Cell Cycle Regulation and Melanoma

First-in-class dual inhibitors of MASTL and Aurora A kinase: Discovery of selective cyclohexa[b]thiophenes with potent anticancer activity

The dysregulation of mitotic kinases, particularly Microtubule Associated Serine/Threonine Kinase Like (MASTL) and Aurora A kinase, play pivotal roles in tumor progression and resistance to therapy. Herein, we report cyclohexa[b]thiophenes as first-in-class dual inhibitors of MASTL and Aurora A kinase. The lead compound, MA4, demonstrated potent inhibition of both kinases with IC50 values of 0.16 ± 0.01 μM for Aurora A and 0.56 ± 0.16 μM for MASTL. Kinase selectivity profiling against a panel of 277 kinases revealed a high degree of specificity against both targets. In vitro antiproliferative screening using the NCI-60 human cancer cell line panel revealed broad-spectrum cytotoxicity, with MA4 exhibiting submicromolar GI50 values across multiple malignancies, outperforming previously reported cyclohexa[b]thiophenes in the multidose screening. Mechanistic studies, including microscale thermophoresis (MST) and NanoBRET target engagement assays, confirmed direct binding to both kinases. Computational studies, including molecular docking and molecular dynamics simulations, revealed key interactions stabilizing MA4 within the ATP-binding sites of both kinases. We demonstrated the potent anticancer activity of MA4 in 3D tumor spheroids, along with its favorable pharmacokinetic profile. Additionally, MA4 exhibited no inhibitory activity against hERG and demonstrated selectivity toward cancer cells over normal cell lines, further supporting its potential for in vivo applications. These findings establish cyclohexa[b]thiophenes as promising dual kinase inhibitors with high selectivity, offering a compelling strategy for targeting mitotic dysregulation in cancer therapy.

Transcriptome analysis reveals the mechanism of Rhodiola polysaccharide affecting the proliferation of porcine Leydig cells under hypoxia

Hypoxia can affect the function of the male reproductive system and reduce fertility. Rhodiola polysaccharide (RDP) is the active ingredient of Rhodiola rosea L. and has a positive effect on reproductive cells. However, the mechanism of the effect of RDP on the proliferation of cells under hypoxia is still unclear. The experiment selected porcine Leydig cells (PLCs) as the test object and divided them into three groups: normal group, hypoxia group, and hypoxia + RDP-treated group. Cell viability was detected using CCK8 assay. RNA-Seq technology was used to identify the key genes that influence the effect of RDP on PLCs under hypoxia conditions and to determine their regulatory pathways. Transcriptome sequencing of PLCs from the N and H groups identified 6,794 differentially expressed genes (DEGs), including 3,329 up-regulated genes and 3,465 down-regulated genes. These DEGs were significantly enriched in the cell cycle signaling pathway, indicating that hypoxia mainly affects the cell cycle and inhibits cell proliferation. Furthermore, comparison of the transcriptomes between the H and HR group revealed 285 DEGs, including 137 up-regulated and 148 down-regulated, most of DEGs were found to be enriched in oxidative phosphorylation pathways. RDP inhibits PLCs apoptosis and promotes cell proliferation by up-regulating the expression of CXCL2, JUNB and VCAM1 of the TNF signaling pathway, and VEGFA, SGK2 and SPP1 of the PI3K/AKT signaling pathway. These genes deserve further study as candidate for understanding the role of RDP in alleviating the hypoxia stress.

Oxidative State in Cutaneous Melanoma Progression: A Question of Balance

Reactive oxygen species (ROS) are highly bioactive molecules involved not only in tissue physiology but also in the development of different human conditions, including premature aging, cardiovascular pathologies, neurological and neurodegenerative disorders, inflammatory diseases, and cancer. Among the different human tumors, cutaneous melanoma, the most aggressive and lethal form of skin cancer, is undoubtedly one of the most well-known "ROS-driven tumor", of which one of the main causes is represented by ultraviolet (UV) rays' exposure. Although the role of excessive ROS production in melanoma development in pro-tumorigenic cell fate is now well established, little is known about its contribution to the progression of the melanoma metastatic process. Increasing evidence suggests a dual role of ROS in melanoma progression: excessive ROS production may enhance cellular growth and promote therapeutic resistance, but at the same time, it can also have cytotoxic effects on cancer cells, inducing their apoptosis. In this context, the aim of the present work was to focus on the relationship between cell redox state and the signaling pathways directly involved in the metastatic processes. In addition, oxidative or antioxidant therapeutic strategies for metastatic melanoma were also reviewed and discussed.

Primary oral and sinonasal mucosal melanomas in Latin America: a systematic review

Primary oral and sinonasal mucosal melanomas (POSNMMs) are aggressive neoplasms with limited therapeutic alternatives. The aim of this review was to characterize the demographic, clinical, immunohistochemical, and molecular information regarding these tumors in the Latin American population. Articles published in English, Spanish, or Portuguese (1990-2022) retrieved from the PubMed/MEDLINE, Scopus, CAS, Web of Science, EBSCO, and Google Academic databases were included. Thirty-three studies, with a total of 1212 cases, were identified. Clinicopathological data were available for 870 cases and immunohistochemical and/or molecular information for 342. Nineteen studies (57.6%) reported cases of oral melanoma, three (9.1%) sinonasal melanoma, and 11 (33.3%) oral and sinonasal melanoma. Fifteen studies (45.5%) provided only clinicopathological data, 12 (36.4%) reported only immunohistochemical data, two (6.1%) shared clinicopathological and immunohistochemical data, one (3.0%) offered clinicopathological, immunohistochemical, and molecular data, one (3.0%) provided immunohistochemical and molecular data, one (3.0%) clinicopathological and molecular data, and one (3.0%) only molecular data. The mean age of individuals with POSNMMs was 58 years, and slightly more were male (male 51.3%, female 48.7%). In Latin America, POSNMMs are a rare but aggressive malignancy with a poor prognosis and limited treatment options. Although molecular data and targeted therapy are still being researched, data from Latin America indicate the need for multicenter collaborative clinical trials to unite individual and isolated efforts.

An ATP-binding cassette transporter G2 (CgABCG2) regulates the haemocyte proliferation by modulating the G1/S phase transition of cell cycle in oyster Crassostrea gigas

ATP-binding cassette transporter G2 (ABCG2) is a half-transporter of the G subfamily in ATP-binding cassette transporters (ABC transporter), which is involved in the regulation of multidrug-resistant, cell cycle, and cell proliferation. In the present study, a homologue of ABCG2 (named as CgABCG2) with the conserved AAA domain and ABC2 membrane domain was identified from the Pacific oyster Crassostrea gigas. The open reading frame (ORF) of CgABCG2 was of 1956 bp encoding a predicted polypeptide of 652 amino acids, which shared 56.7%-65.7% sequence similarities with previously identified ABCG2s from other animals. The mRNA transcripts of CgABCG2 were detected in all the tested tissues with higher expression levels in gonad and haemocytes (19.31-fold and 11.23-fold of that in adductor muscle respectively, p < 0.05). CgABCG2 was mainly distributed on the cell membrane of the haemocytes with a partial distribution in the cytoplasm and nucleus. After Vibrio splendidus stimulation, the mRNA expression level of CgABCG2 in haemocytes was significantly up-regulated at 3 h and 6 h, which was 5.22-fold and 8.60-fold (p < 0.05) of that in control, respectively. After the expression of CgABCG2 was interfered by RNAi, the number of cells with EdU positive signals was reduced in both haemocytes and the potential hematopoietic sites. And the mRNA expression level of CgPCNA, CgGATA3, CgRunx, CgSCL and CgC-kit decreased significantly (p < 0.05), which were about 0.66-, 0.37-, 0.32-, 0.50-, and 0.50-fold of that in the negative control group, respectively. While the mRNA expression level of CgCDK2 increased significantly (1.84-fold to that in control, p < 0.05) and that of stem cell-related factor CgSOX2 did not change significantly in the si-CgABCG2 oysters. Moreover, the cell cycle of haemocytes was detected by flow cytometry, which was arrested at G0/G1 phase in the si-CgABCG2 oysters. All the results collectively suggested that CgABCG2 might involve the proliferation of haemocytes by regulating the expression of haematopoiesis related transcription factors and the G1/S phase transition of the cell cycle in oyster C. gigas.

