Research strategies of small molecules as chemotherapeutics to overcome multiple myeloma resistance.

Multiple myeloma (MM), a cancer of plasma cells, is the second most common hematological malignancy which is characterized by aberrant plasma cells infiltration in the bone marrow and complex heterogeneous cytogenetic abnormalities. Over the past two decades, novel treatment strategies such as proteasome inhibitors, immunomodulators, and monoclonal antibodies have significantly improved the relative survival rate of MM patients. However, the development of drug resistance results in the majority of MM patients suffering from relapse, limited treatment options and uncontrolled disease progression after relapse. There are urgent needs to develop and explore novel MM treatment strategies to overcome drug resistance and improve efficacy. Here, we review the recent small molecule therapeutic strategies for MM, and introduce potential new targets and corresponding modulators in detail. In addition, this paper also summarizes the progress of multi-target inhibitor therapy and protein degradation technology in the treatment of MM.

Discovery of RORγ Allosteric Fluorescent Probes and Their Application: Fluorescence Polarization, Screening, and Bioimaging.

Retinoic acid receptor-related orphan receptor γ (RORγ) acts as a crucial transcription factor in Th17 cells and is involved in diverse autoimmune disorders. RORγ allosteric inhibitors have gained significant research focus as a novel strategy to inhibit RORγ transcriptional activity. Leveraging the high affinity and selectivity of RORγ allosteric inhibitor MRL-871 (1), this study presents the design, synthesis, and characterization of 11 allosteric fluorescent probes. Utilizing the preferred probe 12h, we established an efficient and cost-effective fluorescence polarization-based affinity assay for screening RORγ allosteric binders. By employing virtual screening in conjunction with this assay, 10 novel RORγ allosteric inhibitors were identified. The initial SAR studies focusing on the hit compound G381-0087 are also presented. The encouraging outcomes indicate that probe 12h possesses the potential to function as a powerful tool in facilitating the exploration of RORγ allosteric inhibitors and furthering understanding of RORγ function.

Unraveling the Promise of RET Inhibitors in Precision Cancer Therapy by Targeting RET Mutations.

Over the past decades, the role of rearranged during transfection (RET) alterations in tumorigenesis has been firmly established. RET kinase inhibition is an essential therapeutic target in patients with RET-altered cancers. In clinical practice, initial efficacy can be achieved in patients through the utilization of multikinase inhibitors (MKIs) with RET inhibitory activity. However, the effectiveness of these MKIs is impeded by the adverse events associated with off-target effects. Recently, many RET-selective inhibitors, characterized by heightened specificity and potency, have been developed, representing a substantial breakthrough in the field of RET precision oncology. This Perspective focuses on the contemporary understanding of RET mutations, recent advancements in next-generation RET inhibitors, and the challenges associated with resistance to RET inhibitors. It provides valuable insights for the development of next-generation MKIs and selective RET inhibitors.

Design and synthesis 1H-Pyrrolo[2,3-b]pyridine derivatives as FLT3 inhibitors for the treatment of Acute myeloid Leukemia.

Acute myeloid leukemia (AML) is the most common type of blood cancer and has been strongly correlated with the overexpression of Fms-like tyrosine kinase 3 (FLT3), a member of the class III receptor tyrosine kinase family. With the emergence of FLT3 internal tandem duplication alteration (ITD) and tyrosine kinase domain (TKD) mutations, the development of FLT3 small molecule inhibitors has become an effective medicinal chemistry strategy for AML. Herein, we have designed and synthesized two series of 1H-pyrrolo[2,3-b]pyridine derivatives CM1-CM24, as FLT3 inhibitors based on F14, which we previously reported, that can target the hydrophobic FLT3 back pocket. Among these derivates, CM5 showed significant inhibition of FLT3 and FLT3-ITD, with inhibitory percentages of 57.72 % and 53.77 % respectively at the concentration of 1 µΜ. Furthermore, CM5 demonstrated potent inhibition against FLT3-dependent human AML cell lines MOLM-13 and MV4-11 (both harboring FLT3-ITD mutant), with IC50 values of 0.75 µM and 0.64 µM respectively. In our cellular mechanistic studies, CM5 also effectively induces apoptosis by arresting cell cycle progression in the G0/G1 phase. In addition, the amide and urea linker function were discussed in detail based on computational simulations studies. CM5 will serve as a novel lead compound for further structural modification and development of FLT3 inhibitors specifically targeting AML with FLT3-ITD mutations.

Triptolide Reduces MDA-MB-231 Cell Metastasis by Attenuating Epithelial-Mesenchymal Transition through the ROCK/PTEN/Akt Axis.

