CK2 modulates adipocyte insulin-signaling and is up-regulated in human obesity

The dual targeting effects of KD025 on casein kinase 2 and ROCK2 in a mouse model of diet-induced obesity

KD025(belumosudil), a selective ROCK2 inhibitor, exhibits unique anti-adipogenic activity through inhibition of casein kinase 2 (CK2). This study investigated the dual inhibitory effects of KD025 on metabolism in a diet-induced obese model. C57BL/6 mice on a high fat diet (HFD) were treated with KD025 for 4 weeks, while fasudil (a pan-ROCK inhibitor) and CX-4945 (a CK2-specific inhibitor) served as comparison treatments. KD025 significantly reduced body weight gain without affecting food intake, serum insulin, or fasting blood glucose levels. In contrast, while both CX-4945 and fasudil treatments showed a trend toward weight reduction, these results were not statistically significant. KD025 improved lipid metabolism by significantly lowering LDL cholesterol and triglyceride, although it slightly impaired glucose metabolism, as observed in insulin and glucose tolerance tests. Weight reduction in the KD025- and CX-4945-treated groups was attributed to decreased adipose tissue mass, particularly in inguinal (ingWAT) and epididymal (epiWAT) fat depots. Hematoxylin and eosin (H&E) staining confirmed smaller adipocyte size in these groups. KD025 had no significant effect on serum levels of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), or monocyte chemoattractant protein-1 (MCP-1) with varied inflammatory responses. Furthermore, KD025 and CX-4945 upregulated adipogenic and browning markers, such as Cebpa, Cidea, and Pparg in the epiWAT, though without significant UCP1 expression. Overall, KD025 effectively reduced weight gain in HFD-fed mice through dual inhibition of CK2 and ROCK2, highlighting its potential as a therapeutic agent for obesity-related conditions.

Body weight control via protein kinase CK2: diet-induced obesity counteracted by pharmacological targeting

BACKGROUND

Protein kinase CK2 is a highly conserved enzyme implicated in the pathogenesis of various human illnesses including obesity. Despite compelling evidence for the involvement of this kinase in the pathophysiology of obesity, the molecular mechanisms by which CK2 might regulate fat metabolism are still poorly understood.

METHODS AND RESULTS

In this study, we aimed to elucidate the role of CK2 on lipid metabolism by employing both in vitro and in vivo approaches using mouse pre-adipocytes and a mouse model of diet-induced obesity. We show that pharmacological inhibition of CK2 by CX-4945 results in premature upregulation of p27KIP1 preventing the progression of cells into mature adipocytes by arresting their development at the intermediate phase of adipogenic differentiation. Consistent with this, we show that in vivo, CK2 regulates the expression levels and ERK-mediated phosphorylation of C/EBPβ, which is one of the earliest transcription factors responsive to adipogenic stimuli. Furthermore, we demonstrate the functional implication of CK2 in the expression of late markers of adipogenesis and factors regulating lipogenesis in liver and white adipose tissue. Finally, we show that while mice subjected to high-fat diet increased their body weight, those additionally treated with CX-4945 gained considerably less weight. NMR-based body composition analysis revealed that this is linked to significant differences in body fat mass.

CONCLUSIONS

Taken together, our study provides novel insights into the role of CK2 in fat metabolism in response to chronic lipid overload and confirms CK2 pharmacological targeting as a potentially powerful strategy for body weight control and/or the treatment of obesity and related metabolic disorders.

Protein kinase CK2 sustains de novo fatty acid synthesis by regulating the expression of SCD-1 in human renal cancer cells

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is a type of cancer characterized by a vast intracellular accumulation of lipids that are critical to sustain growth and viability of the cells in the tumour microenvironment. Stearoyl-CoA 9-desaturase 1 (SCD-1) is an essential enzyme for the synthesis of monounsaturated fatty acids and consistently overexpressed in all stages of ccRCC growth.

METHODS

Human clear cell renal cell carcinoma lines were treated with small-molecule inhibitors of protein kinase CK2. Effects on the expression levels of SCD-1 were investigated by RNA-sequencing, RT-qPCR, Western blot, and in vivo studies in mice. Phase-contrast microscopy, fluorescence microscopy, flow cytometry, and MALDI-mass spectrometry analysis were carried out to study the effects on endogenous lipid accumulation, induction of endoplasmic reticulum stress, rescue effects induced by exogenous MUFAs, and the identity of lipid populations. Cell proliferation and survival were investigated in real time employing the Incucyte® live-cell analysis system. Statistical significance was determined by applying the two-tailed Student's t test when comparing two groups of data whereas the two-way ANOVA, multiple Tukey's test was employed for multiple comparisons.