Zanthoxylum bungeanum seed oil inhibits tumorigenesis of human melanoma A375 by regulating CDC25A/CyclinB1/CDK1 signaling pathways in vitro and in vivo

Background:Zanthoxylum bungeanum seed oil (ZBSO) is extracted from the seeds of the traditional Chinese medicine Z. bungeanum Maxim, which has been shown to have anti-melanoma effects. However, the specific mechanisms are not illustrated adequately.

Aims: To further investigate the mechanism by which ZBSO inhibits melanoma and to provide scientific evidence to support ZBSO as a potential melanoma therapeutic candidate.

Methods: CCK-8 assays were used to detect the function of ZBSO on A375 cells. Based on transcriptomics analyses, Western blot analysis was applied to determine whether an association existed in ZBSO with the CDC25A/CyclinB1/CDK1 signaling pathway. In addition, RT-qPCR and immunohistochemistry analysis validated that ZBSO has the anti-melanoma effect in a nude mouse xenograft model of human melanoma. Then, 16S rRNA sequencing was used to detect the regulation of gut microbes.

Results: Cellular assays revealed that ZBSO could inhibit A375 cell viability by regulating the cell cycle pathway. Further studies presented that ZBSO could constrain CDC25A/CyclinB1/CDK1 signaling pathway in vitro and in vivo models of melanoma. ZBSO did not produce toxicity in mice, and significantly reduced tumor volume in xenotransplants of A375 cells. Genome analysis indicated that ZBSO successfully altered specific gut microbes.

Conclusion: ZBSO inhibited the growth of A375 cells by regulating CDC25A/cyclinB1/CDK1 signaling pathway both in vitro and in vivo, suggesting that ZBSO may be a novel potential therapeutic agent.

Sulforaphane-Induced Cell Mitotic Delay and Inhibited Cell Proliferation via Regulating CDK5R1 Upregulation in Breast Cancer Cell Lines

Our research has revealed that sulforaphane (SFN) has chemopreventive properties and could be used in chemotherapy treatments. Further investigation is needed to understand the mechanisms behind sulforaphane's (SFN) antitumor activity in breast adenocarcinoma, as observed in our studies. This research looked into the effects of SFN on mitosis delay and cell cycle progression in MDA-MB-231 and ZR-75-1 cells, two types of triple-negative breast cancer adenocarcinoma.The proliferation of the cancer cells after SFN exposure was evaluated using MTT assay, DNA content and cell cycle arrest induction by flow cytometry, and expressions of cdc25c, CDK1, cyclin B1 and CDK5R1 were assessed through qRT-PCR and Western blot analysis. SFN was found to inhibit the growth of cancer cells. The accumulation of G2/M-phase cells in SFN-treated cells was attributed to CDK5R1. The disruption of the CDC2/cyclin B1 complex suggested that SFN may have antitumor effects on established breast adenocarcinoma cells. Our findings suggest that, in addition to its chemopreventive properties, SFN could be used as an anticancer agent for breast cancer, as it was found to inhibit growth and induce apoptosis of cancer cells.

Antimelanoma effect of manool in 2D cell cultures and reconstructed human skin models

Melanoma is the most aggressive and lethal type of skin cancer, characterized by therapeutic resistance. In this context, the present study aimed to investigate the cytotoxic potential of manool, a diterpene from Salvia officinalis L., in human (A375) and murine (B16F10) melanoma cell lines. The analysis of cytotoxicity using the XTT assay showed the lowest IC₅₀ after 48 h of treatment with the manool, being 17.6 and 18.2 µg/ml for A375 and B16F10, respectively. A selective antiproliferative effect of manool was observed on the A375 cells based on the colony formation assay, showing an IC₅₀ equivalent to 5.6 µg/ml. The manool treatments led to 43.5% inhibition of the A375 cell migration at a concentration of 5.0 µg/ml. However, it did not affect cell migration in the B16F10 cells. Cell cycle analysis revealed that the manool interfered in the cell cycle of the A375 cells, blocking the G2/M phase. No changes in the cell cycle were observed in the B16F10 cells. Interestingly, manool did not induce apoptosis in the A375 cells, but apoptosis was observed after treatment of the B16F10 cells. Additionally, manool showed an antimelanoma effect in a reconstructed human skin model. Furthermore, in silico studies, showed that manool is stabilized in the active sites of the tubulin dimer with comparable energy concerning taxol, indicating that both structures can inhibit the proliferation of cancer cells. Altogether, it is concluded that manool, through the modulation of the cell cycle, presents a selective antiproliferative activity and a potential antimelanoma effect.

Endophytic Fungus of Achyrocline satureioides: Molecular Identification, Chemical Characterization, and Cytotoxic Evaluation of its Metabolites in Human Melanoma cell line

Endophytic fungi are important sources of anticancer compounds. An endophytic fungus was isolated from the medicinal plant Achyrocline satureioides, and molecularly identified as Biscogniauxia sp. (family Xylariaceae) based on partial nucleotide sequences of the internal transcribed spacer genomic region (GenBank Accession No. ON257911). The chemical characterization and cytotoxic properties of secondary metabolites produced by Biscogniauxia sp. were evaluated in a human melanoma cell line (A375). The fungus was grown in potato-dextrose liquid medium for 25 days, and the extracted compounds were subjected to solid-phase fractionation to obtain the purified F_DCM fraction, for which the metabolites were elucidated via ultra-performance chromatography coupled to a mass spectrometer. In the present study, 17 secondary metabolites of Biscogniauxia sp., including nine polyketide derivatives, five terpenoids, and three isocoumarins, were putatively identified. This is the first study to report of the ability of Biscogniauxia sp. in the production of isocoumarin orthosporin; the terpenoids nigriterpene A and 10-xylariterpenoid; the polyketide derivatives daldinin C, 7'dechloro-5'-hydroxygriseofulvin, daldinone D, Sch-642305, curtachalasin A, cytochalasin E, epoxycytochalasins Z8, Z8 isomer, and Z17. Furthermore, this study has reported the biosynthesis of Sch-642305 by a Xylariaceae fungus for the first time. F_DCM significantly reduced the viability and proliferation of human melanoma cells at half-maximal inhibitory concentrations ​​of 10.34 and 6.89 µg/mL, respectively, and induced late apoptosis/necrosis and cell cycle arrest in G2/M phase after 72 h of treatment. Given its ability to produce unique metabolites with promising cytotoxic effects, Biscogniauxia sp. of A. satureioides may be a reservoir of compounds with important therapeutic applications.

EOAI, a ubiquitin-specific peptidase 5 inhibitor, prevents non-small cell lung cancer progression by inducing DNA damage

OBJECTIVE

Targeting deubiquitinases (DUBs) has emerged as a promising avenue for anticancer drug development. However, the effect and mechanism of pan-DUB inhibitor EOAI on non-small cell lung cancer (NSCLC) remains to be studied.

MATERIALS AND METHODS

The expression of ubiquitin-specific peptidase 5 (USP5) in NSCLC was evaluated by immunohistochemistry. The effect of the USP5 inhibitor, EOAI, on NSCLC cell growth and cell cycle was evaluated by CCK-8 and PI staining. Apoptosis was detected by Annexin V-FITC/PI double staining. Autophagy was examined by LC3 immunofluorescence. Comet assay and γ-H2AX immunofluorescence staining were used to detect DNA damage, and Western blotting was used to detect the expression of apoptosis, cycle, autophagy and DNA damage-related proteins. In vivo experiments demonstrated the effect of EOAI on NSCLC.

RESULTS

We also found that USP5 was significantly upregulated in NSCLC tissues in this study. In addition, we show that EOAI can cause DNA damage in NSCLC cells while modulating the transcriptional activity of P53, thereby inducing cell cycle arrest in NSCLC cells, autophagy and apoptosis. In vivo experiments have shown that EOAI can inhibit tumors and synergistically enhance the anti-tumor effect of cisplatin.

CONCLUSION

USP5-mediated epigenetic regulation of oncogenes promotes the occurrence of NSCLC, which provides ideas for developing potential targeted therapy.