Triple-negative breast cancer (TNBC) is a highly heterogeneous and invasive subtype of breast cancer. The prognosis of TNBC is poor because of its high distant metastasis rate. Triptolide is a type of diterpene trioxide natural compound with potential anti-tumor activities. This study explored the metastatic inhibitory effect of triptolide on MDA-MB-231 cells and its underlying mechanism. Triptolide suppressed cell proliferation and induced cell apoptosis in a time- and dose-dependent manner. Low doses of triptolide (0-8 nM) reduced the migration and invasion capabilities of MDA-MB-231 cells. Triptolide decreased ROCK1, p-Akt, N-cadherin, vimentin and MMP-9 expressions, but increased PTEN and E-cadherin expressions on protein and mRNA levels. Furthermore, the down-regulation of ROCK1 expression in MDA-MB-231 cells after being treated by triptolide could be rescued by ROCK1 specific inhibitor Y27632. Molecular docking showed that triptolide and Y27632 shared the same active center of ROCK1 protein. This article's findings taken together showed that ROCK1 is the primary target of triptolide, which can cause cell apoptosis and inhibit the epithelial-mesenchymal transition of MDA-MB-231 cells.

Preclinical characterization of danatinib as a novel FLT3 inhibitor with excellent efficacy against resistant acute myeloid leukemia.

The therapeutic benefits of available FLT3 inhibitors for AML are limited by drug resistance, which is related to mutations, as well toxicity caused by off-target effects. In this study, we introduce a new small molecule FLT3 inhibitor called danatinib, which was designed to overcome the limitations of currently approved agents. Danatinib demonstrated greater potency and selectivity, resulting in cytotoxic activity specific to FLT3-ITD and/or FLT3-TKD mutated models. It also showed a superior kinome inhibition profile compared to several currently approved FLT3 inhibitors. In diverse FLT3-TKD models, danatinib exhibited substantially improved activity at clinically relevant doses, outperforming approved FLT3 inhibitors. In vivo safety evaluations performed on the granulopoiesis of transgenic myeloperoxidase (MPO) zebrafish and mice models proved danatinib to have an acceptable safety profile. Danatinib holds promise as a new and improved FLT3 inhibitor for the treatment of AML, offering long-lasting remissions and improved overall survival rates.

A Universal Cyclodextrin-Based Nanovaccine Platform Delivers Epitope Peptides for Enhanced Antitumor Immunity.

Currently, there is still an intense demand for a simple and scalable delivery platform for peptide-based cancer vaccines. Herein, a cyclodextrin-based polymer nanovaccine platform (CDNP) is designed for the codelivery of peptides with two immune adjuvants [the Toll-like receptor (TLR)7/8 agonist R848 and the TLR9 agonist CpG] that is broadly applicable to epitope peptides with diverse sequences. Specifically, the cyclodextrin-based polymers are covalently linked to epitope peptides via a bioreactive bond-containing cross-linker (PNC-DTDE-PNC) and then physically load with R848 and CpG to obtain CDNP. The CDNP efficiently accumulats in the lymph nodes (LNs), greatly facilitating antigen capture and cross-presentation by antigen-presenting cells. The immunogenicity of the epitope peptides is significantly enhanced by the codelivery and synergy of the adjuvants, and the CDNP shows the ability to inhibit tumor progression in diverse tumor-bearing mouse models. It is concluded that CDNP holds promise as an optimized peptide-based cancer vaccine platform.

Natural products as potential lead compounds to develop new antiviral drugs over the past decade.

Virus infection has been one of the main causes of human death since the ancient times. Even though more and more antiviral drugs have been approved in clinic, long-term use can easily lead to the emergence of drug resistance and side effects. Fortunately, there are many kinds of metabolites which were produced by plants, marine organisms and microorganisms in nature with rich structural skeletons, and they are natural treasure house for people to find antiviral active substances. Aiming at many types of viruses that had caused serious harm to human health in recent years, this review summarizes the natural products with antiviral activity that had been reported for the first time in the past ten years, we also sort out the source, chemical structure and safety indicators in order to provide potential lead compounds for the research and development of new antiviral drugs.

Challenges for the development of mutant isocitrate dehydrogenases 1 inhibitors to treat glioma.

