Licia Montagna

Aberrant Wnt/β-Catenin Pathway Activation in Idiopathic Pulmonary Fibrosis

To investigate the molecular events that may underpin dysfunctional repair processes that characterize idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP), we analyzed the expression patterns of β-catenin on 20 IPF/UIP lung samples, together with two downstream target genes of Wnt signaling, cyclin-D1, and matrilysin. In 18 of 20 cases of IPF/UIP investigated on serial sections, nuclear β-catenin immunoreactivity and abnormal levels of cyclin-D1 and matrilysin were demonstrated in proliferative bronchiolar lesions (basal-cell hyperplasia, squamous metaplasia, bronchiolization, honeycombing). The nature of these lesions was precisely defined using specific markers (ΔN-p63, surfactant-protein-A, cytokeratin-5). Interestingly, nuclear β-catenin accumulation was also demonstrated in fibroblast foci in most (16 of 20) IPF/UIP samples, often associated with bronchiolar lesions. Similar features were not observed in normal lung and other fibrosing pulmonary diseases (diffuse alveolar damage, organizing pneumonia, nonspecific interstitial pneumonia, desquamative interstitial pneumonia). Sequence analysis performed on DNA extracted from three samples of IPF/UIP did not reveal abnormalities affecting the β-catenin gene. On the basis of these findings new models for IPF/UIP pathogenesis can be hypothesized, centered on the aberrant activation of Wnt/β-catenin signaling, with eventual triggering of divergent epithelial regeneration at bronchiolo-alveolar junctions and epithelial-mesenchymal-transitions, leading to severe and irreversible remodeling of the pulmonary tissue.

Chronic lymphocytic leukemia B cells are endowed with the capacity to attract CD4+, CD40L+ T cells by producing CCL22.

The natural history of B‐chronic lymphocytic leukemia (CLL) is not entirely explained by intrinsic defects of the neoplastic cell, but is also favored by microenvironmental signals. As CLL cells retain the capacity to respond to CD40 ligand (CD40L) and as CD4+ T cells are always present in involved tissues, we asked whether malignant CLL cells might produce T cell‐attracting chemokines. We studied the chemokine expression of CD19+/CD5+ malignant B cells from peripheral blood (PB), lymph nodes (LN) or bone marrow (BM) of 32 patients and found a major difference. LN‐ and BM‐, but not PB‐derived cells, expressed a readily detectable reverse transcription‐PCR band for CCL22 and one for CCL17 of variable intensity. CD40 ligation of PB cells induced the mRNA expression of both CCL22 and CCL17. CCL22 was also released in the culture supernatants. These supernatants induced the migration of activated CD4+, CD40L+ T cells expressing the CCL22 receptor, CCR4. T cell migration was abrogated by anti‐CCL22 antibodies. Immunohistochemistry and cytofluorography studies revealed that a proportion of CD4+ T cells in CLL LN and BM expressed CD40L. Our data demonstrate that malignant CLL cells chemo‐attract CD4+ T cells that in turn induce a strong chemokine production by the leukemic clone, suggesting a vicious circle, leading to the progressive accumulation of the neoplastic cells.

Abnormal Re-epithelialization and Lung Remodeling in Idiopathic Pulmonary Fibrosis: The Role of ΔN-p63

Products of the p63 gene, a recently described member of the p53 family, are constitutively expressed in the basal cells of human bronchi and bronchioli. The truncated isoforms of the p63 gene (ΔN-p63 proteins) counteract the apoptotic and cell cycle inhibitory functions of p53 after DNA damage, and this property is likely to be central in the cell renewal strategy of stratified epithelial tissues. To investigate the dysfunctional repair processes that characterize idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP), we immunohistochemically analyzed the expression of the transactivating and dominant-negative isoforms of the p63 gene on 16 tissue samples obtained from patients suffering from this disorder. In most IPF cases herein investigated, epithelial cells expressing ΔN-p63 were observed at sites of abnormal proliferation at the bronchiolo-alveolar junctions, characterized by epithelial hyperplasia, squamous metaplasia, bronchiolization, and abnormal p53 nuclear accumulation. Similar features were not observed in normal lung and in samples taken from other pulmonary diseases used as controls, including acute interstitial pneumonia, idiopathic bronchiolitis obliterans organizing pneumonia, nonspecific interstitial pneumonia, and desquamative interstitial pneumonia. On the basis of these findings, we can hypothesize a new model for UIP pathogenesis, involving a deregulated development of mesenchymal-epithelial interactions and abnormal proliferation of epithelial cells at the bronchiolo-alveolar junction after cell injury. In our view, the progressive loss of alveolar tissue and lung remodeling after injury in IPF/UIP is concomitantly produced by pneumocyte loss and alveolar collapse on one hand and by progressive bronchiolar proliferation and architectural distortion on the other.

