Friend or Foe: UCHL3 Mediated Carcinogenesis and Current Approaches in Small Molecule Inhibitors' Development.

As cancer continues to be one of the leading causes of death, various cancer treatments are being developed from traditional surgery to the more recent emergence of target therapy. However, therapy resistance is a restricting problem that needs to be overcome. Henceforth, the field of research shifts to new plausible drug targets, among which is the ubiquitin-proteasome system. This review is focused on the ubiquitin carboxyl-terminal hydrolase (UCH) protease family, which are members of Deubiquitinating enzymes (DUBs), specifically Ubiquitin carboxyl-terminal hydrolase L3 (UCHL3). DUBs regulate a broad array of regulatory processes, including cell-cycle progression, tissue development, and differentiation. DUBs are classified into seven subfamilies, including ubiquitin-specific proteases (USPs), JAB1/MPN/Mov34 metalloenzyme, ovarian tumor proteases (OTUs), Josephin and JAB1/MPN+(MJP), MIU-containing novel DUB (MINDY), zinc finger-containing ubiquitin peptidase 1 (ZUP1), and ubiquitin C-terminal hydrolases (UCHs). Having a significant role in tumorigenesis, UCHL3 is thus emerging as a therapeutic target. Knowing its involvement in cancer, it is important to understand the structure of UCHL3, its substrate specificity, and interaction to pave the way for the development of potential inhibitors. This review covers several directions of proteasome inhibitors drug discovery and small molecule inhibitors development.

Loss of the malignant phenotype of human neuroblastoma cells by a catalytically inactive dominant-negative hTERT mutant.

Telomerase, a ribonucleoprotein complex mainly composed of the reverse transcriptase catalytic subunit (human telomerase reverse transcriptase, hTERT) and the RNA component (hTR), is a key enzyme of cancer progression. That aggressive stage 4-neuroblastoma expressed high levels of telomerase activity, whereas favorable tumors had no or little telomerase expression and activity, prompted us to investigate the role of this enzyme in this tumor model of altered proliferation, neuronal differentiation, and apoptosis. A human MYCN-amplified neuroblastoma cell line (IGR-N-91) was engineered to stably express either the normal hTERT protein (WT-hTERT) or a catalytically inactive dominant-negative mutant of this protein (DN-hTERT). We showed that DN-hTERT expression inhibited the endogenous hTERT in the malignant neuroblasts without telomere shortening nor loss of in vitro proliferative capacity. Importantly, DN-hTERT expression induced major changes in cell morphology of neuroblasts that switched them from a neuronal to a substrate adherent phenotype, which was more prone to apoptosis and lost their tumorigenic properties in nude mice. These biologic effects arose from modifications in the expression of genes involved in both apoptosis and neuroblastoma biology. Taken together these results highlighted the functional relevance of noncanonical functions of hTERT in the determination of neuroblast cell fate. Therefore, our results envision new therapeutic strategies for metastatic neuroblastoma therapeutic management.

hTERT promotes imatinib resistance in chronic myeloid leukemia cells: therapeutic implications.

Imatinib mesylate has shown remarkable efficacy in the treatment of patients in the chronic phase of chronic myeloid leukemia. However, despite an overall significant hematological and cytogenetic response, imatinib therapy may favor the emergence of drug-resistant clones, ultimately leading to relapse. Some imatinib resistance mechanisms had not been fully elucidated yet. In this study we used sensitive and resistant sublines from a Bcr-Abl positive cell line to investigate the putative involvement of telomerase in the promotion of imatinib resistance. We showed that sensitivity to imatinib can be partly restored in imatinib-resistant cells by targeting telomerase expression, either by the introduction of a dominant-negative form of the catalytic protein subunit of the telomerase (hTERT) or by the treatment with all-trans-retinoic acid, a clinically used drug. Furthermore, we showed that hTERT overexpression favors the development of imatinib resistance through both its antiapoptotic and telomere maintenance functions. Therefore, combining antitelomerase strategies to imatinib treatment at the beginning of the treatment should be promoted to reduce the risk of imatinib resistance development and increase the probability of eradicating the disease.

Pattern of matrix metalloproteinases-9, P53 and BCL-2 proteins in Egyptian patients with pulmonary Mycobacterium tuberculosis.

Matrix metalloproteinases (MMPs) constitute a large family of enzymes that degrade extracellular matrix proteins (ECM). MMPs are implicated in different pathological conditions such as cancer. Bcl-2 and P53 are key controllers of programmed cell death (PCD) or apoptosis. The aim of the present study was to determine the MMP-9, P53 and Bcl-2 levels in Egyptian patients with Mycobacterium tuberculosis (MTB) (Group I) compared with healthy control individuals (Group II). The concentrations of serum MMP-9 were determined quantitatively using enzyme immunoassay (EIA). P53 and Bcl-2 levels were assayed by flow cytometric analysis using specific monoclones. MMP-9 level was significantly higher in MTB patients compared with healthy control. Similarly, P53 and Bcl-2 levels were increased in MTB patients compared with healthy ones. These data reflect the alteration of MMP-9 level during the course of MTB infection, accompanied with apparent dysregulation of cellular apoptosis as indicated by P53 and Bcl-2 over-expression.