The heat-shock factor Hsp70 and other molecular chaperones play a central role in nascent protein folding. Elucidating the task performed by individual chaperones within the complex cellular milieu, ...however, has been challenging. One strategy for addressing this goal has been to monitor protein biogenesis in the absence and presence of inhibitors of a specific chaperone, followed by analysis of folding outcomes under both conditions. In this way, the role of the chaperone of interest can be discerned. However, development of chaperone inhibitors, including well-known proline-rich antimicrobial peptides, has been fraught with undesirable side effects, including decreased protein expression yields. Here, we introduce KLR-70, a rationally designed cationic inhibitor of the Escherichia coli Hsp70 chaperone (also known as DnaK). KLR-70 is a 14-amino acid peptide bearing naturally occurring residues and engineered to interact with the DnaK substrate-binding domain. The interaction of KLR-70 with DnaK is enantioselective and is characterized by high affinity in a buffered solution. Importantly, KLR-70 does not significantly interact with the DnaJ and GroEL/ES chaperones, and it does not alter nascent protein biosynthesis yields across a wide concentration range. Some attenuation of the anti-DnaK activity of KLR-70, however, has been observed in the complex E. coli cell-free environment. Interestingly, the d enantiomer D-KLR-70, unlike its all-L KLR-70 counterpart, does not bind the DnaK and DnaJ chaperones, yet it strongly inhibits translation. This outcome suggests that the two enantiomers (KLR-70 and D-KLR-70) may serve as orthogonal inhibitors of chaperone binding and translation. In summary, KLR-70 is a novel chaperone inhibitor with high affinity and selectivity for bacterial Hsp70 and with considerable potential to help in parsing out the role of Hsp70 in nascent protein folding.
Anfinsen’s thermodynamic hypothesis does not explicitly take into account the possibility of protein aggregation. Here, we introduce a cyclic-perturbation approach to prove that not only the native ...state but also soluble aggregates of most proteins can be highly populated under mild, physiologically relevant conditions, even at very low concentration. Surprisingly, these aggregates are not necessarily amyloid in nature and are usually not observed in bioactive proteins due to the extremely low kinetic flux from the native state toward a region of the chemical-potential landscape encoding aggregates. We first illustrate this concept for the representative model protein apomyoglobinat room temperature and no denaturantand demonstrate kinetic trapping of the native state relative to at least two different types of soluble, predominantly nonamyloid aggregates. The concentration and temperature dependence of aggregation confirm the above scenario. Extension of our analysis to the Escherichia coli proteome shows that the majority of the soluble bacterial proteome is also kinetically trapped in the nonaggregated state. Hence, the existence and low kinetic accessibility of large aggregates at room temperature and pH 6–7 is a general phenomenon. We also show that the average critical protein concentration for aggregation of most of the bacterial proteome is extremely small, much lower than the typical cellular protein concentration. Hence, the thermodynamic driving force for protein aggregation is large even if aggregation does not usually occur in healthy cells due to kinetic trapping. A broader view of Anfinsen’s thermodynamic hypothesis encompassing all protein states, including aggregates, is necessary to understand the behavior of proteins in their natural environment.
Background
Inactivating alterations in SPOP frequently occur in prostate cancer and promote increased dependency on androgen receptor (AR)‐mediated oncogenic signaling. The presence of SPOP mutation ...(SPOP‐mutant SPOP‐mut) may therefore impact therapeutic outcomes with AR‐directed therapies and docetaxel in metastatic castration‐resistant (mCRPC).
Methods
This was a retrospective study of mCRPC patients treated at an urban academic hospital (n = 103). Patients underwent tumor DNA sequencing to determine SPOP mutational status (SPOP‐mut). Outcomes measured were overall survival (OS) from diagnosis and treatment with second‐generation AR signaling inhibitor (ARSI) or docetaxel and time to PSA progression (prostate‐specific antigen‐progression‐free survival PSA‐PFS) compared by SPOP status using Kaplan–Meier curves and log‐rank test. The univariable and multivariable Cox proportional hazard model evaluated the association of SPOP mutation and outcomes adjusted for clinicopathologic features.
