The diverse roles of nonsteroidal anti-inflammatory drug activated gene (NAG-1/GDF15) in cancer

Nonsteroidal anti-inflammatory drug (NSAID) activated gene-1, NAG-1, is a divergent member of the transforming growth factor-beta (TGF-β) superfamily that plays a complex but poorly understood role in several human diseases including cancer. NAG-1 expression is substantially increased during cancer development and progression especially in gastrointestinal, prostate, pancreatic, colorectal, breast, melanoma, and glioblastoma brain tumors. Aberrant increases in the serum levels of secreted NAG-1 correlate with poor prognosis and patient survival rates in some cancers. In contrast, the expression of NAG-1 is up-regulated by several tumor suppressor pathways including p53, GSK-3β, and EGR-1. NAG-1 expression is also induced by many drugs and dietary compounds which are documented to prevent the development and progression of cancer in mouse models. Studies with transgenic mice expressing human NAG-1 demonstrated that the expression of NAG-1 inhibits the development of intestinal tumors and prostate tumors in animal models. Laboratory and clinical evidence suggest that NAG-1, like other TGF-β family members, may have different or pleiotropic functions in the early and late stages of carcinogenesis. Upon understanding the molecular mechanism and function of NAG-1 during carcinogenesis, NAG-1 may serve as a potential biomarker for the diagnosis and prognosis of cancer and a therapeutic target for the inhibition and treatment of cancer development and progression.

COX inhibitors directly alter gene expression: role in cancer prevention?

Inflammation is an important contributor to the development and progression of human cancers. Inflammatory lipid metabolites, prostaglandins, formed from arachidonic acid by prostaglandin H synthases commonly called cyclooxygenases (COXs) bind to specific receptors that activate signaling pathways driving the development and progression of tumors. Inhibitors of prostaglandin formation, COX inhibitors, or nonsteroidal anti-inflammatory drugs (NSAIDs) are well documented as agents that inhibit tumor growth and with long-term use prevent tumor development. NSAIDs also alter gene expression independent of COX inhibition and these changes in gene expression also appear to contribute to the anti-tumorigenic activity of these drugs. Many NSAIDs, as illustrated by sulindac sulfide, alter gene expressions by altering the expression or phosphorylation status of the transcription factors specificity protein 1 and early growth response-1 with the balance between these two events resulting in increases or decreases in specific target genes. In this review, we have summarized and discussed the various genes altered by this mechanism after NSAID treatment and how these changes in expression relate to the anti-tumorigenic activity. A major focus of the review is on NSAID-activated gene (NAG-1) or growth differentiation factor 15. This unique member of the TGF-β superfamily is highly induced by NSAIDs and numerous drugs and chemicals with anti-tumorigenic activities. Investigations with a transgenic mouse expressing the human NAG-1 suggest it acts to suppress tumor development in several mouse models of cancer. The biochemistry and biology of NAG-1 were discussed as potential contributor to cancer prevention by COX inhibitors.

Where will the next generation of stroke treatments come from?

Remarkable progress has occurred over the last two decades in stroke interventions. Many have been developed on the basis of their efficacy in other disorders. This "inheritance" approach should continue, but two areas where completely novel therapeutic targets might emerge are the stimulation of neuroplasticity and unraveling the genetic code of stroke heterogeneity (Table 2). For the former, the next steps are to identify small-molecule, nontoxic compounds that most effectively enhance plasticity in animal models, and then subject them to clinical trial in humans. For the latter, more and larger-scale cooperative GWASs in carefully phenotyped stroke populations are required to better understand the polygenic nature of cerebrovascular disease. Then, the physiological relevance of genetic abnormalities can be determined in in vitro and in vivo systems before candidate compounds are developed.

Cerebral microbleeds: old leaks and new haemorrhages

Black dots in the brain parenchyma diagnosed in T2(*)-weighted magnetic resonance imaging should be interpreted in light of the patient's history as well as the location, number and distribution of the lesions and associated imaging findings. These dots will correspond to haemoglobin degradation products in most of the cases referred to as cerebral microbleeds in patients with small vessel disease. Cerebral microbleeds have a prevalence of 5.7% (range 3.7-7.7%) and are observed more frequently with increasing age. cerebral microbleeds have been observed in 47-80% of the primary intracerebral haemorrhage patients and in 0-78% of the patients with ischaemic cerebrovascular disease and appear to be a general marker of various types of bleeding-prone, small vessel disease and a predictor of recurrent vascular events. The occurrence and the number of cerebral microbleeds are associated with the degree of cerebral white matter abnormalities. Current data does not support the hypothesis that cerebral microbleeds are associated with a higher risk for a clinically relevant intracerebral haemorrhage, after anticoagulation/antiaggregation therapy, or after thrombolytic therapy in stroke patients. Therefore, the current data do not support the general exclusion of patients from therapy based on the presence of cerebral microbleeds. In the future, cerebral microbleeds may be incorporated into the design of clinical trials of anticoagulation/antiaggregation drugs in stroke patients for potential individual stratification for both the risk of recurrent ischaemic stroke and for the risk of intracerebral haemorrhage.

Stroke

Stroke is the second most common cause of death and major cause of disability worldwide. Because of the ageing population, the burden will increase greatly during the next 20 years, especially in developing countries. Advances have occurred in the prevention and treatment of stroke during the past decade. For patients with acute stroke, management in a stroke care unit, intravenous tissue plasminogen activator within 3 h or aspirin within 48 h of stroke onset, and decompressive surgery for supratentorial malignant hemispheric cerebral infarction are interventions of proven benefit; several other interventions are being assessed. Proven secondary prevention strategies are warfarin for patients with atrial fibrillation, endarterectomy for symptomatic carotid stenosis, antiplatelet agents, and cholesterol reduction. The most important intervention is the management of patients in stroke care units because these provide a framework within which further study might be undertaken. These advances have exposed a worldwide shortage of stroke health-care workers, especially in developing countries.