Glioma is one of the most common types of brain tumors, and its high recurrence and mortality rates threaten human health. In 2008, the frequent isocitrate dehydrogenase 1 (IDH1) mutations in glioma were reported, which brought a new strategy in the treatment of this challenging disease. In this perspective, we first discuss the possible gliomagenesis after IDH1 mutations (mIDH1). Subsequently, we systematically investigate the reported mIDH1 inhibitors and present a comparative analysis of the ligand-binding pocket in mIDH1. Additionally, we also discuss the binding features and physicochemical properties of different mIDH1 inhibitors to facilitate the future development of mIDH1 inhibitors. Finally, we discuss the possible selectivity features of mIDH1 inhibitors against WT-IDH1 and IDH2 by combining protein-based and ligand-based information. We hope that this perspective can inspire the development of mIDH1 inhibitors and bring potent mIDH1 inhibitors for the treatment of glioma.

Discovery of 4-(4-aminophenyl)-6-phenylisoxazolo[3,4-b]pyridine-3-amine derivatives as novel FLT3 covalent inhibitors for the intervention of acute myeloid leukemia.

Small molecule covalent drugs have proved to be desirable therapies especially on drug resistance related to point mutations. Secondary mutations of FLT3 have become the main mechanism of FLT3 inhibitors resistance which further causes the failure of treatment. Herein, a series of 4-(4-aminophenyl)-6-phenylisoxazolo[3,4-b]pyridine-3-amine covalent derivatives were synthesized and optimized to overcome the common secondary resistance mutations of FLT3. Among these derivatives, compound F15 displayed potent inhibition activities against FLT3 (IC50 = 123 nM) and FLT3-internal tandem duplication (ITD) by 80% and 26.06%, respectively, at the concentration of 1 µM. Besides, F15 exhibited potent activity against FLT3-dependent human acute myeloid leukemia (AML) cell lines MOLM-13 (IC50 = 253 nM) and MV4-11 (IC50 = 91 nM), as well as BaF3 cells with variety of secondary mutations. Furthermore, cellular mechanism assays indicated that F15 inhibited phosphorylation of FLT3 and its downstream signaling factors. Notably, F15 could be considered for further development as potential drug candidate to treat AML.

Design and synthesis of selective FLT3 inhibitors via exploration of back pocket II.

Aim: The clinical benefits of FLT3 inhibitors against acute myeloid leukemia (AML) have been limited by selectivity and resistance mutations. Thus, to identify FLT3 inhibitors possessing high selectivity and potency is of necessity. Methods & results: The authors used computational methods to systematically compare pocket similarity with 269 kinases. Subsequently, based on these investigations and beginning with in-house compound 10, they synthesized a series of 6-methyl-isoxazol[3,4-b]pyridine-3-amino derivatives and identified that compound 45 (IC50: 103 nM) displayed gratifying potency in human AML cell lines with FLT3-internal tandem duplications mutation as well as FLT3-internal tandem duplications-tyrosine kinase domain-transformed BaF3 cells. Conclusion: The integrated biological activity results indicated that compound 45 deserves further development for therapeutic remedies for AML.

Co-delivery of proanthocyanidin and mitoxantrone induces synergistic immunogenic cell death to potentiate cancer immunotherapy.

Immunological checkpoint inhibitors provide a revolutionary method for cancer treatment. However, due to low tumor mutations and insufficient infiltration of immune cells into the tumor microenvironment, 85% of colorectal cancer patients cannot respond to checkpoint blockade immunotherapy. In this study, tumor microenvironment-responsive deformable nanoparticles (DMP@NPs) were rationally designed to improve immunotherapy by synergistically modulating the immune tumor microenvironment. DMP@NPs self-assemble from a newly synthesized tumor acidity responsive polypeptide checkpoint inhibitor polymer (PEG-DMA-DPPA-1) with immunogenic cell death (ICD) enhanced combination drugs containing a certain proportion of mitoxantrone (MITX) and proanthocyanidins (PC). Upon tumor acidity-triggered cleavage of PEG-DMA-DPPA-1, DMP@NPs undergo special "sphere-ring deformation" dissociation, gradually releasing polypeptide checkpoint inhibitor DPPA-1, MITX and PC. MITX/PC in vitro synergistically triggers higher ICD with the release of the high mobility group box-1 (HMGB-1) and calreticulin (CRT). After intravenous injection of DMP@NPs, the local tumor microenvironment of CT26 tumor-bearing mice was reprogrammed, and dendritic cell activation and T cell infiltration were significantly increased. Most importantly, the synergistic immune nanodrug DMP@NPs improved the efficacy of colorectal cancer immunotherapy and reduced toxicity and side effects for the immune organs.

Synthesis and biological evaluation of 4-(4-aminophenyl)-6-methylisoxazolo[3,4-b] pyridin-3-amine covalent inhibitors as potential agents for the treatment of acute myeloid leukemia.

