Structural Insights of Transcriptionally Active, Full-Length Androgen Receptor Coactivator Complexes.

Steroid receptors activate gene transcription by recruiting coactivators to initiate transcription of their target genes. For most nuclear receptors, the ligand-dependent activation function domain-2 (AF-2) is a primary contributor to the nuclear receptor (NR) transcriptional activity. In contrast to other steroid receptors, such as ERα, the activation function of androgen receptor (AR) is largely dependent on its ligand-independent AF-1 located in its N-terminal domain (NTD). It remains unclear why AR utilizes a different AF domain from other receptors despite that NRs share similar domain organizations. Here, we present cryoelectron microscopy (cryo-EM) structures of DNA-bound full-length AR and its complex structure with key coactivators, SRC-3 and p300. AR dimerization follows a unique head-to-head and tail-to-tail manner. Unlike ERα, AR directly contacts a single SRC-3 and p300. The AR NTD is the primary site for coactivator recruitment. The structures provide a basis for understanding assembly of the AR:coactivator complex and its domain contributions for coactivator assembly and transcriptional regulation.

NgR1 binding to reovirus reveals an unusual bivalent interaction and a new viral attachment protein.

Nogo-66 receptor 1 (NgR1) binds a variety of structurally dissimilar ligands in the adult central nervous system to inhibit axon extension. Disruption of ligand binding to NgR1 and subsequent signaling can improve neuron outgrowth, making NgR1 an important therapeutic target for diverse neurological conditions such as spinal crush injuries and Alzheimer's disease. Human NgR1 serves as a receptor for mammalian orthoreovirus (reovirus), but the mechanism of virus-receptor engagement is unknown. To elucidate how NgR1 mediates cell binding and entry of reovirus, we defined the affinity of interaction between virus and receptor, determined the structure of the virus-receptor complex, and identified residues in the receptor required for virus binding and infection. These studies revealed that central NgR1 surfaces form a bridge between two copies of viral capsid protein σ3, establishing that σ3 serves as a receptor ligand for reovirus. This unusual binding interface produces high-avidity interactions between virus and receptor to prime early entry steps. These studies refine models of reovirus cell-attachment and highlight the evolution of viruses to engage multiple receptors using distinct capsid components.

hENT1's role in adjuvant intra-arterial gemcitabine-based chemotherapy for resectable pancreatic cancer patients.

BACKGROUND: We aimed to verify the role of hENT1 as a prognostic predictor for patients with resectable pancreatic ductal adenocarcinoma (PDAC) who underwent radical resection followed by intra-arterial infusion of gemcitabine-based regimen. METHODS: We collected surgical samples from 102 patients with resectable PDAC who received radical resection followed by intra-arterial infusion of gemcitabine-based regimen. The hENT1 expression with the help of immunohistochemistry was conducted using formalin-fixed and paraffin embedded tissues. The Kaplan-Meier analyses and Cox regression were used to evaluate the mortality hazard associated with the discrepancy between strong and weak of hENT1 expression. Patients' clinical and pathological characteristics were compared between the two groups, then the role of hENT1 as a prognostic predictor was further explored. RESULTS: A total of 102 patients were included to assess the hENT1 expression. 50 patients were classified into high hENT1 expression group, the other 52 patients were attributed into low hENT1 expression group. High hENT1 expression was related to a significantly improved overall survival (OS) (p = 0.014) and disease-free survival (DFS) (p = 0.004). Both univariate (p = 0.001) and multivariate analyses (p < 0.001) indicated that high hENT1 expression was related to a decreased mortality. CONCLUSIONS: High expression of hENT1 is positive prognostic factor for adjuvant intra-arterial gemcitabine-based chemotherapy in resectable PDAC.

The role of main pancreatic duct stent in the enucleation of benign/borderline pancreatic head tumors: a cohort study.