Pancreatic cancer spheres are more than just aggregates of stem marker-positive cells

Pancreatic cancer stem-like cells are described by membrane expression of CD24, CD44 and ESA (epithelial-specific antigen) and their capacity to grow as spheres in a serum-free medium containing well-defined growth factors. The capacity of a panel of four pancreatic cancer cell lines (PANC-1, CFPAC-1, PancTu-1 and PSN-1) to form spheres was tested. All cell lines with the exception of PancTu-1 developed spheres. Phenotypically, the sphere-growing cells showed an increased in vitro invasion capability. Both gene and protein expressions of markers of metastases [CXCR4 (CXC chemokine receptor 4), OPN (osteopontin) and CD44v6] and components of active hedgehog pathway signalling were assessed. Spheres clearly demonstrated increased expression of the above-mentioned markers when compared with their adherent counterpart. With the aim of identifying a minimum set of markers able to separate cells that have the capacity to form spheres from those incapable of forming spheres, a PCA (principal component analysis) of the multidimensional dataset was performed. Although PCA of the ‘accepted’ stemness genes was unable to separate sphere-forming from sphere-incapable cell lines, the addition of the ‘aggressiveness’ marker CD44v6 allowed a clear differentiation. Moreover, inoculation of the spheres and the adherent cells in vivo confirmed the superior aggressiveness (proliferation and metastasis) of the spheres over the adherent cells. In conclusion, the present study suggests that the sphere-growing cell population is not only composed of cells displaying classical stem membrane markers but also needs CD44v6-positive cells to successfully form spheres. Our results also emphasize the potential therapeutic importance of pathways such as CXCR4 and hedgehog for pancreatic cancer treatment.

Constitutive expression of ΔN-p63α isoform in human thymus and thymic epithelial tumours

Abstractp63, a member of the p53 family, is involved in the survival and differentiation of reserve/stem cells in different epithelia. To unveil the possible role of p63 in thymic physiology and pathology, we investigated the expression of p63 isoforms in normal thymus, thymomas and other mediastinal tumours. All samples were analysed using immunohistochemistry with three different antibodies: 4A4 antibody recognising all p63 isoforms, p40 antibody reacting only with truncated dominant-negative isoforms (ΔN-p63) and H-129 antibody recognising all alpha-isoforms. Reverse-transcription polymerase chain reaction (RT-PCR), and real-time PCR analyses were performed on RNA extracted from frozen samples of four thymomas and two primary-mediastinal large-B-cell lymphoma (PMLBCL). In normal thymus, ΔN-p63α was expressed in all cortical and medullary epithelial cells, with decreasing intensity in Hassalls corpuscles. This phenotype was conserved in neoplastic transformation since all 54 investigated thymomas (World Health Organization types A, AB, B1, B2, B3, C) expressed ΔN-p63α (virtually 100% cells). The predominance of ΔN-p63α isoform mRNA was confirmed by real-time PCR. Among other mediastinal tumours, ΔN-p63α was only expressed in those displaying either a stratified epithelial component (teratomas) or epidermoid differentiation (lung carcinoma). Among lymphomas, T-cell-precursor lymphomas did not express p63, whereas most PMLBCL expressed TA-p63α (7/8).

Expression Pattern of Claudins 5 and 7 Distinguishes Solid-pseudopapillary From Pancreatoblastoma, Acinar Cell and Endocrine Tumors of the Pancreas

Solid-pseudopapillary tumor (SPT) of the pancreas is characterized by a discohesive appearance of the neoplastic cells. This has been linked to the displacement of E-cadherin and β-catenin from their normal membrane location, which prevents adherens junctions to form. The nuclear localization of β-catenin is also a feature of SPT that helps in differential diagnosis. This latter includes pancreatic endocrine tumor (PET) as SPT may show neuroendocrine differentiation, and pancreatic acinar cell carcinoma (ACC) and pancreatoblastoma (PB) that may often show nuclear β-catenin staining. However, the role of additional cell-cell adhesion systems remains to be elucidated in SPT, particularly that of claudins that are essential components of tight junctions showing modulated expression in diverse tumor types. We studied 20 SPT, 20 nonfunctioning PET, 7 ACC, 2 PB, and their matched normal pancreas for the immunohistochemical expression of claudin family members 1, 2, 3, 4, 5, and 7, β-catenin and E-cadherin. All SPT showed intense membrane claudin 5 and cytoplasmic claudin 2 staining, lack of claudins 3 and 4, and positive cytoplasmic claudins 1 and 7 in few cases. Conversely, PET, ACC, and PB showed strong membrane expression of claudin 7 and lack of claudin 5, whereas claudins 1, 2, 3, and 4 showed variable expression among samples. All SPT showed nuclear β-catenin and lack of E-cadherin membrane staining, whereas PET, ACC, and PB only showed nuclear β-catenin in 1, 2, and 2 cases, respectively. SPT shows a peculiar claudin expression profile and the highly specific pattern of claudins 5 and 7 differentiates SPT from PET, ACC, and PB.

