Molecular Generation, QSAR, and Molecular Dynamic Simulation Studies for Virtual Screening of DNA Polymerase Theta Inhibitors.

AIMS: The machine learning-based QSAR modeling procedure, molecular generations, and molecular dynamic simulations were applied to virtually screen the DNA polymerase theta inhibitors. BACKGROUND: The DNA polymerase theta (Polθ or POLQ) is an attractive target for treatments of homologous recombination deficient (such as BRCA deficient) cancers. There are no approved drugs for targeting POLQ, and only one inhibitor is in Phase Ⅱclinical trials; thus, it is necessary to develop novel POLQ inhibitors. OBJECTIVES: To build machine learning models that predict the bioactivities of POLQ inhibitors. To build molecular generation models that generate diverse molecules. To virtually screen the generated molecules by the machine learning models. To analyze the binding modes of the screening results by molecular dynamic simulations. METHODS: In the present work, 325 inhibitors with POLQ polymerase domain bioactivities were Collected. Two machine learning methods, random forest and deep neural network, were used for building the ligand- and structure-based quantitative structure-activity relationship (QSAR) models. The substructure replacement-based method and transfer learning-based deep recurrent neural network method were used for molecular generations. Molecular docking and consensus QSAR models were carried out for virtual screening. The molecular dynamic simulations and MM/GBSA binding free energy calculation and decomposition were used to further analyze the screening results. RESULTS: The MCC values of the best ligand- and structure-based consensus QSAR models reached 0.651 and 0.361 for the test set, respectively. The machine learning-based docking scores had better-predicted ability to distinguish the highly and weakly active poses than the original docking scores. The 96490 molecules were generated by both molecular generation methods, and 10 molecules were retained by virtual screening. Four favorable interactions were concluded by molecular dynamic simulations. CONCLUSION: We hope that the screening results and the binding modes are helpful for designing the highly active POLQ polymerase inhibitors and the models of the molecular design workflow can be used as reliable tools for drug design.

Cationic mesoporous silica nanoparticles alleviate osteoarthritis by targeting multiple inflammatory mediators.

Osteoarthritis (OA) is a common and complex inflammatory disorder that is frequently compounded by cartilage degradation, synovial inflammation, and osteophyte formation. Damaged chondrocytes release multiple danger mediators that exacerbate synovial inflammation and accelerate the progression to OA. Conventional treatments targeting only a single mediator of OA have failed to achieve a strong therapeutic effect. Addressing the crucial role of multiple danger mediators in OA progression, we prepared polyethylenimine (PEI)-functionalized diselenide-bridged mesoporous silica nanoparticles (MSN-PEI) with cell-free DNA (cfDNA)-binding and anti-oxidative properties. In models of surgery-induced and collagenase-induced arthritis, we showed that these cationic nanoparticles attenuated cartilage degradation and provided strong chondroprotection against joint damage. Mechanistically, multiple target blockades alleviated oxidative stress and dampened cfDNA-induced inflammation by suppressing the M1 polarization of macrophages. This study suggests a beneficial direction for targeting multiple danger mediators in the treatment of intractable arthritis.

Analysis of Serum Metabolomics in Rats with Osteoarthritis by Mass Spectrometry.

Osteoarthritis is a common multifactorial chronic disease that occurs in articular cartilage, subchondral bone, and periarticular tissue. The pathogenesis of OA is still unclear. To investigate the differences in serum metabolites between OA and the control group, liquid chromatography/mass spectrometry (LC/MS)-based metabolomics was used. To reveal the pathogenesis of OA, 12 SD male rats were randomly divided into control and OA groups using collagenase to induce OA for modeling, and serum was collected 7 days after modeling for testing. The OA group was distinguished from the control group by principal component analysis and orthogonal partial least squares-discriminant analysis, and six biomarkers were finally identified. These biomarkers were metabolized through tryptophan metabolism, glutamate metabolism, nitrogen metabolism, spermidine metabolism, and fatty acid metabolism pathways. The study identified metabolites that may be altered in OA, suggesting a role in OA through relevant metabolic pathways. Metabolomics, as an important tool for studying disease mechanisms, provides useful information for studying the metabolic mechanisms of OA.

