Galbanic Acid Improves Accumulation and Toxicity of Arsenic Trioxide in MT-2 Cells.

BACKGROUND: Galbanic acid (GBA) is a sesquiterpene coumarin with valuable pharmacological effects. Adult T-cell lymphoma (ATL) is an aggressive lymphoid malignancy with a low survival rate. Although arsenic trioxide (ATO) is a standard therapeutic agent for ATL treatment, the efficacy of chemotherapy is limited due to the chemoresistance of cells. OBJECTIVE: The present study was carried out to investigate whether GBA in combination with ATO would improve cytotoxicity against ATL cells. METHODS: GBA was isolated from the roots of Ferula szowitsiana by column chromatography on silica gel. MT-2 cells were treated with 20 µM GBA + 4 µM ATO, and viability was evaluated by alamarBlue assay. The cell cycle was analyzed by PI staining, while the activity of P-glycoprotein (P-gp) was evaluated by mitoxantrone efflux assay. To understand the molecular mechanisms of GBA effects, the expression of NF-κB (RelA), P53, CDK4, c-MYC, c-FLIPL, and c-FLIPS was evaluated using real-time PCR. RESULTS: Combinatorial use of GBA + ATO significantly reduced the viability of MT-2 cells and induced cell cycle arrest in the sub-G1 phase. GBA improved mitoxantrone accumulation in cells, indicating that this agent has inhibitory effects on the functionality of the P-gp efflux pump. Moreover, real-time PCR analysis revealed that GBA + ATO negatively regulated the expression of P53, CDK4, c-FLIPL, and c-FLIPS. CONCLUSION: Due to the interesting effects of GBA on the accumulation and toxicity of ATO, combinatorial use of these agents could be considered a new therapeutic approach for ATL treatment.

The Emerging Roles of Aldehyde Dehydrogenase in Acute Myeloid Leukemia and Its Therapeutic Potential.

Acute myeloid leukemia (AML) is a malignant disorder characterized by myeloid differentiation arrest and uncontrolled clonal expansion of abnormal myeloid progenitor cells. AML is the most common malignant bone marrow (BM) disease in adults and accounts for approximately 80% of adult leukemia cases. There has been little improvement in the treatment of patients with AML over the past decade. Cytogenetic and morphologic heterogeneity of AML and the difficulty in distinguishing leukemic stem cells (LSCs) from normal hematopoietic stem cells (HSCs) continue to be the major challenges in treating this malignancy. In recent years, intensive efforts have been made to explore novel potential markers for the efficient identification and characterization of leukemic stem cells. Aldehyde dehydrogenase (ALDH) is a potential target molecule that plays crucial roles in leukemic stem cell survival and multidrug resistance, mainly through its involvement in the detoxification of many endogenous and exogenous aldehydes. The selection and isolation of cancer stem cells based on high ALDH activity seem to be a useful approach in many human malignancies, especially leukemia. Moreover, it is worth mentioning that several previous studies have indicated that a high ALDH activity (classified as ALDHbr cells in flow cytometry) can act as an independent prognostic factor in several types of cancer. In the present review, we update and critically discuss the available data regarding the importance of ALDH activity in normal and leukemic stem cells and its potential diagnostic and therapeutic implications.

Radiation Response of Human Leukemia/Lymphoma Cells was Improved by 7-Geranyloxycoumarin.

