Cryptotanshinone Inhibits ERα-Dependent and -Independent BCRP Oligomer Formation to Reverse Multidrug Resistance in Breast Cancer.
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ABSTRACT:
SUBMITTER: Ni W
PROVIDER: S-EPMC8100513 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Cryptotanshinone (CPT), a natural compound isolated from the plant Salvia miltiorrhiza Bunge, is a potential anticancer agent. However, the underlying mechanism is not well understood. Here, we show that CPT induced caspase-independent cell death in human tumor cells (Rh30, DU145, and MCF-7). Besides downregulating antiapoptotic protein expression of survivin and Mcl-1, CPT increased phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-jun N-terminal kinase (JNK), and inhibited phosphorylation of extracellular signal-regulated kinases 1/2 (Erk1/2). Inhibition of p38 with SB202190 or JNK with SP600125 attenuated CPT-induced cell death. Similarly, silencing p38 or c-Jun also in part prevented CPT-induced cell death. In contrast, expression of constitutively active mitogen-activated protein kinase kinase 1 (MKK1) conferred resistance to CPT inhibition of Erk1/2 phosphorylation and induction of cell death. Furthermore, we found that all of these were attributed to CPT induction of reactive oxygen species (ROS). This is evidenced by the findings that CPT induced ROS in a concentration- and time-dependent manner; CPT induction of ROS was inhibited by N-acetyl-L-cysteine (NAC), a ROS scavenger; and NAC attenuated CPT activation of p38/JNK, inhibition of Erk1/2, and induction of cell death. The results suggested that CPT induction of ROS activates p38/JNK and inhibits Erk1/2, leading to caspase-independent cell death in tumor cells.
| S-EPMC3410745 | biostudies-literature
Project description:Cryptotanshinone (CPT), isolated from the plant Salvia miltiorrhiza Bunge, is a potential anticancer agent. However, the underlying mechanism remains to be defined. Here, we show that CPT inhibited lymphangiogenesis in an in vitro model (tube formation). This effect was partly attributed to inhibiting expression of VEGF receptor 3 (VEGFR-3) in murine lymphatic endothelial cells (LEC), as overexpression of VEGFR-3 conferred resistance to CPT inhibition of the tube formation, whereas downregulation of VEGFR-3 mimicked the effect of CPT, blocking the tube formation. Furthermore, CPT inhibited phosphorylation of the extracellular signal-related kinase 1/2 (ERK1/2). Overexpression of VEGFR-3 attenuated CPT inhibition of ERK1/2 phosphorylation, whereas downregulation of VEGFR-3 inhibited ERK1/2 phosphorylation in LECs. Expression of constitutively active MKK1 resulted in activation of ERK1/2 and partially prevented CPT inhibition of LEC tube formation. In addition, CPT also inhibited protein expression and activities of Rac1 and Cdc42 but not RhoA. Expression of constitutively active Rac1 and Cdc42 concurrently, but not Rac1 or Cdc42 alone, conferred resistance to CPT inhibition of LEC tube formation. Taken together, the results suggest that CPT inhibits LEC tube formation, in part, by inhibiting VEGFR-3-mediated ERK1/2 phosphorylation and, in part, by inhibiting expression of the small GTPases.
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Project description:Overexpression of breast cancer resistance protein (BCRP) has been shown to produce multidrug resistance (MDR) in colon cancer, leading to major obstacles for chemotherapy. In this study, we evaluated the effect of regorafenib, an oral multi-kinase inhibitor, in inhibiting BCRP-mediated MDR in silico, in vitro and in vivo. We found that regorafenib significantly sensitized MDR colon cancer cells to BCRP substrates by increasing their intracellular accumulation. There are no significant changes in the expression level or the subcellular distribution of BCRP in the cells exposed to regorafenib. Investigation of the mechanism revealed that regorafenib stimulated BCRP ATPase activity. Our induced-fit docking and molecular dynamics simulations suggested the existence of a strong and stable interaction between regorafenib and the transmembrane domain of human crystalized BCRP. In vivo tumor xenograft study revealed that the combination of regorafenib and topotecan exhibited synergistic effects on mitoxantrone-resistant S1-M1-80 xenograft tumors. In conclusion, our studies indicate that regorafenib would be beneficial in combating MDR in colon cancer.