RESULTS

Here, we show that protein kinase CK2 is critical for preserving the expression of SCD-1 in ccRCC lines maintained in culture and heterotransplanted into nude mice. Consistent with this, pharmacological inhibition of CK2 leads to induction of endoplasmic reticulum stress linked to unfolded protein response activation and decreased proliferation of the cells. Both effects could be reversed by supplementing the growth medium with oleic acid indicating that these effects are specifically caused by reduced expression of SCD-1. Analysis of lipid composition by MALDI-mass spectrometry revealed that inhibition of CK2 results in a significant accumulation of the saturated palmitic- and stearic acids.

CONCLUSIONS

Collectively, our results revealed a previously unidentified molecular mechanism regulating the synthesis of monounsaturated fatty acids corroborating the notion that novel therapeutic approaches that include CK2 targeting, may offer a greater synergistic anti-tumour effect for cancers that are highly dependent on fatty acid metabolism.

MOTS-c modulates skeletal muscle function by directly binding and activating CK2

MOTS-c is a mitochondrial microprotein that improves metabolism. Here, we demonstrate CK2 is a direct and functional target of MOTS-c. MOTS-c directly binds to CK2 and activates it in cell-free systems. MOTS-c administration to mice prevented skeletal muscle atrophy and enhanced muscle glucose uptake, which were blunted by suppressing CK2 activity. Interestingly, the effects of MOTS-c are tissue-specific. Systemically administered MOTS-c binds to CK2 in fat and muscle, yet stimulates CK2 activity in muscle while suppressing it in fat by differentially modifying CK2-interacting proteins. Notably, a naturally occurring MOTS-c variant, K14Q MOTS-c, has reduced binding to CK2 and does not activate it or elicit its effects. Male K14Q MOTS-c carriers exhibited a higher risk of sarcopenia and type 2 diabetes (T2D) in an age- and physical-activity-dependent manner, whereas females had an age-specific reduced risk of T2D. Altogether, these findings provide evidence that CK2 is required for MOTS-c effects.

European Association for the Study of Obesity (EASO) Position Statement on Medical Nutrition Therapy for the Management of Individuals with Overweight or Obesity and Cancer

Obesity, a prevalent and multifactorial disease, is linked to a range of metabolic abnormalities, including insulin resistance, dyslipidemia, and chronic inflammation. These imbalances not only contribute to cardiometabolic diseases but also play a significant role in cancer pathogenesis. The rising prevalence of obesity underscores the need to investigate dietary strategies for effective weight management for individuals with overweight or obesity and cancer. This European Society for the Study of Obesity (EASO) position statement aimed to summarize current evidence on the role of obesity in cancer and to provide insights on the major nutritional interventions, including the Mediterranean diet (MedDiet), the ketogenic diet (KD), and the intermittent fasting (IF), that should be adopted to manage individuals with overweight or obesity and cancer. The MedDiet, characterized by high consumption of plant-based foods and moderate intake of olive oil, fish, and nuts, has been associated with a reduced cancer risk. The KD and the IF are emerging dietary interventions with potential benefits for weight loss and metabolic health. KD, by inducing ketosis, and IF, through periodic fasting cycles, may offer anticancer effects by modifying tumor metabolism and improving insulin sensitivity. Despite the promising results, current evidence on these dietary approaches in cancer management in individuals with overweight or obesity is limited and inconsistent, with challenges including variability in adherence and the need for personalized dietary plans.

Can Bone Morphogenetic Protein 1 (BMP1) Be a Potential Biomarker of Obesity?

