凝血酶蛋白酶激活受体-1作为转移性黑色素瘤治疗潜在靶点的研究进展

黑色素瘤由于转移性强,成为皮肤癌中死亡率最高的恶性肿瘤之一,目前没有有效的治疗方法。凝血酶蛋白酶激活受体-1(PAR-1)在黑色素瘤的发病过程中起到重要作用,PAR-1通过激活肿瘤细胞黏附和侵袭以及新生血管因子生成促进黑色素瘤转移。PAR-1有望成为治疗转移性黑色素瘤药物新靶点。     

Endoglin and alk1 as therapeutic targets for hereditary hemorrhagic telangiectasia

Introduction: Hereditary Haemorrhagic Telangiectasia (HHT) is as an autosomal dominant trait characterized by frequent nose bleeds, mucocutaneous telangiectases, arteriovenous malformations (AVMs) of the lung, liver and brain, and gastrointestinal bleedings due to telangiectases. HHT is originated by mutations in genes whose encoded proteins are involved in the transforming growth factor β (TGF-β) family signalling of vascular endothelial cells. In spite of the great advances in the diagnosis as well as in the molecular, cellular and animal models of HHT, the current treatments remain just at the palliative level.

Areas covered: Pathogenic mutations in genes coding for the TGF-β receptors endoglin (ENG) (HHT1) or the activin receptor-like kinase-1 (ACVRL1 or ALK1) (HHT2), are responsible for more than 80% of patients with HHT. Therefore, ENG and ALK1 are the main potential therapeutic targets for HHT and the focus of this review. The current status of the preclinical and clinical studies, including the anti-angiogenic strategy, have been addressed.

Expert opinion: Endoglin and ALK1 are attractive therapeutic targets in HHT. Because haploinsufficiency is the pathogenic mechanism in HHT, several therapeutic approaches able to enhance protein expression and/or function of endoglin and ALK1 are keys to find novel and efficient treatments for the disease.     

Use of HIV-1 p24 as a sensitive, precise and inexpensive marker for infection, disease progression and treatment failure

HIV RNA is an acknowledged marker of disease activity and predictive of progression, while the p24 antigen is considered unsuitable. This is at odds with the fact that viral pathogenesis is usually mediated by proteins. One might expect that p24, if analyzed properly, might even be superior to RNA. This hypothesis was investigated in clinical studies using a sensitive and precise p24 test (heat-mediated immune complex dissociation with signal amplification-boosted ELISA). This test was as sensitive and specific as the polymerase chain reaction (PCR) for viral RNA (200–400 copy detection), an overall better predictor of CD4 decline and survival, while RNA prevailed in predicting AIDS. The lower costs of p24 testing also permit a closer monitoring of patients with an earlier detection of anti-retroviral treatment failures.     

Clinical pharmacokinetics and pharmacodynamics of dolutegravir used as a single tablet regimen for the treatment of HIV-1 infection

Introduction: With the introduction of the coformulated dolutegravir, abacavir and lamivudine, a new single tablet regimen (STR) is made available for the use in treatment-naive and treatment-experienced HIV-infected patients. This drug combination is the fourth STR that will be positioned next to the STRs with efavirenz, rilpivirine or elvitegravir as third agents, respectively.

Areas covered: The objective of this review is to provide an overview of the efficacy and safety of the combined dolutegravir/abacavir/lamivudine coformulation. The review will focus on dolutegravir and includes both published data as well as data presented at recent major international HIV/AIDS conferences.

Expert opinion: The dolutegravir/abacavir/lamivudine regimen is highly effective in achieving sustained suppression of HIV-1 RNA plasma concentrations. The STR has a favorable safety profile and a low potential for drug interactions, which will contribute to a prominent role in therapy. As this STR contains abacavir as backbone component, the use requires patients to be HLA-B*5701 negative, with good hepatic function. Other first-line treatment combinations are preferred for patients with hepatitis B co-infection or with a high cardiovascular risk.     

Phospho-p70S6K and cdc2/cdk1 as therapeutic targets for diffuse large B-cell lymphoma

p70S6K/p85S6K and cdc2/cdk1 are members of the serine/threonine protein kinase family. p70S6K/p85S6K is one of the downstream effectors of the PI3K/Akt/mTOR signal transduction pathway. It phosphorylates S6 protein of 40S ribosomal subunit and thus functions in protein synthesis and cell growth. cdc2/cdk1 is a cyclin-dependent protein kinase that controls the cell cycle entry from G2 to M phase. Overexpression of phospho-p70S6K and cdc2/cdk1 has recently been identified in the majority of diffuse large B-cell lymphoma (DLBCL) specimens. Combination of small molecules that target phosphorylation of p70S6K and cdc2/cdk1 synergistically induced cell apoptosis and cell cycle G1 and G2 arrest, suggesting that they are potential molecular targets for DLBCL therapy. This review will summarize recent advances in the study of phospho-p70S6K and cdc2/cdk1 as molecular markers and therapeutic targets for DLBCL. We propose that multilevel inhibition of the PI3K/Akt/mTOR pathway and double brake at the G1 and G2 phases of the cell cycle progression are effective strategies in treating DLBCL that overexpress phospho-p70S6K and cdc2/cdk1.     

