High Fat High Sugar Diet Reduces Small Intestinal Secretion by Sex-Dependent Mechanisms.

BACKGROUND/AIMS: The goal of this study was to determine the influence of high-fat high-sugar diet (Western diet) on intestinal function and subsequently to determine if there were any beneficial effects of exercise, genistein (a naturally occurring phytoestrogen) or both, on the intestine. METHODS: We measured transepithelial short circuit current (Isc), across freshly isolated segments of jejunum from male and female C57Bl/6J mice randomly assigned to one of the following groups for the 12-week study duration: high-fat high-sugar diet (HFS), HFS with genistein (Gen), HFS with exercise (Ex), or HFS with both genistein and exercise (Gen+Ex) and compared them to lean controls. Genistein concentration was 600 mg genistein/kg diet. Exercise comprised of moderate intensity treadmill running (150 min per week). At the completion of the study, segments of jejunum were frozen for western blot determination of key proteins involved in secretory and absorptive functions, as well as senescence. Intestinal morphology was assessed. Serum cytokine assays were performed. RESULTS: Basal Isc was significantly decreased (by 70%, P<0.05) in HFS females and males versus leans. This decrease was partially mitigated by exercise in both sexes. In females, the HFS-induced decrease in Isc was attributed to a significant loss of CLC2, NKCC1 and CFTR expression whereas in males this was due to a significant loss of Na/K-ATPase, KCa and NKCC1 expression (indicating sex-dependent mechanisms). Exercise mitigated most of the loss of Isc in both sexes. Our data suggested that A2BR levels were dysregulated in HFS fed mice and that concomitant treatment with Gen or Gen+Ex prevented this disruption in females only. Inflammatory state was associated with body weight changes. CONCLUSION: Our data suggests that the reduced basal jejunal Isc in HFS mice is attributed to sex-dependent mechanisms and while exercise partially mitigated this, it's mechanism of action was unclear. Improved understanding of Western diet induced intestinal dysfunctions may allow for the development of novel drug targets to treat gastrointestinal disturbances in diabetic obesity.

Modification of the structural stability of human serum albumin in rheumatoid arthritis.

Differential scanning calorimetry (DSC) can indicate changes in structure and/or concentration of the most abundant proteins in a biological sample via heat denaturation curves (HDCs). In blood serum for example, HDC changes result from either concentration changes or altered thermal stabilities for 7-10 proteins and has previously been shown capable of differentiating between sick and healthy human subjects. Here, we compare HDCs and proteomic profiles of 50 patients experiencing joint-inflammatory symptoms, 27 of which were clinically diagnosed with rheumatoid arthritis (RA). The HDC of all 50 subjects appeared significantly different from expected healthy curves, but comparison of additional differences between the RA and the non-RA subjects allowed more specific understanding of RA samples. We used mass spectrometry (MS) to investigate the reasons behind the additional HDC changes observed in RA patients. The HDC differences do not appear to be directly related to differences in the concentrations of abundant serum proteins. Rather, the differences can be attributed to modified thermal stability of some fraction of the human serum albumin (HSA) proteins in the sample. By quantifying differences in the frequency of artificially induced post translational modifications (PTMs), we found that HSA in RA subjects had a much lower surface accessibility, indicating potential ligand or protein binding partners in certain regions that could explain the shift in HSA melting temperature in the RA HDCs. Several low abundance proteins were found to have significant changes in concentration in RA subjects and could be involved in or related to binding of HSA. Certain amino acid sites clusters were found to be less accessible in RA subjects, suggesting changes in HSA structure that may be related to changes in protein-protein interactions. These results all support a change in behavior of HSA which may give insight into mechanisms of RA pathology.

DNA methylation markers and early recurrence in stage I lung cancer.

BACKGROUND: Despite optimal and early surgical treatment of non-small-cell lung cancer (NSCLC), many patients die of recurrent NSCLC. We investigated the association between gene methylation and recurrence of the tumor. METHODS: Fifty-one patients with stage I NSCLC who underwent curative resection but who had a recurrence within 40 months after resection (case patients) were matched on the basis of age, NSCLC stage, sex, and date of surgery to 116 patients with stage I NSCLC who underwent curative resection but who did not have a recurrence within 40 months after resection (controls). We investigated whether the methylation of seven genes in tumor and lymph nodes was associated with tumor recurrence. RESULTS: In a multivariate model, promoter methylation of the cyclin-dependent kinase inhibitor 2A gene p16, the H-cadherin gene CDH13, the Ras association domain family 1 gene RASSF1A, and the adenomatous polyposis coli gene APC in tumors and in histologically tumor-negative lymph nodes was associated with tumor recurrence, independently of NSCLC stage, age, sex, race, smoking history, and histologic characteristics of the tumor. Methylation of the promoter regions of p16 and CDH13 in both tumor and mediastinal lymph nodes was associated with an odds ratio of recurrent cancer of 15.50 in the original cohort and an odds ratio of 25.25 when the original cohort was combined with an independent validation cohort of 20 patients with stage I NSCLC. CONCLUSIONS: Methylation of the promoter region of the four genes in patients with stage I NSCLC treated with curative intent by means of surgery is associated with early recurrence.

