Luisa Benerini Gatta

Partial V(D)J Recombination Activity Leads to Omenn Syndrome

Genomic rearrangement of the antigen receptor loci is initiated by the two lymphoid-specific proteins Rag-1 and Rag-2. Null mutations in either of the two proteins abrogate initiation of V(D)J recombination and cause severe combined immunodeficiency with complete absence of mature B and T lymphocytes. We report here that patients with Omenn syndrome, a severe immunodeficiency characterized by the presence of activated, anergic, oligoclonal T cells, hypereosinophilia, and high IgE levels, bear missense mutations in either the Rag-1 or Rag-2 genes that result in partial activity of the two proteins. Two of the amino acid substitutions map within the Rag-1 homeodomain and decrease DNA binding activity, while three others lower the efficiency of Rag-1/Rag-2 interaction. These findings provide evidence to indicate that the immunodeficiency manifested in patients with Omenn syndrome arises from mutations that decrease the efficiency of V(D)J recombination.

Inhibition of heme synthesis alters Amyloid Precursor Protein processing

Decay of mitochondria, energy failure and increased oxidative stress are features commonly detected in brains from Alzheimer’s disease (AD) patients. Recent findings indicate that neuronal heme deficiency may contribute to the appearance of those cytopathologies and potentially alter the course of AD. We repressed heme synthesis in cells by inhibiting ferrochelatase enzyme with small interfering RNA and N-methylprotoporphyrin IX. The treatments induced a severe perturbation of mitochondria and energy production, with decrease of the subunit II of Cytochrome c Oxidase, alteration of the membrane potential and a 50% reduction of intracellular ATP. The state and processing of the Amyloid Precursor Protein (APP) was also affected, with the appearance of APP aggregates and a significant decrease (30–40%) of sAPPα secretion, associated with perturbation of ADAM10 and TACE, enzymes involved in the α-secretase cleavage. The production of sAPPβ was increased, without augment of Amyloid β generation. Our findings strengthen the hypothesis that a reduced availability of heme may play a role in AD pathogenesis.

Transforming growth factor-beta1 induces microvascular abnormalities through a down-modulation of neural cell adhesion molecule in human hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a very angiogenic and malignant cancer. Conventional chemotherapy is poorly effective because of the abnormal structural organization of HCC-infiltrating vessels. In previous work, we demonstrated that HCC angiogenesis is driven by transforming growth factor beta-1(TGF-β1)/CD105 axis, stimulating liver-derived microvascular endothelial cells (Ld-MECs) migration. As TGF-β1 also affects mural cells (MCs) recruitment and maturation, we asked whether it may contribute to HCC-induced vascular abnormalities. HCC and adjacent non-neoplastic liver (nNL) biopsies obtained from 12 patients were analyzed by immunohistochemistry for angiogenic markers CD105, TGF-β1, CD44 and vascular endothelial growth factor-a (VEGFa) and for MC markers NG2, α-smooth muscle actin (αSMA) and neural cell adhesion molecule (NCAM). The same markers were also investigated by immunocytochemistry on cultured HCC-derived stromal cells (HCC-StCs) and nNL-derived StCs (nNL-StCs) isolated from the same liver biopsies. Angiogenic factors released by StCs were analyzed by ELISA and the interaction between StCs and Ld-MECs by adhesion assay. Compared with nNL, HCC biopsies showed increased angiogenic markers and αSMA that was localized in vessels. By contrast, NG2 and NCAM were substantially localized in tumor cells but absent in vessels and stroma. Cultured HCC-StCs showed less expression of NG2, αSMA and NCAM. They also demonstrated a lower capacity to release angiogenic factors and adhered on Ld-MECs. HCC-StCs and nNL-StCs treated with TGF-β1 or with of HepG2 (a human hepatoma cell line) derived conditioned medium (CM), down-modulated NCAM expression, whereas anti-NCAM antibodies significantly reduced the adhesion of StCs to Ld-MECs. By further blocking TGF-β1 with anti-TGF-β1 antibodies or with Ly-364947 (a specific inhibitor TGF-β1-receptor) adhesion to Ld-MECs and NCAM expression respectively was partially restored. TGF-β1 contributes to HCC-induced vascular alterations by affecting the interaction between HCC-StCs and Ld-MECs through a down-modulation of NCAM expression.

