Isabella Tognarini

Osteogenic Differentiation of Human Adipose Tissue-Derived Stem Cells Is Modulated by the miR-26a Targeting of the SMAD1 Transcription Factor†‡

The molecular mechanisms that regulate hADSC differentiation toward osteogenic precursors and subsequent bone‐forming osteoblasts is unknown. Using osteoblast precursors obtained from subcutaneous human adipose tissue, we observed that microRNA‐26a modulated late osteoblasts differentiation by targeting the SMAD1 transcription factor.

Multiple endocrine neoplasia type 2.

Multiple Endocrine Neoplasia Type 2 (MEN2) is a rare hereditary complex disorder characterized by the presence of medullary thyroid carcinoma (MTC), unilateral or bilateral pheochromocytoma (PHEO) and other hyperplasia and/or neoplasia of different endocrine tissues within a single patient. MEN2 has been reported in approximately 500 to 1000 families worldwide and the prevalence has been estimated at approximately 1:30,000. Two different forms, sporadic and familial, have been described for MEN2. Sporadic form is represented by a case with two of the principal MEN2-related endocrine tumors. The familial form, which is more frequent and with an autosomal pattern of inheritance, consists of a MEN2 case with at least one first degree relative showing one of the characteristic endocrine tumors. Familial medullary thyroid carcinoma (FMTC) is a subtype of MEN2 in which the affected individuals develop only medullary thyroid carcinoma, without other clinical manifestations of MEN2. Predisposition to MEN2 is caused by germline activating mutations of the c-RET proto-oncogene on chromosome 10q11.2. The RET gene encodes a single-pass transmembrane tyrosine kinase that is the receptor for glial-derived neurotrophic growth factors. The combination of clinical and genetic investigations, together with the improved understanding of the molecular and clinical genetics of the syndrome, helps the diagnosis and treatment of patients. Currently, DNA testing makes possible the early detection of asymptomatic gene carriers, allowing to identify and treat the neoplastic lesions at an earlier stage. In particular, the identification of a strong genotype-phenotype correlation in MEN2 syndrome may enable a more individualized treatment for the patients, improving their quality of life. At present, surgical treatment offers the only chance of cure and therefore, early clinical and genetic detection and prophylactic surgery in subjects at risk are the main therapeutic goal.

The Regulatory Network Menin-MicroRNA 26a As a Possible Target for RNA-Based Therapy of Bone Diseases

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression, interplaying with transcription factors in complex regulatory networks. Menin is the product of the MEN1 oncosuppressor gene, responsible for multiple endocrine neoplasia type 1 syndrome. Recent data suggest that menin functions as a general regulator of transcription. Menin expression modulates mesenchymal cell commitment to the myogenic or osteogenic lineages. The microRNA 26a (miR-26a) modulates the expression of SMAD1 protein during the osteoblastic differentiation of human adipose tissue-derived stem cells (hADSCs). We used siRNA silencing against MEN1 mRNA and pre-miR-26 mimics to study the interplay between them and to investigate the interplay between menin and miR-26a as regulators of osteogenic differentiation in the hADSCs. We found that in hADSCs the siRNA-induced silencing of MEN1 mRNA resulted in a down regulation of miR-26a, with a consequent up-regulation of SMAD1 protein. Chromatin immunoprecipitation (ChIP) showed that menin occupies the miR-26-a gene promoter, thus inducing its expression and confirming that menin is a positive regulator of miR-26a. In conclusion, results from this study evidenced, for the first time, a direct interaction between menin transcription factor and miRNA, interaction that seems to play a pivotal role during the hADSCs osteogenesis, thus suggesting a novel target for bone disease RNA-based therapy.

Methodological models for in vitro amplification and maintenance of human articular chondrocytes from elderly patients.