Background Obesity has long been a severe threat to public health as an epidemic, and studies on its pathogenesis and treatment have been ongoing. Our study aims to compare the serum levels of bone morphogenetic protein 1 (BMP1), neuregulin 4 (NRG4), and apolipoprotein A5 (ApoA5) in obese and non-obese individuals and investigate their association with obesity. Methodology Our study included a total of 111 participants, of whom 46 were obese (body mass index (BMI) ≥30 kg/m2), aged 18-65 years, and had no comorbidities, and 65 were non-obese (BMI = 18.5-29.9 kg/m2) without any additional disease. For all participants, BMP1, NRG4, and ApoA5 levels were determined and compared with clinical and biochemical parameters. Results Overall, 60.4% (n = 67) of the participants were female and 39.6% (n = 44) were male. In terms of the BMI scores, 58.6% (n = 65) had a BMI <30 kg/m2 and 41.4% (n = 46) had a BMI ≥30 kg/m2. Both, the BMI and the gender groups did not differ significantly in terms of age (p = 0.093 and p = 0.795, respectively). The weight, fat-free mass, mineral quantity, protein quantity, fluid weight, and fluid ratio values of the male participants were significantly higher than females (p = 0.011, p = 0.001, p = 0.001, p = 0.001, p = 0.001, and p = 0.001, respectively). The aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratios and the triglyceride/glucose (TG/Glu) ratios were found to be significantly higher in males than in females (p = 0.001 and p = 0.001, respectively). The respective BMP1 (15.88 vs. 13.35), AST/ALT (1.36 vs. 1.04) and TG/Glu ratios (1.47 vs. 1.29) were significantly higher, while the quantitative insulin sensitivity check index (QUICKI) was lower in obese individuals than in non-obese individuals (0.32 vs. 0.34). NRG4 and ApoA5 values were similar between the two groups. BMP1, QUICKI values, and AST/ALT ratios proved to be statistically significant in obesity through the univariable logistic regression analysis (β = 1.066, p = 0.048; β = 0.0001, p = 0.001, and β = 3.707, p = 0.003, respectively). On multiple logistic regression analysis, QUICKI values (β = 0.001, p = 0.001) had a negative and significant effect on obesity, and the AST/ALT ratios (β = 2.803, p = 0.033) had a positive and significant effect on obesity. Conclusions Our study indicates that detecting an important link between BMP1 in obese patients will help elucidate the pathogenesis of obesity and come up with a potential therapeutic candidate. BMP1 levels, along with AST/ALT and TG/Glu ratios, were significantly higher in obese patients. BMP1 levels were also an independent significant predictor of obesity together with AST/ALT ratio and QUICKI in this study, suggesting that it may exhibit a metabolic deterioration in obese individuals. However, the results cannot absolutely tell whether it supported deterioration or was a component of the repair mechanism. Althoughit is generally known from recent studies that BMP1 plays a role in osteogenesis, some encouraging results were obtained in our study indicating that BMP1 may play a role in the pathogenesis of obesity. It is expected that our results will not only promote the elucidation of the pathogenesis of obesity, but also provide a therapeutic agent.

Unraveling the rationale and conducting a comprehensive assessment of KD025 (Belumosudil) as a candidate drug for inhibiting adipogenic differentiation-a systematic review

Rho-associated kinases (ROCKs) are crucial during the adipocyte differentiation process. KD025 (Belumosudil) is a newly developed inhibitor that selectively targets ROCK2. It has exhibited consistent efficacy in impeding adipogenesis across a spectrum of in vitro models of adipogenic differentiation. Given the novelty of this treatment, a comprehensive systematic review has not been conducted yet. This systematic review aims to fill this knowledge void by providing readers with an extensive examination of the rationale behind KD025 and its impacts on adipogenesis. Preclinical evidence was gathered owing to the absence of clinical trials. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, and the study's quality was assessed using the Joanna Briggs Institute (JBI) Checklist Critical Appraisal Tool for Systematic Reviews. In various in vitro models, such as 3T3-L1 cells, human orbital fibroblasts, and human adipose-derived stem cells, KD025 demonstrated potent anti-adipogenic actions. At a molecular level, KD025 had significant effects, including decreasing fibronectin (Fn) expression, inhibiting ROCK2 and CK2 activity, suppressing lipid droplet formation, and reducing the expression of proadipogenic genes peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα). Additionally, KD025 resulted in the suppression of fatty acid-binding protein 4 (FABP4 or AP2) expression, a decrease in sterol regulatory element binding protein 1c (SREBP-1c) and Glut-4 expression. Emphasis must be placed on the fact that while KD025 shows potential in preclinical studies and experimental models, extensive research is crucial to assess its efficacy, safety, and potential therapeutic applications thoroughly and directly in human subjects.

Protein Kinase CK2α', More than a Backup of CK2α

The serine/threonine protein kinase CK2 is implicated in the regulation of fundamental processes in eukaryotic cells. CK2 consists of two catalytic α or α' isoforms and two regulatory CK2β subunits. These three proteins exist in a free form, bound to other cellular proteins, as tetrameric holoenzymes composed of CK2α2/β2, CK2αα'/β2, or CK2α'2/β2 as well as in higher molecular forms of the tetramers. The catalytic domains of CK2α and CK2α' share a 90% identity. As CK2α contains a unique C-terminal sequence. Both proteins function as protein kinases. These properties raised the question of whether both isoforms are just backups of each other or whether they are regulated differently and may then function in an isoform-specific manner. The present review provides observations that the regulation of both CK2α isoforms is partly different concerning the subcellular localization, post-translational modifications, and aggregation. Up to now, there are only a few isoform-specific cellular binding partners. The expression of both CK2α isoforms seems to vary in different cell lines, in tissues, in the cell cycle, and with differentiation. There are different reports about the expression and the functions of the CK2α isoforms in tumor cells and tissues. In many cases, a cell-type-specific expression and function is known, which raises the question about cell-specific regulators of both isoforms. Another future challenge is the identification or design of CK2α'-specific inhibitors.

Obesity, the Adipose Organ and Cancer in Humans: Association or Causation?

