Salinomycin inhibits Wnt signaling and selectively induces apoptosis in chronic lymphocytic leukemia cells

Salinomycin, an antibiotic potassium ionophore, has been reported recently to act as a selective breast cancer stem cell inhibitor, but the biochemical basis for its anticancer effects is not clear. The Wnt/β-catenin signal transduction pathway plays a central role in stem cell development, and its aberrant activation can cause cancer. In this study, we identified salinomycin as a potent inhibitor of the Wnt signaling cascade. In Wnt-transfected HEK293 cells, salinomycin blocked the phosphorylation of the Wnt coreceptor lipoprotein receptor related protein 6 (LRP6) and induced its degradation. Nigericin, another potassium ionophore with activity against cancer stem cells, exerted similar effects. In otherwise unmanipulated chronic lymphocytic leukemia cells with constitutive Wnt activation nanomolar concentrations of salinomycin down-regulated the expression of Wnt target genes such as LEF1, cyclin D1, and fibronectin, depressed LRP6 levels, and limited cell survival. Normal human peripheral blood lymphocytes resisted salinomycin toxicity. These results indicate that ionic changes induced by salinomycin and related drugs inhibit proximal Wnt signaling by interfering with LPR6 phosphorylation, and thus impair the survival of cells that depend on Wnt signaling at the plasma membrane.     

Production of β2-microglobulin by chronic lymphocytic leukaemia cells in vitro

The in vitro production of β₂-microglobulin (β₂m) by leukaemic cells was studied in 22 patients with chronic B-lymphocytic leukaemia (CLL). In addition, the concentration of β₂m in serum (S-β₂m) was determined and expressed as percent of the upper normal limit, after a correction for elevated S-Creatinine values. Patients with progressive disease usually had CLL cells with a high rate of in vitro synthesis and an increased S-β₂m. This was not found in patients with non-progressive disease. The in vitro synthesis of β₂m × the lymphocyte count correlated with S-β₂m in the total material (r = 0.65). The increased S-β₂m frequently observed in CLL may therefore originate from the tumour cells. Hence, S-β₂m is promising as a clinically useful tumour cell-associated marker in CLL.     

MTNR1B loss promotes chordoma recurrence by abrogating melatonin‐mediated β‐catenin signaling repression

Chordoma is an extremely rare malignant bone tumor with a high rate of relapse. While cancer stem cells (CSCs) are closely associated with tumor recurrence, which depend on its capacity to self‐renew and induce chemo‐/radioresistance, whether and how CSCs participate in chordoma recurrence remains unclear. The current study found that tumor cells in recurrent chordoma displayed more dedifferentiated CSC‐like properties than those in corresponding primary tumor tissues. Meanwhile, MTNR1B deletion along with melatonin receptor 1B (MTNR1B) down‐regulation was observed in recurrent chordoma. Further investigation revealed that activation of Gαi2 by MTNR1B upon melatonin stimulation could inhibit SRC kinase activity via recruiting CSK and SRC, increasing SRC Y530 phosphorylation, and decreasing SRC Y419 phosphorylation. This subsequently suppressed β‐catenin signaling and stemness via decreasing β‐catenin p‐Y86/Y333/Y654. However, MTNR1B loss in chordoma mediated increased CSC properties, chemoresistance, and tumor progression by releasing melatonin's repression of β‐catenin signaling. Clinically, MTNR1B deletion was found to correlate with patients’ survival. Together, our study establishes a novel convergence between melatonin and β‐catenin signaling pathways and reveals the significance of this cross talk in chordoma recurrence. Besides, we propose that MTNR1B is a potential biomarker for prediction of chordoma prognosis and selection of treatment options, and chordoma patients might benefit from targeting MTNR1B/Gαi2/SRC/β‐catenin axis.     