Regulators CDCA8 as potential targets and biomarkers for the prognosis of human skin cutaneous melanoma

Cutaneous melanoma (CM) is considered as the most malignant skin tumor with high distant metastasis and poor prognosis. Cell division cycle-associated protein (CDCA) family has a role in regulating cell proliferation and modulating immune cell and tumor cell proliferation in the tumor microenvironment to regulate tumor oncogenesis, development and affect patient outcomes. However, the differential expression pattern and prognostic value of CDCA factors (CDCAs) have not been clarified. In this study, the role of CDCAs in CM was analyzed by using bioinformatics and found that the transcriptional expressions of CDCA1/2/3/5/6/8 were upregulating in CM samples than in normal compares. CM patients with downregulated of CDCA1/3/4/5/6/8 and high transcriptional levels of CDCA7 suggest a significantly better prognosis. Furthermore, the significant correlations among the expression of CDCAs and the infiltration of immune cells. In terms of the protein level, we found CDCA8 was upregulated in CM patients. In conclusion, CDCA8 is a powerful prognostic biomarker for CM and can be a novel target for immunotherapy.

Targeting the USP7/RRM2 axis drives senescence and sensitizes melanoma cells to HDAC/LSD1 inhibitors

Deubiquitinating enzymes are key regulators of the ubiquitin-proteasome system and cell cycle, and their dysfunction leads to tumorigenesis. Our in vivo drop-out screens in patient-derived xenograft models identify USP7 as a regulator of melanoma. We show that USP7 downregulation induces cellular senescence, arresting melanoma growth in vivo and proliferation in vitro in BRAF- and NRAS-mutant melanoma. We provide a comprehensive understanding of targets and networks affected by USP7 depletion by performing a global transcriptomic and proteomics analysis. We show that RRM2 is a USP7 target and is regulated by USP7 during S phase of the cell cycle. Ectopic expression of RRM2 in USP7-depleted cells rescues the senescent phenotype. Pharmacological inhibition of USP7 by P5091 phenocopies the shUSP7-induced senescent phenotype. We show that the bifunctional histone deacetylase (HDAC)/LSD1 inhibitor domatinostat has an additive antitumor effect, eliminating P5091-induced senescent cells, paving the way to a therapeutic combination for individuals with melanoma.

Effect of Titanium Dioxide Nanoparticles on Mammalian Cell Cycle In Vitro: A Systematic Review and Meta-Analysis

Although most studies that explore the cytotoxicity of titanium dioxide nanoparticles (nano-TiO₂) have focused on cell viability and oxidative stress, the cell cycle, a basic process of cell life, can also be affected. However, the results on the effects of nano-TiO₂ on mammalian cell cycle are still inconsistent. A systematic review and meta-analysis were therefore performed in this research based on the effects of nano-TiO₂ on the mammalian cell cycle in vitro to explore whether nano-TiO₂ can induce cell cycle arrest. Meanwhile, the impact of physicochemical properties of nano-TiO₂ on the cell cycle in vitro was investigated, and the response of normal cells and cancer cells was compared. A total of 33 articles met the eligibility criteria after screening. We used Review Manager 5.4 and Stata 15.1 for analysis. The results showed an increased percentage of cells in the sub-G1 phase and an upregulation of the p53 gene after being exposed to nano-TiO₂. Nevertheless, nano-TiO₂ had no effect on cell percentage in other phases of the cell cycle. Furthermore, subgroup analysis revealed that the cell percentage in both the sub-G1 phase of normal cells and S phase of cancer cells were significantly increased under anatase-form nano-TiO₂ treatment. Moreover, nano-TiO₂ with a particle size <25 nm or exposure duration of nano-TiO₂ more than 24 h induced an increased percentage of normal cells in the sub-G1 phase. In addition, the cell cycle of cancer cells was arrested in the S phase no matter if the exposure duration of nano-TiO₂ was more than 24 h or the exposure concentration was over 50 μg/mL. In conclusion, this study demonstrated that nano-TiO₂ disrupted the cell cycle in vitro. The cell cycle arrest induced by nano-TiO₂ varies with cell status and physicochemical properties of nano-TiO₂.

A novel 7‑hypoxia‑related long non‑coding RNA signature associated with prognosis and proliferation in melanoma

Hypoxia‑related long non‑coding RNAs (lncRNAs) are important indicators of the poor prognosis of cancers. The present study aimed to explore the potential relationship between melanoma and hypoxia‑related lncRNAs. The transcriptome and clinical data of patients with melanoma were downloaded from The Cancer Genome Atlas database. The prognostic hypoxia‑related lncRNAs were screened out using Pearson's correlation test and univariate Cox analysis. As a result, a hypoxia‑related‑lncRNA signature based on the expression of 7 lncRNAs was constructed, with one unfavourable [MIR205 host gene (MIR205HG)] and six favourable (T cell receptor β variable 11‑2, HLA‑DQB1 antisense RNA 1, AL365361.1, AC004847.1, ubiquitin specific peptidase 30 antisense RNA 1 and AC022706.1) lncRNAs as prognostic factors for melanoma. Patients with melanoma were divided into high‑ and low‑risk groups based on the risk score obtained. Survival analyses were performed to assess the prognostic value of the present risk model. Potential tumour‑associated biological pathways associated with the present signature were explored using gene set enrichment analysis. The CIBERSORT algorithm demonstrated the important role of the hypoxia‑related lncRNAs in regulating tumour‑infiltrating immune cells. Clinical samples collected from our center partly confirmed our findings. Cell Counting Kit‑8 and flow cytometry assays indicated the suppression of proliferation of melanoma cells following inhibition of MIR205HG expression. Indicators of the canonical Wnt/β‑catenin signalling pathway were detected by western blotting. The present study demonstrated that MIR205HG could promote melanoma cell proliferation partly via the canonical Wnt/β‑catenin signalling pathway. These findings indicated a 7‑hypoxia‑related‑lncRNA signature that can serve as a novel predictor of melanoma prognosis.

Differential Gene Expression and Methylation Analysis of Melanoma in TCGA Database to Further Study the Expression Pattern of KYNU in Melanoma

BACKGROUND

The aim of this study was to analyze and compare melanoma gene expression profiles in TCGA database through the application of different genes to explore the pathogenesis of melanoma. Furthermore, we confirmed the extent of the role of KYNU in melanoma and whether it can be a potential target for the diagnosis and treatment of melanoma.

METHODS

The gene expression profiles of melanoma samples were downloaded from TCGA database, and matrix files were synthesized to screen differential genes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analysis and GCDA broad institute were used to analyze common gene locus mutations and expression changes in melanoma, as well as methylation. In addition, the expression patterns of KYNU in melanoma were quantified by immunohistochemistry, Western blotting, qRT-PCR, software such as GEO DataSets and the Human Protein Atlas, and meta-analysis of skin diseases. KYNU was overexpressed in keratinocytes (HaCaT and HEKα) and melanoma cells (A375 and H1205-lu). CFDA-SE, Annexin V-PI double staining, and PI single staining were used to investigate the mechanism of KYNU in melanoma and its effects on melanoma proliferation, apoptosis, invasion, and migration.

RESULTS

The main signaling pathways involved in melanoma were EGF/EGFR-RAS-BRAF-MEK-ERK-CyclinD1/CDK4, Ras-PI3K-PTEN-PKB/AKT, and p14/p16 (CDKN2A)-MDM2-p53-p21-cyclinD1/CDK4/6-Rb/E2F. Moreover, MITF, KIT, CDH1. NRAS, AKT1, EGFR, TP53, KIT, and CDK4 were elevated in melanoma, whereas PTEN, cAMP, and BCL2 were reduced in melanoma. The copy number of tumor-promoting genes increased, while the copy number of tumor suppressor genes decreased. Changes in the copy number of the above tumor genes enriched in chromosomes were found through SNP gene mutations. The genes whose expression was negatively regulated by DNA methylation in melanoma included KRT18, CDK2, JAK3, BCL2, MITF, MET, CXCL10, EGF, SOX10, SOCS3, and KIT. The mutation rate of KYNU was high according to TCGA database. The KYNU level was decreased in melanoma. Overexpression of KYNU can promote changes in apoptotic BCL-2, metabolic KYN, 3-HAA, invasion and migration MMP9, E-cadherin, and other related proteins in melanoma. Fluorescence staining and flow analysis showed that a slower proliferation rate led to a stronger fluorescence intensity. In melanoma tumor cells with a low expression of KYNU, overexpression of KYNU could promote tumor cell apoptosis. IL-10 induced immunoregulatory changes in melanoma. The expression of MMP9 and AMPK decreased in A375, but the change in BCL-2 was not obvious. The expression of BCL-2 decreased significantly in H1205-lu. A375 showed cell-cycle arrest, indicating that IL-10 could slow down the cell cycle of melanoma.