Epidemiological observations, experimental studies and clinical data show that obesity is associated with a higher risk of developing different types of cancer; however, proof of a cause-effect relationship that meets the causality criteria is still lacking. Several data suggest that the adipose organ could be the protagonist in this crosstalk. In particular, the adipose tissue (AT) alterations occurring in obesity parallel some tumour behaviours, such as their theoretically unlimited expandability, infiltration capacity, angiogenesis regulation, local and systemic inflammation and changes to the immunometabolism and secretome. Moreover, AT and cancer share similar morpho-functional units which regulate tissue expansion: the adiponiche and tumour-niche, respectively. Through direct and indirect interactions involving different cellular types and molecular mechanisms, the obesity-altered adiponiche contributes to cancer development, progression, metastasis and chemoresistance. Moreover, modifications to the gut microbiome and circadian rhythm disruption also play important roles. Clinical studies clearly demonstrate that weight loss is associated with a decreased risk of developing obesity-related cancers, matching the reverse-causality criteria and providing a causality correlation between the two variables. Here, we provide an overview of the methodological, epidemiological and pathophysiological aspects, with a special focus on clinical implications for cancer risk and prognosis and potential therapeutic interventions.

Hyperphosphorylation of hepatic proteome characterizes nonalcoholic fatty liver disease in S-adenosylmethionine deficiency

Methionine adenosyltransferase 1a (MAT1A) is responsible for hepatic S-adenosyl-L-methionine (SAMe) biosynthesis. Mat1a ^-/- mice have hepatic SAMe depletion, develop nonalcoholic steatohepatitis (NASH) which is reversed with SAMe administration. We examined temporal alterations in the proteome/phosphoproteome in pre-disease and NASH Mat1a ^-/- mice, effects of SAMe administration, and compared to human nonalcoholic fatty liver disease (NAFLD). Mitochondrial and peroxisomal lipid metabolism proteins were altered in pre-disease mice and persisted in NASH Mat1a ^-/- mice, which exhibited more progressive alterations in cytoplasmic ribosomes, ER, and nuclear proteins. A common mechanism found in both pre-disease and NASH livers was a hyperphosphorylation signature consistent with casein kinase 2α (CK2α) and AKT1 activation, which was normalized by SAMe administration. This was mimicked in human NAFLD with a metabolomic signature (M-subtype) resembling Mat1a ^-/- mice. In conclusion, we have identified a common proteome/phosphoproteome signature between Mat1a ^-/- mice and human NAFLD M-subtype that may have pathophysiological and therapeutic implications.

Adipogenic progenitors in different organs: Pathophysiological implications

In physiological conditions, the adipose organ resides in well-defined areas, where it acts providing an energy supply and as an endocrine organ involved in the control of whole-body energy metabolism. Adipose tissue adipokines connect the body's nutritional status to the regulation of energy balance. When it surrounds organs, it provides also for mechanical protection. Adipose tissue has a complex and heterogenous cellular composition that includes adipocytes, adipose tissue-derived stromal and stem cells (ASCs) which are mesenchymal stromal cells, and endothelial and immune cells, which signal to each other and to other tissues to maintain homeostasis. In obesity and in other nutrition related diseases, as well as in age-related diseases, biological and functional changes of adipose tissue give rise to several complications. Obesity triggers alterations of ASCs, impairing adipose tissue remodeling and adipose tissue function, which induces low-grade systemic inflammation, progressive insulin resistance and other metabolic disorders. Adipose tissue grows by hyperplasia recruiting new ASCs and by hypertrophy, up to its expandability limit. To overcome this limitation and to store the excess of nutrients, adipose tissue develops ectopically, involving organs such as muscle, bone marrow and the heart. The origin of ectopic adipose organ is not clearly elucidated, and a possible explanation lies in the stimulation of the adipogenic differentiation of mesenchymal precursor cells which normally differentiate toward a lineage specific for the organ in which they reside. The chronic exposition of these newly-formed adipose depots to the pathological environment, will confer to them all the phenotypic characteristics of a dysfunctional adipose tissue, perpetuating the organ alterations. Visceral fat, but also ectopic fat, either in the liver, muscle or heart, can increase the risk of developing insulin resistance, type 2 diabetes, and cardiovascular diseases. Being able to prevent and to target dysfunctional adipose tissue will avoid the progression towards the complications of obesity and other nutrition-related diseases. The aim of this review is to summarize some of the knowledge regarding the presence of adipose tissue in particular tissues (where it is not usually present), describing the composition of its adipogenic precursors, and the interactions responsible for the development of organ pathologies.

