Percutaneous transhepatic stenting for acute superior mesenteric vein stenosis after pancreaticoduodenectomy with portal vein reconstruction: A case report.

BACKGROUND: Percutaneous transhepatic stent placement has become a common strategy for the postoperative treatment of portal vein (PV)/superior mesenteric veins (SMV) stenosis/occlusion. It has been widely used after liver transplantation surgery; however, reports on stent placement for acute PV/SMV stenosis after pancreatic surgery within postoperative 3 d are rare. CASE SUMMARY: Herein, we reported a case of intestinal edema and SMV stenosis 2 d after pancreatic surgery. The patient was successfully treated using stent grafts. Although the stenosis resolved after stent placement, complications, including bleeding, pancreatic fistula, bile leakage, and infection, made the treatment highly challenging. The use of anticoagulants was adjusted multiple times to prevent venous thromboembolism and the risk of bleeding. After careful treatment, the patient stabilized, and stent placement effectively managed postoperative PV/SMV stenosis. CONCLUSION: Stent placement is effective and feasible for treating acute PV/SMV stenosis after pancreatic surgery even within postoperative 3 d.

Copper Nanodrugs by Atom Transfer Radical Polymerization.

In this study, some copper catalysts used for atom transfer radical polymerization (ATRP) were explored as efficient anti-tumor agents. The aqueous solution of copper-containing nanoparticles with uniform spheric morphology was in situ prepared through a copper-catalyzed activator generated by electron transfer (AGET) ATRP in water. Nanoparticles were then directly injected into tumor-bearing mice for antitumor chemotherapy. The copper nanodrugs had prolonged blood circulation time and enhanced accumulation at tumor sites, thus showing potent antitumor activity. This work provides a novel strategy for precise and large-scale preparation of copper nanodrugs with high antitumor activity.

IFIT1 modulates the proliferation, migration and invasion of pancreatic cancer cells via Wnt/ß-catenin signaling.

OBJECTIVES: Previously, Interferon-induced Protein with Tetratricopeptide Repeats 1 (IFIT1) has been shown to promote cancer development. Here, we aimed to explore the role of IFIT1 in the development and progression of pancreatic cancer, including the underlying mechanisms. METHODS: We explored IFIT1 expression in pancreatic cancer samples using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. Cell Counting Kit-8 (CCK8), colony formation, scratch wound-healing and Transwell assays were performed to assess the proliferation, migration and invasion abilities of pancreatic cancer cells. Gene Set Enrichment Analysis (GSEA) and Western blotting were performed to assess the regulatory effect of IFIT1 on the Wnt/ß-catenin pathway. RESULTS: We found that upregulation of IFIT1 expression is common in pancreatic cancer and is negatively associated with overall patient survival. Knockdown of IFIT1 expression led to decreased proliferation, migration and invasion of pancreatic cancer cells. We also found that IFIT1 could regulate Wnt/ß-catenin signaling, and that a Wnt/ß-catenin agonist could reverse this effect. In addition, we found that IFIT1 can promote epithelial-mesenchymal transition (EMT) of pancreatic cancer cells. CONCLUSIONS: Our data indicate that IFIT1 increases pancreatic cancer cell proliferation, migration and invasion by activating the Wnt/ß-catenin pathway. In addition, we found that EMT could be regulated by IFIT1. IFIT1 may serve as a potential therapeutic target for pancreatic cancer.

Development and validation of a nomogram model based on pretreatment ultrasound and contrast-enhanced ultrasound to predict the efficacy of neoadjuvant chemotherapy in patients with borderline resectable or locally advanced pancreatic cancer.

