Immunohistochemical, pharmacovigilance, and omics analyses reveal the involvement of ATP-sensitive K+ channel subunits in cancers: role in drug–disease interactions

Background: ATP-sensitive-K+ channels (KATP) are involved in diseases, but their role in cancer is poorly described. Pituitary macroadenoma has been observed in Cantu’ syndrome (C.S.), which is associated with the gain-of-function mutations of the ABCC9 and KCNJ8 genes. We tested the role of the ABCC8/Sur1, ABCC9/Sur2A/B, KCNJ11/Kir6.2, and KCNJ8/Kir6.1 genes experimentally in a minoxidil-induced renal tumor in male rats and in the female canine breast cancer, a spontaneous animal model of disease, and in the pharmacovigilance and omics databases.Methods: We performed biopsies from renal tissues of male rats (N = 5) following a sub-chronic high dosing topical administration of minoxidil (0.777–77.7 mg/kg/day) and from breast tissues of female dogs for diagnosis (N = 23) that were analyzed by immunohistochemistry. Pharmacovigilance and omics data were extracted from EudraVigilance and omics databases, respectively.Results: An elevated immunohistochemical reactivity to Sur2A-mAb was detected in the cytosol of the Ki67+/G3 cells other than in the surface membrane in the minoxidil-induced renal tumor and the breast tumor samples. KCNJ11, KCNJ8, and ABCC9 genes are upregulated in cancers but ABCC8 is downregulated. The Kir6.2-Sur2A/B-channel opener minoxidil showed 23 case reports of breast cancer and one case of ovarian cancer in line with omics data reporting, respectively, and the negative and positive prognostic roles of the ABCC9 gene in these cancers. Sulfonylureas and glinides blocking the pancreatic Kir6.2-Sur1 subunits showed a higher risk for pancreatic cancer in line with the positive prognostic role of the ABCC8 gene but low risks for common cancers. Glibenclamide, repaglinide, and glimepiride show a lower cancer risk within the KATP channel blockers. The Kir6.2-Sur1 opener diazoxide shows no cancer reactions.Conclusion: An elevated expression of the Sur2A subunit was found in proliferating cells in two animal models of cancer. Immunohistochemistry/omics/pharmacovigilance data reveal the role of the Kir6.1/2-Sur2A/B subunits as a drug target in breast/renal cancers and in C.S

Zoledronic acid blocks overactive Kir6.1/SUR2-dependent KATP channels in skeletal muscle and osteoblasts in a murine model of Cantú syndrome

Cantú syndrome (CS) is caused by the gain of function mutations in th

Consequences of SUR2[A478V] mutation in skeletal muscle of murine model of Cantu syndrome

(1) Background: Cantu syndrome (CS) arises from gain-of-function (GOF) mutations in th

Consequences of SUR2[A478V] mutation in skeletal muscle of murine model of Cantu syndrome

(1) Background: Cantu syndrome (CS) arises from gain-of-function (GOF) mutations in th

ATP Sensitive Potassium Channels in the Skeletal Muscle Function: Involvement of the KCNJ11(Kir6.2) Gene in the Determination of Mechanical Warner Bratzer Shear Force

The ATP-sensitive K-channels (KATP) are distributed in the tissues coupling metabolism with K ions efflux. KATP subunits are encoded by KCNJ8 (Kir6.1), KCNJ11 (Kir6.2), ABCC8 (SUR1), and ABCC9 (SUR2) genes, alternative RNA splicing give rise to SUR variants that confer distinct physiological properties on the channel. An high expression/activity of the sarco-KATP channel is observed in various rat fast-twitch muscles, characterized by elevated muscle strength, while a low expression/activity is observed in the slow twitch muscles characterized by reduced strength and frailty. Down-regulation of the KATP subunits of fast-twitch fibers is found in conditions characterized by weakness and frailty. KCNJ11 gene knockout mice have reduced glycogen, lean phenotype, lower body fat, and weakness. KATP channel is also a sensor of muscle atrophy. The KCNJ11 gene is located on BTA15, close to a QTL for meat tenderness, it has also a role in glycogen storage, a key mechanism of the postmortem transformation of muscle into meat. The role of KCNJ11 gene in muscle function may underlie an effect of KCNJ11 genotypes on meat tenderness, as recently reported. The fiber phenotype and genotype are important in livestock production science. Quantitative traits including meat production and quality are influenced both by environment and genes. Molecular markers can play an important role in the genetic improvement of animals through breeding strategies. Many factors influence the muscle Warner-Bratzler shear force including breed, age, feeding, the biochemical, and functional parameters. The role of KCNJ11gene and related genes on muscle tenderness will be discussed in the present review