CONCLUSIONS

These results provide insights into the pathologic mechanisms of melanoma target genes and KYNU as a biomarker and potential therapeutic factor for melanoma.

L-Theanine inhibits melanoma cell growth and migration via regulating expression of the clock gene BMAL1

PURPOSE

L-Theanine is a unique non-protein amino acid found in green tea, which has been identified as a safe dietary supplement. It has been reported that L-theanine exerts various biological activities. In this study, we explored the anti-cancer effects of L-theanine on melanoma cells.

METHODS

A375, B16-F10, and PIG1 cell lines were used in the present study. EdU labeling, TUNEL and Annexin V/PI staining, wound-healing, and transwell migration assay were performed to detect the effects of L-theanine on melanoma cell proliferation, apoptosis, and migration. Brain and muscle Arnt-like protein 1 (BMAL1) was knocked down in melanoma cells to evaluate if L-theanine plays the anti-cancer role through regulating circadian rhythm of melanoma cells. The western blot, qRT-PCR, and dual luciferase assay were performed to explore the mechanism involved in the effects of L-theanine on melanoma cells.

RESULTS

L-Theanine apparently reduced the viability of melanoma cells. Further experiments showed that L-theanine attenuated the proliferation and migration, and promoted apoptosis of melanoma cells. L-Theanine significantly enhanced the expression of BMAL1, a clock gene in melanoma cells. Down-regulation of BMAL1 suppressed the anti-cancer effects of L-theanine on melanoma cells. Further experiments indicated that the p53 transcriptional activity raised by L-theanine was dependent on BMAL1 expression in melanoma cells.

CONCLUSION

L-Theanine exerts the anti-cancer effect on melanoma cells through attenuating the proliferation and migration, and promoting apoptosis of them, which is dependent on the regulation of the clock gene Bmal1 in melanoma cells.

Side effect prediction based on drug-induced gene expression profiles and random forest with iterative feature selection

One in every ten drug candidates fail in clinical trials mainly due to efficacy and safety related issues, despite in-depth preclinical testing. Even some of the approved drugs such as chemotherapeutics are notorious for their side effects that are burdensome on patients. In order to pave the way for new therapeutics with more tolerable side effects, the mechanisms underlying side effects need to be fully elucidated. In this work, we addressed the common side effects of chemotherapeutics, namely alopecia, diarrhea and edema. A strategy based on Random Forest algorithm unveiled an expression signature involving 40 genes that predicted these side effects with an accuracy of 89%. We further characterized the resulting signature and its association with the side effects using functional enrichment analysis and protein-protein interaction networks. This work contributes to the ongoing efforts in drug development for early identification of side effects to use the resources more effectively.

SC66 inhibits the proliferation and induces apoptosis of human bladder cancer cells by targeting the AKT/β-catenin pathway

Bladder cancer (BC) is a major disease of the genitourinary tract, and chemotherapy is one of the main treatments commonly used at present. SC66 is a new type of allosteric AKT inhibitor that is reported to play an effective inhibitory role in the progression of many other types of tumours, but there is no reported research on its role in BC. In this study, we found that SC66 significantly inhibited the proliferation and EMT‐mediated migration and invasion of T24 and 5637 cells. In addition, experiments confirmed that SC66 achieved its antitumour effect by inducing cell apoptosis and affecting the cell cycle. Luciferase assays confirmed that SC66 exerted an antitumour effect through the AKT/β‐catenin signalling pathway, and this inhibitory effect was reversed after the addition of the β‐catenin signalling pathway activator, CHIR‐99021. In addition, animal studies have shown that, compared with the control group, the experimental group with SC66 intraperitoneal injection showed significantly reduced the tumour weight and volume in nude mice with T24 tumours and that SC66 combined with cisplatin achieved better inhibition on tumours. Western blot analysis and immunohistochemistry staining confirmed that SC66 inhibited the EMT process in vivo and induced apoptosis through the AKT/β‐catenin signalling pathway. In conclusion, our study demonstrated that SC66 exerts a significant antitumour effect through the AKT/β‐catenin signalling pathway, thereby providing a new potential treatment for BC.

Ropivacaine Induces Cell Cycle Arrest in the G0/G1 Phase and Apoptosis of PC12 Cells via Inhibiting Mitochondrial STAT3 Translocation

STAT3 has neuroprotective effect via non-canonical activation and mitochondrial translocation, but its effect on ropivacaine-induced neurotoxicity remains unclear. Our previous study revealed that apoptosis was an important mechanism of ropivacaine-induced neurotoxicity; this study is to illustrate the relationship between STAT3 with ropivacaine-induced apoptosis. Those results showed that ropivacaine treatment decreased cell viability, induced cell cycle arrest in the G0/G1 phase, apoptosis, oxidative stress, and mitochondrial dysfunction in PC12 cells. Moreover, ropivacaine decreased the phosphorylated levels of STAT3 at Ser727 and downregulated the expression of STAT3 upstream gene IL-6. The mitochondrial translocation of STAT3 was also hindered by ropivacaine. To further illustrate the connection of STAT3 protein structure with ropivacaine, the autodock-vina was used to examine the interaction between STAT3 and ropivacaine, and the results showed that ropivacaine could bind to STAT3's proline site and other sites. In addition, the activator and inhibitor of mitoSTAT3 translocation were used to demonstrate it was involved in ropivacaine-induced apoptosis; the results showed that enhancing the mitochondrial STAT3 translocation could prevent ropivacaine-induced apoptosis. Finally, the expression of p-STAT3 and the levels of apoptosis in the spinal cord were also detected; the results were consistent with the cell experiment; ropivacaine decreased the expression of p-STAT3 protein and increased the levels of apoptosis in the spinal cord. We demonstrated that ropivacaine induced apoptosis by inhibiting the phosphorylation of STAT3 at Ser727 and the mitochondrial STAT3 translocation. This effect was reversed by the activation of the mitochondrial STAT3 translocation.

Phase I-II Open-Label Multicenter Study of Palbociclib + Vemurafenib in BRAF V600MUT Metastatic Melanoma Patients: Uncovering CHEK2 as a Major Response Mechanism

PURPOSE

In BRAF ^V600MUT metastatic melanoma, cyclin D-CDK4/6-INK4-Rb pathway alterations are involved in resistance to MAPK inhibitors, suggesting a clinical benefit of cyclin-dependent kinase 4 (CDK4) inhibitors. In this phase I-II study, we aimed to establish the MTD of palbociclib when added to vemurafenib.

PATIENTS AND METHODS

Patients with BRAF ^V600E/KMUT metastatic melanoma harboring CDKN2A loss and RB1 expression were included and stratified into two groups according to previous BRAF inhibitor treatment (no:strata 1; yes:strata 2). Treatment comprised palbociclib once daily for 14 days followed by a 7-day break + continuous dosing of vemurafenib. The primary endpoint was the occurrence of dose-limiting toxicity (DLT), and the secondary endpoints included the best response, survival, pharmacokinetics, and tumor molecular profiling.

RESULTS

Eighteen patients were enrolled, with 15 in strata 2. Characteristics at inclusion were American Joint Committee on Cancer stage IVM1c (N = 16; 88.9%), high lactate dehydrogenase (N = 9; 50.0%), and median number of previous treatments of 2. One and 5 patients experienced DLT in strata 1 and 2, respectively, defining the MTD at palbociclib 25 mg and vemurafenib 960 mg in strata 2. No significant evidence for drug-drug interactions was highlighted. The median progression-free survival was 2.8 months, and 5 (27.8%) patients showed a clinical response. The baseline differential mRNA expression analysis and in vitro data revealed the role of CHEK2 in the response to palbociclib.

