of-action of the CK1 inhibition in one well. The provided data are a result of the 6 day in vitro co-culture of primary CLL cells with the CD40L+ HS5 stromal cells along with the treatment (for more information, see the protocol or the attached publications). We next gathered used multiple clinical parameters to further characterize the resistant group of sanples and correlate the response to the known clinical parameters. All samples from the peripheral blood of the CLL patients were taken after signature of informed consent approved by the Ethical Committee of the University Hospital Brno in accordance with the Declaration of Helsinki.