Pharmacological Inhibition of PKCθ Counteracts Muscle Disease in a Mouse Model of Duchenne Muscular Dystrophy

A Hypothesized Therapeutic Role of (Z)-Endoxifen in Duchenne Muscular Dystrophy (DMD)

Duchenne Muscular Dystrophy (DMD) is an inherited, X-linked disorder that is progressive, debilitating, and ultimately fatal. The current therapeutic landscape offers no cures, but does include palliative treatments that delay disease progression, and there is progress on genetic therapies that have the promise to be curative. There is much room for new therapies, and foundational work with the estrogen receptor modulator tamoxifen suggests the potential of a unique spectrum of therapeutic benefit from endoxifen, a metabolite of tamoxifen. Here we describe the potential for this new DMD therapy in the context of the overall DMD therapeutic landscape.

The Interaction of Duchenne Muscular Dystrophy and Insulin Resistance

Duchenne muscular dystrophy (DMD), caused by deficiency of functional dystrophin protein, is a fatal, progressive muscle disease that frequently includes metabolic dysregulation. Herein, we explore the physiologic consequences of dystrophin deficiency within the context of obesity and insulin resistance. We hypothesized that dystrophin deficiency increases the frequency of insulin resistance, and insulin resistance potentiates muscle pathology caused by dystrophin deficiency.

Update on anti-fibrotic pharmacotherapies in skeletal muscle disease

Fibrosis, defined as an excessive accumulation of extracellular matrix, is the end point of a defective regenerative process, unresolved inflammation and/or chronic damage. Numerous muscle disorders (MD) are characterized by high levels of fibrosis associated with muscle wasting and weakness. Fibrosis alters muscle homeostasis/regeneration and fiber environment and may interfere with gene and cell therapies. Slowing down or reversing fibrosis is a crucial therapeutic goal to maintain muscle identity in the context of therapies. Several pathways are implicated in the modulation of the fibrotic progression and multiple therapeutic compounds targeting fibrogenic signals have been tested in MDs, mostly in the context of Duchenne Muscular Dystrophy. In this review, we present an up-to-date overview of pharmacotherapies that have been tested to reduce fibrosis in the skeletal muscle.

Nano-Immunomodulation: A New Strategy for Skeletal Muscle Diseases and Aging?

The skeletal muscle has a very remarkable ability to regenerate upon injury under physiological conditions; however, this regenerative capacity is strongly diminished in physio-pathological conditions, such as those present in diseased or aged muscles. Many muscular dystrophies (MDs) are characterized by aberrant inflammation due to the deregulation of both the lymphoid and myeloid cell populations and the production of pro-inflammatory cytokines. Pathological inflammation is also observed in old muscles due to a systemic change in the immune system, known as "inflammaging". Immunomodulation represents, therefore, a promising therapeutic opportunity for different skeletal muscle conditions. However, the use of immunomodulatory drugs in the clinics presents several caveats, including their low stability in vivo, the need for high doses to obtain therapeutically relevant effects, and the presence of strong side effects. Within this context, the emerging field of nanomedicine provides the powerful tools needed to control the immune response. Nano-scale materials are currently being explored as biocarriers to release immunomodulatory agents in the damaged tissues, allowing therapeutic doses with limited off-target effects. In addition, the intrinsic immunomodulatory properties of some nanomaterials offer further opportunities for intervention that still need to be systematically explored. Here we exhaustively review the state-of-the-art regarding the use of nano-sized materials to modulate the aberrant immune response that characterizes some physio-pathological muscle conditions, such as MDs or sarcopenia (the age-dependent loss of muscle mass). Based on our learnings from cancer and immune tolerance induction, we also discuss further opportunities, challenges, and limitations of the emerging field of nano-immunomodulation.

