Nanoparticle drug delivery system for the treatment of brain tumors: Breaching the blood-brain barrier.

The current status of clinical trials utilizing nanoparticle drug delivery system (NDDS) for brain tumors was summarized.Image 1.

Clinical observation of ultraviolet therapy combined with autologous platelet-rich plasma in the treatment of chronic refractory wounds.

Refractory wounds present complex and serious clinical dilemmas in plastic and reconstructive surgeries. Currently, there are no standard guidelines for the treatment of refractory wounds. To observe the clinical effects of ultraviolet (UV) therapy combined with autologous platelet-rich plasma (PRP) on chronic refractory wounds. Between January 2021 and December 2022, 60 inpatients with chronic refractory wounds were enrolled. Twenty patients were assigned to each of control groups 1 and 2 and treatment group according to whether they received PRP or UV treatment. All the patients underwent thorough debridement. Control group 2 received UV radiation. The treatment group underwent UV radiation combined with PRP gel covering the wound. Control group 1 underwent routine dressing changes after surgery, followed by skin grafting or skin key transfer if needed. One month later, we observed the wound healing in the two groups. After 2-4 PRP gel treatments, the wounds of patients in the treatment group healed. The healing time was 25.25 ± 4.93 days, and the dressings were changed 4.15 ± 3.30 times, both of which were better outcomes than in both control groups. In the treatment group, epidermal growth factor (EGF), insulin-like growth factor (IGF), platelet-derived growth factor (PGF), and transforming growth factor ß (TGF-ß) were slightly higher, and the concentration of vascular endothelial growth factor (VEGF) was significantly higher than in the control group (p < 0.05). PRP combined with UV therapy significantly increased the concentration of wound growth factors, accelerated wound healing, shortened treatment time, reduced treatment costs, and alleviated pain in patients.

Cyclin B1 is an efficacy-predicting biomarker for Chk1 inhibitors.

Chk1 is the major mediator of cell-cycle checkpoints in response to various forms of genotoxic stress. Although it was previously speculated that checkpoint abrogation due to Chk1 inhibition may potentiate the efficacy of DNA-damaging agents through induction of mitotic catastrophe, there has not been direct evidence proving this process. Here, through both molecular marker and morphological analysis, we directly demonstrate that specific downregulation of Chk1 expression by Chk1 siRNA potentiates the cytotoxicities of topoisomerase inhibitors through the induction of premature chromosomal condensation and mitotic catastrophe. More importantly, we discovered that the cellular cyclin B1 level is the major determinant of the potentiation. We show that downregulation of cyclin B1 leads to impairment of the induction of mitotic catastrophe and correspondingly a reduction of the potentiation ability of either Chk1 siRNA or a small molecule Chk1 inhibitor. More significantly, we have extended the study by examining a panel of 10 cancer cell-lines with different tissue origins for their endogenous levels of cyclin B1 and the ability of a Chk1 inhibitor to sensitize the cells to DNA-damaging agents. The cellular levels of cyclin B1 positively correlate with the degrees of potentiation achieved. Of additional interest, we observed that the various colon cancer cell lines in general appear to express higher levels of cyclin B1 and also display higher sensitivity to Chk1 inhibitors, implying that Chk1 inhibitor may be more efficacious in treating colon cancers. In summary, we propose that cyclin B1 is a biomarker predictive of the efficacy of Chk1 inhibitors across different types of cancers. Unlike previously established efficacy-predictive biomarkers that are usually the direct targets of the therapeutic agents, cyclin B1 represents a non-drug-target biomarker that is based on the mechanism of action of the target inhibitor. This finding may be potentially very useful for the stratification of patients for Chk1 inhibitor clinical trials and hence, maximize its chance of success.

Synthesis and in-vitro biological activity of macrocyclic urea Chk1 inhibitors.

A variety of macrocyclic urea compounds were prepared as potent Chk1 inhibitors by modifying the C5 position of the benzene ring of the macrocyclic urea with ether moieties, aliphatic carbon chains, amide and halides. Enzymatic activity less than 20nM was observed in 29 of 40 compounds. Compounds 14, 46d, and 48j provided the best overall results in the cellular assays as they abrogated doxorubicin-induced cell cycle arrest (IC(50)=3.31, 3.08, and 3.13microM) and enhanced doxorubicin cytotoxicity (IC(50)=0.54, 1.27, and 0.96microM) while displaying no single agent activity, respectively.

Design, synthesis, and biological activity of 5,10-dihydro-dibenzo[b,e][1,4]diazepin-11-one-based potent and selective Chk-1 inhibitors.

A novel series of 5,10-dihydro-dibenzo[b,e][1,4]diazepin-11-ones have been synthesized as potent and selective checkpoint kinase 1 (Chk1) inhibitors via structure-based design. Aided by protein X-ray crystallography, medicinal chemistry efforts led to the identification of compound 46d, with potent enzymatic activity against Chk1 kinase. While maintaining a low cytotoxicity of its own, compound 46d exhibited a strong ability to abrogate G2 arrest and increased the cytotoxicity of camptothecin by 19-fold against SW620 cells. Pharmacokinetic studies revealed that it had a moderate bioavailabilty of 20% in mice. Two important binding interactions between compound 46b and Chk1 kinase, revealed by X-ray cocrystal structure, were hydrogen bonds between the hinge region and the amide bond of the core structure and a hydrogen bond between the methoxy group and Lys38 of the protein.