Objectives: Adult T-cell leukemia/lymphoma (ATLL) is a blood neoplasm with specific geographic distribution. Although radiotherapy is a palliative treatment that provides long-term local control, single use of radiation leads to complications for patients. To introduce a novel multimodal approach against ATLL, we investigated combinatorial effects of 7-geranyloxycoumarin and radiation in vitro. Methods: Viability of MT-2 cells was determined by resazurin assay upon administration of 7-geranyloxycoumarin alone and followed by radiation. Then, apoptosis was detected by annexin V and propidium iodide, and the expression of candidate genes was analyzed by qPCR. Results: Findings revealed significant (P<.0001) improvement in radiation effects upon 7-geranyloxycoumarin pretreatment, most notably when cells were pretreated with 5 µg/ml 7-geranyloxycoumarin for 96 h, exposed to 6 Gy radiation and recovered for 48 h. These results were confirmed by flow cytometry, as the percentage of early and late apoptotic cells was increased after combinatorial treatment. In addition, significant (P< .0001) changes in CD44, c-MYC, cFLIPL, BMI-1, NF-κB (Rel A), and P53 expression was induced by 7-geranyloxycoumarin and radiation. Conclusions: Current research indicated, for the first time, that combinatorial use of 7-geranyloxycoumarin and ionizing radiation could be considered as an effective therapeutic modality for ATLL.

Comparing toxicity of galbanic acid, auraptene and umbelliprenin on adult T-cell leukaemia-lymphoma in normoxia and hypoxia.

Natural coumarins are valuable agents that induce anticancer effects and/or enhance sensitivity to therapeutic modalities. Galbanic acid (GBA), auraptene (AUR) and umbelliprenin (UMB) are coumarins derived from Ferula species with various pharmaceutical activities. The aim of the current research was to compare toxic effects of GBA, AUR, and UMB on human lymphoma cells in normoxia and hypoxia. In this regard, GBA and AUR were extracted from the roots of F. szowitsiana and UMB was derived from the roots of F. persica, all by thin-layer chromatography. MT-2 cells were treated with each agent for 3 consequent periods, while exposed to different O2 contents (21% and 2%). By the end of each treatment, the viability of MT-2 cells was determined by resazurin dye-based colorimetric assay. Obtained results revealed that low doses of GBA (10 and 20 µM) induced significant (p < 0.0001) toxic effects in hypoxia. However, similar toxicity was observed when cells were treated with 40 µM AUR in normoxia and hypoxia. Notably, UMB was the only coumarin that exerted cytotoxic effects in all time points (48, 72 and 96 h) in normoxia and hypoxia, although its concentration was highest (80 µM). In conclusion, this is the first report indicating GBA was the most toxic coumarin against ATL cells in hypoxia, AUR induced similar effects in normoxia and hypoxia, and low toxicity of UMB was stable during the time and different O2 contents. Future studies on other ATL cell lines are recommended to better evaluate the toxic effects of GBA, AUR and UMB in vitro.

Prognostic significance of ATM mutations in chronic lymphocytic leukemia: A meta-analysis.

BACKGROUND: The ATM protein acts as an essential part of the signal transduction pathway upstream of p53 which activates following induction of DNA double-strand breaks (DSBs) and leads to transcriptional proapoptotic genes activation that synchronizes DNA repair. AIM: Several studies have assessed the relationship between ATM mutations and the clinical prognosis in patients with chronic lymphocytic leukemia (CLL). However, its prognostic value has not yet been fully clarified. Hence, we aimed this meta-analysis to investigate the prognostic effect of ATM mutations in patients with CLL. METHOD: The selected clinical studies were extracted from various electronic databases such as PubMed, EMBASE, the Cochrane Library, and Web of Science. In our meta-analysis, Hazard Ratio (HRs) and 95 % confidence interval (CI) for overall survival (OS) were chosen to estimate the prognostic impact of ATM mutations and to compare ATM mutations to those with wild-type. RESULTS: A total of 1299 patients from seven studies were collected. The pooled HRs for OS recommended that patients with CLL had a poorer prognosis HR = 1.24 (95 % CI: 0.97-1.59). The incidence of ATM mutations was found 15.8 % in patients with CLL. Begg's and Egger's tests did not show any significant bias between studies. CONCLUSION: In conclusion, this meta-analysis indicated that ATM mutations were significantly associated with adverse prognostic effect in patients with CLL. However, a randomized controlled prospective study with a large number of patients with different types of ATM mutations is required to assert these results.