Statins Induce Locomotion and Muscular Phenotypes in Drosophila melanogaster That Are Reminiscent of Human Myopathy: Evidence for the Role of the Chloride Channel Inhibition in the Muscular Phenotypes

The underlying mechanisms for statin-induced myopathy (SIM) are still equivocal. In this study, we employ Drosophila melanogaster to dissect possible underlying mechanisms for SIM. We observe that chronic fluvastatin treatment causes reduced general locomotion activity and climbing ability. In addition, transmission microscopy of dissected skeletal muscles of fluvastatin-treated flies reveals strong myofibrillar damage, including increased sarcomere lengths and Z-line streaming, which are reminiscent of myopathy, along with fragmented mitochondria of larger sizes, most of which are round-like shapes. Furthermore, chronic fluvastatin treatment is associated with impaired lipid metabolism and insulin signalling. Mechanistically, knockdown of the statin-target Hmgcr in the skeletal muscles recapitulates fluvastatin-induced mitochondrial phenotypes and lowered general locomotion activity; however, it was not sufficient to alter sarcomere length or elicit myofibrillar damage compared to controls or fluvastatin treatment. Moreover, we found that fluvastatin treatment was associated with reduced expression of the skeletal muscle chloride channel, ClC-a (Drosophila homolog of CLCN1), while selective knockdown of skeletal muscle ClC-a also recapitulated fluvastatin-induced myofibril damage and increased sarcomere lengths. Surprisingly, exercising fluvastatin-treated flies restored ClC-a expression and normalized sarcomere lengths, suggesting that fluvastatin-induced myofibrillar phenotypes could be linked to lowered ClC-a expression. Taken together, these results may indicate the potential role of ClC-a inhibition in statin-associated muscular phenotypes. This study underlines the importance of Drosophila melanogaster as a powerful model system for elucidating the locomotion and muscular phenotypes, promoting a better understanding of the molecular mechanisms underlying SIM.

Inhibition of PKCθ Improves Dystrophic Heart Phenotype and Function in a Novel Model of DMD Cardiomyopathy

Chronic cardiac muscle inflammation and subsequent fibrotic tissue deposition are key features in Duchenne Muscular Dystrophy (DMD). The treatment of choice for delaying DMD progression both in skeletal and cardiac muscle are corticosteroids, supporting the notion that chronic inflammation in the heart plays a pivotal role in fibrosis deposition and subsequent cardiac dysfunction. Nevertheless, considering the adverse effects associated with long-term corticosteroid treatments, there is a need for novel anti-inflammatory therapies. In this study, we used our recently described exercised mdx (ex mdx) mouse model characterised by accelerated heart pathology, and the specific PKCθ inhibitor Compound 20 (C20), to show that inhibition of this kinase leads to a significant reduction in the number of immune cells infiltrating the heart, as well as necrosis and fibrosis. Functionally, C20 treatment also prevented the reduction in left ventricle fractional shortening, which was typically observed in the vehicle-treated ex mdx mice. Based on these findings, we propose that PKCθ pharmacological inhibition could be an attractive therapeutic approach to treating dystrophic cardiomyopathy

Genetic reduction of the extracellular matrix protein versican attenuates inflammatory cell infiltration and improves contractile function in dystrophic mdx diaphragm muscles

There is a persistent, aberrant accumulation of V0/V1 versican in skeletal muscles from patients with Duchenne muscular dystrophy and in diaphragm muscles from mdx mice. Versican is a provisional matrix protein implicated in fibrosis and inflammation in various disease states, yet its role in the pathogenesis of muscular dystrophy is not known. Here, female mdx and male hdf mice (haploinsufficient for the versican allele) were bred. In the resulting F1 mdx-hdf male pups, V0/V1 versican expression in diaphragm muscles was decreased by 50% compared to mdx littermates at 20-26 weeks of age. In mdx-hdf mice, spontaneous physical activity increased by 17% and there was a concomitant decrease in total energy expenditure and whole-body glucose oxidation. Versican reduction improved the ex vivo strength and endurance of diaphragm muscle strips. These changes in diaphragm contractile properties in mdx-hdf mice were associated with decreased monocyte and macrophage infiltration and a reduction in the proportion of fibres expressing the slow type I myosin heavy chain isoform. Given the high metabolic cost of inflammation in dystrophy, an attenuated inflammatory response may contribute to the effects of versican reduction on whole-body metabolism. Altogether, versican reduction ameliorates the dystrophic pathology of mdx-hdf mice as evidenced by improved diaphragm contractile function and increased physical activity.

