A high-resolution mass spectrometric approach to a qualitative and quantitative comparative metabolism of the humantenine-type alkaloid rankinidine.

RATIONALE: Rankinidine belongs to the humantenine-type alkaloids isolated from Gelsemium. Currently, the mechanism behind the toxicity differences of rankinidine has not been explained. In this study, our purpose was to elucidate the major in vitro metabolic pathways of rankinidine and to compare the formation of metabolites of rankinidine in human (HLMs), rat (RLMs), goat (GLMs) and pig (PLMs) liver microsomes. METHODS: This is the first study to compare the in vitro metabolism of rankinidine with high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOF). The MS/MS data and LC/MS peak area acquired in positive ion mode were used to analyze metabolite structures and compare metabolism. RESULTS: We identified 11 metabolites (M1-M11) in total and found five main metabolic pathways, consisting of demethylation (M1), reduction (M2), oxidation at different positions (M3-M5), oxidation and reduction (M6-M10) and demethylation and oxidation (M11). The metabolism of rankinidine has qualitative and quantitative species-specific differences in vitro. In PLMs and GLMs, the main metabolic pathway of rankinidine was oxidation. Notably, among the four species, the oxidation ability of rankinidine was highest in pigs and goats, and the demethylation and reduction abilities of rankinidine were highest in humans and rats. CONCLUSIONS: The interspecific metabolic differences of rankinidine in HLMs, PLMs, GLMs and RLMs were compared and studied for the first time using LC/QTOF. These findings will certainly support future studies of rankinidine metabolism in vivo and will contribute to elucidating the cause of species-specific differences behind Gelsemium toxicity.

CHK1 Inhibitor Blocks Phosphorylation of FAM122A and Promotes Replication Stress.

While effective anti-cancer drugs targeting the CHK1 kinase are advancing in the clinic, drug resistance is rapidly emerging. Here, we demonstrate that CRISPR-mediated knockout of the little-known gene FAM122A/PABIR1 confers cellular resistance to CHK1 inhibitors (CHK1is) and cross-resistance to ATR inhibitors. Knockout of FAM122A results in activation of PP2A-B55α, a phosphatase that dephosphorylates the WEE1 protein and rescues WEE1 from ubiquitin-mediated degradation. The resulting increase in WEE1 protein expression reduces replication stress, activates the G2/M checkpoint, and confers cellular resistance to CHK1is. Interestingly, in tumor cells with oncogene-driven replication stress, CHK1 can directly phosphorylate FAM122A, leading to activation of the PP2A-B55α phosphatase and increased WEE1 expression. A combination of a CHK1i plus a WEE1 inhibitor can overcome CHK1i resistance of these tumor cells, thereby enhancing anti-cancer activity. The FAM122A expression level in a tumor cell can serve as a useful biomarker for predicting CHK1i sensitivity or resistance.

A mitotic CDK5-PP4 phospho-signaling cascade primes 53BP1 for DNA repair in G1.

Mitotic cells attenuate the DNA damage response (DDR) by phosphorylating 53BP1, a critical DDR mediator, to prevent its localization to damaged chromatin. Timely dephosphorylation of 53BP1 is critical for genome integrity, as premature recruitment of 53BP1 to DNA lesions impairs mitotic fidelity. Protein phosphatase 4 (PP4) dephosphorylates 53BP1 in late mitosis to allow its recruitment to DNA lesions in G1. How cells appropriately dephosphorylate 53BP1, thereby restoring DDR, is unclear. Here, we elucidate the underlying mechanism of kinetic control of 53BP1 dephosphorylation in mitosis. We demonstrate that CDK5, a kinase primarily functional in post-mitotic neurons, is active in late mitotic phases in non-neuronal cells and directly phosphorylates PP4R3ß, the PP4 regulatory subunit that recognizes 53BP1. Specific inhibition of CDK5 in mitosis abrogates PP4R3ß phosphorylation and abolishes its recognition and dephosphorylation of 53BP1, ultimately preventing the localization of 53BP1 to damaged chromatin. Our results establish CDK5 as a regulator of 53BP1 recruitment.

TIRR regulates 53BP1 by masking its histone methyl-lysine binding function.