OBJECTIVES: To develop a nomogram using pretreatment ultrasound (US) and contrast-enhanced ultrasound (CEUS) to predict the clinical response of neoadjuvant chemotherapy (NAC) in patients with borderline resectable pancreatic cancer (BRPC) or locally advanced pancreatic cancer (LAPC). METHODS: A total of 111 patients with pancreatic ductal adenocarcinoma (PDAC) treated with NAC between October 2017 and February 2022 were retrospectively enrolled. The patients were randomly divided (7:3) into training and validation cohorts. The pretreatment US and CEUS features were reviewed. Univariate and multivariate logistic regression analyses were used to determine the independent predictors of clinical response in the training cohort. Then a prediction nomogram model based on the independent predictors was constructed. The area under the curve (AUC), calibration plot, C-index and decision curve analysis (DCA) were used to assess the nomogram's performance, calibration, discrimination and clinical benefit. RESULTS: The multivariate logistic regression analysis showed that the taller-than-wide shape in the longitudinal plane (odds ratio [OR]:0.20, p = 0.01), time from injection of contrast agent to peak enhancement (OR:3.64; p = 0.05) and Peaktumor/ Peaknormal (OR:1.51; p = 0.03) were independent predictors of clinical response to NAC. The predictive nomogram developed based on the above imaging features showed AUCs were 0.852 and 0.854 in the primary and validation cohorts, respectively. Good calibration was achieved in the training datasets, with C-index of 0.852. DCA verified the clinical usefulness of the nomogram. CONCLUSIONS: The nomogram based on pretreatment US and CEUS can effectively predict the clinical response of NAC in patients with BRPC and LAPC; it may help guide personalized treatment.

Long-term impact of prophylactic central neck dissection in non-invasive classic papillary thyroid carcinoma.

BACKGROUND: The utilization of prophylactic central neck dissection (pCND) in cases of non-invasive clinical node-negative (cN0) papillary thyroid carcinoma (PTC) remains a topic of debate, with a dearth of long-term evidence. MATERIALS AND METHODS: We retrospectively reviewed 1181 cN0 PTC patients from 1997 to 2011. Of these, 641 underwent pCND (pCND + group) and 540 did not (pCND-group). Propensity score matching (PSM) was used to identify similar patients. Event-free survival and long-term complications including permanent hyperparathyroidism and permanent recurrent laryngeal nerve (RLN) paralysis were analyzed after PSM. RESULTS: The pCND + group had more aggressive characteristics. In the matched cohort after PSM, the 5-year, 10-year, and 15-year EFS rates were 98.9 %, 98.2 %, and 97.1 % for the pCND + group, and 97.7 %, 97.1 %, and 97.1 % for the pCND-group, respectively. There was no statistically significant difference in EFS rates between the two groups (Log Rank P = 0.38). There was no statistically significant difference in the incidence of permanent hyperparathyroidism (3.3 % vs. 1.5 %, P = 0.08) and permanent RLN paralysis (1.7 % vs. 0.9 %, P = 0.13) between the pCND+ and pCND- groups. CONCLUSION: Our study, with a median follow-up duration of 107 months, indicates that pCND does not lead to a significant reduction in nodal recurrence among non-invasive cN0 PTC patients.

Lateral lymph node metastasis in papillary thyroid microcarcinoma: a study of 5241 follow-up patients.

PURPOSE: To investigate the impact of lateral lymph node metastasis in papillary thyroid microcarcinoma (PTMC). METHODS: 5241 PTMC patients with follow-up information were enrolled in the current study. These patients underwent primary surgery in our situation from January 1997 to December 2016. Additionally, a validation cohort consisting of 274 PTMC patients who underwent primary surgery between January 2020 and December 2021 was also included. Univariable and multivariate logistic analyses were conducted to identify the association between clinicopathologic features and lateral lymph node metastasis (LLNM). Kaplan-Meier survival curve analysis was used to calculate the disease-free survival (DFS) rate. The fitting curve was generated to identify the quantitative relationship between central lymph node metastases (CLNM) and LLNM. RESULTS: Of 5241 PTMC patients, cervical lymph node metastasis was detected in 1494 (28.5%) cases, including 1364 (26.0%) with CLNM only and 130 (2.5%) with LLNM. With a median follow-up time of 60 months (interquartile range [IQR], 44-81), recurrence was detected in 114 patients (2.2%). Multivariate Cox regression analyses showed that LNM was the only independent risk factor for recurrence, with HR values of 3.03 in CLNM and 11.14 in LLNM, respectively. Tumor diameter >0.5 cm (hazard ratio [HR]:1.80), multifocality (HR:2.59), bilaterality (HR:2.13), extrathyroidal invasion (HR:2.13), and CLNM (HR:5.11) were independent risk factors for LLNM. The prevalence of LLNM escalated significantly with increasing number of lymph node involvement in CLNM when stratified by the number of metastatic lymph nodes and trend was observed similarly in the validation cohort. The fitting curve showed that the incidence of LLNM could be as high as 20.7% when the number of CLNM ≥ 5. CONCLUSIONS: By analyzing a large database with follow-up information, our study provides evidence that LLNM is significantly correlated with tumor recurrence in patients with PTMC. Tumor size (>0.5 cm), multifocality, bilaterality, extrathyroidal extension (ETE) and CLNM are independent risk factors for LLNM.