Kinin B1 receptors as a therapeutic target for inflammation

Introduction: Kinins are peptide mediators exerting their pro-inflammatory actions by the selective stimulation of two distinct G-protein coupled receptors, termed BKB1R and BKB2R. While BKB2R is constitutively expressed in a multitude of tissues, BKB1R is hardly expressed at baseline but highly inducible by inflammatory mediators. In particular, BKB1R was shown to be involved in the pathogenesis of numerous inflammatory diseases.

Areas covered: This review intends to evaluate the therapeutic potential of substances interacting with the BKB1R. To this purpose we summarize the published literature on animal studies with antagonists and knockout mice for this receptor.

Expert Opinion: In most cases the pharmacological inhibition of BKB1R or its genetic deletion was beneficial for the outcome of the disease in animal models. Therefore, several companies have developed BKB1R antagonists and tested them in phase I and II clinical trials. However, none of the developed BKB1R antagonists was further developed for clinical use. We discuss possible reasons for this failure of translation of preclinical findings on BKB1R antagonists into the clinic.     

Development of small-molecule immune checkpoint inhibitors of PD-1/PD-L1 as a new therapeutic strategy for tumour immunotherapy

Abstract

Cancer immunotherapy has been increasingly utilised to treat advanced malignancies. The signalling network of immune checkpoints has attracted considerable attention. Immune checkpoint inhibitors are revolutionising the treatment options and expectations for patients with cancer. The reported clinical success of targeting the T-cell immune checkpoint receptors PD-1/PD-L1 has demonstrated the importance of immune modulation. Indeed, antibodies binding to PD-1 or PD-L1 have shown remarkable efficacy. However, antibody drugs have many disadvantages, such as their production cost, stability, and immunogenicity and, therefore, small-molecule inhibitors of PD-1 and its ligand PD-L1 are being introduced. Small-molecule inhibitors could offer inherent advantages in terms of pharmacokinetics and druggability, thereby providing additional methods for cancer treatment and achieving better therapeutic effects. In this review, we first discuss how PD-1/PD-L1-targeting inhibitors modulate the relationship between immune cells and tumour cells in tumour immunotherapy. Second, we discuss how the immunomodulatory potential of these inhibitors can be exploited via rational combinations with immunotherapy and targeted therapy. Third, this review is the first to summarise the current clinical and preclinical evidence regarding small-molecule inhibitors of the PD-1/PD-L1 immune checkpoint, considering features and responses related to the tumours and to the host immune system.

Trial registration: ClinicalTrials.gov identifier: NCT02812875.     

Integrins as attractive targets for cancer therapeutics

Integrins are transmembrane receptors that have been implicated in the biology of various human physiological and pathological processes. These molecules facilitate cell–extracellular matrix and cell–cell interactions, and they have been implicated in fibrosis, inflammation, thrombosis, and tumor metastasis. The role of integrins in tumor progression makes them promising targets for cancer treatment, and certain integrin antagonists, such as antibodies and synthetic peptides, have been effectively utilized in the clinic for cancer therapy. Here, we discuss the evidence and knowledge on the contribution of integrins to cancer biology. Furthermore, we summarize the clinical attempts targeting this family in anti-cancer therapy development.     

Development of a selective S1P1 receptor agonist,Syl930, as a potential therapeutic agent for autoimmune encephalitis

Sphingosine-1-phosphate receptor subtype 1 (S1P₁) is essential for lymphocyte egress from secondary lymphoid organs and is a validated drug target for the treatment of autoimmune disorders. However, during the preclinical and clinical trials of S1P₁ modulators, the undesired activation of S1P₃, a subtype of sphingosine 1-phosphate (S1P) receptors family, by S1P₁ modulators often results in bradycardia in patients. Thus, we designed and synthesized a new series of selective S1P₁ agonists. One of them, Syl930 (the prodrug), is preference to activate S1P₁ but not S1P₃. In this study, we further investigated the therapeutic potential of Syl930 on an experimental autoimmune encephalomyelitis (EAE) model in Lewis rats. We found that Syl930 can activate and internalize S1P₁ receptors and effectively decreased the periphery blood lymphocytes (PBL) in SD rats, and subsequently rendered PBL insensitive to egress signal from secondary lymphoid organs (SLO). Intriguingly, the treatment of Syl930 did not bring any side effect on heart rate of the tested rats. Furthermore, the suppressed PBL caused by Syl930 was able to recover within 3 days after the last dose of treatment, which is correlated to the relatively short elimination half-life of Syl930. In the rat EAE model, therapeutic treatment with Syl930 significantly inhibited the progression of EAE and EAE-associated histological changes in brain and spinal cord of Lewis rats. These results illustrate that, as a selective S1P₁ agonist, Syl930 exhibits a profound and rapidly reversible suppression of lymphocyte trafficking and it has the potential to serve as a therapeutic agent for autoimmune encephalitis.     