CONCLUSIONS

Although the combination of palbociclib + fixed-dose vemurafenib did not allow an increased palbociclib dosage above 25 mg, a significant clinical benefit was achieved in pretreated patients with melanoma. An association between the transcriptomic data and clinical response was highlighted.

BRAF Gene and Melanoma: Back to the Future

As widely acknowledged, 40-50% of all melanoma patients harbour an activating BRAF mutation (mostly BRAF V600E). The identification of the RAS-RAF-MEK-ERK (MAP kinase) signalling pathway and its targeting has represented a valuable milestone for the advanced and, more recently, for the completely resected stage III and IV melanoma therapy management. However, despite progress in BRAF-mutant melanoma treatment, the two different approaches approved so far for metastatic disease, immunotherapy and BRAF+MEK inhibitors, allow a 5-year survival of no more than 60%, and most patients relapse during treatment due to acquired mechanisms of resistance. Deep insight into BRAF gene biology is fundamental to describe the acquired resistance mechanisms (primary and secondary) and to understand the molecular pathways that are now being investigated in preclinical and clinical studies with the aim of improving outcomes in BRAF-mutant patients.

Cryptotanshinone Attenuates Ischemia/Reperfusion-induced Apoptosis in Myocardium by Upregulating MAPK3

ABSTRACT

Chinese people have used the root of Salvia miltiorrhiza Bunge (called "Danshen" in Chinese) for centuries as an anticancer agent, anti-inflammatory agent, antioxidant, and cardiovascular disease drug. In addition, Danshen is considered to be a drug that can improve ischemia/reperfusion (I/R)-induced myocardium injury in traditional Chinese medicine. However, Danshen is a mixture that includes various bioactive substances. In this study, we aimed to identify the protective component and mechanism of Danshen on myocardium through network pharmacology and molecular simulation methods. First, cryptotanshinone (CTS) was identified as a potential active compound from Danshen that was associated with apoptosis by a network pharmacology approach. Subsequently, biological experiments validated that CTS inhibited ischemia/reperfusion-induced cardiomyocyte apoptosis in vivo and in vitro. Molecular docking techniques were used to screen key target information. Based on the simulative results, MAPKs were verified as well-connected molecules of CTS. Western blotting assays also demonstrated that CTS could enhance MAPK expression. Furthermore, we demonstrated that inhibition of the MAPK pathway reversed the CTS-mediated effect on cardiomyocyte apoptosis. Altogether, our work screened out CTS from Danshen and demonstrated that it protected cardiomyocytes from apoptosis.

Advances in cyclin-dependent kinase inhibitors for the treatment of melanoma

Introduction: Despite the recent advances in the treatment of malignant melanoma with immunotherapy and BRAF/MEK targeted agents, advanced disease still beholds a poor prognosis for a significant proportion of patients. Cyclin-dependent kinase (CDK) inhibitors have been investigated as novel melanoma therapeutics throughout a range of phase 1 and 2 trials, as single agents and in combination with established treatments. Areas covered: This article summarizes the rationale for, and development of CDK inhibitors in melanoma, with their evolution from pan-CDK inhibitors to highly specific agents, throughout clinical trials and finally their potential future use. Expert opinion: Whilst CDK inhibitors have been practice changing in breast cancer management, their efficacy is yet to be proven in melanoma. Combination with BRAF/MEK inhibitors has been hindered by dose-limiting toxicities, but their role may yet to be found within the spectrum of biomarker-derived personalized melanoma management. The effect that CDK inhibitors can have as an adjunct to immunotherapy also remains to be seen.

Targeted therapies in melanoma beyond BRAF: targeting NRAS-mutated and KIT-mutated melanoma

PURPOSE OF REVIEW

Melanoma treatment have been revolutionized since 2010 by the development of immune checkpoint inhibitors, and, for BRAF-mutated melanoma, targeted therapies based on BRAF and MEK inhibitors, which is a model of effective targeted therapy in cancer. However, patients with BRAF wild type cannot benefit for such treatments. In this review, we will focus on the current clinical development of targeted therapies beyond BRAF, in NRAS-mutated and KIT-altered melanoma.

RECENT FINDINGS

In NRAS-mutated melanoma, targeted therapies based on MEK inhibition are being developed as monotherapy or in combination with MAPK, PI3K or CDK4/6 inhibitor. Targeted therapies of KIT-altered melanoma patients is based in KIT inhibitor (mostly imatinib, nilotinib), although for both melanoma subtypes, results are for now disappointing as compared with BRAF and MEK inhibitors in BRAF-mutated melanoma.

SUMMARY

Combined therapeutic targeted strategies are awaited in NRAS-mutated and KIT-altered melanoma and could provide additional benefit.

Paeonol exerts anti‑tumor activity against colorectal cancer cells by inducing G0/G1 phase arrest and cell apoptosis via inhibiting the Wnt/β‑catenin signaling pathway

Paeonol is a simple phenolic compound isolated from herbal root bark, which has been reported to possess numerous biological and pharmacological characteristics, including a desirable anti‑tumor effect. To date, the effect of paeonol against colorectal cancer (CRC) cells is yet to be fully elucidated. Therefore, the present study aimed to identify the underlying mechanism via which paeonol exerts its anti‑tumor activity on HCT116 cells. After incubation with various concentrations of paeonol (7.8125, 15.625, 31.25, 62.5, 125, 250 and 500 µg/ml), the inhibitory effect of paeonol on cell viability was assessed using a Cell Counting Kit‑8 assay. Cell apoptosis and cell cycle distribution were measured using flow cytometry. Moreover, caspase activity was measured using a colorimetric caspase assay. Luciferase assay was also used to determine the β‑catenin‑mediated transcriptional activity of T‑cell specific transcription factor/lymphoid‑enhancer binding factor (TCF/LEF), and western blotting analysis was performed to measure the related expression of proteins. The results indicated that paeonol exhibited a notable effect against HCT116 cells by inducing G0/G1‑phase arrest, as demonstrated by downregulation of the cell cycle regulators cyclin‑dependent kinase 4 and cyclin D1 and upregulation of p21Cip1 in a dose‑dependent manner. Furthermore, paeonol dose‑dependently induced cell apoptosis, accompanied by an increase in the Bax/Bcl‑2 ratio, release of cytochrome c and further activation of caspases. Paeonol also dose‑dependently blocked the activation of the Wnt/β‑catenin signaling pathway by suppressing the expression of β‑catenin, resulting in a decrease in β‑catenin‑mediated activity of TCF/LEF and downregulation of downstream target genes, including cyclin D1, survivin and c‑Myc. Therefore, the present results suggested that paeonol exerted its anti‑tumor effects on CRC cells, including the inhibition of cell proliferation, induction of cell cycle arrest and initiation of apoptosis, at least partly by suppressing the Wnt/β‑catenin pathway, which may offer a promising therapeutic strategy for CRC.

Anticancer activities of phytoconstituents and their liposomal targeting strategies against tumor cells and the microenvironment

Various bioactive ingredients have been extracted from Chinese herbal medicines (CHMs) that affect tumor progression and metastasis. To further understand the mechanisms of CHMs in cancer therapy, this article summarizes the effects of five categories of CHMs and their active ingredients on tumor cells and the tumor microenvironment. Despite their treatment potential, the undesirable physicochemical properties (poor permeability, instability, high hydrophilicity or hydrophobicity, toxicity) and unwanted pharmacokinetic profiles (short half-life in blood and low bioavailability) restrict clinical studies of CHMs. Therefore, development of liposomes through relevant surface modifying techniques to achieve targeted CHM delivery for cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature, have been reviewed. Current challenges of liposomal targeting of these phytoconstituents and future perspective of CHM applications are discussed to provide an informative reference for interested readers.