Diagnostic Implications of L1, p16, and Ki-67 Proteins and HPV DNA in Low-grade Cervical Intraepithelial Neoplasia

The expressions of p16, Ki-67, and L1 proteins and human papillomavirus DNA were investigated using polymerase chain reaction (HPV/PCR) and catalyzed signal-amplified colorimetric DNA in situ hybridization (CSAC/ISH) as potential molecular markers for the diagnosis and transforming potential of low cervical intraepithelial neoplasia (CIN1). Ki-67 and p16 protein expression increased linearly from control cases to more dysplastic cases (CIN1, CIN2, and CIN3), peaking in squamous cell carcinoma cases (P<0.05). In contrast, L1 expression was inversely correlated with malignant transformation. Patients with CIN1 were divided into 4 groups: L1–p16+, L1+p16–, L1–p16–, and L1+p16+, and the immunohistochemical results were combined with HPV/PCR, L1/PCR, and high-risk E6/E7 genome and CSAC/ISH data. Malignant transformation correlated with L1–p16+ patients (100% of CIN2, CIN3, and squamous cell carcinoma cases) and was evident in approximately 23% of CIN1 cases. In addition, the presence of HPV/DNA+ was evident in 52% of CIN1 cases, and within the L1–p16+ group. In 4 of 7 cases, the high-risk E6/E7 HPV genome was present and in 1 case it was integrated into the host DNA, as confirmed using CSAC/ISH. In patients with CIN1, investigating the presence of HPV/DNA using PCR and the presence of the high-risk E6/E7 genome is necessary to distinguish high-risk oncogenic patient groups from low-risk groups. This study highlights the importance of combining immunohistochemical analysis with HPV/PCR and CSAC/ISH to identify patients with CIN1 with a risk of neoplastic progression.

DNA sequence variations in the prolyl isomerase Pin1 gene and Alzheimer's disease

Senile plaques and neurofibrillary tangles (NFT) are the prominent lesions in the brain of Alzheimers disease (AD) patients. NFT are mainly composed of an abnormally phosphorylated form of tau protein, which has lost its function to bind microtubules and promote their assembly. Tau hyperphosphorylation critically decreases tau function and precedes neurodegeneration. The majority of tau phosphorylation sites are Ser/Thr-Pro motifs, which are known to exist in two distinct cis and trans conformations. The prolyl isomerase Pin1 catalyses the conversion of those conformations. Pin1 binds to tau specifically at the Thr231-Pro site and restores tau function, either by inducing conformational changes or facilitating dephosphorylation. It has been shown that Pin1 expression levels inversely correlate with the predicted vulnerability of different brain areas to neurodegeneration and soluble Pin1 is depleted in neurons from AD brains; furthermore, Pin1 knock-out mice develop signs and symptoms of tau-related pathologies late in life. It seems that Pin1 plays an important role in maintaining tau function, thereby preserving neuronal homeostasis and preventing age-dependent neurodegeneration. DNA sequence variations in Pin1 gene may affect its expression level or function and influence the individual risk for developing AD. We screened by denaturing high performance liquid chromatography the genomic DNA of 120 AD subjects and 134 age-matched controls and we found very few and rare sequence variations in the promoter region and in exons 2 and 3. We conclude that Pin1 is a very well conserved gene, whose rare nucleotide variations have no effect on the individual genetic risk for AD.

Association analysis between anterior-pharynx defective-1 genes polymorphisms and Alzheimer's disease.

Recent biological studies indicate the importance of anterior-pharynx defective-1 (APH-1) proteins in Alzheimers disease (AD) pathogenesis. We scanned APH-1 genes for the presence of sequence variations by denaturing high performance liquid chromatography and analyzed their distribution in an Italian sample of 113 AD patients and 132 controls. We found six different polymorphisms: three of them, all in APH-1b, predict an aminoacid substitution (T27I, V199L and F217L); the others are either silent or in non-coding regions. None of them is significantly associated with the disease; data stratification by the apolipoprotein E epsilon4 carrier status show a trend for coexistence of the transversion c+651T>G (F217L) with the epsilon4 allele. Our data suggest that polymorphisms in APH-1a/b coding regions are not linked with higher risk for sporadic AD in our Italian population sample.