P53-binding protein 1 (53BP1) is a multi-functional double-strand break repair protein that is essential for class switch recombination in B lymphocytes and for sensitizing BRCA1-deficient tumours to poly-ADP-ribose polymerase-1 (PARP) inhibitors. Central to all 53BP1 activities is its recruitment to double-strand breaks via the interaction of the tandem Tudor domain with dimethylated lysine 20 of histone H4 (H4K20me2). Here we identify an uncharacterized protein, Tudor interacting repair regulator (TIRR), that directly binds the tandem Tudor domain and masks its H4K20me2 binding motif. Upon DNA damage, the protein kinase ataxia-telangiectasia mutated (ATM) phosphorylates 53BP1 and recruits RAP1-interacting factor 1 (RIF1) to dissociate the 53BP1-TIRR complex. However, overexpression of TIRR impedes 53BP1 function by blocking its localization to double-strand breaks. Depletion of TIRR destabilizes 53BP1 in the nuclear-soluble fraction and alters the double-strand break-induced protein complex centring 53BP1. These findings identify TIRR as a new factor that influences double-strand break repair using a unique mechanism of masking the histone methyl-lysine binding function of 53BP1.

Laparoscopic surgery assisted by colonoscopy for a submucosal cecal fecalith presenting as acute appendicitis: A case report.

RATIONALE: A cecal submucosal fecalith is extremely rare and is likely to be misdiagnosed as appendicitis with an incarcerated fecalith. PATIENT CONCERNS: This review presents the case of a female patient complaining of recurrent abdominal pain in the right lower quadrant, similar to the clinical symptoms of appendicitis. Physical examination revealed an abdominal tenderness in the right lower quadrant without rebound tenderness or muscular tension. An ultrasound examination found a mass located in the right lower abdomen. Computed tomography showed a high-density shadow in the cecal cavity. DIAGNOSES: A fecalith was detected in the submucosal cecal wall. The postoperative pathologic examination showed that the fecalith was located in the submucosa. INTERVENTIONS: A partial cecal excision was performed under laparoscopic surgery assisted by colonoscopy. OUTCOMES: The patient was discharged 1 week after surgery without postoperative complications. LESSONS: Fecaliths should be considered in the differential diagnosis of submucosal occupying lesions of the cecum.

MicroRNA-711 is a prognostic factor for poor overall survival and has an oncogenic role in breast cancer.

MicroRNAs are important in cancer development and progression. In the present study, the clinical significance and function of microRNA-711 (miR-711) expression in breast cancer were investigated. The expression level of miR-711 was analyzed in breast cancer tissue samples using reverse transcription-quantitative polymerase chain reaction. Cell proliferation, colony formation, apoptosis and Transwell assays were performed in breast cancer cell lines transfected with miR-711 mimics or inhibitors, or control sequence. miR-711 was found to be upregulated in 30 formalin-fixed paraffin-embedded breast cancer tissue samples compared with paired non-cancerous breast tissues (P<0.05). Furthermore, a higher miR-711 expression was demonstrated to be associated with poor overall and disease-free survival times in 161 breast cancer patients, and miR-711 was identified as an independent prognostic factor using multivariate Cox regression analysis. In vitro, overexpression of miR-711 resulted in a significant increase in proliferation, colony formation, migration and invasion of breast cancer cells. By contrast, downregulating miR-711 inhibited cell proliferation, colony formation, migration and invasion and enhanced the rate of apoptosis of breast cancer cells. To the best of our knowledge, the present study is the first to demonstrate that miR-711 is an independent prognostic factor and serves an important oncogenic function in breast cancer, suggesting that miR-711 is a potential biomarker of prognosis and a molecular therapeutic target in breast cancer.

The MHF complex senses branched DNA by binding a pair of crossover DNA duplexes.

