Background & Aims The incidence of colorectal cancer (CRC) is increasing in the United States (US) among adults under the age of 50 years. Studies of young-onset CRC have focused on outcomes and treatment patterns. We examined patient presentation, provider evaluation, and time to diagnosis, which can affect stage and prognosis. Methods In a retrospective study, we collected data from patients with a diagnosis of colorectal adenocarcinoma, confirmed by pathologists, seen at the Stanford Cancer Institute from January 1, 2008 through December 31, 2014. We compared symptoms, clinical features, time to diagnosis, and cancer stage in patients with young-onset CRC (diagnosed at an age younger than 50 years, n=253) vs patients diagnosed with CRC at an age of 50 years or older (n=232). Results A higher proportion of patients with young-onset CRC were diagnosed with advanced-stage tumors (72%) compared with older patients (63%) (P=.03). Larger proportions of patients with young-onset CRC also had a family history of CRC (25% vs 17% in older patients; P=.03), confirmed or probable hereditary cancer syndromes (7% vs 1% in older patients, P<.01), and left-sided disease (distal colon cancer in 41% vs 34% in older patients; P=.01 and rectal cancer in 40% vs 35% in older patients; P=0.29). Patients with young-onset CRC had a significantly longer median time to diagnosis (128 vs 79 days for older patients; P<0.05), symptom duration (60 vs 30 days for older patients; P<.01), and time of evaluation (31 vs 22 days; P<.05). In multivariable analyses, time to diagnosis was 1.4-fold longer for younger than for older patients (P<.01). Among younger patients, those with stage III or IV CRC had shorter durations of symptoms and evaluations than those with stage I or II CRC. Conclusion In a retrospective analysis of patients with CRC, we found that greater proportions of patients younger than 50 years were diagnosed with advanced stage tumors than older patients; this difference could not be explained simply by delays from symptom onset to diagnosis. Although tumor biology may be an important determinant of stage at diagnosis, clinicians should be aware of CRC alarm symptoms, family history, and genetic Syndromes, to speed evaluation and diagnosis of younger patients and potentially improve outcomes. It remains to be determined whether subgroups of persons at risk for young-onset CRC who benefit from early screening can be identified.

Cation-chloride cotransporters (CCCs) mediate the electroneutral transport of chloride, potassium, and/or sodium across the membrane. They play critical roles in regulating cell volume, controlling ion absorption and secretion across epithelia, and maintaining intracellular chloride homeostasis. These transporters are the primary targets for some of the most commonly prescribed drugs. Here, we determined the cryo-EM structure of a Na-K-Cl cotransporter NKCC1, an extensively-studied

SUMMARY The lack of small-molecule inhibitors for anion-selective transporters and channels has impeded our understanding of the complex mechanisms that underlie ion passage. The ubiquitous CLC “Chloride Channel” family represents a unique target for biophysical and biochemical studies because its distinctive protein fold supports both passive chloride channels and secondary-active chloride-proton transporters. Here, we describe the synthesis and characterization of the first specific small-molecule inhibitor directed against a CLC antiporter (ClC-ec1). This compound, 4,4′-octanamidostilbene-2,2′-disulfonate (OADS), inhibits ClC-ec1 with low micromolar affinity and has no specific effect on a CLC channel (ClC-1). Inhibition of ClC-ec1 occurs by binding to two distinct intracellular sites. The location of these sites and the lipid-dependence of inhibition suggest potential mechanisms of action. The discovery of this compound will empower research to elucidate differences between antiporter and channel mechanisms and to develop treatments for CLC-mediated disorders.

No abstract

CLC transporters catalyze the exchange of Cl- for H+ across cellular membranes. To do so, they must couple Cl- and H+ binding and unbinding to protein conformational change. However, the sole conformational changes distinguished crystallographically are small movements of a glutamate side chain that locally gates the ion-transport pathways. Therefore, our understanding of whether and how global protein dynamics contribute to the exchange mechanism has been severely limited. To overcome the limitations of crystallography, we used solution-state 13C-methyl NMR with labels on methionine, lysine, and engineered cysteine residues to investigate substrate (H+) dependent conformational change outside the restraints of crystallization. We show that methyl labels in several regions report H+-dependent spectral changes. We identify one of these regions as Helix R, a helix that extends from the center of the protein, where it forms the part of the inner gate to the Cl--permeation pathway, to the extracellular solution. The H+-dependent spectral change does not occur when a label is positioned just beyond Helix R, on the unstructured C-terminus of the protein. Together, the results suggest that H+ binding is mechanistically coupled to closing of the intracellular access-pathway for Cl-.

No abstract

No abstract

In this paper, we study how cytoskeletal remodeling is correlated to changes in subcellular microrheology. We analyze the changes in the magnitude and directionality of the shear and elastic moduli of bovine aortic endothelial cells (BAECs) exposed to cyclical, uniaxial stretch. We find that, when stretched, BAECs stiffen and align their softest direction of mechanical polarization perpendicular to stretch. We hypothesize that the response of VECs to stretch acts to minimize intracellular strain in response to stress.