Dysfunctional KEAP1-NRF2 interaction in non-small-cell lung cancer.

BACKGROUND: Nuclear factor erythroid-2 related factor 2 (NRF2) is a redox-sensitive transcription factor that positively regulates the expression of genes encoding antioxidants, xenobiotic detoxification enzymes, and drug efflux pumps, and confers cytoprotection against oxidative stress and xenobiotics in normal cells. Kelch-like ECH-associated protein 1 (KEAP1) negatively regulates NRF2 activity by targeting it to proteasomal degradation. Increased expression of cellular antioxidants and xenobiotic detoxification enzymes has been implicated in resistance of tumor cells against chemotherapeutic drugs. METHODS AND FINDINGS: Here we report a systematic analysis of the KEAP1 genomic locus in lung cancer patients and cell lines that revealed deletion, insertion, and missense mutations in functionally important domains of KEAP1 and a very high percentage of loss of heterozygosity at 19p13.2, suggesting that biallelic inactivation of KEAP1 in lung cancer is a common event. Sequencing of KEAP1 in 12 cell lines and 54 non-small-cell lung cancer (NSCLC) samples revealed somatic mutations in KEAP1 in a total of six cell lines and ten tumors at a frequency of 50% and 19%, respectively. All the mutations were within highly conserved amino acid residues located in the Kelch or intervening region domain of the KEAP1 protein, suggesting that these mutations would likely abolish KEAP1 repressor activity. Evaluation of loss of heterozygosity at 19p13.2 revealed allelic losses in 61% of the NSCLC cell lines and 41% of the tumor samples. Decreased KEAP1 activity in cancer cells induced greater nuclear accumulation of NRF2, causing enhanced transcriptional induction of antioxidants, xenobiotic metabolism enzymes, and drug efflux pumps. CONCLUSIONS: This is the first study to our knowledge to demonstrate that biallelic inactivation of KEAP1 is a frequent genetic alteration in NSCLC. Loss of KEAP1 function leading to constitutive activation of NRF2-mediated gene expression in cancer suggests that tumor cells manipulate the NRF2 pathway for their survival against chemotherapeutic agents.

Can we improve the cytologic examination of malignant pleural effusions using molecular analysis?

BACKGROUND: Currently, 40% of patients remain undiagnosed after routine cytologic examination for malignant pleural effusions. Deoxyribonucleic acid (DNA) methylation is a robust strategy for detecting cancer early in tissue. We hypothesized that DNA methylation would be more sensitive in diagnosing patients with malignant pleural effusions than cytology. METHODS: We conducted a prospective cohort study of 31 inpatients with pleural effusions (24 malignant pleural effusions metastatic from 10 different organs and 7 benign) over 18 months. Aspirated pleural fluid underwent cytologic examination and DNA extraction for nested methylation-specific polymerase chain reaction (PCR). We assayed for promoter hypermethylation in 8 genes known to be methylated in many cancers. Pleural fluid was considered positive if 2 or more genes were methylated by methylation-specific PCR. RESULTS: Cytology alone confirmed malignant pleural effusions in 15 of 24 patients (sensitivity 63%), whereas methylation alone positively identified 16 of 24 patients (sensitivity 67%). Both tests had 100% specificity in predicting benign effusions. If cytology and methylation were considered together, they exhibited 88% sensitivity and 100% specificity in discriminating benign and malignant effusions. Combined, the two assays were more sensitive than either test alone. Although the positive predictive value of each test was 100%, the negative predictive value of cytology and methylation combined was 78%, better than 47% and 44% for methylation and cytology alone, respectively. CONCLUSIONS: Epigenetic analysis of pleural fluid can detect malignant DNA from a variety of neoplasms, provide complementarity with cytology, and improve the diagnostic yield of the current standard examination of pleural fluid.