ROCK2-Specific Inhibitor KD025 Suppresses Adipocyte Differentiation by Inhibiting Casein Kinase 2

KD025, a ROCK2 isoform-specific inhibitor, has an anti-adipogenic activity which is not mediated by ROCK2 inhibition. To identify the target, we searched binding targets of KD025 by using the KINOMEscanTM screening platform, and we identified casein kinase 2 (CK2) as a novel target. KD025 showed comparable binding affinity to CK2α (Kd = 128 nM). By contrast, CK2 inhibitor CX-4945 and ROCK inhibitor fasudil did not show such cross-reactivity. In addition, KD025 effectively inhibited CK2 at a nanomolar concentration (IC50 = 50 nM). We examined if the inhibitory effect of KD025 on adipocyte differentiation is through the inhibition of CK2. Both CX-4945 and KD025 suppressed the generation of lipid droplets and the expression of proadipogenic genes Pparg and Cebpa in 3T3-L1 cells during adipocyte differentiation. Fasudil exerted no significant effect on the quantity of lipid droplets, but another ROCK inhibitor Y-27632 increased the expression of Pparg and Cebpa. Both CX-4945 and KD025 acted specifically in the middle stage (days 1-3) but were ineffective when treated at days 0-1 or the late stages, indicating that CX-4945 and KD025 may regulate the same target, CK2. The mRNA and protein levels of CK2α and CK2β generally decreased in 3T3-L1 cells at day 2 but recovered thereafter. Other well-known CK2 inhibitors DMAT and quinalizarin inhibited effectively the differentiation of 3T3-L1 cells. Taken together, the results of this study confirmed that KD025 inhibits ROCK2 and CK2, and that the inhibitory effect on adipocyte differentiation is through the inhibition of CK2.

Protein kinase CK2: a potential therapeutic target for diverse human diseases

CK2 is a constitutively active Ser/Thr protein kinase, which phosphorylates hundreds of substrates, controls several signaling pathways, and is implicated in a plethora of human diseases. Its best documented role is in cancer, where it regulates practically all malignant hallmarks. Other well-known functions of CK2 are in human infections; in particular, several viruses exploit host cell CK2 for their life cycle. Very recently, also SARS-CoV-2, the virus responsible for the COVID-19 pandemic, has been found to enhance CK2 activity and to induce the phosphorylation of several CK2 substrates (either viral and host proteins). CK2 is also considered an emerging target for neurological diseases, inflammation and autoimmune disorders, diverse ophthalmic pathologies, diabetes, and obesity. In addition, CK2 activity has been associated with cardiovascular diseases, as cardiac ischemia-reperfusion injury, atherosclerosis, and cardiac hypertrophy. The hypothesis of considering CK2 inhibition for cystic fibrosis therapies has been also entertained for many years. Moreover, psychiatric disorders and syndromes due to CK2 mutations have been recently identified. On these bases, CK2 is emerging as an increasingly attractive target in various fields of human medicine, with the advantage that several very specific and effective inhibitors are already available. Here, we review the literature on CK2 implication in different human pathologies and evaluate its potential as a pharmacological target in the light of the most recent findings.

In vitro chronic glycation induces AGEs accumulation reducing insulin-stimulated glucose uptake and increasing GLP1R in adipocytes

Intracellular AGEs accumulation increases RAGE and GLP1R and reduces glucose uptake in adipocytes.

How can a traffic light properly work if it is always green? The paradox of CK2 signaling

CK2 is a constitutively active protein kinase that assuring a constant level of phosphorylation to its numerous substrates supports many of the most important biological functions. Nevertheless, its activity has to be controlled and adjusted in order to cope with the varying needs of a cell, and several examples of a fine-tune regulation of its activity have been described. More importantly, aberrant regulation of this enzyme may have pathological consequences, e.g. in cancer, chronic inflammation, neurodegeneration, and viral infection. Our review aims at summarizing our current knowledge about CK2 regulation. In the first part, we have considered the most important stimuli shown to affect protein kinase CK2 activity/expression. In the second part, we focus on the molecular mechanisms by which CK2 can be regulated, discussing controversial aspects and future perspectives.

Structural basis for the design of bisubstrate inhibitors of protein kinase CK2 provided by complex structures with the substrate-competitive inhibitor heparin

The Ser/Thr kinase CK2, a member of the superfamily of eukaryotic protein kinases, has an acidophilic substrate profile with the substrate recognition sequence S/T-D/E-X-D/E, and it is inhibited by polyanionic substances like heparin. The latter, a highly sulphated glucosamino glycan composed mainly of repeating 2-O-sulpho-α-l-idopyranuronic acid/N,O6-disulpho-α-d-glucosamine disaccharide units, is the longest known substrate-competitive CK2 inhibitor. The structural basis of CK2's preference for anionic substrates and substrate-competitive inhibitors is only vaguely known which limits the value of the substrate-binding region for the structure-based development of CK2 bisubstrate inhibitors. Here, a tetragonal and a monoclinic co-crystal structure of CK2α, the catalytic subunit of CK2, with a decameric heparin fragment are described. In the tetragonal structure, the heparin molecule binds to the polybasic stretch at the beginning of CK2α's helix αC, whereas in the monoclinic structure it occupies the central substrate-recognition region around the P+1 loop. Together, the structures rationalize the inhibitory efficacy of heparin fragments as a function of chain length. The monoclinic CK2α/heparin structure, in which the heparin fragment is particularly well defined, is the first CK2 structure with an anionic inhibitor of considerable size at the central part of the substrate-recognition site. The bound heparin fragment is so close to the binding site of ATP-competitive inhibitors that it can guide the design of linkers and pave the way to efficient CK2 bisubstrate inhibitors in the future.

