Targeting colorectal cancer cells by a novel sphingosine kinase 1 inhibitor PF-543.

In this study, we showed that PF-543, a novel sphingosine kinase 1 (SphK1) inhibitor, exerted potent anti-proliferative and cytotoxic effects against a panel of established (HCT-116, HT-29 and DLD-1) and primary human colorectal cancer (CRC) cells. Its sensitivity was negatively associated with SphK1 expression level in the CRC cells. Surprisingly, PF-543 mainly induced programmed necrosis, but not apoptosis, in the CRC cells. CRC cell necrotic death was detected by lactate dehydrogenase (LDH) release, mitochondrial membrane potential (MMP) collapse and mitochondrial P53-cyclophilin-D (Cyp-D) complexation. Correspondingly, the necrosis inhibitor necrostatin-1 largely attenuated PF-543-induced cytotoxicity against CRC cells. Meanwhile, the Cyp-D inhibitors (sanglifehrin A and cyclosporin A), or shRNA-mediated knockdown of Cyp-D, remarkably alleviated PF-543-induced CRC cell necrotic death. Reversely, over-expression of wild-type Cyp-D in HCT-116 cells significantly increased PF-543's sensitivity. In vivo, PF-543 intravenous injection significantly suppressed HCT-116 xenograft growth in severe combined immunodeficient (SCID) mice, whiling remarkably improving the mice survival. The in vivo activity by PF-543 was largely attenuated when combined with the Cyp-D inhibitor cyclosporin A. Collectively, our results demonstrate that PF-543 exerts potent anti-CRC activity in vitro and in vivo. Mitochondrial programmed necrosis pathway is likely the key mechanism responsible for PF-543's actions in CRC cells.

Anticancer activity of Honokiol against lymphoid malignant cells via activation of ROS-JNK and attenuation of Nrf2 and NF-κB.

PURPOSE: To evaluate the effect of Honokiol (HK) in the ROS-JNK pro-apoptotic pathway and NF-κB, Nrf2 anti-apoptotic pathways, in order to seek a possible explanation for its anticancer efficacy. METHODS: The Raji and Molt4 cell lines were utilized for the determination of anticancer activity against lymphoid malignant cells. BALB/C nude mice, weighing 18-20g each and aged 4-5 weeks, were procured from the central animal house facility. For establishing non-Hodgkin lymphoma in BALB/C, the nude mice were subcutaneously administered 1×10(7) Raji cells, suspended in 0.2 mL sterile PBS on the back. The mice were then randomly divided into 3 groups (6 mice in each group). HK cytotoxicity was determined using the colorimetric MTT assay. RESULTS: In colorimetry-based MTT assay, the cytotoxicity of HK was determined at different time intervals, in lymphoid malignant Raji and Molt4 cell lines. HK exhibited prominent cytotoxicity against Raji cell lines with IC50 of 0.092 ± 0.021 µM. In Molt4 cells, the administration of HK caused significant cytotoxicity with IC50 of 0.521 ± 0.115 µM. The treatment of HK caused significant increase in the activity of reactive oxygen species (ROS) in Raji cells at various time intervals. Moreover, the level of NF-κB was significantly reduced in the presence of HK, which could be easily understood by a decreased level of p-65. Furthermore, in the presence of ROS inhibitor NAC (10mM) for 24 hrs, the JNK pathway was markedly activated, together with inhibition of NF-κB activity and a reduced level of Nrf2 expression. To further confirm the in vitro results by in vivo activity, HK was observed to inhibit the proliferation of Raji cells in vivo, which might be attributable to its inhibitory effect against the progression of the tumor (p<0.05). CONCLUSION: The present study suggests that HK causes considerable induction of apoptosis in lymphoid malignant cells, both in vitro and in vivo, whereas the generation of ROS might serve as an underlying mechanism for inducing apoptosis.

Top management team career experience heterogeneity, digital transformation, and the corporate green innovation: a moderated mediation analysis.