Human myeloma cells express the CD38 ligand CD31

Multiple myeloma (MM) plasma cells (PC) are CD38+. A ligand for CD38 is the adhesion molecule CD31. By flow cytometry and immunocytochemistry we have investigated whether malignant PC co‐express CD38 and CD31. All 68 patients studied were CD38+. 14/14 monoclonal gammopathies of undetermined significance (MGUS) and 39/39 plasmacytic MM patients co‐expressed CD38 and CD31 at high density. Only 1/11 plasmablastic MM and 1/4 plasma cell leukaemias (PCL) expressed CD31. These data indicated that PC malignancies co‐expressed high levels of both CD38 and its ligand CD31, with the exception of plasmablastic MM and PCL.

Oncogene-induced senescence distinguishes indolent from aggressive forms of pulmonary and non-pulmonary Langerhans cell histiocytosis

Abstract The clonal/neoplastic nature of Langerhans cell histiocytosis (LCH) has recently been demonstrated by a high prevalence of BRAF mutations, including pulmonary LCH (PLCH). We hypothesized that BRAF-induced senescence, as demonstrated in nevi and melanoma, is involved in the pathogenesis of LCH and PLCH. In a series of pulmonary (19 cases) and non-pulmonary LCH (19 cases), including five aggressive cases, we investigated occurrence of the BRAF V600E mutation by molecular analysis and/or immunohistochemistry using a validated antibody (VE1). The expression of cell-senescence markers p16INK4a and p21CIP1/WAF1 was also immunohistochemically investigated. We demonstrated that 6/19 cases of LCH and 12/19 cases of PLCH were VE1 positive, matching with molecular analysis, and in all cases both p16INK4a and p21CIP1/WAF1 were expressed, irrespective of BRAF mutation status. Interestingly, all the aggressive cases did not express p16INK4a, thus suggesting that loss of senescence control could be related to clinical aggressiveness of LCH, as in melanoma.

Pulmonary Adenocarcinoma With Enteric Differentiation: Immunohistochemistry and Molecular Morphology

Pulmonary adenocarcinoma with enteric differentiation (PAED) is a rare subtype of lung adenocarcinoma recently recognized in the WHO classification. It is defined as an adenocarcinoma in which the enteric component exceeds 50% and have to show the expression of at least 1 immunohistochemical marker of enteric differentiation. Although the definition of this tumor type is very important, above all in the differential diagnosis between a primary lung tumor and a metastasis of colorectal adenocarcinoma, this cancer still lacks a distinctive immunohistochemical and molecular signature. We recruited the largest series in the literature of PAEDs according to the morphology and the positivity for intestinal markers. Then, we evaluated the immunohistochemical and molecular profile of these adenocarcinomas. In our series, CDX-2 and CK7 were the immunohistochemical markers mostly expressed by PAEDs. There was an inverse relationship between the expression of pnuemocytes markers, such as TTF-1, and intestinal markers. Molecular analysis revealed KRAS as the most frequently mutated gene (>60% of cases), with very few cases harboring abnormalities affecting EGFR, BRAF, and ALK genes. PAEDs are morphologically very heterogenous. The immunohistochemical profile based on CDX-2 and CK7 positivity of PAEDs appears very robust to support this diagnosis, and it is applicable also on small biopsies. KRAS appears as the most important mutated gene in such tumors.

Cellular Senescence Markers p16INK4a and p21CIP1/WAF Are Predictors of Hodgkin Lymphoma Outcome

Purpose: There is evidence that Hodgkin Reed-Sternberg (HRS) cells in classical Hodgkin lymphoma (cHL) could display some molecular and morphologic markers of cellular senescence (CS). We hypothesized that CS mechanisms may have potential prognostic relevance in cHL and investigated whether the expression of the well-established CS biomarkers p21CIP1/WAF1 and p16INK4a by HRS cells might be predictive of the probability of event-free survival (EFS). Experimental Design: The study analyzed a retrospective cohort of 147 patients and the results were validated on a cohort of 91 patients independently diagnosed and treated in a different institution. p16INK4a and p21CIP1/WAF1 were categorized as dichotomous variables (< or ≥ 30% of HRS cells at diagnosis) and evaluated in univariate and multivariate analysis. Results: Both molecules were independent prognostic factors. A positive staining of one of the two molecules in more than 30% HRS cells predicted a better EFS (P < 0.01). p16INK4a/p21CIP1/WAF1 together as a unique categorical variable (both <30%, either <30%, both ≥ 30%) sorted out three prognostic groups with better, intermediate, or worse outcome either overall or within I–II, bulky and advanced stages. The presence or the lack of the robust expression of p21CIP1/WAF1 and/or p16INK4a defined the prognosis in our series. Conclusions: These findings point to (i) the relevance of CS-related mechanisms in cHL, and to (ii) the prognostic value of a simple, reproducible, and low-cost immunohistochemical evaluation of p16INK4a and p21CIP1/WAF1 expression. Clin Cancer Res; 21(22); 5164–72. ©2015 AACR.