MASTL is enriched in cancerous and pluripotent stem cells and influences OCT1/OCT4 levels

First-in-class dual inhibitors of MASTL and Aurora A kinase: Discovery of selective cyclohexa[b]thiophenes with potent anticancer activity

The dysregulation of mitotic kinases, particularly Microtubule Associated Serine/Threonine Kinase Like (MASTL) and Aurora A kinase, play pivotal roles in tumor progression and resistance to therapy. Herein, we report cyclohexa[b]thiophenes as first-in-class dual inhibitors of MASTL and Aurora A kinase. The lead compound, MA4, demonstrated potent inhibition of both kinases with IC50 values of 0.16 ± 0.01 μM for Aurora A and 0.56 ± 0.16 μM for MASTL. Kinase selectivity profiling against a panel of 277 kinases revealed a high degree of specificity against both targets. In vitro antiproliferative screening using the NCI-60 human cancer cell line panel revealed broad-spectrum cytotoxicity, with MA4 exhibiting submicromolar GI50 values across multiple malignancies, outperforming previously reported cyclohexa[b]thiophenes in the multidose screening. Mechanistic studies, including microscale thermophoresis (MST) and NanoBRET target engagement assays, confirmed direct binding to both kinases. Computational studies, including molecular docking and molecular dynamics simulations, revealed key interactions stabilizing MA4 within the ATP-binding sites of both kinases. We demonstrated the potent anticancer activity of MA4 in 3D tumor spheroids, along with its favorable pharmacokinetic profile. Additionally, MA4 exhibited no inhibitory activity against hERG and demonstrated selectivity toward cancer cells over normal cell lines, further supporting its potential for in vivo applications. These findings establish cyclohexa[b]thiophenes as promising dual kinase inhibitors with high selectivity, offering a compelling strategy for targeting mitotic dysregulation in cancer therapy.

Targeted inhibition of MASTL kinase activity induces apoptosis in breast cancer

Microtubule-associated serine/threonine kinase-like (MASTL) (or Greatwall kinase (GWL)) is an important cell cycle regulating kinase that regulates the G2-M transition. Uncontrolled MASTL activity is implicated in breast cancer progression. To date, very few inhibitors have been reported against this protein. Here, structure-based computational modeling indicates that the natural product flavopiridol (FLV) binds strongly to MASTL and these results are validated using molecular dynamics simulation studies. An in vitro kinase assay reveals an EC50 (effective concentration) value of FLV to be 82.1 nM and a better IC50 compared to the positive reference compound, staurosporine. FLV is found to inhibit MASTL kinase activity, arresting the cell growth in the G1 phase and inducing apoptosis in breast cancer cells. Consistent with these results differential gene expression obtained using RNA sequencing studies, and validated by RT PCR and immunoblot analysis, indicate that MASTL inhibition induces cell cycle arrest and apoptotic-related genes. Furthermore, metastasis- and inflammation-related genes are downregulated. Thus, the deregulation of MASTL signaling pathways on targeted inhibition of its kinase activity is revealed. This study lays a strong foundation for investigating FLV as a lead compound in breast cancer therapeutics.

Molecular Mechanisms Underlying Pluripotency and Self-Renewal of Embryonic Stem Cells

Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of the blastocyst. ESCs have two distinctive properties: ability to proliferate indefinitely, a feature referred as "self-renewal", and to differentiate into different cell types, a peculiar characteristic known as "pluripotency". Self-renewal and pluripotency of ESCs are finely orchestrated by precise external and internal networks including epigenetic modifications, transcription factors, signaling pathways, and histone modifications. In this systematic review, we examine the main molecular mechanisms that sustain self-renewal and pluripotency in both murine and human ESCs. Moreover, we discuss the latest literature on human naïve pluripotency.