Contribution of the CK2 Catalytic Isoforms α and α' to the Glycolytic Phenotype of Tumor Cells

CK2 is a Ser/Thr protein kinase overexpressed in many cancers. It is usually present in cells as a tetrameric enzyme, composed of two catalytic (α or α’) and two regulatory (β) subunits, but it is active also in its monomeric form, and the specific role of the different isoforms is largely unknown. CK2 phosphorylates several substrates related to the uncontrolled proliferation, motility, and survival of cancer cells. As a consequence, tumor cells are addicted to CK2, relying on its activity more than healthy cells for their life, and exploiting it for developing multiple oncological hallmarks. However, little is known about CK2 contribution to the metabolic rewiring of cancer cells. With this study we aimed at shedding some light on it, especially focusing on the CK2 role in the glycolytic onco-phenotype. By analyzing neuroblastoma and osteosarcoma cell lines depleted of either one (α) or the other (α’) CK2 catalytic subunit, we also aimed at disclosing possible pro-tumor functions which are specific of a CK2 isoform. Our results suggest that both CK2 α and α’ contribute to cell proliferation, survival and tumorigenicity. The analyzed metabolic features disclosed a role of CK2 in tumor metabolism, and suggest prominent functions for CK2 α isoform. Results were also confirmed by CK2 pharmacological inhibition. Overall, our study provides new information on the mechanism of cancer cells addiction to CK2 and on its isoform-specific functions, with fundamental implications for improving future therapeutic strategies based on CK2 targeting.

Protein kinase CK2 inhibition as a pharmacological strategy

CK2 is a constitutively active Ser/Thr protein kinase which phosphorylates hundreds of substrates. Since they are primarily related to survival and proliferation pathways, the best-known pathological roles of CK2 are in cancer, where its targeting is currently being considered as a possible therapy. However, CK2 activity has been found instrumental in many other human pathologies, and its inhibition will expectably be extended to different purposes in the near future. Here, after a description of CK2 features and implications in diseases, we analyze the different inhibitors and strategies available to target CK2, and update the results so far obtained by their in vivo application.

A new insulin-sensitive enhancer from Silene viscidula, WPTS, treats type 2 diabetes by ameliorating insulin resistance, reducing dyslipidemia, and promoting proliferation of islet β cells

Wacao pentacyclic triterpenoid saponins (WPTS) is a newly discovered insulin sensitivity enhancer. It is a powerful hypoglycemic compound derived from Silene viscidula, which has a hypoglycemic effect similar to that of insulin. It can rapidly reduce blood glucose levels, normalizing them within 3 days of administration. However, its mechanism of action is completely different from that of insulin. Thus, we aimed to determine the pharmacological effects and mechanism of activity of WPTS on type 2 diabetes to elucidate the main reasons for its rapid effects. The results showed that WPTS could effectively improve insulin resistance in KKAy diabetic mice. Comparative transcriptomics showed that WPTS could upregulate the expression of insulin resistance-related genes such as glucose transporter type 4 (Glut4), insulin receptor substrate 1 (Irs1), Akt, and phosphoinositide 3-kinase (PI3K), and downregulate the expression of lipid metabolism-related genes such as monoacylglycerol O-acyltransferase 1 (Moat1), lipase C (Lipc), and sphingomyelin phosphodiesterase 4 (Smpd4). The results indicated that the differentially expressed genes could regulate lipid metabolism via the PI3K/AKT metabolic pathway, and it is noteworthy that WPTS was found to upregulate Glut4 expression, decrease blood glucose levels, and attenuate insulin resistance via the PI3K/AKT pathway. Q-PCR and western blotting further validated the transcriptomics findings at the mRNA and protein levels, respectively. We believe that WPTS can achieve a rapid hypoglycemic effect by improving the lipid metabolism and insulin resistance of the diabetic KKAy mice. WPTS could be a very promising candidate drug for the treatment of diabetes and deserves further research.

Role of CK2 inhibitor CX-4945 in anti-cancer combination therapy - potential clinical relevance

BACKGROUND

Protein kinase CK2 inhibition has long been considered as an attractive anti-cancer strategy based on the following considerations: CK2 is a pro-survival kinase, it is frequently over-expressed in human tumours and its over-expression correlates with a worse prognosis. Preclinical evidence strongly supports the feasibility of this target and, although dozens of CK2 inhibitors have been described in the literature so far, CX-4945 (silmitasertib) was the first that entered into clinical trials for the treatment of both human haematological and solid tumours. However, kinase inhibitor monotherapies turned out to be effective only in a limited number of malignancies, probably due to the multifaceted causes that underlie them, supporting the emerging view that multi-targeted approaches to treat human tumours could be more effective.