MBD1 protects replication fork stability by recruiting PARP1 and controlling transcription-replication conflicts.

The replication-stress response is essential to ensure the faithful transmission of genetic information to daughter cells. Although several stress-resolution pathways have been identified to deal with replication stress, the precise regulatory mechanisms for replication fork stability are not fully understood. Our study identified Methyl-CpG Binding Domain 1 (MBD1) as essential for the maintaining genomic stability and protecting stalled replication forks in mammalian cells. Depletion of MBD1 increases DNA lesions and sensitivity to replication stress. Mechanistically, we found that loss of MBD1 leads to the dissociation of Poly(ADP-ribose) polymerase 1 (PARP1) from the replication fork, potentially accelerating fork progression and resulting in higher levels of transcription-replication conflicts (T-R conflicts). Using a proximity ligation assay combined with 5-ethynyl-2'-deoxyuridine, we revealed that the MBD1 and PARP1 proteins were recruited to stalled forks under hydroxyurea (HU) treatment. In addition, our study showed that the level of R-loops also increased in MBD1-delated cells. Without MBD1, stalled replication forks resulting from T-R conflicts were primarily degraded by the DNA2 nuclease. Our findings shed light on a new aspect of MBD1 in maintaining genome stability and providing insights into the mechanisms underlying replication stress response.

PP2A inhibition causes synthetic lethality in BRCA2-mutated prostate cancer models via spindle assembly checkpoint reactivation.

Mutations in the BRCA2 tumor suppressor gene have been associated with an increased risk of developing prostate cancer. One of the paradoxes concerning BRCA2 is the fact that its inactivation affects genetic stability and is deleterious for cellular and organismal survival, while BRCA2-mutated cancer cells adapt to this detriment and malignantly proliferate. Therapeutic strategies for tumors arising from BRCA2 mutations may be discovered by understanding these adaptive mechanisms. In this study, we conducted forward genetic synthetic viability screenings in Caenorhabditis elegans brc-2 (Cebrc-2) mutants and found that Ceubxn-2 inactivation rescued the viability of Cebrc-2 mutants. Moreover, loss of NSFL1C, the mammalian ortholog of CeUBXN-2, suppressed the spindle assembly checkpoint (SAC) activation and promoted the survival of BRCA2-deficient cells. Mechanistically, NSFL1C recruited USP9X to inhibit the polyubiquitination of AURKB and reduce the removal of AURKB from the centromeres by VCP, which is essential for SAC activation. SAC inactivation is common in BRCA2-deficient prostate cancer patients, but PP2A inhibitors could reactivate the SAC and achieve BRCA2-deficient prostate tumor synthetic lethality. Our research reveals the survival adaptation mechanism of BRCA2-deficient prostate tumor cells and provides different angles for exploring synthetic lethal inhibitors in addition to targeting DNA damage repair pathways.

Metabolic regulation of homologous recombination repair by MRE11 lactylation.