Introduction: Drawing upon upper echelon theory and the resource-based view, this study employs a moderated mediation model to investigate the moderating role and underlying mechanisms of digital transformation in the influence of top management teams (TMT) on corporate green innovation. Methods: Our analysis of panel data from 19,155 Chinese A-share listed companies (2011-2020) demonstrates that TMT career experience heterogeneity has a positive effect on green innovation, a relationship that is further strengthened by digital transformation. Results: This study shows the role of digital transformation in amplifying the effects of TMT diversity on green innovation and the crucial role of industry-academia-research collaboration as a mediator. Heterogeneity analysis highlights that non-state-owned enterprises (non-SOEs) show more agility than state-owned enterprises (SOEs) in leveraging heterogeneous TMT to drive green innovation. Conversely, green innovation in SOEs benefits more from digital transformation, which includes both its direct and indirect effects of digital transformation. Enterprises located in non-Yangtze River Economic Belt regions benefit more from digital transformation, demonstrating the importance of a balanced distribution of digital resources. Discussion: This study provides novel insights into leveraging inclusive leadership and digital capabilities to enhance ecological sustainability. This study underscores the potential of diversified TMTs and digitalization technology integration to catalyze green innovation, which is critical for environmentally responsible transformation.

Developing hybrid approaches to predict pKa values of ionizable groups.

Accurate predictions of pKa values of titratable groups require taking into account all relevant processes associated with the ionization/deionization. Frequently, however, the ionization does not involve significant structural changes and the dominating effects are purely electrostatic in origin allowing accurate predictions to be made based on the electrostatic energy difference between ionized and neutral forms alone using a static structure and the subtle structural changes be accounted by using dielectric constant larger than two. On another hand, if the change of the charge state is accompanied by a large structural reorganization of the target protein, then the relevant conformational changes have to be explicitly taken into account in the pKa calculations. Here we report a hybrid approach that first predicts the titratable groups whose ionization is expected to cause large conformational changes, termed "problematic" residues, and then applies a special protocol on them, while the rest of the pK(a)s are predicted with rigid backbone approach as implemented in multi-conformation continuum electrostatics (MCCE) method. The backbone representative conformations for "problematic" groups are generated with either molecular dynamics simulations with charged and uncharged amino acid or with ab-initio local segment modeling. The corresponding ensembles are then used to calculate the titration curves of the "problematic" residues and then the results are averaged to obtain the corresponding pKa.

Computational design of a thermostable mutant of cocaine esterase via molecular dynamics simulations.

Cocaine esterase (CocE) has been known as the most efficient native enzyme for metabolizing naturally occurring cocaine. A major obstacle to the clinical application of CocE is the thermoinstability of native CocE with a half-life of only ∼11 min at physiological temperature (37 °C). It is highly desirable to develop a thermostable mutant of CocE for therapeutic treatment of cocaine overdose and addiction. To establish a structure-thermostability relationship, we carried out molecular dynamics (MD) simulations at 400 K on wild-type CocE and previously known thermostable mutants, demonstrating that the thermostability of the active form of the enzyme correlates with the fluctuation (characterized as the root-mean square deviation and root-mean square fluctuation of atomic positions) of the catalytic residues (Y44, S117, Y118, H287, and D259) in the simulated enzyme. In light of the structure-thermostability correlation, further computational modelling including MD simulations at 400 K predicted that the active site structure of the L169K mutant should be more thermostable. The prediction has been confirmed by wet experimental tests showing that the active form of the L169K mutant had a half-life of 570 min at 37 °C, which is significantly longer than those of the wild-type and previously known thermostable mutants. The encouraging outcome suggests that the high-temperature MD simulations and the structure-thermostability relationship may be considered as a valuable tool for the computational design of thermostable mutants of an enzyme.

Chronic myelomonocytic leukemia-associated pulmonary alveolar proteinosis: A case report and review of literature.

BACKGROUND: Pulmonary alveolar proteinosis (PAP) is a rare condition that can cause progressive symptoms including dyspnea, cough and respiratory insufficiency. Secondary PAP is generally associated with hematological malignancies including chronic myelomonocytic leukemia (CMML). To the best of our knowledge, this is the first reported case of PAP occurring secondary to CMML. CASE SUMMARY: We report the case of a 63-year-old male who presented with a recurrent cough and gradually progressive dyspnea in the absence of fever. Based upon clinical symptoms, computed tomography findings, bone marrow aspiration, flow cytometry studies and cytogenetic analyses, the patient was diagnosed with PAP secondary to CMML. He underwent whole lung lavage in March 2016 to alleviate his dyspnea, after which he began combined chemotherapeutic treatment with decitabine and cytarabine. The patient died in January 2020 as a consequence of severe pulmonary infection. CONCLUSION: This case offers insight regarding the mechanistic basis for PAP secondary to CMML and highlights potential risk factors.