Diacylglycerol-evoked activation of PKC and PKD isoforms in regulation of glucose and lipid metabolism: a review

Protein kinase C (PKC) and Protein kinase D (PKD) isoforms can sense diacylglycerol (DAG) generated in the different cellular compartments in various physiological processes. DAG accumulates in multiple organs of the obese subjects, which leads to the disruption of metabolic homeostasis and the development of diabetes as well as associated diseases. Multiple studies proved that aberrant activation of PKCs and PKDs contributes to the development of metabolic diseases. DAG-sensing PKC and PKD isoforms play a crucial role in the regulation of metabolic homeostasis and therefore might serve as targets for the treatment of metabolic disorders such as obesity and diabetes.

Heterogenetic parabiosis between healthy and dystrophic mice improve the histopathology in muscular dystrophy

Duchenne muscular dystrophy (DMD) is a progressive muscle disease, characterized by mutations in the X-linked dystrophin, that has several therapeutic options but no curative treatment. Transplantation of muscle progenitor cells for treatment of DMD has been widely investigated; however, its application is hindered by limited cell survival due to the harmful dystrophic microenvironment. An alternative approach to utilize progenitor cells and circulatory factors and to improve the dystrophic muscle pathology and microenvironment is through parabiotic pairing, where mice are surgically sutured to create a joint circulatory system. Parabiotic mice were generated by surgically joining wild type (WT) mice expressing green fluorescent protein (GFP) with mdx mice. These mice developed a common circulation (approximately 50% green cells in the blood of mdx mice) 2-weeks after parabiotic pairing. We observed significantly improved dystrophic muscle pathology, including decreased inflammation, necrotic fibers and fibrosis in heterogenetic parabionts. Importantly, the GFP + cells isolated from the mdx mice (paired with GFP mice) underwent myogenic differentiation in vitro and expressed markers of mesenchymal stem cells and macrophages, which may potentially be involved in the improvement of dystrophic muscle pathology. These observations suggest that changing the dystrophic microenvironment can be a new approach to treat DMD.

Targeting PKCθ Promotes Satellite Cell Self-Renewal

Skeletal muscle regeneration following injury depends on the ability of satellite cells (SCs) to proliferate, self-renew, and eventually differentiate. The factors that regulate the process of self-renewal are poorly understood. In this study we examined the role of PKCθ in SC self-renewal and differentiation. We show that PKCθ is expressed in SCs, and its active form is localized to the chromosomes, centrosomes, and midbody during mitosis. Lack of PKCθ promotes SC symmetric self-renewal division by regulating Pard3 polarity protein localization, without affecting the overall proliferation rate. Genetic ablation of PKCθ or its pharmacological inhibition in vivo did not affect SC number in healthy muscle. By contrast, after induction of muscle injury, lack or inhibition of PKCθ resulted in a significant expansion of the quiescent SC pool. Finally, we show that lack of PKCθ does not alter the inflammatory milieu after acute injury in muscle, suggesting that the enhanced self-renewal ability of SCs in PKCθ-/- mice is not due to an alteration in the inflammatory milieu. Together, these results suggest that PKCθ plays an important role in SC self-renewal by stimulating their expansion through symmetric division, and it may represent a promising target to manipulate satellite cell self-renewal in pathological conditions.

Effect of Stem Cells, Ascorbic Acid and SERCA1a Gene Transfected Stem Cells in Experimentally Induced Type I Diabetic Myopathy

Background and Objectives

Sarco/endoplasmic reticulum Ca^2＋-ATPase (SERCA) inhibition was proved in streptozotocin (STZ)-diabetic rats. The present study aimed at investigating and comparing the therapeutic effect of bone marrow mesenchymal stem cells (BMMSCs), BMMSCs combined with ascorbic acid (AA) and SERCA1a gene transfected BMMSCs in induced type I diabetic myopathy of male albino rat.