SHARPIN regulates cell proliferation of cutaneous basal cell carcinoma via inactivation of the transcriptional factors GLI2 and c‑JUN

SHANK‑associated RH domain‑interacting protein (SHARPIN) is a component of the linear ubiquitin chain assembly complex that can enhance the NF‑κB and JNK signaling pathways, acting as a tumor‑associated protein in a variety of cancer types. The present study investigated the role of SHARPIN in cutaneous basal cell carcinoma (BCC). Human BCC (n=26) and normal skin (n=5) tissues, and BCC (TE354.T) and normal skin (HaCaT) cell lines were used to evaluate SHARPIN expression level using immunohistochemistry and western blotting, respectively. A lentivirus carrying SHARPIN‑targeting or negative control short hairpin RNA was infected into TE354.T cells, and the infected stable cells were assayed to analyze tumor cell proliferation, cell cycle, apoptosis, migration and invasion by Cell Counting Kit‑8 and 5‑ethynyl‑2'‑deoxyuridine incorporation assays, flow cytometry and Transwell assays. Western blotting was performed to assess the protein expression levels of gene signaling in SHARPIN‑silenced BCC cells. SHARPIN protein expression levels were downregulated or absent in BCC cancer nests and precancerous lesions compared with normal skin samples. In addition, SHARPIN expression levels were lower in TE354.T cells compared with HaCaT cells. SHARPIN shRNA enhanced tumor cell proliferation and the S phase of the cell cycle, whereas BCC cell apoptotic rates, and migratory and invasive abilities were not significantly altered. The expression levels of cyclin D1, cyclin‑dependent kinase 4, phosphorylated‑c‑JUN and GLI family zinc finger 2 proteins were increased, whereas Patched 1 (PTCH1) and PTCH2 were decreased in the SHARPIN‑shRNA‑infected BCC cells. Therefore, the present results suggested that SHARPIN may act as a tumor suppressor during BCC development.

Knockdown of STIM1 expression inhibits non-small-cell lung cancer cell proliferation in vitro and in nude mouse xenografts

Stromal interaction molecule 1 (STIM1) is a calcium-sensing protein localized in the membrane of the endoplasmic reticulum. The expression of STIM1 has been shown to be closely associated with cell proliferation. The aim of the present study was to investigate the role of STIM1 in the regulation of cancer progression and its clinical relevance. The data demonstrated that the expression of the STIM1 was significantly higher in non-small-cell lung cancer (NSCLC) tissues than in benign lesions and was associated with advanced NSCLC T stage. Knockdown of STIM1 expression in NSCLC cell lines A549 and SK-MES-1 significantly inhibited cell proliferation and induces A549 and SK-MES-1 cell arrest at the G2/M and S phases of the cell cycle. Western blotting showed that the expression of cyclin-dependent kinase (CDK) 1 and CDK2 were reduced while knockdown of STIM1 expression. Furthermore, knockdown of STIM1 in NSCLC cells significantly reduced the levels of xenograft tumor growth in nude mice. These data indicate that aberrant expression of the STIM1 protein may contribute to NSCLC progression. Future studies should focus on targeting STIM1 as a novel strategy for NSCLC therapy.

A Novel Probe for Spliceosomal Proteins that Induces Autophagy and Death of Melanoma Cells Reveals New Targets for Melanoma Drug Discovery

Background/Aims:

Despite recent advances in melanoma drug discovery, the average overall survival of patients with late stage metastatic melanoma is approximately 3 years, suggesting a need for approaches that identify new melanoma targets. We have previously reported a discovery of novel anti-melanoma compound 2155–14 (Onwuha-Ekpete et al., J Med Chem. 2014 Feb 27; 57(4):1599–608). In the report presented herein we aim to identify its target(s) and mechanism of action.

Methods:

We utilized biotinylated analog of 2155–14 to pull down its targets from melanoma cells. Proteomics in combination with western blot were used to identify the targets. Mechanism of action of 2155–14 was determined using flow cytometry, RT-PCR, microscopy, western blot, and enzymatic activity assays. Where applicable, one-way analysis of variance (ANOVA) was used followed by Dunnett post hoc test.

Results:

In the present study, we identified ATP-dependent RNA helicase DDX1 and heterogeneous nuclear ribonucleoproteins (hnRNPs) H1, H2 and A2/B1 as targets of anti-melanoma compound 2155–14. To the best of our knowledge, this is a first report suggesting that these proteins could be targeted for melanoma therapy. Mechanistic investigations showed that 2155–14 induces ER stress leading to potentiation of basal autophagy resulting in melanoma cell death in BRAF and NRAS mutated melanoma cells.

Conclusion:

Identification of mode of action of 2155–14 may provide insight into novel therapies against a broad range of melanoma subtypes. These studies were enabled by the novel probe derived from a mixture-based library, an important class of chemical biology tools for discovering novel targets.

Lycorine exerts antitumor activity against osteosarcoma cells in vitro and in vivo xenograft model through the JAK2/STAT3 pathway

Background: Lycorine, a natural alkaloid, has been indicated to have various physiological effects, including a potential effect against cancer. However, the anticancer effect of lycorine on osteosarcoma (OS) and the detailed molecular mechanisms involved remain unclear.

Purpose: The purpose of this study was to examine the effect of lycorine on human OS and elucidated it underlying mechanisms

Materials and methods: In vitro assays, OS cells were treated with lycorine at various concentrations. Then the cell proliferation, colony formation, cell cycle distribution, apoptosis, migration and invasion were assayed to detect the anticancer effect of lycorine on OS cell lines. Western blotting analysis was used to verify the expression of related proteins. In addition, the mouse xenograft model was performed to evaluate lycorine’s therapeutic potential on OS in vivo.

Results: The in vitro results demonstrated that lycorine induced apoptosis and cell cycle arrest and suppressed the migration and invasion by suppressing constitutive signal transducers and activators of transcription 3 (STAT3) activation through enhancing the expression of SH2 domain-containing phosphatase 1 (SHP-1) and downregulating the expression of STAT3 target proteins. Moreover, our mouse xenograft model revealed that lycorine inhibited the tumor growth in vivo.

Conclusion: These results demonstrated that the anti-OS effects of lycorine were at least partly due to the suppression of the Janus kinase 2/signal transducers and activators of transcription 3 (JAK2)/STAT3 pathway. Taken together, these results indicate that lycorine possesses the potential to be a promising candidate in clinical therapy for human OS in the future.

Loss of miR-155 upregulates WEE1 in metastatic melanoma

Significant advances have been made in the treatment of melanoma by targeting key cellular pathways, but additional targets are needed as many patients do not respond or relapse with resistant disease. MicroRNA-155 (MiR-155) has previously been shown to regulate melanoma cell growth and acts as a tumor suppressor. We tested a clinical population of melanoma tumors for miR-155 expression, and find that expression is low in most patients, although not predictive of outcome. We identified the protein kinase WEE1 as a novel target of miR-155. A mouse model of experimental metastasis finds that both increased expression of miR-155 and silencing of WEE1 lead to decreased metastases. Loss of miR-155 and increased expression of WEE1 may contribute to the metastatic phenotype in patients with melanoma.

8:2 fluorotelomer alcohol inhibited proliferation and disturbed the expression of pro-inflammatory cytokines and antigen-presenting genes in murine macrophages

Fluorotelomer alcohols (FTOHs, F(CF₂)_nCH₂CH₂OH) are members of per- and polyfluoroalkyl substances (PFASs) and are increasingly used in surfactant and polymer industries. FTOHs pose hepatotoxicity, nephrotoxicity and endocrine-disrupting risks. Nevertheless, there is limited research on the immunotoxic effects of FTOHs. In this study, we examined the immunotoxicity of 8:2 FTOH (n = 8) on murine macrophage cell line RAW 264.7. The results showed that 8:2 FTOH exposure reduced cell viability in dose- and time-dependent manners, inhibited cell proliferation and caused cell cycle arrest. Exposure to 8:2 FTOH downregulated the mRNA expression of some cell cycle-related genes, including Cdk4, Ccnd1, Ccne1, and p53, but also upregulated the mRNA expression of other cell cycle related genes, including Ccna2, p21, and p27. Additionally, exposure to 8:2 FTOH under unstimulated and LPS-stimulated conditions downregulated the mRNA expression of pro-inflammatory genes, including Il1b, Il6, Cxcl1, and Tnfa, and secreted levels of IL-6 and TNF-α. Treatment with 8:2 FTOH upregulated the mRNA expression of antigen-presenting-related genes, including H2-K1, H2-Ka, Cd80, and Cd86. The abovementioned immunotoxic effects caused by 8:2 FTOH in RAW 264.7 cells were partially or completely blocked by co-treatment with hydralazine hydrochloride (Hyd), a reactive carbonyl species (RCS) scavenger. However, exposure to 8:2 FTOH did not exhibit any effects on intracellular reactive oxygen species (ROS) level with or without LPS stimulation. Taken together, these results suggest that 8:2 FTOH may have immunotoxic effects on macrophages and RCS may underlie the responsible mechanism. The present study aids in understanding the health risks caused by FTOHs.