Results
SPOP‐mut was associated with longer PSA‐PFS in mCRPC (median 1.79 vs. 0.84 years; p = 0.06) and multivariate analysis (hazard ratio HR = 0.37; 95% confidence interval CI: 0.17–0.84; p = 0.02). SPOP‐mut demonstrated a higher median PSA decline compared to SPOP wild‐type (median decline 100% vs. 92%, p = 0.02). SPOP‐mut was not associated with OS from the start of ARSI or docetaxel (median OS not reached vs. 2.0 years) or PSA‐PFS on docetaxel (median PSA‐PFS 0.4 vs. 0.5 years) in mCRPC. The majority of SPOP mutations were identified in African American (AA) patients (69.2%) compared to Caucasian patients (30.8%). Race‐associated multivariate analysis revealed no significant differences in OS from the start of ARSI or the start of docetaxel and no differences in ARSI or docetaxel PSA‐PFS between AA and Caucasian patients. Molecular profiling demonstrated that AA patients had a higher frequency of SPOP mutations and greater heterogeneity of SPOP variants within the coding sequence. Analysis of concurrent genomic alterations revealed that SPOP mutations co‐occur with APC mutations (p = 0.001) and alterations in the Wnt pathway (p = 0.017).
Conclusions
Inactivating mutations in SPOP are associated with better response to ARSI treatment in mCRPC overall. Additional analysis with a larger cohort is needed to evaluate the association of SPOP status and outcomes with docetaxel. Race‐associated clinical outcomes and molecular features were observed, suggesting the benefit of biomarker‐directed therapy selection for individualized patient subsets in guiding treatment decisions for mCRPC patients.
Abstract only
160
Background: Predictive markers linking molecular background to treatment response and clinical outcomes are currently lacking in prostate cancer. Missense mutations in SPOP ...(speckle-type POZ protein) define a distinct molecular subtype, occurring in about 12% of both clinically localized and metastatic disease. SPOP mutations occur early in prostate tumorigenesis and facilitate dysregulation of the androgen-receptor (AR) signaling network, suggesting mutant SPOP can impact response to AR-directed therapies. We hypothesized that SPOP mutation will be associated with superior response to next-generation AR inhibitors in metastatic castration-resistant prostate cancer (mCRPC). Methods: This is a retrospective study to evaluate patients who progressed to mCRPC and were treated with AR-targeted therapy (i.e. enzalutamide, abiraterone acetate). Eligibility criteria inlcuded androgen deprivation therapy, metastatic disease documented by bone lesion or soft tissue identified on imaging, castrate testosterone level ( < 50g/dL), and evaluable tissue for DNA analysis. SPOP status was determined by next-generation sequencing. Time to PSA progression (PSA TTP) was defined per PCWG2 as PSA increase of 25% from nadir and a minimum of 2 ng/ml calculated from date of primary treatment initiation to the date of PSA progression. Overall survival (OS) was calculated from start of treatment to date of death. Statisitcal comparision of the SPOP mutant or wild-type was determined using Kaplan-Meier and independent t-test analysis. Results: The analysis included 69 men with mCRPC with previous or ongoing ADT and receipt of AR-directed therapy (aberaterone acetate, enzalutamide). SPOP status was determined for all patients: 7 patients SPOP mutant, 62 patients SPOP wild-type. Mutant SPOP was associated with significantly longer PSA TTP (22.5 vs. 9.7 months, p = 0.031) and improved OS (21 vs. 29 months, p = 0.12) with enzalutamide or abiraterone as compared to SPOP wild-type patients. Conclusions: Our data demonstrate that SPOP mutations predict for better outcomes with next-generation AR inhibitors in men with mCRPC. SPOP mutations are a prominent molecular sub-type with potential to impact clinical management in men with metastatic, therapy resistant prostate cancer.