Methods and Results

54 rats were divided into donor group of 6 rats for isolation, propagation and characterization of BMMSCs and SERCA1a transfected BMMSCs, groups I∼V 48 rats. Group I of 8 control rats, group II (Diabetic) of 10 rats given STZ 50 mg/kg intraperitoneal, group III (BMMSCs) of 10 rats given STZ and BMMSCs intravenous (IV), group IV (BMMSCs and AA) of 10 rats given STZ, BMMSCs IV and AA 500 mg/kg and group V (SERCA 1a transfected BMMSCs) of 10 rats given STZ and SERCA1a transfected BMMSCs IV. The rats were sacrificed after 8 weeks. Gastrocnemius specimens were subjected to biochemical, histological, morphometric and statistical studies. Diabetic rats revealed inflammatory and degenerative muscle changes, a significant increase in blood glucose level, mean DNA fragmentation and mean MDA values and a significant decrease in mean GSH and catalase values, area of pale nuclei, area% of CD105 and CD34 ＋ve cells, SERCA1a protein and gene values. The morphological changes regressed by therapy. In group III significant decrease in DNA fragmentation and MDA, significant increase in GSH and catalase, significant increase in the mean area of pale nuclei, area % of CD105 and CD34 ＋ve cells versus diabetic group. In group IV, same findings as group III versus diabetic and BMMSCs groups. In group V, same findings as group IV versus diabetic and treated groups. Western blot and PCR proved a mean value of SERCA1a protein and gene comparable to the control group. Mean calcium concentration values revealed a significant increase in the diabetic group, in BMMSCs and AA group versus control and SERCA1a group.

Conclusions

SERCA1a transfected BMMSCs proved a definite therapeutic effect, more remarkable than BMMSCs combined with AA. This effect was evidenced histologically and confirmed by significant changes in the biochemical tests indicating oxidative stress, muscle calcium concentration, morphometric parameters and PCR values of SERCA1a.

Lack of PKCθ Promotes Regenerative Ability of Muscle Stem Cells in Chronic Muscle Injury

Duchenne muscular dystrophy (DMD) is a genetic disease characterized by muscle wasting and chronic inflammation, leading to impaired satellite cells (SCs) function and exhaustion of their regenerative capacity. We previously showed that lack of PKCθ in mdx mice, a mouse model of DMD, reduces muscle wasting and inflammation, and improves muscle regeneration and performance at early stages of the disease. In this study, we show that muscle regeneration is boosted, and fibrosis reduced in mdxθ^−/− mice, even at advanced stages of the disease. This phenotype was associated with a higher number of Pax7 positive cells in mdxθ^−/− muscle compared with mdx muscle, during the progression of the disease. Moreover, the expression level of Pax7 and Notch1, the pivotal regulators of SCs self-renewal, were upregulated in SCs isolated from mdxθ^−/− muscle compared with mdx derived SCs. Likewise, the expression of the Notch ligands Delta1 and Jagged1 was higher in mdxθ^−/− muscle compared with mdx. The expression level of Delta1 and Jagged1 was also higher in PKCθ^−/− muscle compared with WT muscle following acute injury. In addition, lack of PKCθ prolonged the survival and sustained the differentiation of transplanted myogenic progenitors. Overall, our results suggest that lack of PKCθ promotes muscle repair in dystrophic mice, supporting stem cells survival and maintenance through increased Delta-Notch signaling.