CONCLUSIONS

In this review, we will address combined anti-cancer therapeutic strategies described so far which involve the use of CX-4945. Data from preclinical studies clearly show the ability of CX-4945 to synergistically cooperate with different classes of anti-neoplastic agents, thereby contributing to an orchestrated anti-tumour action against multiple targets. Overall, these promising outcomes support the translation of CX-4945 combined therapies into clinical anti-cancer applications.

White Adipose Tissue Expansion in Multiple Symmetric Lipomatosis Is Associated with Upregulation of CK2, AKT and ERK1/2

Multiple symmetric lipomatosis (MSL) is a rare disorder characterized by overgrowing lipomatous tissue (LT) in the subcutaneous adipose tissue (SAT). What LT is and how it expands are not completely understood; previous data suggested that it could derive from brown AT precursors. In six MSL type I patients, we compared LT morphology by histological and immunohistochemistry (IHC) analysis, gene expression, by qPCR, kinase activity, by Western Blot and in vitro assay to paired-control SAT using AT from patients with pheochromocytoma as a human browning reference. In the stromal vascular fraction (SVF), we quantified adipose stem cells (ASCs) by flow cytometry, the proliferation rate, white and beige adipogenic potential and clonogenicity and adipogenicity by a limiting dilution assay. LT displayed white AT morphology and expression pattern and did not show increased levels of the brown-specific marker UCP1. In LT, we evidenced AKT, CK2 and ERK1/2 hyperactivation. LT-SVF contained increased ASCs, proliferated faster, sprouted clones and differentiated into adipocytes better than the control, displaying enhanced white adipogenic potential but not increased browning compared to SAT. In conclusion, LT is a white AT depot expanding by hyperplasia through increased stemness and enhanced white adipogenesis upregulating AKT, CK2 and ERK1/2, which could represent new targets to counteract MSL.

Role of Protein Kinase CK2 in Aberrant Lipid Metabolism in Cancer

Uncontrolled proliferation is a feature defining cancer and it is linked to the ability of cancer cells to effectively adapt their metabolic needs in response to a harsh tumor environment. Metabolic reprogramming is considered a hallmark of cancer and includes increased glucose uptake and processing, and increased glutamine utilization, but also the deregulation of lipid and cholesterol-associated signal transduction, as highlighted in recent years. In the first part of the review, we will (i) provide an overview of the major types of lipids found in eukaryotic cells and their importance as mediators of intracellular signaling pathways (ii) analyze the main metabolic changes occurring in cancer development and the role of oncogenic signaling in supporting aberrant lipid metabolism and (iii) discuss combination strategies as powerful new approaches to cancer treatment. The second part of the review will address the emerging role of CK2, a conserved serine/threonine protein kinase, in lipid homeostasis with an emphasis regarding its function in lipogenesis and adipogenesis. Evidence will be provided that CK2 regulates these processes at multiple levels. This suggests that its pharmacological inhibition combined with dietary restrictions and/or inhibitors of metabolic targets could represent an effective way to undermine the dependency of cancer cells on lipids to interfere with tumor progression.

Endogenous IGF Signaling Directs Heterogeneous Mesoderm Differentiation in Human Embryonic Stem Cells

During embryogenesis, various cell types emerge simultaneously from their common progenitors under the influence of intrinsic signals. Human embryonic stem cells can differentiate to diverse cell types of three embryonic lineages, making them an excellent system for understanding the regulatory mechanism that maintains the balance of different cell types in embryogenesis. In this report, we demonstrate that insulin-like growth factor (IGF) proteins are endogenously expressed during differentiation, and their temporal expression contributes to the cell fate diversity in mesoderm differentiation. Small molecule LY294002 inhibits the IGF pathway to promote cardiomyocyte differentiation while suppressing epicardial and noncardiac cell fates. LY294002-induced cardiomyocytes demonstrate characteristic cardiomyocyte features and provide insights into the molecular mechanisms underlying cardiac differentiation. We further show that LY294002 induces cardiomyocytes through CK2 pathway inhibition. This study elucidates the crucial roles of endogenous IGF in mesoderm differentiation and shows that the inhibition of the IGF pathway is an effective approach for generating cardiomyocytes.

Protein Kinase CK2-A Putative Target for the Therapy of Diabetes Mellitus?