Kinase inhibitor library screening identifies synergistic drug combinations effective in sensitive and resistant melanoma cells

Background

Melanoma is the most aggressive and deadly form of skin cancer with increasing case numbers worldwide. The development of inhibitors targeting mutated BRAF (found in around 60% of melanoma patients) has markedly improved overall survival of patients with late-stage tumors, even more so when combined with MEK inhibitors targeting the same signaling pathway. However, invariably patients become resistant to this targeted therapy resulting in rapid progression with treatment-refractory disease. The purpose of this study was the identification of new kinase inhibitors that do not lead to the development of resistance in combination with BRAF inhibitors (BRAFi), or that could be of clinical benefit as a 2nd line treatment for late-stage melanoma patients that have already developed resistance.

Methods

We have screened a 274-compound kinase inhibitor library in 3 BRAF mutant melanoma cell lines (each one sensitive or made resistant to 2 distinct BRAFi). The screening results were validated by dose-response studies and confirmed the killing efficacies of many kinase inhibitors. Two different tools were applied to investigate and quantify potential synergistic effects of drug combinations: the Chou-Talalay method and the Synergyfinder application. In order to exclude that resistance to the new treatments might occur at later time points, synergistic combinations were administered to fluorescently labelled parental and resistant cells over a period of > 10 weeks.

Results

Eight inhibitors targeting Wee1, Checkpoint kinase 1/2, Aurora kinase, MEK, Polo-like kinase, PI3K and Focal adhesion kinase killed melanoma cells synergistically when combined with a BRAFi. Additionally, combination of a Wee1 and Chk inhibitor showed synergistic killing effects not only on sensitive cell lines, but also on intrinsically BRAFi- and treatment induced-resistant melanoma cells. First in vivo studies confirmed these observations. Interestingly, continuous treatment with several of these drugs, alone or in combination, did not lead to emergence of resistance.

Conclusions

Here, we have identified new, previously unexplored (in the framework of BRAFi resistance) inhibitors that have an effect not only on sensitive but also on BRAFi-resistant cells. These promising combinations together with the new immunotherapies could be an important step towards improved 1st and 2nd line treatments for late-stage melanoma patients.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1038-x) contains supplementary material, which is available to authorized users.

Cumingianoside A, a Phyto-Triterpenoid Saponin Inhibits Acquired BRAF Inhibitor Resistant Melanoma Growth via Programmed Cell Death

Mutated proto-oncogene BRAF is a bona fide therapeutic target for melanomas. Regrettably, melanoma acquires resistance to BRAF inhibitors, e.g., vemurafenib (PLX4032) casting doubt on this promising melanoma targeted therapy. In this study, we explored the bioactivity of triterpenoid saponin cumingianoside A (CUMA), isolated from leaves and twigs of Dysoxylum cumingianum against PLX4032-resistant BRAF^{V 600E} mutant melanoma A375-R in vitro and in vivo. Our data show that CUMA treatment inhibited A375-R melanoma cell proliferation in a time- and dose-dependent manner. CUMA also suppressed the activity of CDK1/cyclin B1 complex and led to G₂/M-phase arrest of A375-R cells. Furthermore, CUMA treatment resulted in induction of apoptosis as shown by the increased activation of caspase 3 and caspase 7, and the proteolytic cleavage of poly(ADP-ribose) polymerase (PARP). We also observed that CUMA induced autophagy-like activity in A375-R cells, as shown by the increased expression of autophagy-related genes and increased formation of autophagosomes. Moreover, we found that CUMA treatment induced ER stress response and co-treatment with an ER stress inhibitor (4-PBA) could attenuate apoptosis induced by CUMA. Importantly, orally administered CUMA as a single agent or in combination with PLX4032 exhibited strong tumor growth inhibition in a PLX4032-resistant A375-R xenograft mouse model, and with little toxicity. This is the first report to explore the anti-tumor activity of CUMA in vitro and in vivo mechanistically, and our results imply that this triterpenoid saponin may be suitable for development into an anti-melanoma agent.

Heme oxygenase 1 facilitates cell proliferation via the B-Raf-ERK signaling pathway in melanoma

BACKGROUND

Despite therapeutic advancements (e.g. B-RAF inhibitors) targeting cutaneous melanoma, many cellular processes, including inducible heme oxygenase 1 (HO-1), counteract treatments for malignancies. So there is an urgent need to find biological treatment targets, develop new therapeutic approaches and achieve longer responses. This study aimed to explore the relationship of HO-1 and B-Raf via mediating ERK1/2 signaling on cell cycle in melanoma.

METHODS

Immunohistochemistry was applied to evaluate the levels of HO-1 and B-Raf expression in melanoma tissues and adjacent healthy tissues. Co-immunoprecipitation (Co-IP) assessed the interaction of HO-1 with B-Raf. Further study overexpression and knock-down of HO-1 in A375 cell lines, especially knockout HO-1 using CRISPR-Cas9, verified HO-1 regulate cell proliferation in vivo and in vitro. Finally, Western blot analysis and qRT-PCR were performed to investigate the mechanisms by which HO-1 mediates cell cycle by B-RAF-ERK1/2 signaling.

RESULTS

First, histology and Co-IP show that HO-1 interacts with B-Raf directly in melanoma tissue. Further study illustrated that HO-1 overexpression promotes melanoma cell proliferation while HO-1 reduction represses melanoma cell proliferation because of HO-1 affects cell cycle. Mechanistic studies revealed that HO-1 was associated with a marked activation of B-RAF-ERK1/2 signaling and led to CDK2/cyclin E activation, thereby promoting melanoma proliferation.

CONCLUSIONS

Our result reveals a previously unknown mechanism that the HO-1-B-RAF-ERK axis plays an important role in melanoma cell proliferation. Therapeutic target on HO-1 could be a novel method for treating melanoma.

S5, a Withanolide Isolated from Physalis Pubescens L., Induces G2/M Cell Cycle Arrest via the EGFR/P38 Pathway in Human Melanoma A375 Cells

S5 is a withanolide natural product isolated from Physalis pubescens L. Our previous experimental studies found that it has significant antitumor activity on renal cell carcinoma. In the present study, the anti-melanoma effect of S5 and the related molecular mechanism was first investigated. It was found that S5 induced an obvious growth inhibitory effect on human melanoma A375 cells with low toxicity to human peripheral blood cells. Furthermore, the results demonstrated that the cell death mode of S5 on A375 cells is not due to inducing apoptosis and autophagy. However, there was a significant time-dependent increase in G2/M phase after treatment of A375 with S5. Meanwhile, S5 could also decrease the protein expression of Cdc25c, Cdc2, and CyclinB1, and increased the expression of p-P53 and P21, suggesting that S5 inhibited A375 cell death through G2/M phase arrest. Moreover, the signal pathway factors P38, extracellular regulated protein kinases (ERK), and epidermal growth factor receptor (EGFR) were observed taking part in the S5-induced A375 cells growth inhibitory effect. In addition, suppressing P38 and EGFR reversed the cell proliferation inhibitory effect and G2/M cell cycle arrest induced by S5 and inhibition of EGFR enhanced the downregulation of the expression of P38 and p-P38, indicating that S5 induced A375 G2/M arrest through the EGFR/P38 pathway. Briefly, this study explained for the first time the mechanism of S5-induced A375 cell growth inhibition in order to provide the basis for its clinical application in melanoma.

