Telomere shortening is correlated with the DNA damage response and telomeric protein down-regulation in colorectal preneoplastic lesions

BACKGROUND

A relation between telomere attrition in early carcinogenesis and activation of DNA damage response (DDR) has been proposed. We explored telomere length and its link with DDR in colorectal multistep carcinogenesis.

PATIENTS AND METHODS

We studied normal mucosa, low-grade dysplasia (LGD) and high-grade dysplasia (HGD) and invasive carcinoma (IC) in matched human colon specimens by evaluating p-ataxia telangiectasia mutated (ATM), p-checkpoint kinase 2 (Chk2), c-H2AX, TRF1 and TRF2 expressions by immunohistochemistry. FISH was used to assess telomere length.

RESULTS

Telomeres shortened significantly from normal (N) to LGD and HGD (P < 0.0001; P = 0.012), then increased in length in IC (P = 0.006). TRF1 and TRF2 expressions were diminished from N to LGD and HGD (P = 0.004, P < 0.0001, ns) and were reexpressed at the invasive stage (P = 0.053 and P = 0.046). Phosphorylated ATM, Chk2 and H2AX appeared already in LGD (respectively, P = 0.001, P = 0.002 and P = 0.02). Their expression decreased from HGD to IC (respectively, P = 0.03, P = 0.02 and P = 0.37). These activating phosphorylations were inversely correlated with telomere length and TRF1/2 expression.

CONCLUSION

In a model of colon multistep carcinogenesis, our data indicate that telomeric length and protein expression levels are inversely correlated with the activation of the DDR pathway.

IL4 gene delivery to the CNS recruits regulatory T cells and induces clinical recovery in mouse models of multiple sclerosis

Central nervous system (CNS) delivery of anti-inflammatory cytokines, such as interleukin 4 (IL4), holds promise as treatment for multiple sclerosis (MS). We have previously shown that short-term herpes simplex virus type 1-mediated IL4 gene therapy is able to inhibit experimental autoimmune encephalomyelitis (EAE), an animal model of MS, in mice and non-human primates. Here, we show that a single administration of an IL4-expressing helper-dependent adenoviral vector (HD-Ad) into the cerebrospinal fluid (CSF) circulation of immunocompetent mice allows persistent transduction of neuroepithelial cells and long-term (up to 5 months) CNS transgene expression without toxicity. Mice affected by chronic and relapsing EAE display clinical and neurophysiological recovery from the disease once injected with the IL4-expressing HD-Ad vector. The therapeutic effect is due to the ability of IL4 to increase, in inflamed CNS areas, chemokines (CCL1, CCL17 and CCL22) capable of recruiting regulatory T cells (CD4+CD69-CD25+Foxp3+) with suppressant functions. CSF delivery of HD-Ad vectors expressing anti-inflammatory molecules might represent a valuable therapeutic option for CNS inflammatory disorders.

Unusual cystic presentation of pulmonary nodular amyloidosis associated with MALT-type lymphoma

The case reported herein consists of nodular pulmonary amyloidosis presenting with unusual cystic radiological features which reveal a pulmonary localisation of an extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma). The present case is the first to report a radiological presentation of nodular pulmonary amyloidosis in the absence of Sjögren's syndrome. Although transthoracic fine-needle biopsy was helpful for the diagnostic of amyloidosis, final diagnosis of associated MALT-type lymphoma required an open lung biopsy. This emphasises the importance of performing surgical investigations in pulmonary nodular amyloidosis in order to depict the presence of underlying lung tumours or lymphoproliferative disorders.

Altered pattern of Cul-1 protein expression and neddylation in human lung tumours: relationships with CAND1 and cyclin E protein levels

The Cul-1 protein is the scaffold element of SCF complexes that are involved in the proteasomal degradation of numerous proteins regulating cell cycle progression. Owing to this central role in cell growth control, aberrant expression of the components of SCF is thought to play a role during tumourigenesis. Nothing is known about Cul-1 expression in human tumours. In this study, we have analysed its status in a series of 128 human lung carcinomas, comprising 50 non-small cell lung cancers (NSCLCs; 29 squamous cell carcinomas and 21 adenocarcinomas) and 78 neuroendocrine (NE) lung tumours (24 typical and atypical carcinoids, 19 large cell NE carcinomas and 35 small cell lung carcinomas), using immunohistochemistry. We report for the first time an altered pattern of Cul-1 expression in human tumours; indeed, we show that Cul-1 expression is up-regulated in 40% (51/128) of all lung tumours as compared to normal lung tissues, including 34% (17/50), 75% (18/24) and 30% (16/54) of NSCLCs, carcinoids and high grade neuroendocrine lung carcinomas, respectively. Furthermore, we demonstrate that high levels of Cul-1 protein are associated with a low KI67 proliferative index (p = 0.005) and with a decrease in the cyclin E oncoprotein (p = 0.0003), one of the major targets of SCF complexes. These data suggest that up-regulation of Cul-1 could protect cells from hyperproliferative signals through cyclin E down-regulation. Cul-1 is modified by neddylation, a post-translational modification that grafts ubiquitin-like Nedd8/Rub1 residues and controls Cul-1 activity. We also provide evidence that neddylated forms of Cul-1 are specifically expressed in high-grade NE lung tumours and are associated with down-regulation of the Cul-1 inhibitor CAND1 (p = 0.03) and a high level of cyclin E (p = 0.0002). These data support the notion that alterations in the Cul-1 neddylation/deneddylation pathway could contribute to the development of these highly aggressive lung tumours.