Knockdown of Enhancer of Zeste Homolog 2 Affects mRNA Expression of Genes Involved in the Induction of Resistance to Apoptosis in MOLT-4 Cells.

BACKGROUND: The Enhancer of Zeste Homolog 2 (EZH2) is a subunit of the polycomb repressive complex 2 that silences the gene transcription via H3K27me3. Previous studies have shown that EZH2 has an important role in the induction of the resistance against the Tumor necrosis factor-Related Apoptosis-Inducing Ligand (TRAIL)-Induced Apoptosis (TIA) in some leukemia cells. OBJECTIVE: The aim of this study was to determine the effect of silencing EZH2 gene expression using RNA interference on the expression of death receptors 4 and 5 (DR4/5), Preferentially expressed Antigen in Melanoma (PRAME), and TRAIL human lymphoid leukemia MOLT-4 cells. METHODS: Quantitative RT-PCR was used to detect the EZH2 expression and other candidate genes following the siRNA knockdown in MOLT-4 cells. The toxicity of the EZH2 siRNA was evaluated using Annexin V/PI assay following the transfection of the cells by 80 pM EZH2 siRNA at 48 hours. RESULTS: Based on the flow-cytometry results, the EZH2 siRNA had no toxic effects on MOLT-4 cells. Also, the EZH2 inhibition increased the expression of DR4/5 but reduced the PRAME gene expression at the mRNA levels. Moreover, the EZH2 silencing could not change the TRAIL mRNA in the transfected cells. CONCLUSION: Our results revealed that the down-regulation of EZH2 in MOLT-4 cells was able to affect the expression of important genes involved in the induction of resistance against TIA. Hence, we suggest that the silencing of EZH2 using RNA interference can be an effective and safe approach to help defeat the MOLT-4 cell resistance against TIA.

Quercetin sensitizes human myeloid leukemia KG-1 cells against TRAIL-induced apoptosis.

INTRODUCTION: Acute myeloid leukemia (AML) is the most common acute leukemia in adults. Conventional treatments are associated with cytotoxicity and systemic side effects. Hence, efforts in the field of cancer treatment are focused on finding the strategies which can specifically target the tumor cells without affecting the normal cells. TNF-related apoptosis-inducing ligand (TRAIL) is a biological cytokine which has the mentioned specificity, but the resistance of some cancer cells limits its use as a therapeutic strategy. Recent studies have shown that quercetin (QUR) can be used as a sensitizing agent alongside with TRAIL. The present study showed that QUR can increase the effect of TRAIL-induced cytotoxicity in KG-1 cells. MATERIALS AND METHODS: In this descriptive study, the IC50 dose for QUR in the KG-1 cell line was first determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. Then, the cells were treated with TRAIL and QUR for 12, 24, and 48 hr. The rate of apoptosis was measured by Annexin V/propidium iodide assay. Also, the molecular evaluation of candidate genes was accomplished before and after the treatment. RESULTS: The results indicated that QUR could sensitize the KG-1 cells against the TRAIL-induced apoptosis. This outcome is achieved by increasing the messenger RNA expression levels of the death receptor genes and reducing the expression of antiapoptotic proteins, as well as decreasing the expression of the NF-κB subunit. CONCLUSION: Our findings suggest that QUR can sensitize the acute myeloid KG-1 cells against TRAIL. Moreover, the combinational therapy of these agents might promisingly improve the clinical efficacy of TRAIL in patients with AML.

TNF-related apoptosis-inducing ligand (TRAIL) as the potential therapeutic target in hematological malignancies.

Despite numerous attempts to find the treatment strategies that can selectively target the cancer cells, cancer still remains a major public health problem. Conventional cancer treatments such as chemo- and radio-therapies are associated with systemic toxicity and the risk of recurrence. Additionally, acquired or pre-existing resistance is the main problem of most therapies. TNF-related apoptosis-inducing ligand (TRAIL), a member of TNF superfamily, has significantly attracted the researchers to use it as an effective treatment strategy for cancer since it can preferentially induce apoptosis in a variety of primary tumor cells without affecting the adjacent normal cells. Recently, recombinant forms of TRAIL and the multiple agonists of its receptor have been evaluated in many cell lines and phase II clinical trials. Hence, we have tried to summarize the TRAIL-related therapies as a potential therapeutic option in hematological malignancies.

Screening for intermediate CGG alleles of FMR1 gene in male Iranian patients with Parkinsonism.

Male carriers of an expansion of CGG alleles (with 55-200 CGG repeats) in the FMR1 gene are affected with Fragile X-associated tremor/ataxia syndrome (FXTAS). On the other hand, individuals with Parkinson's disease (PD) or Parkinsonism spectrum disorders may have some clinical features that overlap with FXTAS. To investigate the possible association between PD and FMR1 expanded alleles, we screened a total of 154 male PD patients and 190 gender- and age-matched healthy control subjects from Iran. Eleven intermediate allele carriers (7.14 %) were detected among PD patients, compared with three carriers (1.57 %) among the controls (P = 0.01). No pre-mutation carriers were identified. Our results indicate that there is a potential association between FMR1 intermediate expanded alleles and PD.