The Small-Molecule Inhibitor MRIA9 Reveals Novel Insights into the Cell Cycle Roles of SIK2 in Ovarian Cancer Cells

Abstract

The activity of the Salt inducible kinase 2 (SIK2), a member of the AMP-activated protein kinase (AMPK)-related kinase family, has been linked to several biological processes that maintain cellular and energetic homeostasis. SIK2 is overexpressed in several cancers, including ovarian cancer, where it promotes the proliferation of metastases. Furthermore, as a centrosome kinase, SIK2 has been shown to regulate the G2/M transition, and its depletion sensitizes ovarian cancer to paclitaxel-based chemotherapy. Here, we report the consequences of SIK2 inhibition on mitosis and synergies with paclitaxel in ovarian cancer using a novel and selective inhibitor, MRIA9. We show that MRIA9-induced inhibition of SIK2 blocks the centrosome disjunction, impairs the centrosome alignment, and causes spindle mispositioning during mitosis. Furthermore, the inhibition of SIK2 using MRIA9 increases chromosomal instability, revealing the role of SIK2 in maintaining genomic stability. Finally, MRIA9 treatment enhances the sensitivity to paclitaxel in 3D-spheroids derived from ovarian cancer cell lines and ovarian cancer patients. Our study suggests selective targeting of SIK2 in ovarian cancer as a therapeutic strategy for overcoming paclitaxel resistance.

Shifting the selectivity of pyrido[2,3-d]pyrimidin-7(8H)-one inhibitors towards the salt-inducible kinase (SIK) subfamily

“…We have recently demonstrated that SIK2 is responsible for cell-cycle progression, particularly the G2/M transition, through CEP250 phosphorylation at Ser2392, which is associated with centrosome cohesion [16,30]. In addition, SIK2 mediates mitotic spindle assembly, and its expression is cell-cycle dependent [16]. Further, chemical inhibition of SIK2 by MRIA9 ( 1 ) blocks centrosome disjunction in the late G2 phase [16].…”

“…Cell-cycle analysis was performed by incubation of the SKOV3 cells with all three compounds for 24 hours and examined by flow cytometry. We recently described the cell cycle-dependent expression of SIK2, with highest expression levels found in G1 and G2 phases [16]. Control cells were found to be almost evenly distributed between the cell-cycle phases G1, S, and G2, with 34%, 32%, and 24%, respectively.…”

“…The anti-proliferative effect of MRIA9-derived SIK2 inhibition was further investigated, revealing that MRIA9 triggered the uncoupling of the centrosomes from the nucleus during interphase and delayed the G2/M transition in SKOV3 cells by blocking the centrosome disjunction [16]. Moreover, MRIA9-dependent inhibition of SIK2 interfered with spindle assembly and orientation during mitosis, leading to aneuploidy, which promoted apoptosis [16]. The basic pyrido [2,3-d]pyrimidin-7(8H)-one scaffold of MRIA9 (1) has already been exploited for the development of multiple PAK inhibitors, including the lead structure G-5555 (2) [17][18][19][20].…”

“…Potent cellular on-target activity against SIK1-3 was found with IC 50 values of 516 ± 5 nM (SIK1), 180 ± 40 nM (SIK2), and 127 ± 23 nM (SIK3) (Figure 1) [15]. Combined treatment of ovarian cancer cells with MRIA9 ( 1 ) and the cytostatic drug paclitaxel resulted in a significant reduction in tumor cell growth compared with single agent treatment [16]. The anti-proliferative effect of MRIA9-derived SIK2 inhibition was further investigated, revealing that MRIA9 triggered the uncoupling of the centrosomes from the nucleus during interphase and delayed the G2/M transition in SKOV3 cells by blocking the centrosome disjunction [16].…”

“…Combined treatment of ovarian cancer cells with MRIA9 ( 1 ) and the cytostatic drug paclitaxel resulted in a significant reduction in tumor cell growth compared with single agent treatment [16]. The anti-proliferative effect of MRIA9-derived SIK2 inhibition was further investigated, revealing that MRIA9 triggered the uncoupling of the centrosomes from the nucleus during interphase and delayed the G2/M transition in SKOV3 cells by blocking the centrosome disjunction [16]. Moreover, MRIA9-dependent inhibition of SIK2 interfered with spindle assembly and orientation during mitosis, leading to aneuploidy, which promoted apoptosis [16].…”