Gail Amir

The sirtuin SIRT6 regulates lifespan in male mice

The significant increase in human lifespan during the past century confronts us with great medical challenges. To meet these challenges, the mechanisms that determine healthy ageing must be understood and controlled. Sirtuins are highly conserved deacetylases that have been shown to regulate lifespan in yeast, nematodes and fruitflies. However, the role of sirtuins in regulating worm and fly lifespan has recently become controversial. Moreover, the role of the seven mammalian sirtuins, SIRT1 to SIRT7 (homologues of the yeast sirtuin Sir2), in regulating lifespan is unclear. Here we show that male, but not female, transgenic mice overexpressing Sirt6 (ref. 4) have a significantly longer lifespan than wild-type mice. Gene expression analysis revealed significant differences between male Sirt6-transgenic mice and male wild-type mice: transgenic males displayed lower serum levels of insulin-like growth factor 1 (IGF1), higher levels of IGF-binding protein 1 and altered phosphorylation levels of major components of IGF1 signalling, a key pathway in the regulation of lifespan. This study shows the regulation of mammalian lifespan by a sirtuin family member and has important therapeutic implications for age-related diseases.

Kidney involvement and renal manifestations in non-Hodgkin's lymphoma and lymphocytic leukemia: a retrospective study in 700 patients

Abstract: Renal involvement as part of systemic lymphoma (LY) is quite frequent, however, primary extranodal renal non‐Hodgkins lymphoma (NHL) is extremely rare, and only about 65 cases have been reported in the world literature. In a retrospective study of renal manifestations in 700 patients with documented LY and chronic lymphocytic leukemia (CLL) seen at our hospital during 1986–95, 83 patients had signs of acute renal failure. Only five of these had proven renal infiltration, but none of them satisfied the criteria for primary renal LY. Glomerulonephritis (GN) has also rarely been reported in association with LY and CLL, and only 37 glomerular lesions in NHL and 42 in CLL have been documented, respectively. GN may precede, coexist, or follow the diagnosis of LY by several years. Of the 42 cases of CLL reported worldwide, 36 had nephrotic syndrome. Renal failure was seen in about one third. The most common glomerular lesion reported is membranoproliferative GN, followed by membranous GN. In our study, we found only five biopsy‐proven cases with GN amongst the 700 patients seen. In this report we also briefly describe some rare interesting associated renal syndromes in CLL and NHL.

Frequent Attenuation of the WWOX Tumor Suppressor in Osteosarcoma Is Associated with Increased Tumorigenicity and Aberrant RUNX2 Expression

The WW domain-containing oxidoreductase (WWOX) is a tumor suppressor that is deleted or attenuated in most human tumors. Wwox-deficient mice develop osteosarcoma (OS), an aggressive bone tumor with poor prognosis that often metastasizes to lung. On the basis of these observations, we examined the status of WWOX in human OS specimens and cell lines. In human OS clinical samples, WWOX expression was absent or reduced in 58% of tumors examined (P < 0.0001). Compared with the primary tumors, WWOX levels frequently increased in tumors resected following chemotherapy. In contrast, tumor metastases to lung often exhibited reduced WWOX levels relative to the primary tumor. In human OS cell lines having reduced WWOX expression, ectopic expression of WWOX inhibited proliferation and attenuated invasion in vitro, and suppressed tumorigenicity in nude mice. Expression of WWOX was associated with reduced RUNX2 expression in OS cell lines, whereas RUNX2 levels were elevated in femurs of Wwox-deficient mice. Furthermore, WWOX reconstitution in HOS cells was associated with downregulation of RUNX2 levels and RUNX2 target genes, consistent with the ability of WWOX to suppress RUNX2 transactivation activity. In clinical samples, RUNX2 was expressed in the majority of primary tumors and undetectable in most tumors resected following chemotherapy, whereas most metastases were RUNX2 positive. Our results deepen the evidence of a tumor suppressor role for WWOX in OS, furthering its prognostic and therapeutic significance in this disease.

CD4+CXCR4highCD69+ T cells accumulate in lung adenocarcinoma.

The chemokine receptor CXCR4 is involved in the growth and metastasis of tumor cells. However, the expression of its ligand, the chemokine CXCL12, in tumors and its role in regulating the accumulation of immune cells within the tumors is not clear. Using ELISA and immunohistochemistry we found that CXCL12 is expressed in the majority of nonsmall cell lung cancer tissue sections obtained from stage IA to IIB nonsmall cell lung cancer patients undergoing operation. Histopathologic examination of these sections indicated that high CXCL12 expression correlated with increased tumor inflammation. In addition, disease recurrence rates in a subgroup of adenocarcinoma patients showed a tendency to correlate with high CXCL12 expression in the tumor. Isolation of adenocarcinoma-infiltrating immune cells demonstrated an increase in the percentage of CD4+CD69+CXCR4+ T cells as compared with normal lung tissue. About 30% of these cells expressed the regulatory T cell markers CD25high and FoxP3. The percentage of CD8 T cells within the tumor did not change, however; the percentage of NK and NK T cells was significantly reduced. In correlation with CXCR4 expression, CD4 T cells showed increased migration in response to CXCL12 compared with CD8 T cells and NK cells. Overall, these observations suggest that CXCL12 expression may influence tumor progression by shaping the immune cell population infiltrating lung adenocarcinoma tumors.