Thermostable variants of cocaine esterase for long-time protection against cocaine toxicity.

Enhancing cocaine metabolism by administration of cocaine esterase (CocE) has been recognized as a promising treatment strategy for cocaine overdose and addiction, because CocE is the most efficient native enzyme for metabolizing the naturally occurring cocaine yet identified. A major obstacle to the clinical application of CocE is the thermoinstability of native CocE with a half-life of only a few minutes at physiological temperature (37 degrees C). Here we report thermostable variants of CocE developed through rational design using a novel computational approach followed by in vitro and in vivo studies. This integrated computational-experimental effort has yielded a CocE variant with a approximately 30-fold increase in plasma half-life both in vitro and in vivo. The novel design strategy can be used to develop thermostable mutants of any protein.

Modeling the catalysis of anti-cocaine catalytic antibody: competing reaction pathways and free energy barriers.

The competing reaction pathways and the corresponding free energy barriers for cocaine hydrolysis catalyzed by an anti-cocaine catalytic antibody, mAb15A10, were studied by using a novel computational strategy based on the binding free energy calculations on the antibody binding with cocaine and transition states. The calculated binding free energies were used to evaluate the free energy barrier shift from the cocaine hydrolysis in water to the antibody-catalyzed cocaine hydrolysis for each reaction pathway. The free energy barriers for the antibody-catalyzed cocaine hydrolysis were predicted to be the corresponding free energy barriers for the cocaine hydrolysis in water plus the calculated free energy barrier shifts. The calculated free energy barrier shift of -6.87 kcal/mol from the dominant reaction pathway of the cocaine benzoyl ester hydrolysis in water to the dominant reaction pathway of the antibody-catalyzed cocaine hydrolysis is in good agreement with the experimentally derived free energy barrier shift of -5.93 kcal/mol. The calculated mutation-caused shifts of the free energy barrier are also reasonably close to the available experimental activity data. The good agreement suggests that the protocol for calculating the free energy barrier shift from the cocaine hydrolysis in water to the antibody-catalyzed cocaine hydrolysis may be used in future rational design of possible high-activity mutants of the antibody as anti-cocaine therapeutics. The general strategy of the free energy barrier shift calculation may also be valuable in studying a variety of chemical reactions catalyzed by other antibodies or proteins through noncovalent bonding interactions with the substrates.

Most efficient cocaine hydrolase designed by virtual screening of transition states.

Cocaine is recognized as the most reinforcing of all drugs of abuse. There is no anticocaine medication available. The disastrous medical and social consequences of cocaine addiction have made the development of an anticocaine medication a high priority. It has been recognized that an ideal anticocaine medication is one that accelerates cocaine metabolism producing biologically inactive metabolites via a route similar to the primary cocaine-metabolizing pathway, i.e., cocaine hydrolysis catalyzed by plasma enzyme butyrylcholinesterase (BChE). However, wild-type BChE has a low catalytic efficiency against the abused cocaine. Design of a high-activity enzyme mutant is extremely challenging, particularly when the chemical reaction process is rate-determining for the enzymatic reaction. Here we report the design and discovery of a high-activity mutant of human BChE by using a novel, systematic computational design approach based on transition-state simulations and activation energy calculations. The novel computational design approach has led to discovery of the most efficient cocaine hydrolase, i.e., a human BChE mutant with an approximately 2000-fold improved catalytic efficiency, promising for therapeutic treatment of cocaine overdose and addiction as an exogenous enzyme in human. The encouraging discovery resulted from the computational design not only provides a promising anticocaine medication but also demonstrates that the novel, generally applicable computational design approach is promising for rational enzyme redesign and drug discovery.

[Prognostic Value of Morphology and Hans Classification in Diffuse Large B Cell Lymphoma].

