Nicoletta Bianchi

Elevated Expression of A3 Adenosine Receptors in Human Colorectal Cancer Is Reflected in Peripheral Blood Cells

Purpose: Adenosine is a ubiquitous nucleoside that accumulates at high levels in hypoxic regions of solid tumors, and A3 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 A3 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 A3 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 A3 receptor was higher in colon carcinomas as compared with normal mucosa originating from the same individuals (P < 0.05). Overexpression of A3 receptors at the protein level was confirmed by immunohistochemical studies, whereas no changes in A3 mRNA accumulation in tumors as compared with the corresponding normal tissue were revealed. The overexpression of A3 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 A3 receptors in circulating blood cells returned to normal after surgical resection for colorectal cancer. Conclusions: This study provides the first evidence that A3 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.

Induction of erythroid differentiation of human K562 cells by cisplatin analogs

Human leukemic K562 cells can be induced in vitro to erythroid differentiation by a variety of chemical compounds, including hemin, butyric acid, 5-azacytidine, and cytosine arabinoside. Differentiation of K562 cells is associated with an increase in the expression of embryo-fetal globin genes, such as the zeta-, epsilon-, and gamma-globin genes. Therefore, the K562 cell line has been proposed as a very useful in vitro model system for determining the therapeutic potential of new differentiating compounds as well as for studying the molecular mechanism(s) regulating changes in the expression of embryonic and fetal human globin genes. Inducers of erythroid differentiation that stimulate gamma-globin synthesis could be considered for possible use in the experimental therapy of hematological diseases associated with a failure in the expression of adult beta-globin genes. In this paper, we analyzed the effects of a series of cisplatin analogs on both cell growth and differentiation of K562 cells. Among seven cisplatin analogs studied, three were found to be potent inducers of erythroid differentiation. Erythroid differentiation was associated with an increase in the accumulation of (a) hemoglobins Gower 1 and Portland and (b) gamma-globin mRNA.

The DNA-binding drugs mithramycin and chromomycin are powerful inducers of erythroid differentiation of human K562 cells

The human leukaemic K562 cell line can be induced in vitro to undergo erythroid differentiation by a variety of chemical compounds, including haemin, butyric acid, 5‐azacytidine and cytosine arabinoside. Differentiation of K562 cells is associated with an increased expression of embryo‐fetal globin genes, such as the ζ, ε and γ globin genes. Therefore the K562 cell line has been proposed as a useful in vitro model system to determine the therapeutic potential of new differentiating compounds as well as to study the molecular mechanism(s) regulating changes in the expression of embryonic and fetal human globin genes. Inducers of erythroid differentiation which stimulate γ‐globin synthesis could be considered for possible use in the experimental therapy of those haematological diseases associated with a failure in the expression of adult β‐globin genes. In this paper we demonstrated that the G + C selective DNA‐binding drugs chromomycin and mithramycin were powerful inducers of erythroid differentiation of K562 cells. Erythroid differentiation was associated with an increase in the accumulation of (a) Hb Gower 1 and Hb Portland and (b) γ‐globin mRNA.

In vitro antiproliferative effects on human tumor cell lines of extracts from the Bangladeshi medicinal plant Aegle marmelos Correa

In the present paper we show that extracts from Aegle marmelos Correa are able to inhibit the in vitro proliferation of human tumor cell lines, including the leukemic K562, T-lymphoid Jurkat, B-lymphoid Raji, erythroleukemic HEL, melanoma Colo38, and breast cancer MCF7 and MDA-MB-231 cell lines. Molecules present within the studied Aegle marmelos C. extracts were identified by gas-chromatography/mass-spectrometry analysis; three derivatives (butyl p-tolyl sulfide, 6-methyl-4-chromanone and butylated hydroxyanisole) were found to exhibit strong activity in inhibiting in vitro cell growth of human K562 cells. The antiproliferative activity of these compounds was found to be comparable to that of known antitumor agents, including cisplatin, chromomycin, cytosine arabinoside and 5-fluorouracil. In addition, the antiproliferative activity of butyl-p-tolyl sulfide, 6-methyl-4-chromanone and 5-methoxypsolaren was associated to activation of the differentiation pattern of K562 cells.