Fms-like tyrosine kinase 3 (FLT3) mutation has been strongly associated with increased risk of relapse, and the irreversible covalent FLT3 inhibitors had the potential to overcome the drug-resistance. In this study, a series of simplified 4-(4-aminophenyl)-6-methylisoxazolo[3,4-b] pyridin-3-amine derivatives containing two types of Michael acceptors (vinyl sulfonamide, acrylamide) were conveniently synthesized to target FLT3 and its internal tandem duplications (ITD) mutants irreversibly. The kinase inhibitory activities showed that compound C14 displayed potent inhibition activities against FLT3 (IC50 = 256 nM) and FLT3-ITD by 73 % and 25.34 % respectively, at the concentration of 1 µM. The antitumor activities indicated that C14 had strong inhibitory activity against the human acute myeloid leukemia (AML) cell lines MOLM-13 (IC50 = 507 nM) harboring FLT3-ITD mutant, as well as MV4-11 (IC50 = 325 nM) bearing FLT3-ITD mutation. The biochemical analyses showed that these effects were related to the ability of C14 to inhibit FLT3 signal pathways, and C14 could induce apoptosis in MV4-11 cell as demonstrated by flow cytometry. Fortunately, C14 showed very weak potency against FLT3-independent human cervical cancer cell line HL-60 (IC50 > 10 µM), indicating that it might have no off-target toxic effects. In light of these data, compound C14 represents a novel covalent FLT3 kinase inhibitor for targeted therapy of AML.

Inhibitory Effect of Salvia miltiorrhiza Extract and Its Active Components on Cervical Intraepithelial Neoplastic Cells.

The effective treatment of cervical intraepithelial neoplasia (CIN) can prevent cervical cancer. Salvia miltiorrhiza is a medicinal and health-promoting plant. To identify a potential treatment for CIN, the effect of S. miltiorrhiza extract and its active components on immortalized cervical epithelial cells was studied in vitro. The H8 cell was used as a CIN model. We found that S. miltiorrhiza extract effectively inhibited H8 cells through the CCK8 method. An HPLC-MS analysis revealed that S. miltiorrhiza extract contained salvianolic acid H, salvianolic acid A, salvianolic acid B, monomethyl lithospermate, 9‴-methyl lithospermate B, and 9‴-methyl lithospermate B/isomer. Salvianolic acid A had the best inhibitory effect on H8 cells with an IC50 value of 5.74 ± 0.63 µM. We also found that the combination of salvianolic acid A and oxysophoridine had a synergistic inhibitory effect on H8 cells at molar ratios of 4:1, 2:1, 1:1, 1:2, and 1:4, with salvianolic acid A/oxysophoridine = 1:2 having the best synergistic effect. Using Hoechst33342, flow cytometry, and Western blotting analysis, we found that the combination of salvianolic acid A and oxysophoridine can induce programmed apoptosis of H8 cells and block the cell cycle in the G2/M phase, which was correlated with decreased cyclinB1 and CDK1 protein levels. In conclusion, S. miltiorrhiza extract can inhibit the growth of H8 cells, and the combination of salvianolic acid A (its active component) and oxysophoridine has a synergistic inhibitory effect on H8 cells and may be a potential treatment for cervical intraepithelial neoplasia.

Ring finger protein 6 enhances chemo-resistance by transcriptionally activating proliferating cell nuclear antigen expression and attenuating DNA damage in lung adenocarcinoma.

The E3 ubiquitin ligase RING finger protein 6 (RNF6) is elevated in several cancers, including prostate and colorectal cancers. Here, we extended the finding of elevated RNF6 expression levels and its association with poor prognosis in patients with lung adenocarcinoma (LUAD). Genome-wide RNA sequencing in H3255 cells with RNF6 knockdown, followed by analysis of differentially expressed genes using Clusters of Orthologous Groups and gene set enrichment analysis revealed aberrations in genes related to DNA repair, especially double-strand break (DSB) repair. RNF6 knockdown increased γH2AX foci, a biomarker for DSBs in H3255 and A549 LUAD cells, and enhanced DNA damage induced by chemotherapy in cisplatin-resistant A549/CDDP cells. In a series of experiments in cultured cells, as well as in nude mice carrying xenografts, RNF6 knockdown restored the sensitivity of A549/CDDP cells to cisplatin treatment. Mechanistically, RNA sequencing in RNF6-knockdown cells revealed the significant downregulation of proliferating cell nuclear antigen (PCNA), an oncogene that promotes DNA repair. Re-chromatin immunoprecipitation assay results suggested the formation of a RNF6-TCF4 complex that binds to the PCNA promoter to activate its transcription. Downregulation of RNF6 reduced TCF4 recruitment to PCNA promoters in H3255 and A549 cells, indicating that RNF6 regulates PCNA transcription to a certain extent by regulating TCF4 binding to PCNA promoters. The collective results implicate RNF6 overexpression as a molecular target in the management of cisplatin-resistant LUAD.

