The role of apical lymph node metastasis in right colon cancer.

BACKGROUND: The role of apical lymph node (APN) metastasis in colorectal cancer remains controversial. The main purpose of this study is to explore the prognostic value of APN metastasis in patients with right colon cancer. METHODS: This is a retrospective study of patients with stage III right colon cancer between April 2007 and December 2016. Patients who underwent resection of right colon cancers with D3 lymph node dissection were divided into APN-positive (APN+) and APN-negative (APN-) groups according to the postoperative pathological presence or absence of APN metastasis. Relapse-free survival (RFS) and overall survival (OS) between groups were compared after Cox regression analysis and 1:1 propensity score matching (PSM). RESULTS: A total of 254 patients were included in this study: 28 (11.0%) were APN+ and 226 (89.0%) were APN-. Before matching, the rates of elevated carcinoembryonic antigen (CEA), T3-4 tumor invasion, and N2 lymph node metastasis were significantly higher in the APN+ group (CEA ≥ 5 ng/mL, 53.6% vs. 37.6%, p < 0.001; T3-4, 92.9% vs. 85.4%, p < 0.001; N2 metastasis, 57.1% vs. 20.4%, p < 0.001), and APN+ tumors were associated with significantly higher postoperative relapse rates (39.3% vs. 21.2%; p = 0.03), especially with lung metastases (14.3% vs. 4.0%; p = 0.019), which conferred worse RFS (p = 0.013), although OS was similar (p = 0.078). However, after PSM, there were no apparent between-group differences in RFS (p = 0.29) or overall survival rate (p = 0.637). The Cox regression analysis indicated that lymphatic vessel infiltration and depth of invasion were independent risk factors for OS, while APN+ status was not a significant predictor for RFS or OS. CONCLUSIONS: APN metastasis was not a prognostic indicator for RFS or OS in right colon cancer. However, APN+ patients with elevated CEA levels and deeper tumor invasion should be closely monitored for lung metastasis during postoperative follow-up.

MazF activation causes ACA sequence-independent and selective alterations in RNA levels in Escherichia coli.

Escherichia coli MazF is a toxin protein that cleaves RNA at ACA sequences. Its activation has been thought to cause growth inhibition, primarily through indiscriminate cleavage of RNA. To investigate responses following MazF activation, transcriptomic profiles of mazF-overexpressing and non-overexpressing E. coli K12 cells were compared. Analyses of differentially expressed genes demonstrated that the presence and the number of ACA trimers in RNA was unrelated to cellular RNA levels. Mapping differentially expressed genes onto the chromosome identified two chromosomal segments in which upregulated genes formed clusters, and these segments were absent in the chromosomes of E. coli strains other than K12. These results suggest that MazF regulates selective, rather than indiscriminate, categories of genes, and is involved in the regulation of horizontally acquired genes. We conclude that the primary role of MazF is not only cleaving RNA indiscriminately but also generating a specific cellular state.

Erratum: Author Correction: Bcl11b controls odorant receptor class choice in mice.

[This corrects the article DOI: 10.1038/s42003-019-0536-x.].

Bcl11b controls odorant receptor class choice in mice.

Each olfactory sensory neuron (OSN) expresses a single odorant receptor (OR) gene from the class I or class II repertoire in mice. The mechanisms that regulate OR class choice in OSNs remain unknown. Here, we show that the transcription factor Bcl11b determines the OR class to be expressed in OSNs. Both loss- and gain-of-function analyses demonstrate that class I is a default fate of OSNs and that Bcl11b dictates a class II OR choice by suppressing the effect of the J-element, a class I-OR enhancer. We further demonstrate that OSN-specific genetic manipulations of Bcl11b bias the OR class choice, generating mice with "class I-dominant" and "class II-dominant" noses, which display contrasting innate olfactory behaviors to two distinct aversive odorants. Overall, these findings reveal a unique transcriptional mechanism mediating a binary switch for OR class choice that is crucial to both the anatomical and functional organization of the olfactory system.

A Single Pheromone Receptor Gene Conserved across 400 My of Vertebrate Evolution.

Pheromones are crucial for eliciting social and sexual behaviors in diverse animal species. The vomeronasal receptor type-1 (V1R) genes, encoding members of a pheromone receptor family, are highly variable in number and repertoire among mammals due to extensive gene gain and loss. Here, we report a novel pheromone receptor gene belonging to the V1R family, named ancient V1R (ancV1R), which is shared among most Osteichthyes (bony vertebrates) from the basal lineage of ray-finned fishes to mammals. Phylogenetic and syntenic analyses of ancV1R using 115 vertebrate genomes revealed that it represents an orthologous gene conserved for >400 My of vertebrate evolution. Interestingly, the loss of ancV1R in some tetrapods is coincident with the degeneration of the vomeronasal organ in higher primates, cetaceans, and some reptiles including birds and crocodilians. In addition, ancV1R is expressed in most mature vomeronasal sensory neurons in contrast with canonical V1Rs, which are sparsely expressed in a manner that is consistent with the "one neuron-one receptor" rule. Our results imply that a previously undescribed V1R gene inherited from an ancient Silurian ancestor may have played an important functional role in the evolution of vertebrate vomeronasal organ.