Lysine Methyltransferase 9 (KMT9) Is an Actionable Target in Muscle-Invasive Bladder Cancer

Novel treatment modalities are imperative for the challenging management of muscle-invasive and metastatic BC to improve patient survival rates. The recently identified KMT9, an obligate heterodimer composed of KMT9α and KMT9β, regulates the growth of various types of tumors such as prostate, lung, and colon cancer. While the overexpression of KMT9α was previously observed to be associated with aggressive basal-like MIBC in an analysis of patients' tissue samples, a potential functional role of KMT9 in this type of cancer has not been investigated to date. In this study, we show that KMT9 regulates proliferation, migration, and invasion of various MIBC cell lines with different genetic mutations. KMT9α depletion results in the differential expression of genes regulating the cell cycle, cell adhesion, and migration. Differentially expressed genes include oncogenes such as EGFR and AKT1 as well as mediators of cell adhesion or migration such as DAG1 and ITGA6. Reduced cell proliferation upon KMT9α depletion is also observed in Pten/Trp53 knockout bladder tumor organoids, which cannot be rescued with an enzymatically inactive KMT9α mutant. In accordance with the idea that the catalytic activity of KMT9 is required for the control of cellular processes in MIBC, a recently developed small-molecule inhibitor of KMT9 (KMI169) also impairs cancer cell proliferation. Since KMT9α depletion also restricts the growth of xenografts in mice, our data suggest that KMT9 is an actionable novel therapeutic target for the treatment of MIBC.

Structure-guided design of a selective inhibitor of the methyltransferase KMT9 with cellular activity

Inhibition of epigenetic regulators by small molecules is an attractive strategy for cancer treatment. Recently, we characterised the role of lysine methyltransferase 9 (KMT9) in prostate, lung, and colon cancer. Our observation that the enzymatic activity was required for tumour cell proliferation identified KMT9 as a potential therapeutic target. Here, we report the development of a potent and selective KMT9 inhibitor (compound 4, KMI169) with cellular activity through structure-based drug design. KMI169 functions as a bi-substrate inhibitor targeting the SAM and substrate binding pockets of KMT9 and exhibits high potency, selectivity, and cellular target engagement. KMT9 inhibition selectively downregulates target genes involved in cell cycle regulation and impairs proliferation of tumours cells including castration- and enzalutamide-resistant prostate cancer cells. KMI169 represents a valuable tool to probe cellular KMT9 functions and paves the way for the development of clinical candidate inhibitors as therapeutic options to treat malignancies such as therapy-resistant prostate cancer.

Development of a NanoBRET assay to validate dual inhibitors of Sirt2-mediated lysine deacetylation and defatty-acylation that block prostate cancer cell migration

Sirtuin2 (Sirt2) with its NAD⁺-dependent deacetylase and defatty-acylase activities plays a central role in the regulation of specific cellular functions. Dysregulation of Sirt2 activity has been associated with the pathogenesis of many diseases, thus making Sirt2 a promising target for pharmaceutical intervention. Herein, we present new high affinity Sirt2 selective Sirtuin-Rearranging Ligands (SirReals) that inhibit both Sirt2-dependent deacetylation and defatty-acylation in vitro and in cells. We show that simultaneous inhibition of both Sirt2 activities results in strongly reduced levels of the oncoprotein c-Myc and an inhibition of cancer cell migration. Furthermore, we describe the development of a NanoBRET-based assay for Sirt2, thereby providing a method to study cellular target engagement for Sirt2 in a straightforward and accurately quantifiable manner. Applying this assay, we could confirm cellular Sirt2 binding of our new Sirt2 inhibitors and correlate their anticancer effects with their cellular target engagement.

Sirt2 inhibitors that show simultaneous inhibition of Sirt2 deacetylase and defatty-acylase activity block prostate cancer cell migration and their target engagement is shown by a newly developed NanoBRET assay.