Mini-patient-derived xenograft assay based on microfluidic technology promises to be an effective tool for screening individualized chemotherapy regimens for advanced non-small cell lung cancer.

Patient-derived xenograft (PDX) assay has been widely used in preclinical research in patients with multidrug-resistant lung cancer. One hundred patients with non-small cell lung cancer (NSCLC) were divided into MiniPDX group and conventional group, with 50 cases in each group. The MiniPDX assay was established by enriching high-purity tumor cells using microfluidic technology to detect the drug sensitivity of NSCLC cells. All patients underwent conventional computed tomography (CT) scans of lung and mediastinum at baseline and during follow-up. Kaplan-Meier method was used to compare the overall survival and progression-free survival of two groups. The sensitivity of the same drug in different tumor xenograft varied greatly. The overall survival, progression-free survival, and clinical benefit rate of patients in the MiniPDX-guided chemotherapy group were significantly longer than those in the conventional chemotherapy group. MiniPDX assay may be an effective tool for screening chemotherapy regimens in NSCLC patients.

Histone 3 lysine-27 demethylase KDM6A coordinates with KMT2B to play an oncogenic role in NSCLC by regulating H3K4me3.

Aberrations in epigenetic modulation dysregulate transcription, playing a critical role in the developmental process of tumors, including lung cancer. Aberrant levels of the histone 3 lysine-27 demethylase KDM6A have been found in cancer and are either positively or negatively associated with tumorigenesis and prognosis. However, the clinical relevance and functional role of KDM6A in lung cancer is largely unknown. We found that KDM6A protein expression was higher in NSCLC tissues than in the corresponding paracancer tissues and that high KDM6A expression was associated with poor patient prognosis. Furthermore, KDM6A knockdown in NSCLC cell lines markedly inhibited the tumorigenic phenotype both in vitro and in vivo. Mechanistically, KDM6A colocalized and cooperated with KMT2B to reprogram the transcriptional network via regulating the cancer pathway, in which abnormal activation of the Wnt pathway is the dominant factor. Interestingly, in NSCLC cell lines, H3K4me3 but not H3K27me2/3 or H3K4me1/2 was markedly altered upon KDM6A or KMT2B knockdown, indicating that KDM6A may act independently of H3K27 demethylases in NSCLC. Taken together, these results indicated that KDM6A or KMT2B may be a prognostic biomarker and promising therapeutic target in NSCLC.

Survival comparison of Three histological subtypes of lung squamous cell carcinoma: A population-based propensity score matching analysis.

OBJECTIVES: This study is aimed to analyze the survival differences among patients with lung basaloid squamous cell carcinoma (BSCC), keratinizing squamous cell carcinoma (KSCC), and nonkeratinizing squamous cell carcinoma (NKSCC), and explore the prognostic factors of patients with lung BSCC. MATERIALS AND METHODS: We searched the information of 4743 patients with lung SCC between 2005 and 2014 from the SEER database. Propensity score matching (PSM) was used to adjust confounding factors. The overall survival (OS), cancer-specific survival (CSS), and cumulative incidence of cancer-specific mortality (CSM) were estimated with a comparative analysis. A competing risks regression model was conducted to identify the prognostic factors of lung BSCC. RESULTS: After PSM, patients with lung BSCC had a higher CSS rate than those with lung KSCC or NKSCC (5-year CSS rate: 50.4 % vs. 37.7 % vs. 38.5 %, p = 0.033 and p = 0.033). The cumulative incidence of CSM was lower for patients with lung BSCC than those with lung KSCC or NKSCC (5-year CSM rate: 46.4 % vs. 56.9 % vs. 56.4 %, p = 0.046 and p = 0.042), which were similar to the results before PSM. As for patients with lung KSCC and NKSCC, there was no survival differences between them (5-year CSS rate: 37.7 % vs. 38.5 %, p = 0.997). The competing risks regression analysis showed that T stage, N stage, M stage and surgery were independent prognostic factors for patients with lung BSCC (all p < 0.05). CONCLUSIONS: Patients with lung BSCC had a better survival than those with lung KSCC or NKSCC, while no survival differences were found between lung KSCC and NKSCC. T stage, N stage, M stage and surgery were independent prognostic factors for patients with lung BSCC.