Lactylation is a lactate-induced post-translational modification best known for its roles in epigenetic regulation. Herein, we demonstrate that MRE11, a crucial homologous recombination (HR) protein, is lactylated at K673 by the CBP acetyltransferase in response to DNA damage and dependent on ATM phosphorylation of the latter. MRE11 lactylation promotes its binding to DNA, facilitating DNA end resection and HR. Inhibition of CBP or LDH downregulated MRE11 lactylation, impaired HR, and enhanced chemosensitivity of tumor cells in patient-derived xenograft and organoid models. A cell-penetrating peptide that specifically blocks MRE11 lactylation inhibited HR and sensitized cancer cells to cisplatin and PARPi. These findings unveil lactylation as a key regulator of HR, providing fresh insights into the ways in which cellular metabolism is linked to DSB repair. They also imply that the Warburg effect can confer chemoresistance through enhancing HR and suggest a potential therapeutic strategy of targeting MRE11 lactylation to mitigate the effects.

Reconstitution of the antagonistic effect between C1orf112/FIRRM-FIGNL1 and BRCA2 on RAD51 filament stabilization.

C1orf112/FIRRM is a recently identified DNA damage repair factor that regulates RAD51 in homologous recombination through interacting with the anti-recombinase FIGNL1. Here, we describe steps for purifying C1orf112/FIRRM, FIGNL1, miBRCA2, and RAD51 proteins from Escherichia coli or Saccharomyces cerevisiae cells. We then detail procedures for reconstituting the disassembly of RAD51 filament by C1orf112/FIRRM-FIGNL1 in vitro and the antagonistic effect between C1orf112/FIRRM-FIGNL1 and miBRCA2 on RAD51 filament stabilization. For complete details on the use and execution of this protocol, please refer to Zhou et al. (2023).1.

Spleen-dedicated stiffness measurement performed well to rule out high-risk varices in HBV-related hepatocellular carcinoma: Screening for high-risk varices in HCC.

BACKGROUND: Esophagogastroduodenoscopy (EGD) is required to screen for high-risk varices (HRV) in patients with hepatocellular carcinoma (HCC), especially since overall survival rates have dramatically improved with new systemic therapies. AIM: To assess the Baveno VI and Baveno VII algorithms' ability to rule out HRV in hepatitis B virus (HBV)-related HCC METHODS: We prospectively enrolled consecutive patients with HBV related, compensated cirrhosis and newly diagnosed HCC who underwent liver stiffness measurement, spleen stiffness measurement (SSM) using a 100-Hz shear wave frequency, and EGD. RESULTS: From September 2021 to August 2023, we enrolled 219 patients with HCC, with 107 (48.9%) Barcelona Clinic Liver Cancer (BCLC) A, 28 (12.8%) BCLC B and 84 (38.3%) BCLC C, respectively. HRV prevalence was 28.8% (63/219). Baveno VI criteria safely (HRV missing rate, 3.2%) avoided 27.4% unnecessary EGDs, while the Baveno VII algorithm avoided 49.3% with HRV missing rate at 7.9% (5/63). The SSM ≤40 kPa avoided 47.5% of EGDs safely (HRV missing rate, 4.8%), significantly better than the Baveno VI criteria (p < 0.001) and comparable to the Baveno VII algorithm (p = 0.390). The SSM ≤40 kPa safely avoided EGDs in patient subgroups within Milan criteria, with portal vein tumour thrombosis or BCLC B/C or candidates for systemic therapy. CONCLUSIONS: We validated that the SSM ≤40 kPa using a 100-Hz probe could safely eliminate more unnecessary EGDs than the Baveno VI criteria in patients with HBV-related HCC. However, the efficacy of the Baveno VII algorithm in patients with HCC requires further investigation.

Prognostic value and immune infiltration of ARMC10 in pancreatic adenocarcinoma via integrated bioinformatics analyses.

