Associations of miRNA polymorphisms and female physiological characteristics with breast cancer risk in Chinese population

mircoRNAs (miRNAs) play important roles on regulation of gene expressions. Aberrant expression of miRNAs was involved in various biological and pathological processes, including tumorigenesis of breast cancer. Single-nucleotide polymorphisms (SNPs) were implicated in altered expression or biological functions of mature miRNAs. To explore the relevance of miRNA polymorphisms and female physiological characteristics to breast cancer risk, SNPs located within hsa-miR-605 (rs2043556), hsa-miR-149 (rs2292832), hsa-miR-27a (rs895819), hsa-miR-196a-2 (rs11614913) and hsa-miR-618 (rs2682818) were selected, and their associations with breast cancer risk were analysed. In addition, associations between physiological characteristics-related factors and breast cancer risk were estimated too. We found that the ones with menarche age less than 16 years had increased breast cancer risk (OR = 2.10, 95% CI: 1.23-3.60). Marginally significant association between rs11614913 CT/CC genotypes and reduced breast cancer risk was observed (OR = 0.65, 95% CI: 0.40-1.06), while no significance was detected about the other miRNA polymorphisms. We concluded that menarche at less than 16 years old increased breast cancer risk, while the genetic variants in miR-196-a-2 might decrease the risk.

Associations of lifestyle-related factors, hsa-miR-149 and hsa-miR-605 gene polymorphisms with gastrointestinal cancer risk

To explore the associations of SNPs within hsa-miR-605 (rs2043556) and hsa-miR-149 (rs2292832) and lifestyle-related factors with gastrointestinal cancer, a case-control study including 762 cases and 757 controls was conducted. Marginally significant associations were found both for hsa-miR-149 rs2292832 with gastric cancer risk (TC + CC vs. TT, OR = 0.68, 95% CI: 0.44-1.04) and for hsa-miR-605 rs2043556 with colorectal cancer risk (AG + GG vs. AA, OR = 0.70, 95% CI: 0.48-1.02) in males. Tea drinking showed a protective effect on gastric cancer risk (OR = 0.28, 95% CI: 0.13-0.60), while smoke inhalation increased the risk of gastric cancer (OR = 1.94, 95% CI: 1.08-3.47). Irritability was found to be a risk factor for both colorectal cancer (OR = 1.61, 95% CI: 1.02-2.53) and gastric cancer (OR = 1.96, 95% CI: 1.17-3.29). Among those that engaged in smoke inhalation, miR-149 CT/CC and miR-605 AG/GG genotype carriers had increased susceptibilities to colorectal cancer (OR = 1.90, 95% CI: 1.11-3.25) and gastric cancer (OR = 1.87, 95% CI: 1.03-3.42), respectively. Among the tea drinkers, there exists a marginally protective effect of miR-605 AG/GG genotypes on colorectal cancer incidence (OR = 0.71, 95% CI: 0.47-1.06) and a significantly protective effect of miR-149 CT/CC on gastric cancer incidence (OR = 0.47, 95% CI: 0.29-0.77). The SNPs of rs2292832 and rs2043556 might be able to modify the susceptibility to male gastric and colorectal cancers, respectively. Tea drinking is a protective factor, while smoke inhalation is a risk factor for gastric cancer, and they might have the potential to modify the associations between miR-149 and miR-605 polymorphisms with gastrointestinal cancer risk. In addition, irritability was shown to be a risk factor for both gastric and colorectal cancers.

Deacetylation of FOXO3 by SIRT1 or SIRT2 leads to Skp2-mediated FOXO3 ubiquitination and degradation

Sirtuin deacetylases and FOXO (Forkhead box, class O) transcription factors have important roles in many biological pathways, including cancer development. SIRT1 and SIRT2 deacetylate FOXO factors to regulate FOXO function. Because acetylation and ubiquitination both modify the ɛ-amino group of lysine residues, we investigated whether FOXO3 deacetylation by SIRT1 or SIRT2 facilitates FOXO3 ubiquitination and subsequent proteasomal degradation. We found that SIRT1 and SIRT2 promote FOXO3 poly-ubiquitination and degradation. Proteasome-inhibitor treatment prevented sirtuin-induced FOXO3 degradation, indicating that this process is proteasome dependent. In addition, we demonstrated that E3 ubiquitin ligase subunit Skp2 binds preferentially to deacetylated FOXO3. Overexpression of Skp2 caused poly-ubiquitination of FOXO3 and degradation, whereas knockdown of Skp2 increased the amount of FOXO3 protein. We also present evidence that SCF-Skp2 ubiquitinates FOXO3 directly in vitro. Furthermore, mutating four known acetylated lysine residues (K242, K259, K290 and K569) of FOXO3 into arginines to mimic deacetylated FOXO3 resulted in enhanced Skp2 binding but with inhibition of FOXO3 ubiquitination; this suggests that some or all of these four lysine residues are likely the sites for ubiquitination. In the livers of mice deficient in SIRT1, we detected increased expression of FOXO3, indicating SIRT1 regulates FOXO3 protein levels in vivo. Furthermore, we found that the elevation of SIRT1 and Skp2 expression in malignant PC3 and DU145 prostate cells is responsible for the downregulation of FOXO3 protein levels in these cells. Taken together, our data support the notion that deacetylation of FOXO3 by SIRT1 or SIRT2 facilitates Skp2-mediated FOXO3 poly-ubiquitination and proteasomal degradation.