Concise, scalable and enantioselective total synthesis of prostaglandins.

Prostaglandins are among the most important natural isolates owing to their broad range of bioactivities and unique structures. However, current methods for the synthesis of prostaglandins suffer from low yields and lengthy steps. Here, we report a practicability-oriented synthetic strategy for the enantioselective and divergent synthesis of prostaglandins. In this approach, the multiply substituted five-membered rings in prostaglandins were constructed via the key enyne cycloisomerization with excellent selectivity (>20:1 d.r., 98% e.e.). The crucial chiral centre on the scaffold of the prostaglandins was installed using the asymmetric hydrogenation method (up to 98% yield and 98% e.e.). From our versatile common intermediates, a series of prostaglandins and related drugs could be produced in two steps, and fluprostenol could be prepared on a 20-gram scale.

Berberine inhibits chemotherapy-exacerbated ovarian cancer stem cell-like characteristics and metastasis through GLI1.

Despite the remarkable clinical response in ovarian cancer therapy, the distinctively high metastasis rate is still a barrier to achieve satisfying prognosis. Our study aimed to decipher the role of berberine in inhibiting chemotherapy-exacerbated ovarian cancer metastasis. We found that chemotherapy exacerbated the migration and cancer stem cell (CSC)-like characteristics through transcriptional factor GLI1, which regulated the pluripotency-associated gene BMI1 and the epithelial-mesenchymal transition (EMT) markers Vimentin and Snail. Berberine could not only down-regulate CSC-like characteristics but also reverse EMT and migration through inhibiting chemotherapy-activated GLI1/BMI1 signaling pathway. Together, our study revealed the pivotal role of berberine in overcoming chemotherapy-exacerbated ovarian cancer metastasis, thereby provided a potential adjuvant therapeutic agent in combination with chemotherapeutics to prevent metastasis during ovarian cancer chemotherapy.

Nrf2 knockout dysregulates iron metabolism and increases the hemolysis through ROS in aging mice.

AIMS: Dysregulation of iron homeostasis in the body causes a variety of diseases. Iron deficiency leads to anemia, whereas iron overload aggravates cellular oxidative stress. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a protein that is activated in the nucleus and turns on the production of antioxidant enzymes, protecting cell against oxidative damage. This study aimed to investigate whether Nrf2 gene knockout influences iron homeostasis in aging mice. MATERIALS AND METHODS: Iron content and iron metabolism-related proteins were assessed in different organs and blood serum of the 18 month-old Nrf2 knockout (Nrf2-/-) mice in comparison with the wild-type (WT) mice. KEY FINDINGS: Results showed that the iron contents in spleen and liver all increased, and expression levels of iron transporters were altered in Nrf2-/- mice. In particularly, we found that the expression of iron export protein ferroportin 1 (Fpn1) in liver, spleen and small intestine all decreased in Nrf2-/- mice, which might account for the deposition of iron in different organs and the increased ROS. Surprisingly, we found that the serum iron level of Nrf2-/- mice did not decrease, but increased significantly even when the iron absorption at small intestine decreased. Our further investigation revealed that the increase of serum iron was due to the release of iron from the hemolysis of erythrocytes, which caused by the increased ROS level in red blood cells of the Nrf2-/- mice. SIGNIFICANCE: These findings provide a more comprehensive understanding of the important role of Nrf2 in the regulation of systemic iron metabolism.

Chemotherapy exacerbates ovarian cancer cell migration and cancer stem cell-like characteristics through GLI1.