Background: Armadillo repeat-containing 10 (ARMC10) is involved in the progression of multiple types of tumors. Pancreatic adenocarcinoma (PAAD) is a lethal disease with poor survival and prognosis. Methods: We acquired the data of ARMC10 in PAAD patients from the cancer genome atlas (TCGA) and gene expression omnibus (GEO) datasets and compared the expression level with normal pancreatic tissues. We evaluated the relevance between ARMC10 expression and clinicopathological factors, immune infiltration degree and prognosis in PAAD. Results: High expression of ARMC10 was relevant to T stage, M stage, pathologic stage, histologic grade, residual tumor, primary therapy outcome (P < 0.05) and related to lower Overall-Survival (OS), Disease-Specific Survival (DSS), and Progression-Free Interval (PFI). Gene set enrichment analysis showed that ARMC10 was related to methylation in neural precursor cells (NPC), G alpha (i) signaling events, APC targets, energy metabolism, potassium channels and IL10 synthesis. The expression level of ARMC10 was positively related to the abundance of T helper cells and negatively to that of plasmacytoid dendritic cells (pDCs). Knocking down of ARMC10 could lead to lower proliferation, invasion, migration ability and colony formation rate of PAAD cells in vitro. Conclusions: Our research firstly discovered ARMC10 as a novel prognostic biomarker for PAAD patients and played a crucial role in immune regulation in PAAD.

Local resection for solid pseudopapillary neoplasms of the pancreas shows improved postoperative gastrointestinal function and reduced mental stress: a multiquestionnaire survey from a large cohort.

BACKGROUND: Solid pseudopapillary neoplasm (SPN) of the pancreas is a rare, low-grade malignant pancreatic tumor with a highly favorable prognosis. Most SPN patients are young and middle-aged women. The main controversial topic for SPN is local resection (LR) versus radical resection (RR). Theoretically, LR could lead to better gastrointestinal function (GIF) and less mental stress. However, no data is available to support this hypothesis. METHODS: All SPN patients undergoing surgical treatment in Peking Union Medical College Hospital from 2001 to 2021 were included in the study. A cross-sectional online multiquestionnaire survey containing 110 questions was sent to them (Clinicaltrial.org, NCT05604716). This online multiquestionnaire survey focused on GIF and mental stress and consisted of eight questionnaires. Multiple linear regression analysis was conducted to identify independent factors impacting GIF and mental stress. RESULTS: A total of 183 cases provided valid results. Among them, 46 patients (25.1%) underwent LR, and 137 (74.9%) underwent RR. Ninety-four cases (51.4%) underwent minimally invasive surgery (MIS), while 89 (48.6%) underwent open surgery. The average GSRS score of the patients was 1.9±0.7, indicating that most suffered from mild gastrointestinal dysfunction. The scores of PHQ-9 and GAD-7 in 16 patients (8.7%) and 27 (14.8%) patients, respectively, were beyond 10.0, which indicated clinical depression and anxiety. Additionally, 19 (10.4%) patients reported poor ability to work, and 31(16.9%) patients had significant body image concerns. Compared to other clinicopathological characteristics, LR (LR vs. RR: PHQ-9 score, P =0.018; WAI average score, P =0.010; EORTC QLQ-C30, nine subdomains, P <0.05; GSRS average score, P =0.006) and MIS (MIS vs. open surgery: EORTC QLQ-C30, three subdomains, P <0.05; GSRS average score, P =0.006) were the most significant factors predicting improved GIF and reduced mental stress. CONCLUSIONS: This study systematically presents postoperative GIF and mental stress of SPN patients using validated multiquestionnaires for the first time. It provides solid evidence that LR and MIS can improve GIF and reduce mental stress after surgery for SPN patients, which could be helpful for the surgeons to make more personalized surgical plans for their patients.

Global trends and frontiers of research on total disc replacement: A bibliometric analysis.