Chronic anastomotic sinus after low anterior resection: when can the defunctioning stoma be reversed?

AIM

Anastomotic leakage after low anterior resection may incompletely resolve, resulting in sinus tracts that persist on repeated contrast studies. This case series evaluated the factors that may contribute to sinus healing or to safe reversal of the defunctioning ileostomy.

METHOD

All patients (n = 8) who developed an anastomotic sinus after low anterior resection over an 8-year period were identified from a prospective database.

RESULTS

All patients had been treated with low anterior resections with defunctioning stomas for rectal carcinoma [median follow up 43.5 (13-84) months]. Two patients with an unhealed subclinical leak had the stoma reversed successfully. Of the six patients with clinical leakage, two healed spontaneously, one healed after application of fibrin glue, one developed an anastomotic stricture that was successfully treated by dilatation with subsequent stoma reversal, and one developed recurrent cancer and was not reversed. One patient underwent reversal, despite persistence of the sinus, followed by rectal perforation requiring laparotomy and faecal diversion. Bowel function was satisfactory where the sinus healed spontaneously, but poor where reversal was carried out without sinus healing.

CONCLUSION

Tracks that persist for longer than 1 year are unlikely to heal, but the stoma can be reversed if there had been a subclinical leak previously. A persistent anastomotic sinus leading to a cavity may not be suitable for stoma closure.

Exposure of neurons to excitotoxic levels of glutamate induces cleavage of the RNA editing enzyme, adenosine deaminase acting on RNA 2, and loss of GLUR2 editing

AMPA receptors are glutamate receptors that are tetramers of various combinations of GluR1-4 subunits. AMPA receptors containing GluR1, 3 and 4 are Ca2+ permeable, however, AMPA receptors containing even a single subunit of GluR2 are Ca2+ impermeable. Most AMPA receptors are Ca2+ impermeable due to the presence of GluR2. GluR2 confers special properties on AMPA receptors through the presence of arginine at the pore apex; other subunits (GluR1, 3, 4) contain glutamine at the pore apex and allow Ca2+ influx. Normally, an RNA editing step changes DNA-encoded glutamine to arginine, introduces arginine in the GluR2 pore apex. GluR2 RNA editing is carried out by an RNA-dependent adenosine deaminase (ADAR2). Loss of GluR2 editing leads to the formation of highly excitotoxic AMPA channels [Mahajan and Ziff (2007) Mol Cell Neurosci 35:470-481] and is shown to contribute to loss of motor neurons in amyotrophic lateral sclerosis (ALS). Relatively higher levels of Ca2+-permeable AMPA receptors are found in motor neurons and this has been correlated with lower GluR2 mRNA levels. However, the reason for loss of GluR2 editing is not known. Here we show that exposure of neurons to excitotoxic levels of glutamate leads to specific cleavage of ADAR2 that leads to generation of unedited GluR2. We demonstrate that cleaved ADAR2 leads to a decrease or loss of GluR2 editing, which will further result in high Ca2+ influx and excitotoxic neuronal death.