BACKGROUND: Despite the great clinical response to the first-line chemotherapeutics, metastasis still happens among most of the ovarian cancer patients within 2 years. METHODS: Using multiple human ovarian cancer cell lines, a transwell co-culture system of the carboplatin or VP-16-challenged feeder and receptor cells was established to demonstrate the chemotherapy-exacerbated migration. The migration and cancer stem cell (CSC)-like characteristics were determined by wound healing, transwell migration, flow cytometry and sphere formation. mRNA and protein expression were identified by qPCR and western blot. Bioinformatics analysis was used to investigate the differentially expressed genes. GLI1 expression in tissue samples was analysed by immunohistochemistry. RESULTS: Chemotherapy was found to not only kill tumour cells, but also trigger the induction of CSC-like traits and the migration of ovarian cancer cells. EMT markers Vimentin and Snail in receptor cells were upregulated in the microenvironment of chemotherapy-challenged feeder cells. The transcription factor GLI1 was upregulated by chemotherapy in both clinical samples and cell lines. Follow-up functional experiments illustrated that inhibiting GLI1 reversed the chemotherapy-exacerbated CSC-like traits, including CD44 and CD133, as well as prevented the migration of ovarian cancer cells. CONCLUSIONS: Targeting GLI1 may improve clinical benefits in the chemotherapy-exacerbated metastasis in ovarian cancer treatment.

5-FU preferably induces apoptosis in BRAF V600E colorectal cancer cells via downregulation of Bcl-xL.

Fluorouracil (5-FU) which has been widely used in postoperative adjuvant therapy in patients with colon cancer, remains the main backbone of combination treatment of patients with colon cancer. However, the efficacy of 5-FU alone in colorectal cancer patients with BRAFV600E is not clear. In this study, we demonstrated that BRAFV600E confers sensitivity to 5-FU in vitro and in vivo xenograft model, using the paired isogenic colorectal cancer cell lines RKO with either BRAF Wild Type (WT)(+/-) or mutant (Mut) (600E/-). Our results revealed 5-FU preferably induces marked apoptosis in BRAF-mutant colorectal cancer cells, through attenuating expression of Bcl-xL and activation caspase-3/9 pathway, eventually conferring the anti-tumor efficacy of 5-FU in vitro and in vivo. Meanwhile, expression of Bcl-xL remained unchanged in BRAF WT group after treatment of 5-FU, although low extent of anti-tumor activity of 5-FU still being observed. In conclusion, these results provided a better understanding of clinical outcome of 5-FU between BRAF WT and mutant colorectal cancer patients, and suggested the inhibition of Bcl-xL might present an alternative strategy to enhance the therapeutic efficacy of 5-FU in colorectal cancer patients with BRAF mutation.

Total Syntheses of Asperchalasines†A-E.

The first total syntheses of asperchalasines A-E, a collection of unprecedented merocytochalasans, are reported. Aspochalasin B, a key tricyclic cytochalasan monomer, was first synthesized through a unified approach that hinges on a Diels-Alder reaction and a ring-closing metathesis reaction. The bioinspired Diels-Alder reactions of aspochalasin B with different epicoccine precursors were then explored, which enabled the divergent access of the heterodimers asperchalasines B-E as well as related congeners. Furthermore, the heterotrimer asperchalasine A was obtained from one epicoccine unit and two aspochalasin B units through a biomimetic Diels-Alder reaction followed by an oxidative [5+2]-cycloaddition.

Rh(II)-Catalyzed Transannulation of N-Sulfonyl-1,2,3-Triazoles with 2,1-Benzisoxazoles or 1,2-Benzisoxazoles.

A Rh(II)-catalyzed transannulation of N-sulfonyl-1,2,3-triazoles with 2,1-benzisoxazoles has been developed, which affords an efficient method for the synthesis of quinazoline derivatives. The transformation represents an unprecedented example which utilizes N-sulfonyl-1,2,3-triazole as an aza-[2C]-component in cycloadditions. Meanwhile, a Rh(II)-catalyzed formal [3 + 2] cycloaddition of N-sulfonyl-1,2,3-triazoles with 1,2-benzisoxazoles is also presented, which enables the rapid synthesis of functionalized imidazole derivatives.