The haematopoietic specific signal transducer Vav1 is expressed in a subset of human neuroblastomas

Vav1 is a signal transducer protein expressed exclusively in the haematopoietic system, where it plays a pivotal role in growth factor‐induced differentiation and proliferation. Vav1 couples tyrosine kinase signals with the activation of the Rho/Rac GTPases, leading to cell differentiation and/or proliferation. Vav1 was originally detected as an oncogene, but its involvement in human malignancies has not been reported thus far. We report here that Vav1 is expressed in a neuroblastoma cell line, SK‐N‐MC. Molecular analysis indicated that there are no gross rearrangements or mutations in the Vav1 gene in SK‐N‐MC cells. Vav1 protein from SK‐N‐MC cells was similar to wild‐type Vav1 in apparent molecular weight, phosphorylation state, and ability to associate with active EGFR. We also analysed the expression of Vav1 in 42 specimens of human neuroblastoma. Vav1 was expressed in the majority of these tumours. Our results suggest that Vav1 may play a role in the neoplastic process in a subset of neuroblastomas. Copyright

Diagnosis and management of Rosai-Dorfman disease involving the central nervous system

Abstract Introduction: Rosai–Dorfman disease is a benign non-neoplastic proliferative disorder of histiocytes originally described in the cervical lymph nodes. Extranodal sites were later recognized, and by 1990, they were shown to represent over 40% of cases; however, central nervous system involvement is still considered rare. We review the literature, which shows a steady increase in reports of Rosai–Dorfman disease involving the brain and/or spine. Methods: A literature search was performed for the period 1969–2008, using multiple search engines, with keywords Rosai–Dorfman disease, central nervous system Rosai–Dorfman disease and sinus histiocytosis with massive lymphadenopathy. Results: By December 2008, 111 cases of Rosai–Dorfman disease involving the central nervous system had been reported in the literature, including our cases. In the central nervous system, Rosai–Dorfman disease is ubiquitous. Although it is characterized by unique, indeed pathognomonic, histopathological cytoarchitecture, it may be mistaken for many other neoplastic and inflammatory histioproliferative diseases. Surgical resection with post-operative corticosteroids remains the treatment of choice. Conclusions: Rosai–Dorfman disease involving the central nervous system appears to be more common than previously thought and may well assume a more prominent place in the differential diagnoses of dural-based lesions. Expert awareness of the characteristic histopathology and immunohistochemistry of the disease is required for accurate diagnosis.

Interaction between neoplastic cells and cancer-associated fibroblasts through the CXCL12/CXCR4 axis: Role in non–small cell lung cancer tumor proliferation

OBJECTIVES Carcinoma-associated fibroblasts are reported to communicate microenvironment-derived signals through chemokine/chemokine receptor interaction, influencing carcinogenesis. We sought to characterize roles of CXCL12/CXCR4 in crosstalk between non-small cell lung cancer epithelial cell and carcinoma-associated fibroblasts and in tumor growth. METHODS Non-small cell lung cancer tumor samples obtained at surgery and from tumor arrays, as well as primary carcinoma-associated fibroblast and epithelial cell lines generated from fresh tumors, were assessed for CXCL12/CXCR4 expression, tissue localization, and production. Colony assays, extracellular signal-regulated kinase signaling, and chemokine production were measured to assess cancer cell responsiveness to CXCL12 stimulation with or without CXCR4 antagonists. RESULTS CXCL12 and CXCR4 were detected in all major subtypes of non-small cell lung cancer. CXCL12-expressing carcinoma-associated fibroblasts were mostly located near CXCL12-negative tumor cells, whereas CXCL12-positive tumor cells were mostly surrounded by CXCL12-negative stroma. Intratumoral CXCL12 levels were significantly higher than serum levels. CXCL12 expression correlated with advanced disease stage. In vitro, tumor cell lines produced variable amounts of CXCL12 and expressed high levels of CXCR4. Carcinoma-associated fibroblasts cell lines produced high amounts of CXCL12 and expressed variable levels of CXCR4. Stimulation of non-small cell lung cancer neoplastic cells with CXCL12 increased colony-forming capacity, induced extracellular signal-regulated kinase phosphorylation, and production of the proinflammatory chemokine CCL20. CXCR4 antagonists attenuated these effects. CONCLUSIONS Interaction between carcinoma-associated fibroblasts and tumor epithelial cells through the CXCL12/CXCR4 axis plays a role in non-small cell lung cancer tumor proliferation, marking this axis as a target for immune intervention.