PURPOSE: This study aimed to reveal the role of preoperative main pancreatic duct (MPD) stent placement in reducing the intraoperative main pancreatic duct injury rate and the incidence of postoperative pancreatic leakage following pancreatic tumor enucleation. METHODS: A retrospective cohort analysis was performed for all patients with benign/borderline pancreatic head tumors who were treated with enucleation. The patients were divided into two groups (standard vs. stent) depending on whether they underwent main pancreatic duct stent placement prior to surgery. RESULTS: Thirty-three patients were finally included in the analytical cohort. Compared with the standard group, patients in the stent group had a shorter distance between tumors and main pancreatic duct (p=0.01) and presented with larger tumors (p<0.01). The rates of POPF (grade B&C) were 39.1% (9/23) and 20% (2/10) in the standard and stent groups, respectively (p<0.01). Major postoperative complications occurred more frequently in the standard group than in the stent group (14 versus 2; p<0.01). No significant differences in mortality, in-hospital stay or medical cost were observed between the two groups (p>0.05). CONCLUSIONS: MPD stent placement prior to surgery may facilitate pancreatic tumor enucleation, minimize MPD injury and decrease the occurrence of postoperative fistula.

The relationship between SPARC expression in primary tumor and metastatic lymph node of resected pancreatic cancer patients and patients' survival.

BACKGROUND: Previous researches in pancreatic cancer demonstrated a negative correlation between secreted protein acidic and rich in cysteine (SPARC) expression in primary tumor and survival, but not for SPARC expression in lymph node. In the present study, we aimed to evaluate the SPARC expression in various types of tissues and its impact on patients' prognosis. METHODS: The expression of SPARC was examined by immunohistochemistry in resected pancreatic cancer specimens. Kaplan-Meier analyses and Cox proportional hazards regression were applied to assess the mortality risk. RESULTS: A total of 222 tissue samples from 73 patients were collected to evaluate the SPARC expression, which included 73 paired primary tumor and adjacent normal tissues, 38 paired metastatic and normal lymph nodes. The proportion of positive SPARC expression in metastatic lymph node was high (32/38), whereas in normal lymph node it was negative (0/38). Positive SPARC expression in primary tumor cells was associated with a significantly decreased overall survival (P=0.007) and disease-free survival (P=0.003), whereas in other types of tissues it did not show a predictive role for prognosis. Univariate and multivariate analyses both confirmed this significance. CONCLUSION: SPARC can serve a dual function role as both predictor for prognosis and potentially biomarker for lymph node metastasis in resected pancreatic cancer patients.

Application of albumin-based nanoparticles in the management of cancer.

Over the past three decades, tremendous progress has been made in cancer prevention and treatment. Despite these advances, a substantial number of cancer cases experience early recurrence and metastases. Thus, the better management of cancer, especially developing more effective drugs for combating cancer cells, is an arduous task. Albumin-based nanoparticles are emerging as a promising approach to replace the traditional way of carrying therapeutic drugs to a tumor site. In this review, we describe the basic knowledge on albumin-based nanoparticles, recent progress of using albumin-based nanoparticles in the diagnosis and treatment of cancer, and the application of nanoparticle albumin bound (Nab) paclitaxel for the treatment of lung, breast and pancreatic cancer. Last but not least, we try to discuss future goals and perspectives in the field of drug delivery research, thereby facilitating the antitumor activity.

Splenic vessel preservation versus Warshaw's technique during spleen-preserving distal pancreatectomy: a meta-analysis and systematic review.

BACKGROUND: Splenic preservation can be achieved through splenic vessel resection by Warshaw's technique (WT) or by preserving the splenic vessels. This meta-analysis aims to provide evidence-based comparison regarding the perioperative outcome and long-term benefits between patients with and without splenic vessel preservation (SVP) during spleen-preserving distal pancreatectomy. METHOD: A meta-analysis was performed to evaluate studies comparing splenic vessel preservation versus resection groups. Ten retrospective studies including 699 patients were eligible for an analysis of general, perioperative, and long-term outcomes. A further analysis composed of five subgroups was also conducted in terms of laparoscopic approach. RESULTS: Warshaw's technique related to significant shorter operation time (P < 0.0001). There was no difference in blood loss (P = 0.45) as well as median tumor size (p = 0.1) between the two groups. The overall rate of complications indicated no difference between SVP and WT (P = 0.1), including pancreatic fistula rates, which were not statistically different among the treatment groups (P = 0.27). However, the occurrence of gastric varices and splenic infarction was significant higher in the WT group (P < 0.01). In laparoscopic subgroups, patients treated by WT had much lower blood loss (P = 0.002). CONCLUSION: In spleen-preserving distal pancreatectomy, comparing with SVP, there is no evidence of significant benefit of WT. Nonetheless, surgeons should master both techniques and choose an appropriate one based on personal experience and a "case by case" situation. However, the current available evidence is weak, and further randomized controlled data are warranted.