The conserved MHF1-MHF2 (MHF) complex functions in the activation of the Fanconi anaemia pathway of the DNA damage response, in regulating homologous recombination, and in DNA replication fork maintenance. MHF facilitates the processing of multiple types of branched DNAs by the DNA translocase FANCM. Here we report the crystal structure of a human MHF-DNA complex that reveals the DNA-binding mode of MHF. The structure suggests that MHF prefers branched DNA over double-stranded DNA because it engages two duplex arms. Biochemical analyses verify that MHF preferentially engages DNA forks or various four-way junctions independent of the junction-site structure. Furthermore, genetic experiments provide evidence that the observed DNA-binding interface of MHF is important for cellular resistance to DNA damage. These results offer insights into how the MHF complex recognizes branched DNA and stimulates FANCM activity at such a structure to promote genome maintenance.

[The role of glucagon-like peptide-1 and its receptor in the mechanism of metabolic surgery].

At present, surgery has become one of the treatments for type 2 diabetes, but it is still unclear about the therapeutic mechanism. Many experiments has proved that the anatomical and physiological structure has been altered leading to significant changes related to the secretion of gastrointestinal hormones and neuropeptides. These molecular are related to the metabolism of glucose, functions of islet cells and sensitivity of insulin. Intensive studies of glucagon-like peptide-1 (GLP-1) play an important role in the surgical treatment of diabetes and now it has gained increasing recognition. However, GLP-1 must be combined with GLP-1 receptor (GLP-1R) to execute its function. In this paper we reviewed the role of GLP-1 and its receptor in the mechanism of metabolic surgery.

Allele loss and down-regulation of heparanase gene are associated with the progression and poor prognosis of hepatocellular carcinoma.

OBJECTIVES: The role of heparanase (HPSE) gene in cancers including hepatocellular carcinoma (HCC) is currently controversial. This study was aimed at investigating the impact of genetic alteration and expression change of HPSE on the progression and prognosis of HCC. METHODS: The HPSE gene was studied in three different aspects: (1) loss of heterozygosity (LOH) by a custom SNP microarray and DNA copy number by real-time PCR; (2) mRNA level by qRT-PCR; and (3) protein expression by immunohistochemistry. The clinical significances of allele loss and expression change of HPSE were analyzed. RESULTS: Microarray analysis showed that the average LOH frequency for 10 SNPs located within HPSE gene was 31.6%, three of which were significantly correlated with tumor grade, serum HBV-DNA level, and AFP concentration. In agreement with SNP LOH data, DNA copy number loss of HPSE was observed in 38.74% (43/111) of HCC cases. HPSE mRNA level was notably reduced in 74.1% (83/112) of tumor tissues compared with non-tumor liver tissues, which was significantly associated with DNA copy number loss, increased tumor size, and post-operative metastasis. HPSE protein level was also remarkably reduced in 66.3% (53/80) of tumor tissues, which was correlated with tumor grade. Patients with lower expression level of HPSE mRNA or protein had a significantly lower survival rate than those with higher expression. Cox regression analysis suggested that HPSE protein was an independent predictor of overall survival in HCC patients. CONCLUSIONS: The results in this study demonstrate that genetic alteration and reduction of HPSE expression are associated with tumor progression and poor prognosis of HCCs, suggesting that HPSE behaves like a tumor suppressor gene and is a potential prognostic marker for HCC patients.

A variant of the breast cancer type 2 susceptibility protein (BRC) repeat is essential for the RECQL5 helicase to interact with RAD51 recombinase for genome stabilization.

The BRC repeat is a structural motif in the tumor suppressor BRCA2 (breast cancer type 2 susceptibility protein), which promotes homologous recombination (HR) by regulating RAD51 recombinase activity. To date, the BRC repeat has not been observed in other proteins, so that its role in HR is inferred only in the context of BRCA2. Here, we identified a BRC repeat variant, named BRCv, in the RECQL5 helicase, which possesses anti-recombinase activity in vitro and suppresses HR and promotes cellular resistance to camptothecin-induced replication stress in vivo. RECQL5-BRCv interacted with RAD51 through two conserved motifs similar to those in the BRCA2-BRC repeat. Mutations of either motif compromised functions of RECQL5, including association with RAD51, inhibition of RAD51-mediated D-loop formation, suppression of sister chromatid exchange, and resistance to camptothecin-induced replication stress. Potential BRCvs were also found in other HR regulatory proteins, including Srs2 and Sgs1, which possess anti-recombinase activities similar to that of RECQL5. A point mutation in the predicted Srs2-BRCv disrupted the ability of the protein to bind RAD51 and to inhibit D-loop formation. Thus, BRC is a common RAD51 interaction module that can be utilized by different proteins to either promote HR, as in the case of BRCA2, or to suppress HR, as in RECQL5.