Advances in first‐line treatment of chronic lymphocytic leukemia: current recommendations on management and first‐line treatment by the German CLL Study Group (GCLLSG)

The management of patients with CLL is undergoing significant changes; during the last decade, the outcome of first‐line therapies has been markedly improved with the addition of anti‐CD20 antibodies to chemotherapy. Today, chemoimmunotherapy for physically fit patients ≤65 years should consist of fludarabine, cyclophosphamide, and rituximab (FCR). The combination of bendamustine and rituximab (BR) should be considered in physically fit patients >65 years and in patients with a higher risk of infections. Patients with reduced fitness and/or relevant comorbidity should receive chlorambucil with a CD20 antibody, preferably obinutuzumab. Regardless of their fitness, patients with CLL carrying genetic aberrations such as del(17p) and/or TP53 mutation poorly respond to chemoimmunotherapy and therefore require different therapeutic approaches. An increasing understanding of the disease biology has led to the development of targeted drugs for the treatment of CLL, such as the BTK inhibitor ibrutinib and PI3K inhibitor idelalisib. These agents have shown efficacy in high‐risk and relapsed/refractory patients and are currently being evaluated in clinical trials for first‐line therapy. It is anticipated that these compounds and further other novel agents will profoundly change the therapy of CLL.     

Effect of peroxisome proliferator‐activated receptors‐γ and co‐activator‐1α genetic polymorphisms on plasma adiponectin levels and susceptibility of non‐alcoholic fatty liver disease in Chinese people

Background/Aims: Peroxisome proliferator‐activated receptors‐γ (PPAR‐γ) and its co‐activator‐1α (PGC‐1α) are involved in the regulation of lipid and glucose metabolisms. This study aimed to investigate the genetic polymorphisms of PPAR‐γ and PGC‐1α in Chinese people and their influence on plasma adiponectin levels and non‐alcoholic fatty liver disease (NAFLD) susceptibility. Methods: Ninety‐six patients with NAFLD and 96 healthy controls were included. The single nucleotide polymorphisms (SNPs) of C161T PPAR‐γand Gly482Ser PGC‐1α genes were analysed by polymerase chain reaction and restriction fragment length polymorphism. Result: The CC, CT and TT genotypic distributions of the NAFLD group were significantly different from those of controls (55.2, 39.6, 5.2 vs. 74.0, 25.0, 1.0%; P=0.015). The allelic frequencies of C and T were also different between the two groups (P=0.004). As for the PGC‐1α gene, there was no difference of the genotypic and allelic frequencies between the two groups (P>0.05). In NAFLD patients, the plasma adiponectin concentrations were lower in the PPAR‐γ CT/TT genotypes compared with those in the CC genotype group (3.0±0.6 vs. 4.3±0.9, P=0.02). Multivariate logistic regression analysis showed that CT/TT genotypes of PPAR‐γ, TG, waist hip ratio, hypoadiponectinaemia and homoeostasis model assessment (HOMA)‐IR were the risk factors for NAFLD. Conclusion: SNPs in the PPAR‐γ, but not PGC‐1α, gene are associated with NAFLD susceptibility possibly through the adiponectin pathway.     

Effects of 1‐O‐hexyl‐2,3,5‐trimethylhydroquinone on carbon tetrachloride‐induced hepatic cirrhosis in rats

Aim: The present study was undertaken to evaluate the effects of 1‐O‐hexyl‐2,3,5‐trimethylhydroquinone (HTHQ), a synthesized vitamin E derivative, on carbon tetrachloride (CCl₄)‐induced cirrhosis. Methods: Rats were treated with hypodermic injections of CCl₄ twice a week to induce the hepatic cirrhosis, and given drinking water containing HTHQ or solvent. Primary cultures of rat hepatocytes were performed to evaluate the effects of HTHQ on the expression of inducible nitric oxide synthase (iNOS). Results: Masson's staining of rat livers showed fibrosis around pseudo‐lobules in the CCl₄ group, the lesions being reduced in the CCl₄ HTHQ group. Increases in liver tissue hydroxyproline and α₁(I) collagen, α‐smooth muscle actin and iNOS induced by CCl₄, were also markedly diminished by HTHQ. Furthermore, both HTHQ and vitamin E attenuated interleukin‐1β‐induced iNOS protein expression in cultured hepatocytes, the potency of HTHQ being 10‐times higher than that of vitamin E. Conclusion: HTHQ may inhibit development of hepatic cirrhosis in rats, more potently than vitamin E, by inhibiting the iNOS expression in hepatocytes. Because vitamin E has a radical scavenging action, roles of NO and peroxynitrite will be discussed in the effects of HTHQ on the fibrosis.     