ZNF397 Deficiency Triggers TET2-driven Lineage Plasticity and AR-Targeted Therapy Resistance in Prostate Cancer.

Cancer cells exhibit phenotypical plasticity and epigenetic reprogramming, which allows them to evade lineage-dependent targeted treatments by adopting lineage plasticity. The underlying mechanisms by which cancer cells exploit the epigenetic regulatory machinery to acquire lineage plasticity and therapy resistance remain poorly understood. We identified Zinc Finger Protein 397 (ZNF397) as a bona fide coactivator of the androgen receptor (AR), essential for the transcriptional program governing AR-driven luminal lineage. ZNF397 deficiency facilitates the transition of cancer cell from an AR-driven luminal lineage to a Ten-Eleven Translocation 2 (TET2)-driven lineage plastic state, ultimately promoting resistance to therapies inhibiting AR signaling. Intriguingly, our findings indicate that a TET2 inhibitor can eliminate the resistance to AR targeted therapies in ZNF397-deficient tumors. These insights uncover a novel mechanism through which prostate cancer acquires lineage plasticity via epigenetic rewiring and offer promising implications for clinical interventions designed to overcome therapy resistance dictated by lineage plasticity.

Serum proteomic profiling for the early diagnosis of colorectal cancer.

No ideal serum biomarker currently exists for the early diagnosis of colorectal cancer (CRC). Magnetic bead-based fractionation coupled with MALDI-TOF MS was used to screen serum samples from CRC patients, healthy controls, and other cancer patients. A diagnostic model with five proteomic features (m/z 1778.97, 1866.16, 1934.65, 2022.46, and 4588.53) was generated using Fisher algorithm with best performance. The Fisher-based model could discriminate CRC patients from the controls with 100% (46/46) sensitivity and 100% (35/35) specificity in the training set, 95.6% (43/45) sensitivity and 83.3% (35/42) specificity in the test set. We further validated the model with 94.4% (254/269) sensitivity and 75.5% (83/110) specificity in the external independent group. In other cancers group, the Fisher-based model classified 25 of 46 samples (54.3%) as positive and the other 21 as negative. With FT-ICR-MS, the proteomic features of m/z 1778.97, 1866.16, 1934.65, and 2022.46, of which intensities decreased significantly in CRC, were identified as fragments of complement C3f. Therefore, the Fisher-based model containing five proteomic features was able to effectively differentiate CRC patients from healthy controls and other cancers with a high sensitivity and specificity, and may be CRC-specific. Serum complement C3f, which was significantly decreased in CRC group, may be relevant to the incidence of CRC.

ZNF397 Loss Triggers TET2-driven Epigenetic Rewiring, Lineage Plasticity, and AR-targeted Therapy Resistance in AR-dependent Cancers.

Cancer cells exhibit phenotypical plasticity and epigenetic reprogramming, which allows them to evade lineage-dependent targeted treatments by adopting lineage plasticity. The underlying mechanisms by which cancer cells exploit the epigenetic regulatory machinery to acquire lineage plasticity and therapy resistance remain poorly understood. We identified Zinc Finger Protein 397 (ZNF397) as a bona fide co-activator of the androgen receptor (AR), essential for the transcriptional program governing AR-driven luminal lineage. ZNF397 deficiency facilitates the transition of cancer cell from an AR-driven luminal lineage to a Ten-Eleven Translocation 2 (TET2)-driven lineage plastic state, ultimately promoting resistance to therapies inhibiting AR signaling. Intriguingly, our findings indicate that TET2 inhibitor can eliminate the AR targeted therapies resistance in ZNF397-deficient tumors. These insights uncover a novel mechanism through which prostate and breast cancers acquire lineage plasticity via epigenetic rewiring and offer promising implications for clinical interventions designed to overcome therapy resistance dictated by lineage plasticity. Statement of Significance: This study reveals a novel epigenetic mechanism regulating tumor lineage plasticity and therapy response, enhances understanding of drug resistance and unveils a new therapeutic strategy for prostate cancer and other malignancies. Our findings also illuminate TET2's oncogenic role and mechanistically connect TET2-driven epigenetic rewiring to lineage plasticity and therapy resistance.