Successful treatment of brain tumors such as glioblastoma multiforme (GBM) is limited in large part by the cumulative dose of Radiation Therapy (RT) that can be safely given and the blood-brain ...barrier (BBB), which limits the delivery of systemic anticancer agents into tumor tissue. Consequently, the overall prognosis remains grim. Herein, we report our pilot studies in cell culture experiments and in an animal model of GBM in which RT is complemented by PEGylated-gold nanoparticles (GNPs). GNPs significantly increased cellular DNA damage inflicted by ionizing radiation in human GBM-derived cell lines and resulted in reduced clonogenic survival (with dose-enhancement ratio of ~1.3). Intriguingly, combined GNP and RT also resulted in markedly increased DNA damage to brain blood vessels. Follow-up in vitro experiments confirmed that the combination of GNP and RT resulted in considerably increased DNA damage in brain-derived endothelial cells. Finally, the combination of GNP and RT increased survival of mice with orthotopic GBM tumors. Prior treatment of mice with brain tumors resulted in increased extravasation and in-tumor deposition of GNP, suggesting that RT-induced BBB disruption can be leveraged to improve the tumor-tissue targeting of GNP and thus further optimize the radiosensitization of brain tumors by GNP. These exciting results together suggest that GNP may be usefully integrated into the RT treatment of brain tumors, with potential benefits resulting from increased tumor cell radiosensitization to preferential targeting of tumor-associated vasculature.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
African Americans have a significantly higher risk of developing chronic kidney disease, especially focal segmental glomerulosclerosis -, than European Americans. Two coding variants (G1 and G2) in ...the APOL1 gene play a major role in this disparity. While 13% of African Americans carry the high-risk recessive genotypes, only a fraction of these individuals develops FSGS or kidney failure, indicating the involvement of additional disease modifiers. Here, we show that the presence of the APOL1 p.N264K missense variant, when co-inherited with the G2 APOL1 risk allele, substantially reduces the penetrance of the G1G2 and G2G2 high-risk genotypes by rendering these genotypes low-risk. These results align with prior functional evidence showing that the p.N264K variant reduces the toxicity of the APOL1 high-risk alleles. These findings have important implications for our understanding of the mechanisms of APOL1-associated nephropathy, as well as for the clinical management of individuals with high-risk genotypes that include the G2 allele.
Purpose
Accurate staging of esophageal cancer (ECA) is critical in determining appropriate therapy. Endoscopic ultrasound (EUS), computed tomography (CT) and positron emission tomography (PET) ...scanning can be used, but limited data exists regarding the use of combined PET/CT fusion imaging and EUS in ECA staging. The objective of this study is to evaluate the role of integrated PET/CT imaging and EUS in the staging of ECA.
Procedures
Identification of patients diagnosed with ECA from 2004 to 2007 that underwent staging PET/CT and EUS. Data regarding tumor detection, lymph node identification, presence of metastatic disease, and affect on patient management were collected and compared between PET/CT and EUS.
Results
Eighty-one patients (65 male, 16 female) were identified with mean age of 63.5 years who underwent EUS and PET/CT to stage known ECA. PET/CT identified the primary tumor in 74/81 (91.4%) of cases, compared to 81/81 (100%) with EUS. Locoregional adenopathy was seen by PET/CT in 29/81 (35.8%) of cases, compared to 49/81 (60.5%) by EUS (
p
= 0.0001). PET/CT identified celiac axis adenopathy in 8/81 (9.9%) of cases, compared to 11/81 (13.6%) with EUS (
p
= 0.5050). PET/CT identified 17/81 (21.0%) of patients with distant metastases who subsequently did not undergo attempt at curative surgical resection.
Conclusions
In ECA, EUS is superior to PET/CT for T staging and in identifying locoregional nodes, while PET/CT provides M staging. EUS and integrated PET/CT appear to independently affect treatment decisions, indicating complimentary and necessary roles in the staging of ECA.
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