Multiple pathways suppress telomere addition to DNA breaks in the Drosophila germline.

Telomeres protect chromosome ends from being repaired as double-strand breaks (DSBs). Just as DSB repair is suppressed at telomeres, de novo telomere addition is suppressed at the site of DSBs. To identify factors responsible for this suppression, we developed an assay to monitor de novo telomere formation in Drosophila, an organism in which telomeres can be established on chromosome ends with essentially any sequence. Germline expression of the I-SceI endonuclease resulted in precise telomere formation at its cut site with high efficiency. Using this assay, we quantified the frequency of telomere formation in different genetic backgrounds with known or possible defects in DNA damage repair. We showed that disruption of DSB repair factors (Rad51 or DNA ligase IV) or DSB sensing factors (ATRIP or MDC1) resulted in more efficient telomere formation. Interestingly, partial disruption of factors that normally regulate telomere protection (ATM or NBS) also led to higher frequencies of telomere formation, suggesting that these proteins have opposing roles in telomere maintenance vs. establishment. In the ku70 mutant background, telomere establishment was preceded by excessive degradation of DSB ends, which were stabilized upon telomere formation. Most strikingly, the removal of ATRIP caused a dramatic increase in telomeric retrotransposon attachment to broken ends. Our study identifies several pathways that suppress telomere addition at DSBs, paving the way for future mechanistic studies.

[Duodenojejunal bypass in treatment for 7 cases with non-severe obese type 2 diabetes mellitus].

OBJECTIVE: To investigate the efficacy and feasibility of duodenojejunal bypass(DJB)on non-severe obese patients with type 2 diabetes mellitus(T2DM). METHODS: The body mass index (BMI), fasting plasma glucose(FPG), 2h-postprandial plasma glucose(2hPG), fasting insulin(F-ins), fasting c-peptide(F-CP), glycated hemoglobin and hypoglycemic agents dose changes were tested in 7 patients with non-severe obese T2DM undergoing DJB, preoperatively and within 24 weeks after surgery during the follow-up. Data were collected and the clinical outcomes of T2DM were analyzed. RESULTS: In 7 cases of non-obese T2DM who underwent DJB, one patient was weaned off hypoglycemic agents with normal FPG, 2hPG and HbA1c postoperatively. Five required significantly lower dosage. No significant improvement in 1 case. Complete remission rate of hyperglycemia was 1/7, effective rate was 6/7, and effective rate of HbA1c was 5/7. No significant changes in BMI were observed between the preoperative and postoperative phases. CONCLUSION: Plasma glucose level can be markedly reduced by duodenojejunal bypass in non-obese T2DM, independent of weight loss, and the mechanism remains unclear.

Comparison of laparoscopic and open surgery for pyogenic liver abscess with biliary pathology.

AIM: To investigate the feasibility and therapeutic effect of laparoscopic surgery for pyogenic liver abscess (PLA) with biliary pathology. METHODS: From January 2004 to October 2010, 31 patients with PLA combined with biliary pathology meeting entry criteria received surgical management in our hospital. Of the 31 patients, 13 underwent laparoscopic surgery (LS group) and 18 underwent open surgery (OS group). Clinical data including operation time, intraoperative blood loss, postoperative complication rate, length of postoperative hospital stay, and abscess recurrence rate were retrospectively analyzed and compared between the two groups. RESULTS: All patients received systemic antibiotic therapy. Four patients underwent ultrasound-guided percutaneous catheter drainage before operation. Postoperative complications occurred in 5 patients (16.1%, 5/31) including 2 in the LS group and 3 in the OS group. One patient had retained calculus in the common bile duct and another had liver abscess recurrence in the OS group. No retained calculus and liver abscess recurrence occurred in the LS group. In the two groups, there was no mortality during the perioperative period. There were no significant differences in operation time, intraoperative blood loss and transfusion, postoperative complication rate and abscess recurrence rate between the two groups. Oral intake was earlier (1.9 ± 0.4 d vs 3.1 ± 0.7 d, P < 0.05) and length of postoperative hospital stay was shorter (11.3 ± 2.9 d vs 14.5 ± 3.7 d, P < 0.05) in the LS group than in the OS group. CONCLUSION: Laparoscopic surgery for simultaneous treatment of PLA and biliary pathology is feasible in selected patients and the therapeutic effect is similar to that of open surgery.