Cognition and cerebrovascular function in primary hyperparathyroidism before and after parathyroidectomy

PURPOSE

There are cognitive changes in primary hyperparathyroidism (PHPT) that improve with parathyroidectomy, but the mechanism of cognitive dysfunction has not been delineated. We assessed if cerebrovascular function is impaired in PHPT, improves post-parathyroidectomy and is associated with PTH level and cognitive dysfunction.

METHODS

This is an observational study of 43 patients with mild hypercalcemic or normocalcemic PHPT or goiter. At baseline, cerebrovascular function (dynamic cerebral autoregulation and vasomotor reactivity) by transcranial Doppler and neuropsychological function were compared between all three groups. A subset underwent parathyroidectomy or thyroidectomy, and was compared 6 months post-operatively.

RESULTS

Mean cerebrovascular and neuropsychological function was normal and no worse in PHPT compared to controls preoperatively. Higher PTH was associated with worse intracerebral autoregulation (r = - 0.43, p = 0.02) and worse cognitive performance on some tests. Post-parathyroidectomy, mood improved significantly, but changes did not differ compared to those having thyroidectomy (p = 0.84). There was no consistent improvement in cognition or change in vascular function in either surgical group.

CONCLUSIONS

Although higher PTH was associated with worse intracerebral autoregulation, cerebrovascular function, cognition and mood were normal in mild PHPT. PTX did not improve vascular or cognitive function. The observed improvement in mood cannot be clearly attributed to PTX. Notwithstanding the small sample size, the results do not support changing current criteria for parathyroidectomy to include cognitive complaints. However, the associations between PTH, cognition and cerebral autoregulation merit future studies in those with more severe hyperparathyroidism.

NMR studies of a novel calcium, phosphate and fluoride delivery vehicle-αS1-casein(59–79) by stabilized amorphous calcium fluoride phosphate nanocomplexes

The repair of early tooth enamel lesions has been recently demonstrated by tryptic phosphopeptides derived from milk caseins that associate with amorphous calcium phosphate (ACP) forming stable complexes. These casein phosphopeptides (CPP), containing the cluster sequence-Ser(P)-Ser(P)-Ser(P)-Glu-Glu-, form calcium phosphate delivery vehicles that retard enamel demineralization and promote remineralization. Recently, we have shown that these peptides also stabilize calcium fluoride phosphate as soluble complexes. These complexes designated CPP-ACFP, have the potential to provide superior clinical efficacy in preventing dental caries and treating and repairing early stages of disease. In an approach to determine the ultrastructure of the casein phosphopeptide-amorphous calcium fluoride phosphate complexes, we have studied the structure of the predominant peptide alpha(S1)-CN(59-79) bound to ACFP using nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction. The alpha(S1)-CN(59-79) peptide stabilized calcium fluoride phosphate as amorphous nanocomplexes with a hydrodynamic radius of 2.12+/-0.26 nm. The nanocomplexes exhibited stoichiometry of one peptide to 15 calcium, nine phosphate and three fluoride ions. Sequence-specific resonance assignments were determined for the peptide alpha(S1)-CN(59-79) complexed to the ACFP. The secondary structure of the peptide alpha(S1)-CN(59-79) was characterized by sequential (i, i+1), medium-range (i, i+2) nOes and H alpha chemical shifts. The spectral data were compared with that of the peptide alpha(S1)-CN(59-79) bound to calcium ions, revealing that the structurally significant secondary NH and alpha-chemical shifts were similar.

Modular subdivisions of dolphin insular cortex: does evolutionary history repeat itself?

The structural organization of the insular cortex in the bottlenose dolphin was investigated by examining Nissl- and myelin-stained tissue that was sectioned coronally and tangentially. An uneven distribution of cell clusters that coincided with myelin-light zones was observed in layer II. When the present observations were compared to descriptions of modules in other animals, we found that the range of module size is restricted, while the size of the brain, particularly the neocortex, varies dramatically. Indeed, despite the tremendous expansion of the cetacean neocortex, the size of the modules in the insular cortex is similar to that described for small-brained mammals like the mouse, suggesting that module size is evolutionarily stable across species. Selection for optimal-size processing units, in terms of the lengths of connections within and between them, is a likely source of this stability.