From Morocco to Italy: How Women's Bodies Reflect their Change of Residence

The body structure and nutritional status of Moroccan women who have immigrated to Italy are examined here in relation to changes in their alimentary behaviors and life-styles, and compared with those of women living in Morocco, who still retain a traditional rural life-style. It is known that the choice to migrate to a foreign country may not only lead to conflicting situations, when the people involved encounter socio-cultural contexts which are very different from those of their original countries, but such choices may also involve severe consequences for health and nutritional status, following changes in alimentary behaviors and life-styles. Among groups recently migrated to Italy, the Moroccan-community is an appropriate reference to highlight these effects. The choice to examine women as the focus of this survey allows extension of observations of their nutritional behavior to the whole family group. According to the bio-indicators examined here, groups of immigrant women are quite different from those remaining at home. The former show a considerable increase in weight, as assessed by both anthropometric and impedentiometric parameters. More than one-third of Moroccan immigrant women are obese, to an extent well beyond that of women in Morocco. The cause of this difference is ascribed to quantitative and qualitative changes induced after migration. Migrant women tend to adopt a mixed diet, which includes both traditional food and that typical of the host country. However, there is a considerable increase in the use of prepared foods, such as pasta, among farinaceous products, and meat, although vegetables and fruit are also consumed. Moroccan women consider both their socio-economic status and alimentary behavior as very private matters--an attitude which makes it difficult to recruit them for this kind of research. Future interventions require their preliminary acceptance and involvement in research aims, to demonstrate its great importance in improving the health status of present and future immigrants

Molecular structure and function of big calcium-activated potassium channels in skeletal muscle: Pharmacological perspectives

The large-conductance Ca2+-activated K+(BK) channel is broadly expressed in various mammalian cells and tissues such as neurons, skeletal muscles (sarco-BK), and smooth muscles. These channels are activated by changes in membrane electrical potential and by increases in the concentration of intracellular calcium ion (Ca2+). The BK channel is subjected to many mechanisms that add diversity to the BK channel α-subunit gene. These channels are indeed subject to alternative splicing, auxiliary subunits modulation, posttranslational modifications, and protein-protein interactions. BK channels can be modulated by diverse molecules that may induce either an increase or decrease in channel activity. The linkage of these channels to many intracellular metabolites and pathways, as well as their modulation by extracellular natural agents, have been found to be relevant in many physiological processes. BK channel diversity is obtained by means of alternative splicing and modulatory β- and γ-subunits. The association of the α-subunit with β- or with γ-subunits can change the BK channel phenotype, functional diversity, and pharmacological properties in different tissues. In the case of the skeletal muscle BK channel (sarco-BK channel), we established that the main mechanism regulating BK channel diversity is the alternative splicing of the KCNMA1/slo1 gene encoding for the α-subunit generating different splicing isoform in the muscle phenotypes. This finding helps to design molecules selectively targeting the skeletal muscle subtypes. The use of drugs selectively targeting the skeletal muscle BK channels is a promising strategy in the treatment of familial disorders affecting muscular skeletal apparatus including hyperkalemia and hypokalemia periodic paralysis

Antiproliferative effects of neuroprotective drugs targeting big Ca2+-activated K+ (BK) channel in the undifferentiated neuroblastoma cells

The big Ca2+-activated K+ (BK) channel has a role in regulating cell viability and survival in a variety of cells. The effects of drugs targeting the BK channels in neuronal and smooth muscle tissues in the human SH-SY5Y cell and mouse Neuro2A undifferentiated neuroblastoma cells have never been investigated. The expression/activity of BK channel subunits and the effects of the BK channel openers: acetazolamide (ACTZ) (10-7 - 2 × 10-4 M), resveratrol (RESV) (10-7 - 2 × 10-4 M), dichlorphenamide (DCP) (10-12 - 2 × 10-4 M), bendroflumethiazide (BFT) (10-9 - 10-5 M) and riluzole (RIL) (10-6 - 10-4 M) were evaluated by real time-polymerase chain reaction (RT-PCR)/patch-clamp experiments in SH-SY5Y cells and Neuro2a. Cell proliferation was evaluated by cell-dehydrogenase activity (CCK8-assay), cell impedentiometric (Scepter-counter) and clonogenic assays. An elevated expression/activity of the hslo1-BK channel subunit was observed in the SH-SY5Y, while a low expression/activity of this subunit was found in the Neuro2a. Tetraethylammonium (TEA) (1 - 5 x 10-3) and iberiotoxin (IbTX) (10-9 - 6 × 10-7 M) caused a marked inhibition of the whole-cell K+-currents in SH-SY5Y. A mild inhibition of the K+-currents was found in Neuro2a with these compounds. The application of ACTZ, DCP, RESV and BFT to the patches failed to activate the K+-currents but rather reduced it. The rank order of efficacy of the drugs as K+-current inhibitors at +30 mV (Vm) was: TEA > RESV ≥ IbTX > DCP > ACTZ > BFT. RESV and IbTX irreversibly reduced the K+-currents and the cell number in the enzymatic, clonogenic and impedentiometric assays with RESV being more effective than IbTX. TEA reversibly reduced the K+-currents without affecting cell proliferation. Whereas, RIL potentiated the BK current and reduced cell-dehydrogenases activity with no changes in the cell morphology and number. The observed irreversible BK channel-blocking action exerted by RESV and IbTX can be associated with anti-proliferative effects in cells overexpressing hslo1-BK channel subunit. This can be an additional mechanism contributing to the cytotoxic action of RESV in SH-SY5Y cells