Involvement of CCR6/CCL20/IL-17 Axis in NSCLC Disease Progression

Objectives Autocrine and paracrine chemokine/chemokine receptor-based interactions promote non-small-cell-lung-cancer (NSCLC) carcinogenesis. CCL20/CCR6 interactions are involved in prostatic and colonic malignancy pathogenesis. The expression and function of CCL20/CCR6 and its related Th-17 type immune response in NSCLC is not yet defined. We sought to characterize the role of the CCL20/CCR6/IL-17 axis in NSCLC tumor growth. Methods A specialized histopathologist blindly assessed CCL20/CCR6 expression levels in 49 tissue samples of NSCLC patients operated in our department. Results were correlated to disease progression. Colony assays, ERK signaling and chemokine production were measured to assess cancer cell responsiveness to CCL20 and IL-17 stimulation. Results CCL20 was highly expressed in the majority (38/49, 77.5%) of tumor samples. Only a minority of samples (8/49, 16.5%) showed high CCR6 expression. High CCR6 expression was associated with a shorter disease-free survival (P = 0.008) and conferred a disease stage-independent 4.87-fold increased risk for disease recurrence (P = 0.0076, CI 95% 1.52–15.563). Cancerous cell colony-forming capacity was increased by CCL20 stimulation; this effect was dependent in part on ERK phosphorylation and signaling. IL-17 expression was detected in NSCLC; IL-17 potentiated the production of CCL20 by cancerous cells. Conclusion Our findings suggest that the CCL20/CCR6 axis promotes NSCLC disease progression. CCR6 is identified as a potential new prognostic marker and the CCL20/CCR6/IL-17 axis as a potential new therapeutic target. Larger scale studies are required to consolidate these observations.

miR-142 orchestrates a network of actin cytoskeleton regulators during megakaryopoiesis

Genome-encoded microRNAs (miRNAs) provide a posttranscriptional regulatory layer that controls the differentiation and function of various cellular systems, including hematopoietic cells. miR-142 is one of the most prevalently expressed miRNAs within the hematopoietic lineage. To address the in vivo functions of miR-142, we utilized a novel reporter and a loss-of-function mouse allele that we have recently generated. In this study, we show that miR-142 is broadly expressed in the adult hematopoietic system. Our data further reveal that miR-142 is critical for megakaryopoiesis. Genetic ablation of miR-142 caused impaired megakaryocyte maturation, inhibition of polyploidization, abnormal proplatelet formation, and thrombocytopenia. Finally, we characterized a network of miR-142-3p targets which collectively control actin filament homeostasis, thereby ensuring proper execution of actin-dependent proplatelet formation. Our study reveals a pivotal role for miR-142 activity in megakaryocyte maturation and function, and demonstrates a critical contribution of a single miRNA in orchestrating cytoskeletal dynamics and normal hemostasis. DOI: http://dx.doi.org/10.7554/eLife.01964.001

Osteoporosis in the Cohen Diabetic Rat: Correlation Between Histomorphometric Changes in Bone and Microangiopathy

Osteoporosis is well documented in type I diabetes, but its occurrence is controversial in type II diabetes. Microangiopathy is a major complication of type I and type II diabetes. We studied bone and microvascular changes in the Cohen diabetic rat, a unique nonobese model of noninsulin-dependent diabetes mellitus. The aim of this study was to find whether there is a temporal correlation between the onset of these two complications. The diabetic rats were divided into three groups (A, B, and C) according to duration of diabetes (2 months, 3 months, and 7 to 8 months, respectively). Trabecular bone area was assessed by computerized image analysis and microangiopathy by means of renal function tests, histologic examination of the kidneys, and ultrastructural measurement of the width of capillary basement membranes. Bone density of the distal femur and vertebra was significantly reduced in the diabetic rats relative to the control rats in all three groups (Group A femur: 11.5 ± 1.6% versus 21.8 ± 3.0%, p < 0.02; Group A vertebra: 15.9 ± 1.6% versus 28.5 ± 2.0%, p < 0.02; Group C femur: 7.9 ± 1.1% versus 29.6 ± 3.5%, p < 0.001; Group C vertebra: 11.4 ± 0.7% versus 37.1 ± 1.9%, p < 0.002). Renal function tests were normal in the Group A diabetic rats and there was marked albuminuria in the Group C diabetic rats. Histologic changes in the kidneys were seen only in the Group C diabetic rats. Five of 15 Group C diabetic rats showed no albuminuria or histologic evidence of kidney damage. The bone density in this subgroup was reduced relative to controls to the same degree as that of the rats with renal damage. There was no evidence of capillary basement membrane thickening in the Group A diabetic rats. Our findings indicate that in the Cohen diabetic rat, osteoporosis precedes the onset of microangiopathy. Microangiopathy probably does not play an important role in the pathogenesis of osteoporosis in this animal model.