Accumulation of γ‐globin mRNA and induction of erythroid differentiation after treatment of human leukaemic K562 cells with tallimustine

Human leukaemic K562 cells can be induced in vitro to erythroid differentiation by a variety of chemical compounds, including haemin, butyric acid, 5‐azacytidine, cytosine arabinoside, mithramycin and chromomycin, cisplatin and cisplatin analogues. Differentiation of K562 cells is associated with an increase of expression of embryo‐fetal globin genes, such as the ζ‐, ε‐ and γ‐globin genes. The K562 cell line has been proposed as a very useful in vitro model system to determine the therapeutic potential of new differentiating compounds as well as to study the molecular mechanism(s) regulating changes in the expression of embryonic and fetal human globin genes. Inducers of erythroid differentiation stimulating γ‐globin synthesis could be considered for possible use in the therapy of haematological diseases associated with a failure in the expression of normal β‐globin genes. We have analysed the effects of tallimustine and distamycin on cell growth and differentiation of K562 cells. The results demonstrated that tallimustine is a potent inducer, while distamycin is a weak inducer, of K562 cell erythroid differentiation. Erythroid differentiation was associated with an increase of accumulation of γ‐globin mRNA and of production of both haemoglobin (Hb) Gower 1 and Hb Portland. In addition, tallimustine‐mediated erythroid induction occurred in the presence of activation of the apoptotic pathway. The reasons for proposing tallimustine as an inducer of γ‐globin gene expression are strongly sustained by the finding that this compound stimulates fetal haemoglobin production in human erythroid precursor cells from normal subjects.

Accumulation of gamma-globin mRNA in human erythroid cells treated with angelicin

The aim of the present study was to determine whether angelicin is able to increase the expression of γ‐globin genes in human erythroid cells. Angelicin is structurally related to psoralens, a well‐known chemical class of photosensitizers used for their antiproliferative activity in treatment of different skin diseases (i.e., psoriasis and vitiligo). To verify the activity of angelicin, we employed two experimental cell systems, the human leukemic K562 cell line and the two‐phase liquid culture of human erythroid progenitors isolated from normal donors. The results of our investigation suggest that angelicin, compared with cytosine arabinoside, mithramycin and cisplatin, is a powerful inducer of erythroid differentiation and γ‐globin mRNA accumulation of human leukemia K562 cells. In addition, when normal human erythroid precursors were cultured in the presence of angelicin, increases of γ‐globin mRNA accumulation and fetal hemoglobin (HbF) production, even higher than those obtained using hydroxyurea, were detected. These results could have practical relevance, as pharmacologically‐mediated regulation of the expression of human γ‐globin genes, leading to HbF induction, is considered a potential therapeutic approach in hematological disorders, including β‐thalassemia and sickle cell anemia.

Transcription Factor Decoy Molecules Based on a Peptide Nucleic Acid (PNA)-DNA Chimera Mimicking Sp1 Binding Sites

Peptide nucleic acids (PNAs) are DNA-mimicking molecules in which the sugar-phosphate backbone is replaced by a pseudopeptide backbone composed of N-(2-aminoethyl)glycine units. We determined whether double-stranded molecules based on PNAs and PNA-DNA-PNA (PDP) chimeras could be capable of stable interactions with nuclear proteins belonging to the Sp1 transcription factor family and, therefore, could act as decoy reagents able to inhibit molecular interactions between Sp1 and DNA. Since the structure of PNA/PNA hybrids is very different from that of the DNA/DNA double helix, they could theoretically alter the molecular structure of the double-stranded PNA-DNA-PNA chimeras, perturbing interactions with specific transcription factors. We found that PNA-based hybrids do not inhibit Sp1/DNA interactions. In contrast, hybrid molecules based on PNA-DNA-PNA chimeras are very effective decoy molecules, encouraging further experiments focused on the possible use of these molecules for the development of potential agents for a decoy approach in gene therapy. In this respect, the finding that PDP-based decoy molecules are more resistant than DNA/DNA hybrids to enzymatic degradation appears to be of great interest. Furthermore, their resistance can even be improved after complexation with cationic liposomes to which PDP/PDP chimeras are able to bind by virtue of their internal DNA structure.