Counteractions of a Novel Hydroalcoholic Extract from Lens Culinaria against the Dexamethasone-Induced Osteoblast Loss of Native Murine Cells

The cytoprotective effects of a novel hydroalcoholic extract (0.01–5 mg/mL) from Lens culinaria (Terre di Altamura Srl) were investigated within murine native skeletal muscle fibers, bone marrow cells, and osteoblasts, and in cell lines treated with the apoptotic agent staurosporine (2.14 × 10−6 M), the alkylating drug cisplatin (10−4 M), the topoisomerase I inhibitor irinotecan (10−4 M), the antimitotic pro-oxidant doxorubicin (10−6 M), and the immunosuppressant dexamethasone (2 × 10−6 M). An amount of 10g of plant material was used to obtain a 70% ethanol/water product, following two-step extraction, evaporation, lyophilization, and storage at −20 °C. For the murine osteoblasts, doxorubicin reduced survival by −65%, dexamethasone by −32% and −60% after 24 and 48 h of incubation time, respectively. The extract was effective in preventing the osteoblast count-reduction induced by dexamethasone; it was also effective at preventing the inhibition of mineralization induced by dexamethasone. Doxorubicin and cisplatin caused a significant reduction in cell growth by −77% for bone marrow cells, −43% for irinotecan, and −60% for dexamethasone, but there was no evidence for the cytoprotective effects of the extract in these cells. Staurosporine and doxorubicin caused a fiber death rate of >−40% after 18 and 24 h of incubation, yet the extract was not effective at preventing these effects. The extract was effective in preventing the staurosporine-induced reduction of HEK293 proliferation and colony formation in the crystal violet DNA staining and the clonogenic assays. It was also effective for the cisplatin-induced reduction in HEK293 cell proliferation. The extract, however, failed to protect the SHSY5Y neurons against cisplatin and irinotecan-induced cytotoxicity. A UV/VIS spectroscopy analysis showed three peaks at the wavelengths of 350, 260, and 190 nm, which correspond to flavonoids, proanthocyanins, salicylates, and AA, constituting the extract. These data suggest the possible development of this extract for use against dexamethasone-induced bone loss and renal chemotherapy-induced damage

Zoledronic Acid as a Novel Dual Blocker of KIR6.1/2-SUR2 Subunits of ATP-Sensitive K+ Channels: Role in the Adverse Drug Reactions

Zoledronic acid (ZOL) is used as a bone-specific antiresorptive drug with antimyeloma effects. Adverse drug reactions (A.D.R.) are associated with ZOL-therapy, whose mechanics are unknown. ZOL is a nitrogen-containing molecule whose structure shows similarities with nucleotides, ligands of ATP-sensitive K+ (KATP) channels. We investigated the action of ZOL by performing in vitro patch-clamp experiments on native KATP channels in murine skeletal muscle fibers, bone cells, and recombinant subunits in cell lines, and by in silico docking the nucleotide site on KIR and SUR, as well as the glibenclamide site. ZOL fully inhibited the KATP currents recorded in excised macro-patches from Extensor digitorum longus (EDL) and Soleus (SOL) muscle fibers with an IC50 of 1.2 ± 1.4 × 10−6 and 2.1 ± 3.7 × 10−10 M, respectively, and the KATP currents recorded in cell-attached patches from primary long bone cells with an IC50 of 1.6 ± 2.8 × 10−10 M. ZOL fully inhibited a whole-cell KATP channel current of recombinant KIR6.1-SUR2B and KIR6.2-SUR2A subunits expressed in HEK293 cells with an IC50 of 3.9 ± 2.7 × 10−10 M and 7.1 ± 3.1 × 10−6 M, respectively. The rank order of potency in inhibiting the KATP currents was: KIR6.1-SUR2B/SOL-KATP/osteoblast-KATP > KIR6.2-SUR2A/EDL-KATP >>> KIR6.2-SUR1 and KIR6.1-SUR1. Docking investigation revealed that the drug binds to the ADP/ATP sites on KIR6.1/2 and SUR2A/B and on the sulfonylureas site showing low binding energy <6 Kcal/mol for the KIR6.1/2-SUR2 subunits vs. the <4 Kcal/mol for the KIR6.2-SUR1. The IC50 of ZOL to inhibit the KIR6.1/2-SUR2A/B channels were correlated with its musculoskeletal and cardiovascular risks. We first showed that ZOL blocks at subnanomolar concentration musculoskeletal KATP channels and cardiac and vascular KIR6.2/1-SUR2 channels