Splenic Ly6Chi monocytes are critical players in dystrophic muscle injury and repair

Dystrophic muscle is characterized by chronic injury and a steady recruitment of inflammatory Ly6Chi monocytes. Recent studies have identified the spleen as the dominant reservoir of these cells during chronic inflammation. Here, we investigated the contribution of splenic Ly6Chi monocytes to dystrophic muscle pathology. Using the mdx mouse model of muscular dystrophy, we show that Ly6Chi monocytes accumulate in great numbers in the spleen over the course of the disease. The chemokine receptor CCR2 was upregulated on Ly6Chi monocytes in mdx spleen before disease onset, thereby enabling their recruitment to dystrophic muscle. Splenectomy performed before disease onset significantly reduced the number of Ly6Chi monocytes infiltrating dystrophic limb muscle. Moreover, in the absence of splenic Ly6Chi monocytes there was a significant reduction in dystrophic muscle inflammation and necrosis, along with improved regeneration during early disease. However, during late disease, a lack of splenic Ly6Chi monocytes adversely affected muscle fiber repair, due to a delay in the phenotypic shift of proinflammatory F4/80+Ly6ChiCD206lo to antiinflammatory F4/80+Ly6CloCD206+ macrophages. Overall, we show that the spleen is an indispensable source of Ly6Chi monocytes in muscular dystrophy and that splenic monocytes are critical players in both muscle fiber injury and repair.

PKC and PKN in heart disease

The protein kinase C (PKC) and closely related protein kinase N (PKN) families of serine/threonine protein kinases play crucial cellular roles. Both kinases belong to the AGC subfamily of protein kinases that also include the cAMP dependent protein kinase (PKA), protein kinase B (PKB/AKT), protein kinase G (PKG) and the ribosomal protein S6 kinase (S6K). Involvement of PKC family members in heart disease has been well documented over the years, as their activity and levels are mis-regulated in several pathological heart conditions, such as ischemia, diabetic cardiomyopathy, as well as hypertrophic or dilated cardiomyopathy. This review focuses on the regulation of PKCs and PKNs in different pathological heart conditions and on the influences that PKC/PKN activation has on several physiological processes. In addition, we discuss mechanisms by which PKCs and the closely related PKNs are activated and turned-off in hearts, how they regulate cardiac specific downstream targets and pathways, and how their inhibition by small molecules is explored as new therapeutic target to treat cardiomyopathies and heart failure.

α-Methyl-prednisolone normalizes the PKC mediated brain angiogenesis in dystrophic mdx mice

A fraction of patients affected by Duchenne Muscular Dystrophy (DMD) shows mental disability as a consequence of neuronal and metabolic alteration. In this study, we evaluated the effect of α-methyl-prednisolone (PDN) on the expression of the angiogenic marker HIF1α, VEGFA and VEGFR-2 (FLK1) in correlation with PKC expression in the brain of mdx mouse, an experimental model of DMD. We demonstrated that HIF1α, VEGFA and FLK1 are overexpressed in the brain of dystrophic mdx mice in parallel with an increase of PKC expression and reduction of the tight junctions Occludin leading to altered angiogenesis. Moreover, we demonstrated that PDN treatment induces a significant reduction in the HIF1α, VEGF, FLK1, and PKC mRNA and proteins levels and restores Occludin expression reducing its phosphorylation pattern. Our results suggest a new mechanism of action of PDN that through PKC suppression normalizes the angiogenesis in dystrophic mdx brains.

Kir2.2 p.Thr140Met: a genetic susceptibility to sporadic periodic paralysis

INTRODUCTION

Periodic paralyses (PP) are recurrent episodes of flaccid limb muscle weakness. Next to autosomal dominant forms, sporadic PP (SPP) cases are known but their genetics are unclear.

METHODS

In a patient with hypokalemic SPP, we performed exome sequencing to identify a candidate gene. We sequenced this gene in 263 unrelated PP patients without any known causative mutations. Then we performed functional analysis of all variants found and molecular modelling for interpretation.