Spatial definition of the human progesterone receptor-B transcriptional complex.

We report the quaternary structure of core transcriptional complex for the full-length human progesterone receptor-B (PR-B) homodimer with primary coactivator steroid receptor coactivator-2 (SRC-2) and the secondary coactivator p300/CREB-binding protein (CBP). The PR-B homodimer engages one SRC-2 mainly through its activation function 1 (AF1) in N-terminus. SRC-2 is positioned between PR-B and p300 leaving space for direct interaction between PR-B and p300 through PR-B's C-terminal AF2 and its unique AF3. Direct AF3/p300 interaction provides long-desired structural insights into the known functional differences between PR-B and the PR-A isoform lacking AF3. We reveal the contributions of each AF and demonstrate their structural basis in forming the PR-B dimer interface and PR-B/coactivator complex. Comparison of the PR-B/coactivator complex with other steroid receptor (estrogen receptor and androgen receptor) complexes also shows that each receptor has its unique mechanism for recruiting coactivators due to the highly variable N-termini among receptors.

Steroid receptor-coregulator transcriptional complexes: new insights from CryoEM.

Steroid receptors activate gene transcription through recruitment of a number of coregulators to facilitate histone modification, chromatin remodeling, and general transcription machinery stabilization. Understanding the structures of full-length steroid receptor and coregulatory complexes has been difficult due to their large molecular sizes and dynamic structural conformations. Recent developments in cryo-electron microscopy (cryoEM) technology and proteomics have advanced the structural studies of steroid receptor complexes. Here, we will review the insights we learned from cryoEM studies of the estrogen and androgen receptor transcriptional complexes. Despite similar domain organizations, the two receptors have different coregulator interaction modes. The cryoEM structures now have revealed the fundamental differences between the two receptors and their functional mechanisms.

2.7 Å cryo-EM structure of rotavirus core protein VP3, a unique capping machine with a helicase activity.

In many viruses, including rotavirus (RV), the major pathogen of infantile gastroenteritis, capping of viral messenger RNAs is a pivotal step for efficient translation of the viral genome. In RV, VP3 caps the nascent transcripts synthesized from the genomic dsRNA segments by the RV polymerase VP1 within the particle core. Here, from cryo-electron microscopy, x-ray crystallography, and biochemical analyses, we show that VP3 forms a stable tetrameric assembly with each subunit having a modular domain organization, which uniquely integrates five distinct enzymatic steps required for capping the transcripts. In addition to the previously known guanylyl- and methyltransferase activities, we show that VP3 exhibits hitherto unsuspected RNA triphosphatase activity necessary for initiating transcript capping and RNA helicase activity likely required for separating the RNA duplex formed transiently during endogenous transcription. From our studies, we propose a new mechanism for how VP3 inside the virion core caps the nascent transcripts exiting from the polymerase.

Structural basis for the adsorption of a single-stranded RNA bacteriophage.

Single-stranded RNA bacteriophages (ssRNA phages) infect Gram-negative bacteria via a single maturation protein (Mat), which attaches to a retractile pilus of the host. Here we present structures of the ssRNA phage MS2 in complex with the Escherichia coli F-pilus, showing a network of hydrophobic and electrostatic interactions at the Mat-pilus interface. Moreover, binding of the pilus induces slight orientational variations of the Mat relative to the rest of the phage capsid, priming the Mat-connected genomic RNA (gRNA) for its release from the virions. The exposed tip of the attached Mat points opposite to the direction of the pilus retraction, which may facilitate the translocation of the gRNA from the capsid into the host cytosol. In addition, our structures determine the orientation of the assembled F-pilin subunits relative to the cell envelope, providing insights into the F-like type IV secretion systems.

[Application of SELDI-TOF-MS in detection of liver metastasis from colorectal cancer].

