Histologic grading of breast cancer defines morphologic subtypes informative of metastatic potential, although not without considerable interobserver disagreement and clinical heterogeneity particularly among the moderately differentiated grade 2 (G2) tumors. We posited that a gene expression signature capable of discerning tumors of grade 1 (G1) and grade 3 (G3) histology might provide a more objective measure of grade with prognostic benefit for patients with G2 disease. To this end, we studied the expression profiles of 347 primary invasive breast tumors analyzed on Affymetrix microarrays. Using class prediction algorithms, we identified 264 robust grade-associated markers, six of which could accurately classify G1 and G3 tumors, and separate G2 tumors into two highly discriminant classes (termed G2a and G2b genetic grades) with patient survival outcomes highly similar to those with G1 and G3 histology, respectively. Statistical analysis of conventional clinical variables further distinguished G2a and G2b subtypes from each other, but also from histologic G1 and G3 tumors. In multivariate analyses, genetic grade was consistently found to be an independent prognostic indicator of disease recurrence comparable with that of lymph node status and tumor size. When incorporated into the Nottingham prognostic index, genetic grade enhanced detection of patients with less harmful tumors, likely to benefit little from adjuvant therapy. Our findings show that a genetic grade signature can improve prognosis and therapeutic planning for breast cancer patients, and support the view that low-and high-grade disease, as defined genetically, reflect independent pathobiological entities rather than a continuum of cancer progression.

Double-stranded RNA (dsRNA) accumulates in virus-infected mammalian cells and signals the activation of host defense pathways of the interferon system. We describe here a novel form of dsRNA-triggered signaling that leads to the stimulation of the p38 mitogen-activated protein kinase (p38 MAPK) and the c-Jun NH 2 -terminal kinase (JNK) and of their respective activators MKK3/6 and SEK1/MKK4. The dsRNA-dependent signaling to p38 MAPK was largely intact in cells lacking both RNase L and the dsRNA-activated protein kinase (PKR), i.e., the two best-characterized mediators of dsRNA-triggered antiviral responses. In contrast, activation of both MKK4 and JNK by dsRNA was greatly reduced in cells lacking RNase L (or lacking both RNase L and PKR) but was restored in these cells when introduction of dsRNA was followed by inhibition of ongoing protein synthesis or transcription. These results are consistent with the notion that the role of RNase L and PKR in the activation of MKK4 and JNK is the elimination, via inhibition of protein synthesis, of a labile negative regulator(s) of the signaling to JNK acting upstream of SEK1/MKK4. In the course of these studies, we identified a long-sought site of RNase L-mediated cleavage in the 28S rRNA, which could cause inhibition of translation, thus allowing the activation of JNK by dsRNA. We propose that p38 MAPK is a general participant in dsRNA-triggered cellular responses, whereas the activation of JNK might be restricted to cells with reduced rates of protein synthesis. Our studies demonstrate the existence of alternative (RNase L-and PKR-independent) dsRNA-triggered signaling pathways that lead to the stimulation of stress-activated MAPKs. Activation of p38 MAPK (but not of JNK) was demonstrated in mouse fibroblasts in response to infection with encephalomyocarditis virus (ECMV), a picornavirus that replicates through a dsRNA intermediate. Fibroblasts infected with EMCV (or treated with dsRNA) produced interleukin-6, an inflammatory and pyrogenic cytokine, in a p38 MAPK-dependent fashion. These findings suggest that stress-activated MAPKs participate in mediating inflammatory and febrile responses to viral infections. Double-stranded RNA (dsRNA) produced during viral infections triggers stress response pathways that lead to elimination of infected cells by apoptosis. Two complementary but independent cellular dsRNA-detecting systems have been implicated in the translational inhibition in response to viral infection: the 2-5A system and the dsRNA-activated protein kinase (PKR) (for a recent review, see reference 55). The 2-5A system is composed of a family of dsRNA-dependent enzymes known as 2Ј-5Ј oligoadenylate synthetases (OAS) (5) and the dormant cytosolic RNase L (64) (for recent reviews on the 2-5A system and RNase L, see references 45 and 52, respectively). Upon dsRNA binding, OAS produce unusual second messengers, short 2Ј-5Ј-linked oligoadenylates (2-5A) (32), which, in turn, specifically bind to and activate RNase L (64). Activated RNase L cleaves diverse RNA substrates...

No abstract

China informed the World Health Organization of a novel viral pneumonia in the city of Wuhan, in Hubei Province. Singapore is an independent city-state 3400 km (2125 miles) from Wuhan, but as a major air hub had an average of 330 000 visitor arrivals from China each month in 2019. 1 On January 2, 2020, Singapore's Ministry of Health alerted all physicians to identify any patient with pneumonia and a recent travel history to Wuhan. On January 3, Singapore started temperature screening at its airport of all travelers arriving from Wuhan. Researchers in China identified a novel coronavirus as the causative agent on January 9, 2 the genetic sequence was released on January 12, 3 and human transmission to health care workers was confirmed on January 20. 4 Singapore promptly shifted its public health response level to "enhanced preparedness" and diagnosed its first case, a tourist from Wuhan, on January 23. The range of public health measures that were instituted and rapidly escalated included aggressive contact tracing and quarantine of close contacts of confirmed cases (namely persons who had spent a prolonged period within 2 m of a confirmed case), travel advisories and then entry restrictions on people traveling from Hubei, and on January 31, entry restrictions on people who had traveled to China in the preceding 14 days. Approximately 700 recent travelers from Hubei were quarantined, and Singaporeans, permanent residents, and longterm visa holders returning from China were placed under a 14-day compulsory leave of absence from work.As of February 19, Singapore has 84 cases of coronavirus disease 2019 (COVID-19) infection with positive results by real-time reverse transcriptasepolymerase chain reaction (RT-PCR) tests targeting the N, S, and ORF1ab genes. Of these cases, 23 were imported cases comprising 17 visitors from China and 6 Singaporeans who had been evacuated from Wuhan. Of the 61 locally transmitted cases, 5 clusters with local transmission involving 43 patients have been identified, a further 10 patients were related, and 8 are as yet not linked to any clear exposure. All 84 confirmed case patients were hospitalized, and of these, 34 have been discharged, 4 are currently in intensive care, and to date there have been no deaths. 5 The approach taken by Singapore, learning from its experience with the severe acute respiratory syndrome (SARS), is that all confirmed cases are isolated until 2 consecutive respiratory samples for RT-PCR (sputum or nasal/throat/nasopharyngeal swabs) become negative over 2 days. Close contacts are identified and those individuals without symptoms are quarantined for 14 days from last exposure. As of February 19, a total of 2593 close contacts have been identified.