[Laparoscopic total mesorectal excision combined with intersphincteric resection for ultra-low rectal cancer].

OBJECTIVE: To evaluate clinical outcomes after laparoscopic total mesorectal excision (TME) combined with intersphincteric resection (ISR) for ultra-low rectal tumors. METHODS: Clinical data of 36 patients with ultra-low rectal tumor undergoing laparoscopic TME combined with ISR were analyzed retrospectively. RESULTS: The median distance from the inferior margin of the tumor to the anal verge was 3.4 (2.0-5.0) cm. There were 33 cases of well/moderately differentiated adenocarcinoma and 3 rectal malignant villous adenoma. There were 16 patients with stage I disease, 15 with stage II A, 3 with stage III A, and 1 with III B. Postoperatively, one patient developed stenosis at the end ileostomy and 3 anastomotic leakage. After a median follow-up of 16(4-49) months, one patient developed local recurrence at the anastomosis and one case died of liver metastasis. In the 19 patients who had a minimum follow-up of one year, the bowel movements frequency ranged from 1-4 times per day, and these patients were able to withhold defecation for more than 5 minutes. CONCLUSIONS: Laparoscopic TME combined with ISR can achieve oncologic clearance, sphincter preservation, and minimal invasiveness for ultra-lower rectal cancer. However, patients selection should be cautious.

MHF1-MHF2, a histone-fold-containing protein complex, participates in the Fanconi anemia pathway via FANCM.

FANCM is a Fanconi anemia nuclear core complex protein required for the functional integrity of the FANC-BRCA pathway of DNA damage response and repair. Here we report the isolation and characterization of two histone-fold-containing FANCM-associated proteins, MHF1 and MHF2. We show that suppression of MHF1 expression results in (1) destabilization of FANCM and MHF2, (2) impairment of DNA damage-induced monoubiquitination and foci formation of FANCD2, (3) defective chromatin localization of FA nuclear core complex proteins, (4) elevated MMC-induced chromosome aberrations, and (5) sensitivity to MMC and camptothecin. We also provide biochemical evidence that MHF1 and MHF2 assemble into a heterodimer that binds DNA and enhances the DNA branch migration activity of FANCM. These findings reveal critical roles of the MHF1-MHF2 dimer in DNA damage repair and genome maintenance through FANCM.

Analysis of procedure-related complications after pancreatodoudenectomy.

PURPOSE: To analyze the procedure-related complications after pancreaticoduodenctomy (PD) and their risk factors. METHODS: One hundred twenty-six patients underwent pancreatoduodenectomy for diseases at region of pancreatic head were reviewed retrospectively. RESULTS: The overall surgical morbidity was 40.5% (51/126). Ten (7.9%) of 51 patients were identified as having pancreatic leakage, others included delayed gastric emptying (8.7%, 11), abdominal infection and abscess (7.9%, 10), abdominal bleeding (5.6%, 7), wound infection (4.8%, 6), wound dehiscence (2.4%, 3), biliary fistula (1.6%, 2) and operative death (1.6%, 2). Other postoperative complications were lung inflammation (3.9%, 5) and newly developed diabetes mellitus (2.3%, 3). Age (>60 years), coexisting diabetes mellitus, small main pancreatic duct (≤0.5 cm), and surgeon's experience (<10 patients within 5 years) were demonstrated to be independent risk factors by both univariate and multivariate analysis (p < 0.01). CONCLUSIONS: Old patients with coexisting diabetes mellitus and small main pancreatic duct undergo pancreatoduodenectomy by a less experienced surgeon may be at high risk of procedure-related complications.