OBJECTIVE: To establish a serum protein fingerprint model for prediction of liver metastasis from colorectal cancer by SELDI-TOF-MS analysis, and to determine the differentiatial proteins associated with the metastatic liver cancers. METHODS: Data were collected from the Department of General Surgery in Zhongshan Hospital. A group of patients with colorectal cancer (CRC) without liver metastasis (n = 36) and another group with liver metastasis (n = 36) were included in this study. Serum samples were collected from peripheral venous blood before operation. Special serum protein or peptide fingerprint was determined by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS). The obtained data were analyzed by Biomarker Wizard software to screen the serum protein markers discriminating colorectal cancer patients with and without liver metastasis. A serum protein fingerprint model was established. This model was blindly verified in of CRC patients with and 44 cases without liver metastasis. RESULTS: Comparing the characteristic proteins in those two groups of patients, 10 specific protein peaks were identified with statistical significance (P < 0.05). According to m/z growing from small to large, they were: 2398, 2814, 4084, 4289, 4465, 6422, 6619, 11 482, 11 649 and 13 714. The predictive model had a sensitivity of 91.7% and a specificity of 97.2%. The validation showed a sensitivity of 75.0% and a specificity of 81.8%. CONCLUSION: A predictive model based on differentiatial serum protein fingerprint with high sensitivity and specificity has been successfully established. It should be a very useful tool in detection and diagnosis of liver metastasis in colorectal cancer patients.

[Establish predictive model of colorectal cancer by using surface enhanced laser desorption/ionization-time of flight-mass spectrometry].

OBJECTIVE: To establish serum proteome fingerprinting predictive models and search for proteins associated with colorectal cancer. METHODS: Thirty-six randomly selected colorectal cancer patients and 36 cases with hernia or gall bladder diseases scheduled for elective operation were enrolled as cancer group and control group respectively. Peripheral venous blood samples were collected before the operations. Special serum protein or peptide fingerprint was investigated by using surface enhanced laser desorption/ ionization-time of flight-mass spectrometry (SELDI-TOF-MS) measurement after blood sample had been treated with weak cation exchange protein chip (CM10) for each case. The obtained data were analyzed by Biomarker Wizard software to screen serum proteome tumor markers and set up diagnosis predictive model for colorectal cancer. Blind validation of the model with 44 healthy controls and 88 colorectal cancer patients were carried out by using Biomarker Patterns Software. RESULTS: In comparing colorectal cancer group with control group, 5 specific protein peaks (P < 0.05) were found. The predictive model had a sensitivity of 100% and a specificity of 97.2%. A sensitivity of 71.6% and a specificity of 72.7% was got with the blind validation. The specific protein peaks with a mass-to-charge ratio (m/z) of 8908 and 13,707 showed in all the results and it showed their strong relationship with colorectal cancer. CONCLUSIONS: The predictive models built by the differences of serum proteome fingerprint could be a very useful diagnostic tool in colorectal cancer. Proteins with m/z of 8908 and 13,707 would possibly be the tumor markers of colorectal cancer.

Resection of Liver Metastases: A Treatment Provides a Long-Term Survival Benefit for Patients with Advanced Pancreatic Neuroendocrine Tumors: A Systematic Review and Meta-Analysis.

PURPOSE: Nonsurgical therapies, including biotherapy, chemotherapy, and liver-directed therapy, provided a limit survival benefit for PNET patients with hepatic metastases. With the development of liver resection technique, there was a controversy on whether to perform a liver resection for these patients. METHODS: A computerized search was made of the Medline/PubMed, EMbase, Cochrane Library, and SinoMed (CBM) before March 2018. A meta-analysis was performed to investigate the differences in the efficacy of liver resection and nonliver resection treatments based on the evaluation of morbidity, 30-day mortality, symptom relief rate, and 1-, 3-, and 5-year survival. Two investigators reviewed all included articles and extracted the data of them. The meta-analysis was performed via Review Manager 5.3 software. RESULTS: A total of 13 cohort studies with 1524 patients were included in this meta-analysis. Compared with the nonliver resection group, liver resection group had a longer 1-, 3-, and 5-year survival time and a higher symptom relief with an acceptable mortality and morbidity. CONCLUSIONS: Liver resection is a safe treatment and could significantly prolong the long-term prognosis for highly selected patients with resectable liver metastases from PNET. Further randomized, controlled trials are needed.

Antitumor effect of gemcitabine-loaded albumin nanoparticle on gemcitabine-resistant pancreatic cancer induced by low hENT1 expression.