Since diabetes is a global epidemic, the development of novel therapeutic strategies for the treatment of this disease is of major clinical interest. Diabetes is differentiated in two types: type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). T1DM arises from an autoimmune destruction of insulin-producing β-cells whereas T2DM is characterized by an insulin resistance, an impaired insulin reaction of the target cells, and/or dysregulated insulin secretion. In the past, a growing number of studies have reported on the important role of the protein kinase CK2 in the regulation of the survival and endocrine function of pancreatic β-cells. In fact, inhibition of CK2 is capable of reducing cytokine-induced loss of β-cells and increases insulin expression as well as secretion by various pathways that are regulated by reversible phosphorylation of proteins. Moreover, CK2 inhibition modulates pathways that are involved in the development of diabetes and prevents signal transduction, leading to late complications such as diabetic retinopathy. Hence, targeting CK2 may represent a novel therapeutic strategy for the treatment of diabetes.

Characterization of subcutaneous and omental adipose tissue in patients with obesity and with different degrees of glucose impairment

Although obesity represents a risk factor for the development of type 2 diabetes mellitus (T2DM), the link between these pathological conditions is not so clear. The manner in which the different elements of adipose tissue (AT) interplay in order to grow has been suggested to have a role in the genesis of metabolic complications, but this has not yet been fully addressed in humans. Through IHC, transmission electron microscopy, cytometry, and in vitro cultures, we described the morphological and functional changes of subcutaneous and visceral AT (SAT and VAT) in normoglycemic, prediabetic and T2DM patients with obesity compared to lean subjects. In both SAT and VAT we measured a hypertrophic and hyperplastic expansion, causing similar vascular rarefaction in obese patients with different degrees of metabolic complications. Capillaries display dysfunctional basement membrane thickening only in T2DM patients evidencing VAT as a new target of T2DM microangiopathy. The largest increase in adipocyte size and decrease in adipose stem cell number and adipogenic potential occur both in T2DM and in prediabetes. We showed that SAT and VAT remodeling with stemness deficit is associated with early glucose metabolism impairment suggesting the benefit of an AT-target therapy controlling hypertrophy and hyperplasia already in prediabetic obese patients.

Role of protein kinase CK2 in antitumor drug resistance

Drug resistance represents the major reason of pharmacological treatment failure. It is supported by a broad spectrum of mechanisms, whose molecular bases have been frequently correlated to aberrant protein phosphorylation. CK2 is a constitutively active protein kinase which phosphorylates hundreds of substrates; it is expressed in all cells, but its level is commonly found higher in cancer cells, where it plays anti-apoptotic, pro-migration and pro-proliferation functions. Several evidences support a role for CK2 in processes directly responsible of drug resistance, such as drug efflux and DNA repair; moreover, CK2 intervenes in signaling pathways which are crucial to evade drug response (as PI3K/AKT/PTEN, NF-κB, β-catenin, hedgehog signaling, p53), and controls the activity of chaperone machineries fundamental in resistant cells. Interestingly, a panel of specific and effective inhibitors of CK2 is available, and several examples are known of their efficacy in resistant cells, with synergistic effect when used in combination with conventional drugs, also in vivo. Here we analyze and discuss evidences supporting the hypothesis that CK2 targeting represents a valuable strategy to overcome drug resistance.

New insights into apolipoprotein A5 in controlling lipoprotein metabolism in obesity and the metabolic syndrome patients

Apolipoprotein A5 (apoA5) has been identified to play an important role in lipid metabolism, specifically in triglyceride (TG) and TG-rich lipoproteins (TRLs) metabolism. Numerous evidence has demonstrated for an association between apoA5 and the increased risk of obesity and metabolic syndrome, but the mechanism remains to be fully elucidated. Recently, several studies verified that apoA5 could significantly reduce plasma TG level by stimulating lipoprotein lipase (LPL) activity, and the intracellular role of apoA5 has also been proved since apoA5 is associated with cytoplasmic lipid droplets (LDs) and affects intrahepatic TG accumulation. Furthermore, since adipocytes provide the largest storage depot for TG and play a crucial role in the development of obesity, we could infer that apoA5 also acts as a novel regulator to modulate TG storage in adipocytes. In this review, we focus on the association of gene and protein of apoA5 with obesity and metabolic syndrome, and provide new insights into the physiological role of apoA5 in humans, giving a potential therapeutic target for obesity and associated disorders.

Histone H3 threonine 11 phosphorylation by Sch9 and CK2 regulates chronological lifespan by controlling the nutritional stress response

Upon nutritional stress, the metabolic status of cells is changed by nutrient signaling pathways to ensure survival. Altered metabolism by nutrient signaling pathways has been suggested to influence cellular lifespan. However, it remains unclear how chromatin regulation is involved in this process. Here, we found that histone H3 threonine 11 phosphorylation (H3pT11) functions as a marker for nutritional stress and aging. Sch9 and CK2 kinases cooperatively regulate H3pT11 under stress conditions. Importantly, H3pT11 defective mutants prolonged chronological lifespan (CLS) by altering nutritional stress responses. Thus, the phosphorylation of H3T11 by Sch9 and CK2 links a nutritional stress response to chromatin in the regulation of CLS.