Articular cartilage defects, an exceedingly common problem closely correlated with advancing age, is characterized by lack of spontaneous resolution because of the limited regenerative capacity of adult articular chondrocytes. Medical and surgical therapies yield unsatisfactory short-lasting results. Recently, cultured autologous chondrocytes have been proposed as a source to promote repair of deep cartilage defects. Despite encouraging preliminary results, this approach is not yet routinely applicable in clinical practice, but for young patients. One critical points is the isolation and ex vivo expansion of large enough number of differentiated articular chondrocytes. In general, human articular chondrocytes grown in monolayer cultures tend to undergo dedifferentiation. This reversible process produces morphological changes by which cells acquire fibroblast-like features, loosing typical functional characteristics, such as the ability to synthesize type II collagen. The aim of this study was to isolate human articular chondrocytes from elderly patients and to carefully characterize their morphological, proliferative, and differentiative features. Cells were morphologically analyzed by optic and transmission electron microscopy (TEM). Production of periodic acid-schiff (PAS)-positive cellular products and of type II collagen mRNA was monitored at different cellular passages. Typical chondrocytic characteristics were also studied in a suspension culture system with cells encapsulated in alginate-polylysine-alginate (APA) membranes. Results showed that human articular chondrocytes can be expanded in monolayers for several passages, and then microencapsulated, retaining their morphological and functional characteristics. The results obtained could contribute to optimize expansion and redifferentiation sequences for applying cartilage tissue engineering in the elderly patients.

Ribozyme-mediated compensatory induction of menin-oncosuppressor function in primary fibroblasts from MEN1 patients

Multiple endocrine neoplasia type 1 (MEN1) syndrome is characterized by the occurrence of tumors of parathyroids, neuroendocrine cells of the gastro-enteropancreatic tract and anterior pituitary. MEN1 gene encodes menin-oncosuppressor protein. Loss of heterozygosity at 11q13 is typical of MEN1 tumors. We have analyzed the MEN1 mRNA and menin expression in fibroblasts from normal skin biopsies and from MEN1 patients (two with a frameshift 738del4 (exon 3) mutation, introducing a premature stop codon, and an individual with an R460X (exon 10) nonsense mutation). The expression of full-length menin protein did not differ between MEN1 and normal fibroblasts. Wild-type alleles mRNAs were expressed in MEN1 patients, whereas mutant alleles were partially degraded by nonsense-mediated mRNA decay pathway, suggesting a mechanism of compensation for allelic loss by the up-regulation of wild-type menin expression at a post-transcriptional level. Small-interfering RNA silencing of the wild-type mRNA allele abolished menin compensation, whereas the ribozyme silencing of the MEN1-mutated mRNA allele resulted in strongly enhanced wild-type menin expression. Gel-retardation analysis showed that in vitro-specific RNA–protein complexes bound to MEN1 mRNA. These findings contribute to the understanding of tumorigenesis in MEN1, offering the basis for the development of RNA-based therapies in MEN1 gene mutation carriers.

Inhibition of in vitro growth and arrest in the G0/G1 phase of HCT8 line human colon cancer cells by kaempferide triglycoside from Dianthus caryophyllus

The effects of phytoestrogens have been studied in the hypothalamic‐pituitary‐gonadal axis and in various non‐gonadal targets. Epidemiologic and experimental evidence indicates a protective effect of phytoestrogens also in colorectal cancer. The mechanism through which estrogenic molecules control colorectal cancer tumorigenesis could possibly involve estrogen receptor β, the predominantly expressed estrogen receptor subtype in colon mucosa.

In vitro effects of oestrogens, antioestrogens and SERMs on pancreatic solid pseudopapillary neoplasm-derived primary cell culture

Background: Solid-pseudopapillary neoplasms of the pancreas (SPNs) are uncommon tumours usually frequent in young women. Although the pathogenesis of SPNs is uncertain a potential influence of the sex hormone milieu on the biology of these tumours has been suggested. The controversial expression of oestrogen receptors (ERs) in SPNs, provide a rationale for studying the effects of oestrogenic molecules on SPN development. Methods: The expression of a large series of hormonal ligands and receptors was evaluated in tissue specimens and in a primary cell culture (SPNC), obtained from a SPN in young female patient. The effects of 17β-oestradiol (17βE2), ICI 182,780 and tamoxifen (Tam) on cell replication and growth were examined. Results: We have established SPNC primary line. Immunocytochemical analysis was positive for vimentin, cyclin D1 and β-catenin and negative for cytokeratin, CD10 and neuroendocrine markers, in line with the immunostaining features of the tumoral tissue. Expression of ERα, ERβ and progesterone mRNAs was demonstrated in SPNC and tumor tissue. A proliferative and antiproliferative action of 17βE2 and Tam respectively were proved in SPNC. Conclusions: In conclusion, we provide the first direct evidence that oestrogenic molecules can influence proliferation of SPNC, offering future strategies in the control of this neoplasia via selective ER modulators.