Drug discovery targeting epigenetic codes: The great potential of UHRF1, which links DNA methylation and histone modifications, as a drug target in cancers and toxoplasmosis

UHRF1 plays a central role in transferring methylation status from mother cells to daughter cells. Its SRA domain recognizes hemi-methylated DNA that appears in daughter DNA strands during duplication of DNA. UHRF1 recruits DNMT1 to the site and methylates both strands. UHRF1 also binds to HDAC1 and di- and tri-methyl K9 histone H3, ubiquitinates histone H3, and associates with heterochromatin formation, indicating that UHRF1 links histone modifications, DNA methylation, and chromatin structure. UHRF1 is a direct target of E2F1 and promotes G1/S transition. The tumor suppressor p53, which is deficient in 50% of cancers, down-regulates UHRF1 through up-regulation of p21/WAF1 and subsequent deactivation of E2F1. The expression levels of UHRF1 are up-regulated in many cancers, probably partially because of the absence of wild type p53, but it is probably regulated by several other factors. Knockdown of UHRF1 expression in cancer cells suppressed cell growth, suggesting that UHRF1 can be a useful anticancer drug target. Recently, it was revealed that UHRF1 plays important roles not only in carcinogenesis, but also in toxoplasmosis, which is occasionally fatal to people with a weakened immune system, and can cause blindness in the major pathology of ocular toxoplasmosis. Toxoplasma gondii, which causes toxoplasmosis, utilizes UHRF1 to control the cell cycle phase and enhance its proliferation. Thus, knockdown of UHRF1 can be effective at stopping the proliferation of the parasites in infected cells. In this review, we discuss several possible methods that can inhibit the multiple unique functions of UHRF1, which can be utilized for treating cancers and toxoplasmosis.     

A kinetic study of glucagon-like peptide-1 and glucagon-like peptide-2 truncation by dipeptidyl peptidase IV,in vitro

In vivo inactivation of glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) was found to be associated with the proteolytic removal of their N-terminal dipeptide by the ectopeptidase dipeptidyl peptidase IV (DPP IV). Previous studies suggested that the in vivo metabolism of GLP-1 is much faster than that of GLP-2. In this paper, we investigated the in vitro truncation of GLP-2 and GLP-1 by DPP IV. The slower conversion rate observed for GLP-2 compared to GLP-1 was due to an approximately 10-fold reduction in catalytic rate constant. The selectivity of DPP IV for the glucagon-like peptides was compared with data obtained for other natural substrates using the same enzyme source in identical conditions.     

Characterization of organic anion transporting polypeptide 1b2 knockout rats generated by CRISPR/Cas9: a novel model for drug transport and hyperbilirubinemia disease

Organic anion transporting polypeptide 1B1 and 1B3 (OATP1B1/3) as important uptake transporters play a fundamental role in the transportation of exogenous drugs and endogenous substances into cells. Rat OATP1B2, encoded by the Slco1b2 gene, is homologous to human OATP1B1/3. Although OATP1B1/3 is very important, few animal models can be used to study its properties. In this report, we successfully constructed the Slco1b2 knockout (KO) rat model via using the CRISPR/Cas9 technology for the first time. The novel rat model showed the absence of OATP1B2 protein expression, with no off-target effects as well as compensatory regulation of other transporters. Further pharmacokinetic study of pitavastatin, a typical substrate of OATP1B2, confirmed the OATP1B2 function was absent. Since bilirubin and bile acids are the substrates of OATP1B2, the contents of total bilirubin, direct bilirubin, indirect bilirubin, and total bile acids in serum are significantly higher in Slco1b2 KO rats than the data of wild-type rats. These results are consistent with the symptoms caused by the absence of OATP1B1/3 in Rotor syndrome. Therefore, this rat model is not only a powerful tool for the study of OATP1B2-mediated drug transportation, but also a good disease model to study hyperbilirubinemia-related diseases.     

CRISPR-Cas9: A method for establishing rat models of drug metabolism and pharmacokinetics

The 2020 Nobel Prize in Chemistry recognized CRISPR-Cas9, a super-selective and precise gene editing tool. CRISPR-Cas9 has an obvious advantage in editing multiple genes in the same cell, and presents great potential in disease treatment and animal model construction. In recent years, CRISPR-Cas9 has been used to establish a series of rat models of drug metabolism and pharmacokinetics (DMPK), such as Cyp, Abcb1, Oatp1b2 gene knockout rats. These new rat models are not only widely used in the study of drug metabolism, chemical toxicity, and carcinogenicity, but also promote the study of DMPK related mechanism, and further strengthen the relationship between drug metabolism and pharmacology/toxicology. This review systematically introduces the advantages and disadvantages of CRISPR-Cas9, summarizes the methods of establishing DMPK rat models, discusses the main challenges in this field, and proposes strategies to overcome these problems.