The Effects of Autophagy and PI3K/AKT/m-TOR Signaling Pathway on the Cell-Cycle Arrest of Rats Primary Sertoli Cells Induced by Zearalenone

A high concentration of Zearalenone (ZEA) will perturb the differentiation of germ cells, and induce a death of germ cells, but the toxic mechanism and molecular mechanism remain unclear. The Sertoli cells (SCs) play an irreplaceable role in spermatogenesis. In order to explore the potential mechanism of ZEA male reproductive toxicity, we studied the effects of ZEA on cell proliferation, cell-cycle distribution, cell-cycle-related proteins and autophagy-related pathway the PI3K/Akt/mTOR signaling in primary cultured rats SCs, and the effects of autophagy and PI3K/AKT/m TOR signaling pathway on the SCs cell-cycle arrest induced by ZEA treated with the autophagy promoter RAPA, autophagy inhibitor CQ, and the PI3K inhibitor LY294002, respectively. The data revealed that ZEA could inhibit the proliferation of SCs by arresting the cell cycle in the G2/M phase and trigger the autophagy via inhibiting the PI3K/Akt/m TOR signaling pathway. Promoting or inhibiting the level of autophagy could either augment or reverse the arrest of cell cycle. And it was regulated by PI3K/Akt/m TOR signaling pathway. Taken together, this study provides evidence that autophagy and PI3K/Akt/m TOR signaling pathway are involved in regulating rats primary SCs cell-cycle arrest due to ZEA in vitro. To some extent, ZEA-induced autophagy plays a protective role in this process.

Effects of purified Omphalia lapidescens protein on metastasis, cell cycle, apoptosis and the JAK-STAT signaling pathway in SGC-7901 human gastric cells

Gastric cancer is one of the most common cancers globally with high rates of morbidity and mortality. Purified Omphalia lapidescens protein (pPeOp) is a protein extracted from the sclerotium of Omphalia lapidescens. The present study aimed to investigate the effects of pPeOp on the viability, migration, cell cycle progression and apoptosis of SGC-7901 cells. The expression of numerous proteins, namely matrix metallopeptidase (MMP)2, MMP9, p53, caspase-3, B-cell lymphoma (Bcl)-2, cyclin A2, cyclin B1, cyclin D1, cyclin dependent kinase (CDK)1, CDK2 and CDK4, were investigated using western blot analysis and reverse transcription-quantitative polymerase chain reaction. The results of the present study demonstrated that treating SGC-7901 cells with pPeOp markedly suppressed their migration, induced their apoptosis and arrested their progression in S phase. pPeOp also downregulated the expression of migration-associated proteins (MMP2 and MMP9) and cyclin-associated proteins (cyclin A2, cyclin B1, cyclin D1, CDK1, CDK2 and CDK4) in a dose-dependent manner. Cells treated with pPeOp significantly upregulated caspase-3 and p53 and downregulated Bcl-2. Finally, the impact of pPeOp on three key nodes of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway were investigated and it was revealed that expression levels of JAK1, JAK2 and STAT3 were significantly downregulated following treatment. Together, the results of the present study suggested that pPeOp suppresses metastasis, arrests cell cycle, induces apoptosis and inhibits the JAK-STAT signaling pathway in SGC-7901 cells. Therefore, pPeOp may serve as a novel therapeutic agent for patients with gastric cancer.

Treatment of melanoma with selected inhibitors of signaling kinases effectively reduces proliferation and induces expression of cell cycle inhibitors

Cancer treatment often tends to involve direct targeting enzymes essential for the growth and proliferation of cancer cells. The aim of this study was the recognition of the possible role of selected protein kinases: PI3K, ERK1/2, and mTOR in cell proliferation and cell cycle in malignant melanoma. We investigated the role of protein kinase inhibitors: U0126 (ERK1/2), LY294002 (PI3K), rapamycin (mTOR), everolimus (mTOR), GDC-0879 (B-RAF), and CHIR-99021 (GSK3beta) in cell proliferation and expression of crucial regulatory cell cycle proteins in human melanoma cells: WM793 (VGP) and Lu1205 (metastatic). They were used either individually or in various combinations. The study on the effect of signaling kinases inhibitors on proliferation—BrdU ELISA test after 48–72 h. Their effect on the expression of cell cycle regulatory proteins: cyclin D1 and D3, cyclin-dependent kinase CDK4 and CDK6, and cell cycle inhibitors: p16, p21, and p27, was studied at the protein level (western blot). Treatment of melanoma cells with protein kinase inhibitors led to significantly decreased cell proliferation except the use of a GSK-3β kinase inhibitors—CHIR-99021. The significant decrease in the expression of selected cyclins and cyclin-dependent kinases (CDKs) with parallel increase in the expression of some of cyclin-dependent kinases inhibitors and in consequence meaningful reduction in melanoma cell proliferation by the combinations of inhibitors of signaling kinases clearly showed the crucial role of AKT, ERK 1/2, and mTOR signal transduction in melanoma progression. The results unanimously indicate those pathways as an important target for treatment of melanoma.

Unexpected role for p19INK4d in posttranscriptional regulation of GATA1 and modulation of human terminal erythropoiesis

Terminal erythroid differentiation is tightly coordinated with cell-cycle exit, which is regulated by cyclins, cyclin-dependent kinases, and cyclin-dependent kinase inhibitors (CDKI), yet their roles in erythropoiesis remain to be fully defined. We show here that p19^INK4d, a member of CDKI family, is abundantly expressed in erythroblasts and that p19^INK4d knockdown delayed erythroid differentiation, inhibited cell growth, and led to increased apoptosis and generation of abnormally nucleated late-stage erythroblasts. Unexpectedly, p19^INK4d knockdown did not affect cell cycle. Rather, it led to decreased expression of GATA1 protein. Importantly, the differentiation and nuclear defects were rescued by ectopic expression of GATA1. Because the GATA1 protein is protected by nuclear heat shock protein family (HSP) member HSP70, we examined the effects of p19^INK4d knockdown on HSP70 and found that p19^INK4d knockdown led to decreased expression of HSP70 and its nuclear localization. The reduced levels of HSP70 are the result of reduced extracellular signal-regulated kinase (ERK) activation. Further biochemical analysis revealed that p19^INK4d directly binds to Raf kinase inhibitor PEBP1 and that p19^INK4d knockdown increased the expression of PEBP1, which in turn led to reduced ERK activation. Thus we have identified an unexpected role for p19^INK4d via a novel PEBP1-p-ERK-HSP70-GATA1 pathway. These findings are likely to have implications for improved understanding of disordered erythropoiesis.

Anticancer effect of cucurbitacin B on MKN-45 cells via inhibition of the JAK2/STAT3 signaling pathway

The aim of the present study was to investigate the effect of cucurbitacin B on MKN-45 gastric carcinoma cells. Cell proliferation was determined using a cell counting kit-8 assay, and commercial cell cycle and apoptosis analysis kits were used to determine the cell cycle by flow cytometry. The mRNA expression of genes which mediate cell cycle checkpoints and apoptosis was detected using reverse transcription-quantitative polymerase chain reaction, and a terminal deoxynucleotidyl transferase dUTP nick end labeling assay was used to determine apoptosis rate. Western blot analysis was used to detect the protein expression levels of JAK2/STAT3 signaling pathway-associated proteins. The presented data show that cucurbitacin B significantly inhibited the proliferation of MKN-45 cells in a dose- and time-dependent manner. In accordance with these findings, cucurbitacin B blocked the progression of the cell cycle from G0/G1 to S phase, which was confirmed by the mRNA expression analysis. Cucurbitacin B treatment significantly suppressed the expression of cyclin D1, cyclin E, cyclin-dependent kinase 4 (CDK4) and CDK2, while increasing the expression of p27. Cucurbitacin B also promoted cell apoptosis, as was determined by TUNEL assay and evaluation of mRNA expression. Further experiments suggested that the beneficial effect of cucurbitacin B on blocking the proliferation and inducing the apoptosis of MKN-45 cells may have been associated with suppression of the JAK2/STAT3 signaling pathway. Thus, the present results indicate that cucurbitacin B suppresses proliferation and promoted apoptosis of MKN-45 cells, which may be mediated by inhibition of the JAK2/STAT3 signaling pathway. Cucurbitacin B therefore may warrant further investigation as a feasible therapy for gastric carcinoma.