Polyphyllin I induces cell cycle arrest and apoptosis in human myeloma cells via modulating β‐catenin signaling pathway

Multiple myeloma (MM) is an indolent B‐cell disease characterized by clonal proliferation of malignant plasma cells. Multiple myeloma remains incurable despite new targeted drugs and development of drug resistance or intolerable toxicity emerges as a major problem. Therefore, design, identification, and validation of novel chemicals with therapeutic potential are clearly needed for MM treatment. Here, we explore polyphyllin I (PPI), a major active constituent extracted from Paris polyphyllin, its inhibitory effects and its mechanisms in MM cells in vitro. We found that PPI inhibited the proliferation of myeloma cells. The combination of PPI with dexamethasone, doxorubicin, arsenic trioxide, or bortezomib enhanced the inhibition of cell growth. As analyzed by flow cytometry, MM cells were arrested at G2/M phase and apoptotic cells increased in a time‐dependent manner. Morphological changes of cells undergoing apoptosis were observed under light microscope. To explore the mechanism of apoptosis induced by PPI, we next examined whether the Wingless‐Int (Wnt)/β‐catenin signaling pathway played a role in the PPI‐induced growth inhibition in MM cells. The canonical Wnt signaling pathway is activated in MM cells through constitutively active β‐catenin, a messenger molecule relevant to growth, survival, and migration of MM cells. Western blotting was used to measure the protein levels of β‐catenin, and PPI treatment led to downregulating the expression of β‐catenin protein and was followed by inhibition of β‐catenin nuclear localization. As a result, β‐catenin downstream targets, such as cyclin D1 and survivin, were downregulated. To the best of our knowledge, this is the first report identifying anti‐proliferative potency of PPI against myeloma cells. PPI blocks β‐catenin nuclear translocation and decreasing expression of the downstream targets of β‐catenin. Our results suggest that PPI is a novel inhibitor of β‐catenin activity with potential anti‐myeloma efficacy.     

Laboratory diagnosis of a compound heterozygosity for Hb Hekinan [α27(B8) Glu‐Asp] and a deletional α‐thalassaemia 2 in Thailand

We report the haematological and molecular characterization of a previously undescribed condition of compound heterozygosity for haemoglobin (Hb) Hekinan [α27(B8) Glu‐Asp] and a deletional α‐thalassaemia 2 detected in a Thai individual. Hb analysis demonstrated that although this Hb variant co‐migrates with Hb A on cellulose acetate electrophoresis and cation‐exchange high‐performance liquid chromatography (HPLC), the HPLC procedure using a weak cation‐exchange material with polyaspartic acid could clearly differentiate the two Hb. The variant could then be confirmed using the polymerase chain reaction‐restriction fragment‐length polymorphism (PCR‐RFLP) analysis of the amplified α1‐globin gene.     

Melatonin attenuates TNF‐α and IL‐1β expression in synovial fibroblasts and diminishes cartilage degradation: Implications for the treatment of rheumatoid arthritis

The hormone melatonin has many properties, including antioxidant, anti‐inflammatory, and immunomodulatory effects. Melatonin has been demonstrated to be beneficial in several inflammatory autoimmune diseases, but its effects in rheumatoid arthritis (RA) remain controversial. We sought to determine how melatonin regulates inflammation in RA. We found that melatonin dose‐dependently inhibits tumor necrosis factor‐α (TNF‐α) and interleukin (IL)‐1β expression through the PI3K/AKT, ERK, and NF‐κB signaling pathways. We also identified that melatonin inhibits TNF‐α and IL‐1β production by upregulating miR‐3150a‐3p expression. Synovial tissue specimens from RA patients and culture of human rheumatoid fibroblast‐like synoviocytes confirmed that the MT1 receptor is needed for the anti‐inflammatory activities of melatonin. Importantly, melatonin also significantly reduced paw swelling, cartilage degradation, and bone erosion in the collagen‐induced arthritis mouse model. Our results indicate that melatonin ameliorates RA by inhibiting TNF‐α and IL‐1β production through downregulation of the PI3K/AKT, ERK, NF‐κB signaling pathways, as well as miR‐3150a‐3p overexpression. The role of melatonin as an adjuvant treatment in patients with RA deserves further clinical studies.