RESULTS

Exome sequencing in the proband yielded three heterozygous variants predicted to be linked to disease. These encoded p.Thr140Met in the Kir2.2 potassium channel, p.Asp229Asn in protein kinase C theta, and p.Thr15943Ile in titin. Since all hitherto known causative PP genes code for ion channels, we studied the Kir2.2-encoding gene, KCNJ12, for involvement in PP pathogenesis. KCNJ12 screening in 263 PP patients revealed three further variants, each in a single individual and coding for p.Gly419Ser, p.Cys75Tyr, and p.Ile283Val. All four Kir2.2 variants were functionally expressed. Only p.Thr140Met displayed relevant functional alterations, i.e. homo-tetrameric channels produced almost no current, and hetero-tetrameric channels suppressed co-expressed wildtype Kir2.1 in a dominant-negative manner. Molecular modelling showed Kir2.2 p.Thr140Met to reduce movement of potassium ions towards binding sites in the hetero-tetramer pore compatible with a reduced maximal current. MD simulations revealed loss of hydrogen bonding with the p.Thr140Met substitution.

DISCUSSION

The electrophysiological findings of p.Thr140Met are similar to those found in thyrotoxic PP caused by Kir2.6 mutations. Also, the homologous Thr140 residue is mutated in Kir2.6. This supports the idea that Kir2.2 p.Thr140Met conveys susceptibility to SPP and should be included in genetic screening.

Long-Term Morpholino Oligomers in Hexose Elicits Long-Lasting Therapeutic Improvements in mdx Mice

Approval of antisense oligonucleotide eteplirsen highlights the promise of exon-skipping therapeutics for Duchenne muscular dystrophy patients. However, the limited efficacy of eteplirsen underscores the importance to improve systemic delivery and efficacy. Recently, we demonstrated that a glucose and fructose (GF) delivery formulation effectively potentiates phosphorodiamidate morpholino oligomer (PMO). Considering the clinical potential of GF, it is important to determine the long-term compatibility and efficacy with PMO in mdx mice prior to clinical translation. Here, we report that yearlong administration of a clinically applicable PMO dose (50 mg/kg/week for 3 weeks followed by 50 mg/kg/month for 11 months) with GF elicited sustainably high levels of dystrophin expression in mdx mice, with up to 45% of the normal level of dystrophin restored in most peripheral muscles without any detectable toxicity. Importantly, PMO-GF resulted in phenotypical rescue and mitochondrial biogenesis with functional improvement. Carbohydrate metabolites measurements revealed improved metabolic and energetic conditions after PMO-GF treatment in mdx mice without metabolic anomaly. Collectively, our study shows PMO-GF’s ability to elicit long-lasting therapeutic effects with tolerable toxicity and represents a new treatment modality for Duchenne muscular dystrophy, and provides guidelines for antisense oligonucleotides with GF in clinical use.

Muscle Expression of SOD1G93A Triggers the Dismantlement of Neuromuscular Junction via PKC-Theta

AIM

Neuromuscular junction (NMJ) represents the morphofunctional interface between muscle and nerve. Several chronic pathologies such as aging and neurodegenerative diseases, including muscular dystrophy and amyotrophic lateral sclerosis, display altered NMJ and functional denervation. However, the triggers and the molecular mechanisms underlying the dismantlement of NMJ remain unclear.

RESULTS

Here we provide evidence that perturbation in redox signaling cascades, induced by muscle-specific accumulation of mutant SOD1^G93A in transgenic MLC/SOD1^G93A mice, is causally linked to morphological alterations of the neuromuscular presynaptic terminals, high turnover rate of acetylcholine receptor, and NMJ dismantlement. The analysis of potential molecular mechanisms that mediate the toxic activity of SOD1^G93A revealed a causal link between protein kinase Cθ (PKCθ) activation and NMJ disintegration.

INNOVATION

The study discloses the molecular mechanism that triggers functional denervation associated with the toxic activity of muscle SOD1^G93A expression and suggests the possibility of developing a new strategy to counteract age- and pathology-associated denervation based on pharmacological inhibition of PKCθ activity.

CONCLUSIONS

Collectively, these data indicate that muscle-specific accumulation of oxidative damage can affect neuromuscular communication and induce NMJ dismantlement through a PKCθ-dependent mechanism. Antioxid. Redox Signal. 28, 1105-1119.