Polymorphisms in the LOC387715/ARMS2 Putative Gene and the Risk for Alzheimer’s Disease

Background: Age-related macular degeneration (ARMD) and Alzheimer’s disease (AD) are neurodegenerative disorders that share a high prevalence among elderly people, the extracellular deposition of β-amyloid and the involvement of genetic factors in their aetiology. Genetic linkage with the chromosome regions 10q26 and 10q24–25 have been shown for ARMD and AD, respectively. The rs10490924 polymorphism, the major determinant of the 10q26 association with ARMD, determines the A69S substitution in the LOC387715/ARMS2 gene. Little information is available about the expression of the gene in humans. Methods: We analysed the expression of the gene by RT-PCR in the brain and we looked for nucleotide variations in the gene sequence by DHPLC. Results: We found specific gene transcripts in the hippocampus, cortex and cerebellum. The genetic analysis identified two other common variations, which determine the R3H change (rs10490923) and a premature stop codon (rs2736911), respectively. The analysis of their distribution in 213 AD patients and 149 controls revealed a trend for a reduced frequency of the variant allele of rs2736911 in AD patients (p = 0.038), with an odds ratio of 0.631. Conclusion: The LOC387715/ARMS2 gene is expressed in the human brain, and it may concur to the individual risk for AD.

Simultaneous fluorescence immunophenotyping and Her-2/neu genotyping (FICTION) in breast carcinoma candidates to target therapy.

The study of proto-oncogene Her-2/neu using the fluorescence in situ hybridization (FISH) technique in routinely paraffin-embedded formalin-fixed tissue has become commonplace over the past decade and mandatory among invasive breast cancer expressing a score 2+ by immunohistochemical analysis of c-erbB2 protein. The patient’s eligibility for treatment with the biological drug trastuzumab/herceptin is based on the evidence of a Her-2/neu proto-oncogene amplification (ratio Her-2/neu/CEP-17>2.2). However, although the exclusion is declared in the absence of Her-2/neu gene amplification (ratio Her-2/neu/CEP-17 <1.8) according to the American Society of Clinical Oncology/College of American Pathologists recommendations, there are borderline cases (1.82.2) that need to be investigated (eg, ductal carcinoma in situ with microinvasion, metastatic breast cancer). In such cases with Her-2/neu genetic heterogeneity it is difficult to count the nuclear signals in the areas of invasive tumor using fluorescence. The availability of a Fluorescence Immunophenotyping and Interphase Cytogenetics as a Tool for Investigation of Neoplasms technique, based on the simultaneous evaluation of immunostaining with anticytokeratins (CKAE1/AE3 and CK19), together with FISH for Her-2/neu gene status [it is therefore useful and of current applicability in breast cancer blocks (formalin-fixed and paraffin-embedded)], permits a more easy identification of even single neoplastic cells by immunofluorescence and then a better evaluation of Her-2/neu status gene by the FISH technique, as shown in our study.

Extreme variability of Her-2 expression in gastric cancer.

A 73-year-old man underwent curative resection of metastatic astric adenocarcinoma (GA). The tumour was first staged as pTNM 3 N2M0; subsequently the biopsies were immunostained with ercepTest (DAKOTM) for human epidermal growth factor recepor 2 (Her2) protein expression, and tested by Fluorescence In itu Hybridization (FISH, PathVysion) for Her2 gene amplification. er2 is an important biomarker for therapeutic assessment of astric and gastro-oesophageal junction metastatic tumours, and he monoclonal antibody trastuzumab is indicated for treatment f patients with Her2 protein over-expression and/or Her2 gene mplification. In our patient with gastric adenocarcinoma (Fig. 1A) Her2 xpression was negative (Fig. 1B) and Her2 gene was not amplied (Fig. 1C). However in one gland with severe dysplasia, (Fig. 1D) er2 expression was positive (2+) (Fig. 1E), and Her2 gene was mplified (Fig. 1F). In another block, (Fig. 2A) Her2 expression as also positive (2+) (Fig. 2B) and Her2 gene was amplified Fig. 2C). The patient was successfully treated with a cycle of trastuzumab nd is undergoing clinical follow-up. This case highlights the xtreme intratumoral heterogeneity of Her2 expression. Given the linical relevance of Her2 assessment, thorough immunostaining nalysis should always be performed.