Expression of aberrant beta-catenin and impaired p63 in craniopharyngiomas

Craniopharyngiomas are rare, histologically benign, non-neuroepithelial epithelial tumors arising from the sellar region, the molecular pathogenesis of CPs is yet not understood. The aim of the present study was to assess expression of aberrant beta-catenin and impaired p63 in 66 craniopharyngiomas included 51 adamantinomatous craniopharyngiomas and 15 squamous papillary craniopharyngiomas. On immunohistochemistry, 47 out of 51 adamantinomatous craniopharyngiomas, but not squamous papillary craniopharyngiomas, showed strong nuclear/cytoplasmic expression for beta-catenin predominantly in compactly cohesive epithelial cells within the whorl-like arrays where ki-67 was almost absent and rarely in palisaded cells where ki-67 was mainly present. P63 overexpression was observed in 45 out of 51 adamantinomatous craniopharyngiomas and 14 out of 15 squamous papillary craniopharyngiomas. P63 stained not only in the nuclei of basal layer cells but also within the whorl-like arrays in adamantinomatous craniopharyngiomas and uniformly in squamous papillary craniopharyngiomas. Using quantitative real time polymerase chain reaction techniques to correlate p63 protein expression with p63 mRNA levels, TAp63 isoforms mRNA was reduced, whereas DeltaNp63 mRNA elevated at levels in 5 snap frozen tissue samples with multiple large p63 positive cell clusters compared with normal tissues. In conclusion, the present study confirmed that the two variants of CPs have genetically not only distinctive but also common feature. It demonstrated that cytoplasm/nuclear beta-catenin accumulation is an exclusively characteristic morphology of adaCPs. P63 immunohistochemical overexpression were found in both adaCPs and spCPs variant when analyzed in the same study. Taken together, the impaired p63 expression may be attributed to elevated DeltaNp63 mRNA and reduced TAp63mRNA in CPs.

Arterial stiffness and asymptomatic intracranial large arterial stenosis and calcification in hypertensive chinese

BACKGROUND

Intracranial large artery disease (ICLAD), such as stenosis and calcification, is common in Chinese patients with stroke. However, little is known about ICLAD and its association with large arterial stiffness in hypertensive patients.

METHODS

We recruited 270 (mean age 61.0 years, 45.6% male) untreated hypertensive patients without stroke from a community in Shanghai, China. ICLAD was detected by computerized tomographic angiography (CTA). Carotid-femoral pulse wave velocity (cf-PWV), office, and 24-h ambulatory pulse pressure (PP) as well as ambulatory arterial stiffness index (AASI) were determined as the measures of arterial stiffness.

RESULTS

Among all participants, 26 (9.6%) had concurrent intracranial arterial stenosis and calcification, 11 (4.1%) stenosis only, and 71 (26.3%) calcifications only. After adjustment for age, mean arterial pressure, and other covariables, there was significant difference in cf-PWV (13.1 vs. 13.7 vs. 15.0 m/s; P = 0.0015) and 24-h PP (46.7 vs. 48.8 vs. 55.7 mm Hg; P = 0.0007) between patients with normal vessels (n = 162), with stenosis or calcification (n = 82), and with both lesions (n = 26). Multiple ordinal logistic regression analyses showed that both cf-PWV and 24-h PP were independently associated with ICLAD. Odds ratios (95% confidence interval (CI)) of ICLAD after multivariable and mutually adjustment were 1.51 (1.09-2.10) and 1.46 (1.06-2.01) for 1-s.d. increase in cf-PWV and 24-h PP, respectively. No significant association (P ≥ 0.10) with AASI or office PP was observed in multivariable analysis.

CONCLUSION

Increased arterial stiffness was independently associated with ICLAD. cf-PWV and 24-h PP might be useful in identifying those more likely to have ICLAD among hypertensive patients.

Rectal cancer: 3D dynamic contrast-enhanced MRI; correlation with microvascular density and clinicopathological features

PURPOSE

The primary aim of this prospective study was to evaluate the relationship between three-dimensional dynamic contrast-enhanced magnetic resonance (3D-DCE-MR) imaging parameters and clinicopathological features of rectal cancer and assess their potential as new radiological prognostic predictors.

MATERIALS AND METHODS

Three-dimensional DCE-MR was performed on 26 cases of pathologically proved rectal adenocarcinoma 1 week prior to operation. Data were analysed to calculate transfer constant (Ktrans), leakage space (Ve) and rate constant (Kep) of both tumour and normal rectal wall. Microvessel density (MVD) was evaluated by immunohistochemical staining of surgical specimens. All findings were analysed prospectively and correlated with tumour/node/metastasis (TNM) staging, Dukes staging, histological grading, presence of lymph node metastasis, serosal involvement and MVD.

RESULTS

Mean Ktrans, Ve and Kep for tumours were as follows: Ktrans 7.123±3.850/min, Ve 14.2±3.0%, Kep 49.446±20.404/min, revealing the significant difference between the tumour and normal rectal wall (p=0.001). There was a significant difference for Ktrans not only between patients with and without lymphatic involvement (p=0.000), but also among Dukes staging (p=0.04) and pTNM staging (p=0.03). Kep showed moderate correlation with TNM stages (r=0.479, p=0.02). Ve and MVD revealed no significant correlation with the clinicopathological findings described above (p>0.05).

CONCLUSION

Owing to the moderate and strong relationship between Ktrans and clinicopathological elements, Ktrans might be the prognostic indicator of rectal cancer. Threedimensional DCE high-resolution MR imaging provides a competing opportunity to assess contrast kinetics.