With the increased risk of complications associated with traditional spinal fusion for the treatment of degenerative disc disease, total disc replacement (TDR) has received increasing attention in recent years. Despite the rapid development of its related research fields, its research status and the hotspot analysis are still unclear. Our goal was to identify and analyze the global research trends on TDR using bibliometric tools. All TDR data were obtained from the WoSCC. The information of research field was collected, including title, author, institutions, journals, countries, references, total citations, and years of publication for further analysis. From 1993 to 2022, a total of 1167 articles and 11,348 references were included in this field. These publications are mainly from 53 countries/regions and 174 journals, led by the United States and China. According to the citation report, the US was absolutely in the leading position in this research field. The most contribution institution and author were Sichuan University and Liu H. Spine and European Spine Journal were the most active journal on TDR research, with 205 and 118 articles. Meanwhile, they were also the most frequently cited journals. The "bone loss," "cervical arthroplasty," "hybrid surgery" were the most frequently cited areas of TDR research. Meanwhile, the latest research hotspots and directions were "cervical disc arthroplasty," "7 year follow up," "heterotopic ossification." The scientific research on TDR has increased considerably in recent years. This study clarifies the current research status and future development trends in order to guide clinicians and researchers in the field of TDR. It can be inferred that cervical disc arthroplasty and bone loss will be the research focus in the future.

The complete chloroplast genome sequences of four Liparis species (Orchidaceae) and phylogenetic implications.

Liparis Richard (Malaxideae, Epidendroideae) is a large and diverse genus of the family Orchidaceae, the taxonomy of which is complicated and controversial. In this study, we sequenced, assembled and analyzed four complete chloroplast genomes of Liparis species including L. kumokiri, L. makinoana, L. pauliana, and L. viridiflora, and evaluated their phylogenetic relationships with related species for the first time. These four chloroplast genomes (size range 153,095 to 158,239 bp) possess typical quadripartite structures that consist of a large single copy (LSC, 83,533-86,752 bp), a small single copy (SSC, 17,938-18,156 bp) and a pair of inverted repeats (IRs, 26,421-26,933 bp). The genomes contain 133 genes, including 87 protein coding genes, 38 tRNAs and 8 rRNA genes. The genome arrangements, gene contents, gene order, long repeats and simple sequence repeats were similar with small differences observed among these four chloroplast genomes. Five highly variable regions including ycf1, ndhA, ndhF, trnQ and trnK were identified from the comparative analysis with other nine related Liparis species, which had the potential to be used as DNA markers for species identification and phylogenetic studies of Liparis species. Phylogenetic analysis based on the complete chloroplast genome sequences strongly supported the polyphyly of Liparis and its further division into three branches. These results provided valuable information to illustrate the complicated taxonomy, phylogeny and evolution process of the Liparis genus.

Risk stratification of clinically relevant delayed gastric emptying after pancreaticoduodenectomy.

BACKGROUND: Delayed gastric emptying (DGE) remains one of the major complications after pancreaticoduodenectomy (PD), with discrepant reports of its contributing factors. This study aimed to develop a nomogram to identify potential predictors and predict the probability of DGE after PD. METHODS: This retrospective study enrolled 422 consecutive patients who underwent PD from January 2019 to December 2021 at our institution. The LASSO algorithm and multivariate logistic regression were performed to identify independent risk and protective factors associated with clinically relevant delayed gastric emptying (CR-DGE). A nomogram was established based on the selected variables. Then, the calibration curve, ROC curve, decision curve analysis (DCA), and clinical impact curve (CIC) were applied to evaluate the predictive performance of our model. Finally, an independent cohort of 45 consecutive patients from January 2022 to March 2022 was enrolled to further validate the nomogram. RESULTS: Among 422 patients, CR-DGE occurred in 94 patients (22.2%). A previous history of chronic gastropathy, intraoperative plasma transfusion ≥ 400 ml, end-to-side gastrointestinal anastomosis, intra-abdominal infection, incisional infection, and clinically relevant postoperative pancreatic fistula (CR-POPF) were identified as risk predictors. Minimally invasive pancreaticoduodenectomy (MIPD) was demonstrated to be a protective predictor of CR-DGE. The areas under the curve (AUCs) were 0.768 (95% CI, 0.706-0.830) in the development cohort, 0.766 (95% CI, 0.671-0.861) in the validation cohort, and 0.787 (95% CI, 0.633-0.940) in the independent cohort. Then, we built a simplified scale based on our nomogram for risk stratification. CONCLUSIONS: Our study identified seven predictors and constructed a validated nomogram that effectively predicted CR-DGE for patients who underwent PD.

