Background: Parkinson's disease (PD) is a progressive neurodegenerative disorder which may be misdiagnosed with atypical conditions such as Multiple System Atrophy (MSA), due to overlapping clinical features. MicroRNAs (miRNAs) are small non-coding RNAs with a key role in post-transcriptional gene regulation. We hypothesized that identification of a distinct set of circulating miRNAs (cmiRNAs) could distinguish patients affected by PD from MSA and healthy individuals. Results. Using TaqMan Low Density Array technology, we analyzed 754 miRNAs and found 9 cmiRNAs differentially expressed in PD and MSA patients compared to healthy controls. We also validated a set of 4 differentially expressed cmiRNAs in PD and MSA patients vs. controls. More specifically, miR-339-5p was downregulated, whereas miR-223*, miR-324-3p, and mir-24 were upregulated in both diseases. We found cmiRNAs specifically deregulated in PD (downregulation of miR-30c and miR-148b) and in MSA (upregulation of miR-148b). Finally, comparing MSA and PD, we identified 3 upregulated cmiRNAs in MSA serum (miR-24, miR-34b, miR-148b). Conclusions. Our results suggest that cmiRNA signatures discriminate PD from MSA patients and healthy controls and may be considered specific, non-invasive biomarkers for differential diagnosis.

CD30 ligand (CD30L) is a type-II membrane glycoprotein capable of transducing signals leading to either cell death or proliferation through its specific counterstructure CD30. Although several lines of evidence indicate that CD30L plays a key role as a paracrine- or autocrine-acting surface molecule in the deregulated cytokine cascade of Hodgkin's disease, little is known regarding its distribution and biologic significance in other human hematopoietic malignancies. By analyzing tumor cells from 181 patients with RNA studies and immunostaining by the anti-CD30L monoclonal antibody M80, we were able to show that human hematopoietic malignancies of different lineage and maturation stage display a frequent and broad expression of the ligand. CD30L mRNA and surface protein were detected in 60% of acute myeloid leukemias (AMLs), 54% of B-lineage acute lymphoblastic leukemias (ALLs), and in a consistent fraction (68%) of B-cell lymphoproliferative disorders. In this latter group, hairy cell leukemia and high-grade B-cell non-Hodgkin's lymphoma (B-NHL) expressed a higher surface density of CD30L as compared with B-cell chronic lymphocytic leukemia and low-grade B-NHL. Purified plasmacells from a fraction of multiple myeloma patients also displayed CD30L mRNA and protein. A more restricted expression of CD30L was found in T-cell tumors that was mainly confined to neoplasms with an activated peripheral T-cell phenotype, such as T-cell prolymphocytic leukemia, peripheral T-NHL, and adult T-cell leukemia/lymphoma. In contrast, none of the T-lineage ALLs analyzed expressed the ligand. In AML, a high cellular density of CD30L was detected in French-American-British M3, M4, and M5 phenotypes, which are directly associated with the presence on tumor cells of certain surface structures, including the p55 interleukin-2 receptor α-chain, the αM (CD11b) chain of β2 integrins, and the intercellular adhesion molecule-1 (CD54). Analysis of normal hematopoietic cells evidenced that, in addition to circulating and tonsil B cells, a fraction of bone marrow myeloid precursors, erythroblasts, and subsets of megakaryocytes also express CD30L. Finally, we have shown that native CD30L expressed on primary leukemic cells is functionally active by triggering both mitogenic and antiproliferative signals on CD30+ target cells. As opposed to CD30L, only 10 of 181 primary tumors expressed CD30 mRNA or protein, rendering therefore unlikely a CD30-CD30L autocrine loop in human hematopoietic neoplasms. Taken together, our data indicate that CD30L is widely expressed from early to late stages of human hematopoiesis and suggest a regulatory role for this molecule in the interactions of normal and malignant hematopoietic cells with CD30+ immune effectors and/or microenvironmental accessory cells.

No abstract

Proline-rich homeobox (Prh) is a novel human homeobox-containing gene recently isolated from the CD34+ cell line KG-1A, and whose expression appears mainly restricted to hematopoietic tissues. To define the pattern of Prh expression within the human hematopoietic system, we have analyzed its constitutive expression in purified cells obtained from normal hematopoietic tissues, its levels of transcription in a number of leukemia/lymphoma cell lines representing different lineages and stages of hematolymphopoietic differentiation, and its regulation during in vitro maturation of human leukemic cell lines. Prh transcripts were not detected in leukemic cells of T-lymphoid lineage, irrespective of their maturation stage, and in resting or activated normal T cells from peripheral blood and lymphoid tissues. In contrast, high levels of Prh expression were shown in cells representing early stages of B lymphoid maturation, being maintained up to the level of circulating and tissue mature B cells. Terminal B-cell differentiation appeared to be conversely associated with the deactivation of the gene, since preplasmacytic and plasmocytoma cell lines were found not to express Prh mRNA. Prh transcripts were also shown in human cell lines of early myelomonocytic, erythromegakaryocytic, and preosteoclast phenotypes. Prh expression was lost upon in vitro differentiation of leukemic cell lines into mature monocyte-macrophages and megakaryocytes, whereas it was maintained or upregulated after induction of maturation to granulocytes and osteoclasts. Accordingly, circulating normal monocytes did not display Prh mRNA, which was conversely detected at high levels in purified normal granulocytes. Our data, which show that the acquisition of the differentiated phenotype is associated to Prh downregulation in certain hematopoietic cells but not in others, also suggest that a dysregulated expression of this gene might contribute to the process of leukemogenesis within specific cell lineages.