OBJECTIVE: To investigate the prognostic value of morphology and Hans classification in diffuse large B cell lymphoma（DLBCL）. METHODS: Clinical data of 249 patients diagnosed with DLBCL in our hospital and Hangzhou Xixi hospital during Jan 2006 to Dec 2016 were analyzed retrospectively. These patients were classified into 3 groups: immunoblastic variant（IB） group, centroblastic variant（CB） group and others group according to the cell morphology. And DLBCL was also divided into GCB（germinal center B-cell-like）or non-GCB（non-germinal center B-cell-like） group by analyzing the expression of CD10, BCL6 and MUM1 (GCB: CD10 +,BCL6+-,MUM1+-/CD10-,BCL6+,MUM1-；non-GCB：CD10-,BCL6-,MUM1+-/CD10-,BCL6+,MUM1+). RESULTS: The univariate analysis displayed that the age，LDH level，IPI，IB，non-GCB，B-symptoms and rituximab all could influence the OS and EFS, the CR rate of CB subtype patients was significantly higher than that of the patients with IB subtype （68.3% vs 38.9%)(P=0.02）. IB subtype was the in dependent prognostic factor for both EFS and OS in the whole study. In multivariate analysis, IPI and IB were the independent prognostic factors for OS and EFS. IB subtype was also an independent prognostic factor in EFS and OS with or without rituximab. The expression of BCL2 and BCL6 was related with prognosis in R-CHOP, but not in CHOP treated patients. Other markers (CD5, CD10, IRF4/MUM1, HLA-DR and Ki-67 proliferation index) were not of the significant prognostic value for DLBCL. When accepted rituximab, the GCB and non-GCB were not different significantly for prognosis. However, the non-GCB group showed a poor prognosis without using rituximab （EFS P=0.020；OS P=0.020）. Multivariate Cox models showed that OS and EFS were not significantly different between GCB and non-GCB group, however, the IB subtype had a very significantly poor prognosis in OS and EFS (P=0.001, P=0.002). When the analysis was restricted to DLBCL with CB morphology only, no prognostic value was observed in Hans classification. CONCLUSION: The subtype of immunoblast is a major risk factor in patients treated with CHOP or R-CHOP. There is a significant association between the Hans classification and the morphologic subclassification. Results of this study have supplemented the data for the prognostic factor of DLBCL and demonstrated that the cytomorphologic diagnosis can be reproducible.

Overexpression of NAC1 confers drug resistance via HOXA9 in colorectal carcinoma cells.

Colorectal carcinoma (CRC) is one of the most common types of malignancy worldwide. Recently, neoadjuvant chemotherapy has become an important treatment strategy for CRC. However, treatment frequently fails due to the development of chemoresistance, which is a major obstacle for positive prognosis. However, the underlying mechanisms of chemoresistance remain unclear. The present study assessed the functions of nucleus accumbens­associated protein 1 (NAC1), an important transcriptional regulator, in CRC progression. Reverse transcription­quantitative polymerase chain reaction, western blot analysis and immunohistochemistry were performed to detect the expression levels of NAC1. It was identified that NAC1 was significantly overexpressed in CRC compared with non­tumorous tissues, indicating an oncogenic role. Following this, gain and loss of function analyses were performed in vitro to further investigate the function of NAC1. Cell viability and caspase­3/7 activity assays were used to assess chemotherapy­induced apoptosis. These results indicated that overexpression of NAC1 in CRC cells increased resistance to chemotherapy and inhibited apoptosis. Additionally, RNA interference­mediated knockdown of NAC1 restored the chemosensitivity of CRC cells. Furthermore, mechanistic investigation revealed that NAC1 increased drug resistance via inducing homeobox A9 (HOXA9) expression, and that knockdown of HOXA9 abrogated NAC1­induced drug resistance. In conclusion, the results of the present study demonstrated that NAC1 may be a critical factor in the develo-pment of chemoresistance, offering a potential novel target for the treatment of CRC.

Modeling evolution of hydrogen bonding and stabilization of transition states in the process of cocaine hydrolysis catalyzed by human butyrylcholinesterase.