Synthesis and biological evaluation of 4'-(6,7-disubstituted-2,4-dihydro-indeno[1,2-c]pyrazol-3-yl)-biphenyl-4-ol as potent Chk1 inhibitors.

A new series of potent tricyclic pyrazole-based Chk1 inhibitors are described. Analogues disubstituted on the 6- and 7-positions show improved Chk1 inhibition potency compared with analogues with a single substituent on either the 6- or 7-position. Based on the lead compound 4'-(6,7-dimethoxy-2,4-dihydro-indeno[1,2-c]pyrazol-3-yl)-biphenyl-4-ol (2), detailed SAR studies on the 6- and 7-positions were performed. 3'-morpholin-4'-yl-propoxy, pyridin-4'-ylmethoxy, pyridin-3'-ylmethoxy, 2'-(5''-ethyl-pyridin-2''-yl)-ethoxy, pyridin-2'-ylethoxy, (6'-methyl-pyridin-2'-yl)-propoxyethoxy, 2',3'-dihydroxyl-1'-yl-propoxy, and tetrahydro-furan-3'-yloxy have been identified as the best groups on the 6-position when the 7-position is substituted with methoxyl group. Pyridin-2'-ylmethoxy and pyridin-3'-ylmethoxy have been identified as the best substituents at the 7-position while the 6-position bearing methoxyl group. These compounds significantly potentiate the cytotoxicity of DNA-damaging antitumor agents in a cell-based assay and efficiently abrogate the doxorubicin-induced G2/M and the camptothecin-induced S checkpoints, suggesting that their potent biological activities are mechanism-based through Chk1 inhibition.

Selective Chk1 inhibitors differentially sensitize p53-deficient cancer cells to cancer therapeutics.

The majority of cancer therapeutics induces DNA damage to kill cells. Normal proliferating cells undergo cell cycle arrest in response to DNA damage, thus allowing DNA repair to protect the genome. DNA damage induced cell cycle arrest depends on an evolutionarily conserved signal transduction network in which the Chk1 kinase plays a critical role. In mammalian cells, the p53 and RB pathways further augment the cell cycle arrest response to prevent catastrophic cell death. Given the fact that most tumor cells suffer defects in the p53 and RB pathways, it is likely that tumor cells would depend more on the Chk1 kinase to maintain cell cycle arrest than would normal cells. Therefore Chk1 inhibition could be used to specifically sensitize tumor cells to DNA-damaging agents. We have previously shown that siRNA-mediated Chk1 knockdown abrogates DNA damage-induced checkpoints and potentiates the cytotoxicity of several DNA-damaging agents in p53-deficient cell lines. In this study, we have developed 2 potent and selective Chk1 inhibitors, A-690002 and A-641397, and shown that these compounds abrogate cell cycle checkpoints and potentiate the cytotoxicity of topoisomerase inhibitors and gamma-radiation in p53-deficient but not in p53-proficient cells of different tissue origins. These results indicate that it is feasible to achieve a therapeutic window with 1 or more Chk1 inhibitors in potentiation of cancer therapy based on the status of the p53 pathway in a wide spectrum of tumor types.

Synthesis and biological evaluation of 1-(2,4,5-trisubstituted phenyl)-3-(5-cyanopyrazin-2-yl)ureas as potent Chk1 kinase inhibitors.

Based on the X-ray crystallography of our lead compound 1-(5-chloro-2,4-dimethoxyphenyl)-3-(5-cyanopyrazin-2-yl)urea in the checkpoint kinase 1 (Chk1) enzyme, we modified R4, and to a lesser extent, R2, and R5 of the phenyl ring, and made a variety of N-aryl-N'-pyrazinylurea Chk1 inhibitors. Enzymatic activity less than 20 nM was observed in 15 of 41 compounds. Compound 8i provided the best overall results in the cellular assays as it abrogated doxorubicin-induced cell cycle arrest (IC50=1.7 microM) and enhanced doxorubicin cytotoxicity (IC50=0.44 microM) while displaying no single agent activity.

1-(5-Chloro-2-alkoxyphenyl)-3-(5-cyanopyrazin-2-yl)ureas [correction of cyanopyrazi] as potent and selective inhibitors of Chk1 kinase: synthesis, preliminary SAR, and biological activities.

The discovery of 1-(5-chloro-2-alkoxyphenyl)-3-(5-cyanopyrazin-2-yl)ureas as a new class of potent (IC(50) values of 3-10 nM) and selective inhibitors of Chk1 kinase was described. One of these compounds (2e) potentiates HeLa cells by over 22-fold against doxorubicin in an antiproliferation assay, and SW620 cells against camptothecin by 20-fold in an antiproliferation assay and 14-fold in a soft agar assay. Flow cytometry (FACS) analysis confirmed that 2e abrogated G2 checkpoint arrest of H1299 cells caused by doxorubicin and S checkpoint arrest caused by camptothecin.