We report in this paper that the DNAbinding drug mithramycin is a potent inducer of ␥-globin mRNA accumulation and fetal hemoglobin (HbF) production in erythroid cells from healthy human subjects and ␤-thalassemia patients. Erythroid precursors derived from peripheral blood were grown in 2-phase liquid culture. In this procedure, early erythroid progenitors proliferate and differentiate during phase 1 (in the absence of erythropoietin) into late progenitors. In phase 2, in the presence of erythropoietin, the latter cells continue their proliferation and mature into Hb-containing orthochromatic normoblasts. Compounds were added on days 4 to 5 of phase 2 (when cells started to synthesize Hb), and cells were harvested on day 12. Accumulation of mRNAs for ␥-globin, ␤-globin, ␣-globin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and ␤-actin were measured by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR); induction of HbF was analyzed by high-performance liquid chromatography (HPLC) and, at cellular level, by flow cytometry. We demonstrated that mithramycin was able to up-regulate preferentially ␥-globin mRNA production and to increase HbF accumulation, the percentage of HbF-containing cells, and their IntroductionPharmacologically mediated regulation of the expression of the human ␥-globin genes could be of interest as a potential therapeutic approach for hematologic disorders, including ␤-thalassemia and sickle cell anemia. [1][2][3][4][5][6][7][8] It is well established, indeed, that increase of fetal hemoglobin (HbF) to 30% of the total hemoglobin (Hb) leads to a significant improvement of the clinical status of patients affected by these hematologic disorders. 1-3 Therefore, current research has been focused on screening of various agents, such as hormones, cytotoxic drugs, hemopoietic cytokines, and short fatty acids as agents capable of augmenting HbF levels in humans. [8][9][10][11][12][13] In this respect, DNA-binding drugs appear to be of great interest. 14,15 These agents are known to modify the formation of DNA/nuclear protein complexes and thereby control gene expression. [16][17][18][19][20][21][22] Our research group has recently demonstrated that tallimustine 16 and some cisplatin analogs, 15 as well as the guanosinecytosine (GC)-rich binders chromomycin and mithramycin (MTH), 14 are powerful inducers of erythroid differentiation of the human leukemic K562 cell line, suggesting that the pattern of erythroid differentiation and of ␥-globin gene expression could be influenced by treatment with DNA-binding drugs. Interestingly, while chromomycin binding to DNA generates stable complexes, MTH-DNA complexes are highly unstable. 23 This could explain the low toxicity of MTH as compared with chromomycin. 24 For this reason, MTH was proposed as a therapeutic agent in several neoplastic diseases (such as chronic myelogenous leukemia and testicular cancer), 25 in Paget disease, 26 and in pathologies associated with hypercalcemia. 27,28 The main issue of the present paper w...

Purpose: Adenosine is a ubiquitous nucleoside that accumulates at high levels in hypoxic regions of solid tumors, and A 3 adenosine receptors have been recently demonstrated to play a pivotal role in the adenosine-mediated inhibition of tumor cell proliferation. In the present work, we addressed the question of the putative relevance of A 3 subtypes in colorectal adenocarcinomas.Experimental Design: Seventy-three paired samples of tumor and surrounding peritumoral normal mucosa at a distance of 2 and 10 cm from the tumor and blood samples obtained from a cohort of 30 patients with colorectal cancer were investigated to determine the presence of A 3 receptors by means of binding, immunocytochemistry, and real-time reverse transcription-polymerase chain reaction studies.Results: As measured by receptor binding assays, the density of A 3 receptor was higher in colon carcinomas as compared with normal mucosa originating from the same individuals (P < 0.05). Overexpression of A 3 receptors at the protein level was confirmed by immunohistochemical studies, whereas no changes in A 3 mRNA accumulation in tumors as compared with the corresponding normal tissue were revealed. The overexpression of A 3 receptors in tumors was reflected in peripheral blood cells, where the density was approximately 3-fold higher compared with healthy subjects (P < 0.01). In a cohort of 10 patients studied longitudinally, expression of A 3 receptors in circulating blood cells returned to normal after surgical resection for colorectal cancer.Conclusions: This study provides the first evidence that A 3 receptor plays a role in colon tumorigenesis and, more importantly, can potentially be used as a diagnostic marker or a therapeutic target for colon cancer.

We studied the effects of rapamycin on cultures of erythroid progenitors derived from the peripheral blood of 10 beta-thalassaemia patients differing widely with respect to their potential to produce foetal haemoglobin (HbF). For this, we employed the two-phase liquid culture procedure for growing erythroid progenitors, high performance liquid chromatography for analysis of HbF production and reverse transcription polymerase chain reaction for quantification of the accumulation of globin mRNAs. The results demonstrated that rapamycin induced an increase of HbF in cultures from all the beta-thalassaemia patients studied and an increase of their overall Hb content/cell. The inducing effect of rapamycin was restricted to gamma-globin mRNA accumulation, being only minor for beta-globin and none for alpha-globin mRNAs. The ability of rapamycin to preferentially increase gamma-globin mRNA content and production of HbF in erythroid precursor cells from beta-thalassaemia patients is of great importance as this agent (also known as sirolimus or rapamune) is already in clinical use as an anti-rejection agent following kidney transplantation. These data suggest that rapamycin warrants further evaluation as a potential therapeutic drug in beta-thalassaemia and sickle cell anaemia.

MicroRNAs are a family of small noncoding RNAs regulating gene expression by sequence-selective mRNA targeting, leading to a translational repression or mRNA degradation. The oncomiR miR-221 is highly expressed in human gliomas, as confirmed in this study in samples of low and high grade gliomas, as well in the cell lines U251, U373 and T98G. In order to alter the biological functions of miR-221, a peptide nucleic acid targeting miR-221 (R8-PNA-a221) was produced, bearing a oligoarginine peptide (R8) to facilitate uptake by glioma cells. The effects of R8-PNA-a221 were analyzed in U251, U373 and T98G glioma cells and found to strongly inhibit miR-221. In addition, the effects of R8-PNA-a221 on p27(Kip1) (a target of miR-221) were analyzed in U251 and T98G cells by RT-qPCR and by Western blotting. No change of p27(Kip1) mRNA content occurs in U251 cells in the presence of PNA-a221 (lacking the R8 peptide), whereas significant increase of p27(Kip1) mRNA was observed with the R8-PNA-a221. These data were confirmed by Western blot assay. A clear increment of p27(Kip1) protein expression in the samples treated with R8-PNA-a221 was detected. In addition, R8-PNA-a221 was found able to increase TIMP3 expression (another target of miR-221) in T98G cells. These results suggest that PNAs against oncomiRNA miR-221 might be proposed for experimental treatment of human gliomas.

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