Interaction of the Human NF-κB p52 Transcription Factor with DNA-PNA Hybrids Mimicking the NF-κB Binding Sites of the Human Immunodeficiency Virus Type 1 Promoter

We determined whether peptide nucleic acids (PNAs) are able to interact with NF-κB p52 transcription factor. The binding of NF-κB p52 to DNA-DNA, DNA-PNA, PNA-DNA, and PNA-PNA hybrid molecules carrying the NF-κB binding sites of human immunodeficiency type 1 long terminal repeat was studied by (i) biospecific interaction analysis (BIA) using surface plasmon resonance technology, (ii) electrophoretic mobility shift, (iii) DNase I footprinting, and (iv) UV cross-linking assays. Our results demonstrate that NF-κB p52 does not efficiently bind to PNA-PNA hybrids. However, a DNA-PNA hybrid molecule was found to be recognized by NF-κB p52, although the molecular complexes generated exhibited low stability. From the theoretical point of view, our results suggest that binding of NF-κB p52 protein to target DNA motifs is mainly due to contacts with bases; interactions with the DNA backbone are, however, important for stabilization of the protein-DNA complex. From the practical point of view, our results suggest that DNA-PNA hybrid can be recognized by NF-κB p52 protein, although with an efficiency lower than DNA-DNA NF-κB target molecules; therefore, our results should encourage studies on modified PNAs in order to develop potential agents for the decoy approach in gene therapy.

Targeting microRNAs involved in human diseases: a novel approach for modification of gene expression and drug development.

The identification of all epigenetic modifications (i.e. DNA methylation, histone modifications and expression of noncoding RNAs such as microRNAs) involved in gene regulation is one of the major steps forward for understanding human biology in both normal and pathological conditions and for development of novel drugs. In this context, microRNAs play a pivotal role. This review article focuses on the involvement of microRNAs in the regulation of gene expression, on the possible role of microRNAs in the onset and development of human pathologies, and on the pharmacological alteration of the biological activity of microRNAs. RNA and DNA analogs, which can selectively target microRNAs using Watson-Crick base pairing schemes, provide a rational and efficient way to modulate gene expression. These compounds, termed antago-miR or anti-miR have been described in many examples in the recent literature and have proved to be able to perform regulatory as well as therapeutic functions. Among these, a still not fully exploited class is that of peptide nucleic acids (PNAs), promising tools for the inhibition of miRNA activity, with important applications in gene therapy and in drug development. PNAs targeting miR-122, miR-155 and miR-210 have already been developed and their biological effects studied both in vitro and in vivo.

Biosensor technology and surface plasmon resonance for real-time detection of HIV-1 genomic sequences amplified by polymerase chain reaction.

BACKGROUND The recent development of biosensor technologies for biospecific interaction analysis enables the monitoring of a variety of molecular reactions in real time by surface plasmon resonance (SPR). If the ligand is a biotinylated single stranded DNA, this technology could monitor DNA-DNA hybridization. This approach could be of great interest in virology, since the hybridization step is oftenly required to confirm specificity of molecular diagnosis. OBJECTIVES To determine whether real-time molecular diagnosis of human immunodeficiency virus type I (HIV-1) could be performed using biosensors and SPR technology. STUDY DESIGN Specific hybridization of a biotinylated HIV-1 oligonucleotide probe immobilized on a sensor chip to single stranded DNA obtained by asymmetric polymerase-chain reaction (PCR) was determined using the BIAcore biosensor. RESULTS Direct injection of asymmetric PCR to a sensor chip carrying an internal HIV-1 oligonucleotide probe allows detection of hybridization by SPR using biosensor technology. This enabled us to apply a real-time, one-step, non-radioactive protocol to demonstrate the specificity of amplification of HIV-1 genomic sequences by PCR. CONCLUSION The procedure described in this study for HIV-1 detection is simple, fast (PCR and SPR analyses take 30 min), reproducible and could be proposed as an integral part of automated diagnostic systems based on the use of laboratory workstations and biosensors for DNA isolation, preparation of PCR reactions and analysis of PCR products.