PURPOSE: Gemcitabine is currently the standard first-line chemotherapeutic drug for treating pancreatic cancer. However, many factors can contribute to gemcitabine resistance. One of the most important reasons is the low hENT1 expression. In this study, we tested the antitumor effect of gemcitabine-loaded human serum albumin nanoparticle (GEM-HSA-NP) on gemcitabine-resistant pancreatic cancer induced by low hENT1 expression. MATERIALS AND METHODS: S-(4-nitrobenzyl)-6-thioinosine was utilized to inhibit the activity of hENT1 and simulate low hENT1 expression. Growth inhibition assays and cell cycle and apoptosis analyses were performed on human pancreatic cancer cell lines such as BxPC-3 and SW1990. The in vivo antitumor effect was studied by using patient-derived xenograft (PDX) models. The in vivo toxicity assessment was performed on healthy Kunming mice. RESULTS: In in vitro studies, GEM-HSA-NP showed its ability to inhibit cell proliferation, arrest cell cycle and induce apoptosis when tumor cells were resistant to gemcitabine. In in vivo studies, GEM-HSA-NP was more effective than gemcitabine on inhibiting tumor growth whether the expression levels of hENT1 were high or low in PDX models. The in vivo toxicity assessment showed that the biotoxicity of GEM-HSA-NP did not increase compared with gemcitabine. CONCLUSION: GEM-HSA-NP can overcome gemcitabine resistance induced by low hENT1 expression, which suggests its potential role for the clinical application.

Dose surgical resection of hepatic metastases bring benefits to pancreatic ductal adenocarcinoma? A systematic review and meta-analysis.

OBJECTIVE: The objectives of this systematic review and meta-analysis were to examine morbidity, mortality, and long-term survival after surgical resection of hepatic metastases from pancreatic ductal adenocarcinoma (PDAC) patients. BACKGROUND: Patients with hepatic metastases from pancreatic ductal adenocarcinoma are facing a dilemma of whether to make hepatic resection. METHODS: A systematic literature research was undertaken through computerized databases as well as manually research from unpublished data. A meta-analysis was performed to investigate the differences in the efficacy of liver resection and non-surgical treatments based on the evaluation of morbidity, 30-day mortality, and 1-, 3-, or 5-year survival. RESULTS: 11 cohort studies with 1147 patients were identified in the pool. Compared with the non-surgical approach, hepatic resection can be performed in a safe and feasible manner for all pancreatic cancer patients with liver metastases (p = 0.13 for overall morbidity; p = 0.63 for mortality). For surgical group, the median 1-year, 3-year, and 5-year survival were 40.9%, 13.3%, 2.9%, respectively, with a median survival of 9.9 months. Surgical resection of hepatic metastases was associated with a significantly improved overall 1-year and 3-year survival (p < 0.001). CONCLUSIONS: Hepatic resection is a safe procedure; furthermore, it is worth doing such an extended surgery for PDAC patients due to additional survival benefit in the medium-term (less than 3 years). However, further randomized, controlled trials are urgently needed.

Triple-functional albumin-based nanoparticles for combined chemotherapy and photodynamic therapy of pancreatic cancer with lymphatic metastases.

Lymphatic metastasis is the major metastatic pattern of pancreatic cancer and considered as an independent risk factor of survival. However, there is still no effective way for the diagnosis and treatment for lymphatic metastases of pancreatic cancer. In this study, using albumin as a carrier of gemcitabine (Gem), further modified by pyropheophorbide-a, we have designed and synthesized a nanoparticle (NP) compound named "pheophorbide-a (P@)-Gem-human serum albumin (HSA)-NPs". By utilization of its tracer ability of lymphatic metastases, which is triggered by near-infrared irradiation and its visible dying ability, the compound is used for drug delivery tracking, meanwhile as a treating drug, as well as the combined effect of photodynamic therapy and chemotherapy. By the nude mice model of lymphatic metastases of pancreatic cancer (BxPC-3-LN7), we aim to explore the feasibility, effectiveness, and biological safety of diagnosis and treatment for the lymphatic metastases of pancreatic cancer by P@-Gem-HSA-NP, thereby, providing new methods and strategies for the study of nanodrug carrier and research on lymphatic metastases of pancreatic cancer.