Inhibition of Notch signaling induces apoptosis of myeloma cells and enhances sensitivity to chemotherapy

Drug resistance remains a critical problem in the treatment of patients with multiple myeloma. Recent studies have determined that Notch signaling plays a major role in bone marrow (BM) stroma-mediated protection of myeloma cells from de novo drug-induced apoptosis. Here, we investigated whether pharmacologic inhibition of Notch signaling could affect the viability of myeloma cells and their sensitivity to chemotherapy. Treatment with a gamma-secretase inhibitor (GSI) alone induced apoptosis of myeloma cells via specific inhibition of Notch signaling. At concentrations toxic for myeloma cell lines and primary myeloma cells, GSI did not affect normal BM or peripheral blood mononuclear cells. Treatment with GSI prevented BM stroma-mediated protection of myeloma cells from drug-induced apoptosis. The cytotoxic effect of GSI was mediated via Hes-1 and up-regulation of the proapoptotic protein Noxa. In vivo experiments using xenograft and SCID-hu models of multiple myeloma demonstrated substantial antitumor effect of GSI. In addition, GSI significantly improved the cytotoxicity of the chemotherapeutic drugs doxorubicin and melphalan. Thus, this study demonstrates that inhibition of Notch signaling prevents BM-mediated drug resistance and sensitizes myeloma cells to chemotherapy. This may represent a promising approach for therapeutic intervention in multiple myeloma.     

Molecular Characteristics,Clinical and Immunologic Manifestations of 11 Children with Omenn Syndrome in East Slavs (Russia,Belarus, Ukraine)

Background

Omenn syndrome [Mendelian Inheritance (OMIM 603554)] is a genetic disease of the immune system, characterized by the presence of fatal generalized severe erythroderma, lymphoadenopathy, eosinophilia and profound immunodeficiency.

Objective

We studied clinical and immunologic presentation of the disease manifestation among East Slavs population with genetically confirmed Omenn syndrome.

Results

We collected clinical and immunologic data of 11 patients (1 from Belarus, 5 – Ukraine, 5 – Russia): 6 females, 5 males. The age of Omenn syndrome manifestation varied from the 1st day of life to 1 year and 1 month, the age of diagnosis – 20 days to 1 year and 10 months. Nine out of 11 patients had classic immunologic phenotype T(+/?)B-NK+, 1 pt had TlowB + NK+ with CD3 + TCRgd + expansion and 1 had TlowB+/?NK+ phenotype. Eight out of 11 pts had mutation in RAG1 gene, 4 out of 8 had c.368-369delAA (p.K86fsX118) in homozygous state or heterozygous compound. In our cohort of patients, we also described two new mutations in RAG genes (p.E722Q in RAG1 and p.M459R in RAG2). At present, 7/11 were transplanted and 5 out of the transplanted are alive.

Conclusion

This study demonstrates that the most popular genetic abnormality in East Slavs children with Omenn syndrome is c.368-369delAA (p.K86fs118) in RAG1 gene, which may be connected with more favorable prognosis because 4/4 patients survived after hematopoietic stem cells transplantation.

     

Novel carbon-11 labeled 4-dimethylamino-but-2-enoic acid [4-(phenylamino)-quinazoline-6-yl]-amides: potential PET bioprobes for molecular imaging of EGFR-positive tumors

We have previously reported of labeled reversible and irreversible EGFR inhibitors, such as 4-(3,4-dichloro-6-fluoroanilino)-6,7-dimethoxyquinazoline (ML01) and 6-acrylamido-4-(3,4-dichloro-6-fluoroanilino)quinazoline (ML03), to be suboptimal as imaging agents. On the basis of these studies, a new generation of novel, more chemically stable irreversible inhibitors was labeled with carbon-11 as potential positron emission tomography (PET) biomarkers for molecular imaging of epidermal growth factor receptor (EGFR)-positive tumors. In these new labeled, irreversible inhibitors the acryl-amide group at the 6-position of the quinazoline ring was replaced with a 4-dimethylamino-but-2-enoic amide. The nonlabeled compounds were evaluated in vitro to determine their EGFR autophosphorylation IC(50) values. The IC(50) values indicated that these new irreversible compounds possess similar potencies towards the EGFR, as the parent compound, ML03. These compounds were labeled with carbon-11 at the dimethylamine moiety, using the well known labeling reagent C-11 MeI. The labeling procedure was automated using a commercial module. The final products were obtained with 10% decay corrected radiochemical yield, 99% radiochemical purity, 96% chemical purity, and a high specific activity of 2.7 Ci/micromol EOB. The high potency of these new labeled bioprobes towards the EGFR establishes their potential to serve as PET agents for molecular imaging of EGFR-positive tumors.     

Expression of Cyclophilin A in Gastric Adenocarcinoma Patients and Its Inverse Association with Local Relapses and Distant Metastasis

The aim of this study was to identify new protein markers of the intestinal and diffuse type gastric adenocarcinoma and to determine their relation to local relapses and distant metastasis. Using two-dimensional gel electrophoresis, we searched for proteins that are overexpressed in the intestinal and/or diffuse type gastric adenocarcinoma, as compared to matched normal mucosa samples with further change confirmation by Western blot. Expression of the selected proteins was further assessed by immunohistocemistry in a large panel of gastric adenocarcinoma with various clinicopathological features. Expression level of cyclophilin A measured with western blot appeared to be increased on average ten times in 63 % of gastric adenocarcinoma vs. paired samples of normal mucosa. The frequency of immunihistochemistry detected cyclophilin A protein expression was found to be equal in tumor of both histotypes, but staining intensity was higher in intestinal versus diffuse types of gastric adenocarcinoma. cyclophilin A protein expression appeared to be lower in deeply invading glandular and cribriform structures of intestinal tumors, as well as in discretely placed groups of the intestinal tumor cells. Local relapses as well as distant metastases registered within 3 year follow up were observed to occur much less frequently in patients with positive cyclophilin A immunostaining in gastric tumors. Analysis of cyclophilin A expression has a potential value for prognosis of gastric adenocarcinoma recurrence and distant metastasis.     

De novo reestablishment of gap junctional intercellular communications during reprogramming to pluripotency and differentiation

Gap junctional intercellular communication (GJIC) has been described in embryonic stem cells (ESCs) and various somatic cells. GJIC has been implicated in the regulation of cell proliferation, self-renewal, and differentiation. Recently, a new type of pluripotent stem cells was generated by direct reprogramming of somatic cells. Here, for the first time, we show that during reprogramming events GJIC is re-established upon reaching complete reprogramming. The opposite process of cell differentiation from the pluripotent state leads to the disruption of GJIC between pluripotent and differentiated cell subsets. However, GJIC is subsequently re-established de novo within each differentiated cell type in vitro, forming communication compartments within a histotype. Our results provide the important evidence that reestablisment of functional gap junctions to the level similar to human ESCs is an additional physiological characteristic of somatic cell reprogramming to the pluripotent state and differentiation to the specific cell type.     

Carboranes increase the potency of small molecule inhibitors of nicotinamide phosphoribosyltranferase

Herein we report the use of carboranes to significantly increase the potency of small molecule inhibitors of nicotinamide phosphoribosyltranferase (Nampt), an enzyme that is central to metabolism and cell survival. We compare the inclusion of carborane with other similarly sized substituents and demonstrate that, compared with their purely organic counterparts, these molecules exhibit up to 10-fold greater antiproliferative activity against cancer cells in vitro and a 100-fold increase in Nampt inhibition.