Molecular dynamics (MD) simulations and quantum mechanical/molecular mechanical (QM/MM) calculations were performed on the prereactive enzyme-substrate complex, transition states, intermediates, and product involved in the process of human butyrylcholinesterase (BChE)-catalyzed hydrolysis of (-)-cocaine. The computational results consistently reveal a unique role of the oxyanion hole (consisting of G116, G117, and A199) in BChE-catalyzed hydrolysis of cocaine, compared to acetylcholinesterase (AChE)-catalyzed hydrolysis of acetylcholine. During BChE-catalyzed hydrolysis of cocaine, only G117 has a hydrogen bond with the carbonyl oxygen (O31) of the cocaine benzoyl ester in the prereactive BChE-cocaine complex, and the NH groups of G117 and A199 are hydrogen-bonded with O31 of cocaine in all of the transition states and intermediates. Surprisingly, the NH hydrogen of G116 forms an unexpected hydrogen bond with the carboxyl group of E197 side chain and, therefore, is not available to form a hydrogen bond with O31 of cocaine in the acylation. The NH hydrogen of G116 is only partially available to form a weak hydrogen bond with O31 of cocaine in some structures involved in the deacylation. The change of the estimated hydrogen-bonding energy between the oxyanion hole and O31 of cocaine during the reaction process demonstrates how the protein environment can affect the energy barrier for each step of the BChE-catalyzed hydrolysis of cocaine. These insights concerning the effects of the oxyanion hole on the energy barriers provide valuable clues on how to rationally design BChE mutants with a higher catalytic activity for the hydrolysis of (-)-cocaine.

Bioactive permethrin/beta-cyclodextrin inclusion complex.

Permethrin is popularly used in a variety of therapeutic areas. However, the poor water solubility of permethrin seriously limits its wider clinical applications. The present study demonstrates that solubility of permethrin in aqueous solution can considerably increase in the presence of beta-cyclodextrin (beta-CD). Extensive experimental data along with computational modeling reveal the formation of stable permethrin/beta-CD inclusion complexes, including permethrin(beta-CD) and permethrin(beta-CD)2, through hydrophobic binding. Both permethrin(beta-CD) and permethrin(beta-CD)2 complexes coexisted in aqueous solution, and the ratio of the concentration of permethrin(beta-CD) complex to that of permethrin(beta-CD)2 complex was dependent on the concentration of beta-CD. The complexation of permethrin with beta-CD significantly improved the bioavailability of permethrin and, therefore, increased the bioactivity. The significant increase of the bioactivity of permethrin in the presence of beta-CD provides an effective approach to improve the practical use of permethrin in public health and agriculture.

The solution structure of a DNA*RNA duplex containing 5-propynyl U and C; comparison with 5-Me modifications.

The addition of the propynyl group at the 5 position of pyrimidine nucleotides is highly stabilising. We have determined the thermodynamic stability of the DNA.RNA hybrid r(GAAGAGAAGC)*d(GC(p)U(p)U(p)C(p)U(p) C(p)U(p)U(p)C) where p is the propynyl group at the 5 position and compared it with that of the unmodified duplex and the effects of methyl substitutions. The incorporation of the propyne group at the 5 position gives rise to a very large stabilisation of the hybrid duplex compared with the analogous 5-Me modification. The duplexes have been characterised by gel electrophoresis and NMR spectroscopy, which indicate that methyl substitutions have a smaller influence on local and global conformation than the propynyl groups. The increased NMR spectral dispersion of the propyne-modified duplex allowed a larger number of experimental restraints to be measured. Restrained molecular dynamics in a fully solvated system showed that the propyne modification leads to substantial conformational rearrangements stabilising a more A-like structure. The propynyl groups occupy a large part of the major groove and make favourable van der Waals interactions with their nearest neighbours and the atoms of the rings. This enhanced overlap may account at least in part for the increased thermodynamic stability. Furthermore, the simulations show a spine of hydration in the major groove as well as in the minor groove involving the RNA hydroxyl groups.

Modeling effects of oxyanion hole on the ester hydrolysis catalyzed by human cholinesterases.