C1orf112 teams up with FIGNL1 to facilitate RAD51 filament disassembly and DNA interstrand cross-link repair.

The recombinase RAD51 plays a core role in DNA repair by homologous recombination (HR). The assembly and disassembly of RAD51 filament need to be orderly regulated by mediators such as BRCA2 and anti-recombinases. To screen for potential regulators of RAD51, we perform RAD51 proximity proteomics and identify factor C1orf112. We further find that C1orf112 complexed with FIGNL1 facilitates RAD51 filament disassembly in the HR step of Fanconi anemia (FA) pathway. Specifically, C1orf112 physically interacts with FIGNL1 and enhances its protein stability. Meanwhile, the RAD51 filament disassembly activity of FIGNL1 is directly stimulated by C1orf112. BRCA2 directly interacts with C1orf112-FIGNL1 complex and functions upstream of this complex to protect RAD51 filament from premature disassembly. C1orf112- and FIGNL1-deficient cells are primarily sensitive to DNA interstrand cross-link (ICL) agents. Thus, these findings suggest an important function of C1orf112 in RAD51 regulation in the HR step of ICL repair by FA pathway.

DHX38 restricts chemoresistance by regulating the alternative pre-mRNA splicing of RELL2 in pancreatic ductal adenocarcinoma.

Intron retention plays an important role in cancer progression and chemotherapy resistance and seems to be essential for the maintenance of genome stability in cancer. Here, our goal was to analyze the role of receptor expressed in lymphoid tissue (Relt)-like 2 (RELL2) intron 4 retention in promoting pancreatic ductal adenocarcinoma (PDAC) progression. Our results showed that intron retention (IR) occurs at the fourth intron of RELL2 transcript in gemcitabine resistant PDAC cells, however, the regulatory mechanism and the clinical implications of IR of RELL2 are unclear. Firstly, we found that RELL2 plays an anti-oncogenic role in PDAC by performing in vitro functional assays including cell proliferation, GEM cytotoxicity assay and apoptosis. Subsequently, we identified the upstream gene of RELL2, DEAH-Box Helicase 38 (DHX38), and demonstrated the direct interaction between DHX38 and RELL2 by RIP-qPCR. We also found that altered expression of DHX38 resulted in corresponding changes in intron 4 retention of RELL2. Importantly, we unveiled that overexpression of DHX38 on the basis of knocking down of the fourth intron of RELL2 resulted in an impaired intron 4 intention. Overall, our study identified a new IR site in PDAC, which could be a possible target for PDAC therapy.

A transcription-independent mechanism determines rapid periodic fluctuations of BRCA1 expression.

BRCA1 expression is highly regulated to prevent genomic instability and tumorigenesis. Dysregulation of BRCA1 expression correlates closely with sporadic basal-like breast cancer and ovarian cancer. The most significant characteristic of BRCA1 regulation is periodic expression fluctuation throughout the cell cycle, which is important for the orderly progression of different DNA repair pathways throughout the various cell cycle phases and for further genomic stability. However, the underlying mechanism driving this phenomenon is poorly understood. Here, we demonstrate that RBM10-mediated RNA alternative splicing coupled to nonsense-mediated mRNA decay (AS-NMD), rather than transcription, determines the periodic fluctuations in G1/S-phase BRCA1 expression. Furthermore, AS-NMD broadly regulates the expression of period genes, such as DNA replication-related genes, in an uneconomical but more rapid manner. In summary, we identified an unexpected posttranscriptional mechanism distinct from canonical processes that mediates the rapid regulation of BRCA1 as well as other period gene expression during the G1/S-phase transition and provided insights into potential targets for cancer therapy.