Targeting early PKCθ-dependent T-cell infiltration of dystrophic muscle reduces disease severity in a mouse model of muscular dystrophy

Chronic muscle inflammation is a critical feature of Duchenne muscular dystrophy and contributes to muscle fibre injury and disease progression. Although previous studies have implicated T cells in the development of muscle fibrosis, little is known about their role during the early stages of muscular dystrophy. Here, we show that T cells are among the first cells to infiltrate mdx mouse dystrophic muscle, prior to the onset of necrosis, suggesting an important role in early disease pathogenesis. Based on our comprehensive analysis of the kinetics of the immune response, we further identify the early pre-necrotic stage of muscular dystrophy as the relevant time frame for T-cell-based interventions. We focused on protein kinase C θ (PKCθ, encoded by Prkcq), a critical regulator of effector T-cell activation, as a potential target to inhibit T-cell activity in dystrophic muscle. Lack of PKCθ not only reduced the frequency and number of infiltrating T cells but also led to quantitative and qualitative changes in the innate immune cell infiltrate in mdx/Prkcq^-/- muscle. These changes were due to the inhibition of T cells, since PKCθ was necessary for T-cell but not for myeloid cell infiltration of acutely injured muscle. Targeting T cells with a PKCθ inhibitor early in the disease process markedly diminished the size of the inflammatory cell infiltrate and resulted in reduced muscle damage. Moreover, diaphragm necrosis and fibrosis were also reduced following treatment. Overall, our findings identify the early T-cell infiltrate as a therapeutic target and highlight the potential of PKCθ inhibition as a therapeutic approach to muscular dystrophy. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Effective regeneration of dystrophic muscle using autologous iPSC-derived progenitors with CRISPR-Cas9 mediated precise correction

Duchenne muscular dystrophy (DMD) is a lethal muscle wasting disease caused by a lack of dystrophin, which eventually leads to apoptosis of muscle cells and impaired muscle contractility. Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated protein 9 (CRISPR/Cas9) gene editing of induced pluripotent stem cells (IPSC) offers the potential to correct the DMD gene defect and create healthy IPSC for autologous cell transplantation without causing immune activation. However, IPSC carry a risk of tumor formation, which can potentially be mitigated by differentiation of IPSC into myogenic progenitor cells (MPC). We hypothesize that precise genetic editing in IPSC using CRISPR-Cas9 technology, coupled with MPC differentiation and autologous transplantation, can lead to safe and effective muscle repair. With future research, our hypothesis may provide an optimal autologous stem cell-based approach to treat the dystrophic pathology and improve the quality of life for patients with DMD.

PKCθ utility in diagnosing c-KIT/DOG-1 double negative gastrointestinal stromal tumors

BACKGROUND

The aim of this study was to evaluate the diagnosis value of an immunohistochemical (IHC) panel of three antibodies for the diagnosis of gastrointestinal stromal tumors (GISTs).

MATERIAL AND METHODS

In 80 consecutive GISTs without lymph node metastases, the IHC examinations were performed using the antibodies CD117 (c-KIT), DOG-1 and c-theta (PKCθ) protein. The diagnostic value of PKCθ in c-KIT/DOG-1 negative GISTs has been explored in fewer than 10 Medline-indexed papers.

RESULTS

The c-KIT, PKCθ and DOG-1 positivity was noted in 92.50% (n = 74), 90% (n = 72) and 76.25% (n = 61) of the cases, respectively. All of the C-KIT negative cases (n = 6) were also DOG-1 negative but displayed PKCθ positivity. All of the DOG-1 positive cases (n = 61) also expressed c-KIT. No correlation between the examined markers and clinicopathological parameters was noted.

CONCLUSIONS

The PKCθ sensitivity is similar to c-KIT and superior to DOG-1 sensitivity. All of the c-KIT/DOG-1 negative GISTs seem to express PKCθ. For a proper diagnosis of GIST, the c-KIT/DOG-1/PKCθ panel should be used, with possible therapeutic but not prognostic value.