Molecular dynamics (MD) simulations and hydrogen bonding energy (HBE) calculations have been performed on the prereactive enzyme-substrate complexes (ES), transition states (TS1), and intermediates (INT1) for acetylcholinesterase (AChE)-catalyzed hydrolysis of acetylcholine (ACh), butyrylcholinesterase (BChE)-catalyzed hydrolysis of ACh, and BChE-catalyzed hydrolysis of (+)/(-)-cocaine to examine the protein environmental effects on the catalytic reactions. The hydrogen bonding of cocaine with the oxyanion hole of BChE is found to be remarkably different from that of ACh with AChE/BChE. Whereas G121/G116, G122/G117, and A204/A199 of AChE/BChE all can form hydrogen bonds with ACh to stabilize the transition state during the ACh hydrolysis, BChE only uses G117 and A199 to form hydrogen bonds with cocaine. The change of the estimated total HBE from ES to TS1 is ca. -5.4/-4.4 kcal/mol for AChE/BChE-catalyzed hydrolysis of ACh and ca. -1.7/-0.8 kcal/mol for BChE-catalyzed hydrolysis of (+)/(-)-cocaine. The remarkable difference of approximately 3 to 5 kcal/mol reveals that the oxyanion hole of AChE/BChE can lower the energy barrier of the ACh hydrolysis significantly more than that of BChE for the cocaine hydrolysis. These results help to understand why the catalytic activity of AChE against ACh is considerably higher than that of BChE against cocaine and provides valuable clues on how to improve the catalytic activity of BChE against cocaine.

Successful use of splenectomy in a patient with hepatitis C virus-related thrombocytopenia.

This case report describes a 44-year-old female with hepatitis C virus-related thrombocytopenia. The laboratory tests showed a platelet count of 3×109/l, positive HCV serology and high serum concentration of HCV-RNA of 6.74×106 copy/ml. She was refractory to standard therapies including corticosteroids, intravenous immunoglobulin (IVIG), thrombopoietin (TPO) and even interferon (IFN) regimens, due to the persistence of a low platelet count. At first, splenectomy was thought to be impossible, but then splenectomy was successfully performed and patient showed good tolerance and a constant normal platelet count after surgery. In conclusion, splenectomy is feasible in selected patients and may allow us to acquire a reasonable platelet count and completion of an anti-HCV protocol. Low platelet count itself should not be the contraindication of operation specifically for these patients. Further studies in larger numbers of patients and over a longer period of time are warranted.

Free energy perturbation simulation on transition states and high-activity mutants of human butyrylcholinesterase for (-)-cocaine hydrolysis.

A unified computational approach based on free energy perturbation (FEP) simulations of transition states has been employed to calculate the mutation-caused shifts of the free energy change from the free enzyme to the rate-determining transition state for (-)-cocaine hydrolysis catalyzed by the currently most promising series of mutants of human butyrylcholinesterase (BChE) that contain the A199S/A328W/Y332G mutations. The FEP simulations were followed by Michaelis-Menten kinetics analysis determining the individual k(cat) and K(M) values missing for the A199S/F227A/A328W/Y332G mutant in this series. The calculated mutation-caused shifts of the free energy change from the free enzyme to the rate-determining transition state are in good agreement with the experimental kinetic data, demonstrating that the unified computational approach based on the FEP simulations of the transition states may be valuable for future computational design of new BChE mutants with a further improved catalytic efficiency against (-)-cocaine.

Structural analysis of thermostabilizing mutations of cocaine esterase.

Cocaine is considered to be the most addictive of all substances of abuse and mediates its effects by inhibiting monoamine transporters, primarily the dopamine transporters. There are currently no small molecules that can be used to combat its toxic and addictive properties, in part because of the difficulty of developing compounds that inhibit cocaine binding without having intrinsic effects on dopamine transport. Most of the effective cocaine inhibitors also display addictive properties. We have recently reported the use of cocaine esterase (CocE) to accelerate the removal of systemic cocaine and to prevent cocaine-induced lethality. However, wild-type CocE is relatively unstable at physiological temperatures (tau(1/2) approximately 13 min at 37 degrees C), presenting challenges for its development as a viable therapeutic agent. We applied computational approaches to predict mutations to stabilize CocE and showed that several of these have increased stability both in vitro and in vivo, with the most efficacious mutant (T172R/G173Q) extending half-life up to 370 min. Here we present novel X-ray crystallographic data on these mutants that provide a plausible model for the observed enhanced stability. We also more extensively characterize the previously reported variants and report on a new stabilizing mutant, L169K. The improved stability of these engineered CocE enzymes will have a profound influence on the use of this protein to combat cocaine-induced toxicity and addiction in humans.