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Project description:The difficulty in identifying the toxic agents in all amyloid-related diseases is likely due to the complicated kinetics and thermodynamics of the nucleation process and subsequent fibril formation. The slow progression of these diseases suggests that the formation, incorporation, and/or action of toxic agents are possibly rate limiting. Candidate toxic agents include precursors (some at very low concentrations), also called oligomers and protofibrils, and the fibrils. Here, we investigate the kinetic and thermodynamic behavior of human insulin oligomers (imaged by cryo-EM) under fibril-forming conditions (pH 1.6 and 65 degrees C) by probing the reaction pathway to insulin fibril formation using two different types of experiments-cooling and seeding-and confirm the validity of the nucleation model and its effect on fibril growth. The results from both the cooling and seeding studies confirm the existence of a time-changing oligomer reaction process prior to fibril formation that likely involves a rate-limiting nucleation process followed by structural rearrangements of intermediates (into beta-sheet rich entities) to form oligomers that then form fibrils. The latter structural rearrangement step occurs even in the absence of nuclei (i.e., with added heterologous seeds). Nuclei are formed at the fibrillation conditions (pH 1.6 and 65 degrees C) but are also continuously formed during cooling at pH 1.6 and 25 degrees C. Within the time-scale of the experiments, only after increasing the temperature to 65 degrees C are the trapped insulin nuclei and resultant structures able to induce the structural rearrangement step and overcome the energy barrier to form fibrils. This delay in fibrillation and accumulation of nuclei at low temperature (25 degrees C) result in a decrease in the mean length of the fibers when placed at 65 degrees C. Fits of an empirical model to the data provide quantitative measures of the delay in the lag-time during the nucleation process and subsequent reduction in fibril growth rate resulting from the cooling. Also, the seeding experiments, within the time-scale of the measurements, demonstrate that fibers can initiate fast fibrillation with dissolved insulin (fresh or taken during the lag-period) but not with other fibers. Qualitatively this is explained with a conjectual free-energy space plot.
| S-EPMC2737737 | biostudies-literature
Project description:Background and purposeCannabinoids are used therapeutically for the palliation of the adverse side effects associated with cancer chemotherapy. However, cannabinoids also inhibit both the activity and expression of the multidrug transporter, P-glycoprotein in vitro. Here we address the interaction of cannabinol (CBN), cannabidiol (CBD) and delta 9-tetrahydrocannabinol (THC) with the related multidrug transporter, ABCG2.Experimental approachCannabinoid inhibition of Abcg2/ABCG2 was assessed using flow cytometric analysis of substrate accumulation and ATPase activity assays. The cytotoxicity and chemosensitization by cannabinoids was determined with cell viability assays. Expression of cannabinoid and vanilloid receptors was assessed using reverse transcriptase polymerase chain reaction, and cannabinoid modulation of ABCG2 expression was examined using immunoblotting.Key resultsCBN, CBD and THC increased the intracellular accumulation of the Abcg2/ABCG2 substrate, mitoxantrone, in an over-expressing cell line. The THC metabolite, (-)-11-nor-9-carboxy-delta 9-THC was much less potent. The plant cannabinoids inhibited both basal and substrate stimulated ATPase activity of human ABCG2. Cannabinoid cytotoxicity occurred in the absence of known cannabinoid cell surface receptors, and only at concentrations higher than those required for Abcg2/ABCG2 inhibition. Sub-toxic concentrations of the cannabinoids resensitized the overexpressing cell line to the cytotoxic effect of Abcg2/ABCG2 substrates, mitoxantrone and topotecan. This occurred in the absence of any effect on ABCG2 expression.Conclusions and implicationsCannabinoids are novel Abcg2/ABCG2 inhibitors, reversing the Abcg2-mediated multidrug-resistant phenotype in vitro. This finding may have implications for the co-administration of cannabinoids with pharmaceuticals that are ABCG2 substrates.
| S-EPMC2190019 | biostudies-literature
Project description:Malignant gliomas (MGs) are one of the most common primary brain cancers in adults with a high mortality rate and relapse rate. Thus, finding better effective approaches to treat MGs has become very urgent. Here, we studied the effects of cryptotanshinone (CTS) on MGs in vitro and in vivo, and explored the underlying mechanisms. Effects of CTS in vitro on cell proliferation, cycle, migration and invasion were evaluated. The activation of JAK/STATs signaling was detected by western blot and immunofluorescenc staining. SHP-2 inhibitor or SiRNA were used to determine the involvement of SHP-2. The in vivo anti-MGs activity of CTS was studied with nude mice bearing intracerebral U87 xenografts. Our results revealed that CTS significantly inhibited the proliferation of MGs in vitro via inhibiting STAT3 signal pathway. The cell cycle was arrested at G0/G1 phase. Although CTS did not change the expression of total SHP-2 protein, the tyrosine phosphatase activity of SHP-2 protein was increased by CTS treatment in a dose-dependent manner in vivo and in vitro. SHP-2 inhibitor or SiRNA could reverse the inhibitory effect of CTS on phosphorylation of STAT3 Tyr705. In vivo study also showed that CTS inhibited the intracranial tumor growth and extended survival of nude mice bearing intracerebral U87 xenografts, confirming an inhibitory effect of CTS on MGs. Our results indicated CTS may be a potential therapeutic agent for MGs. The inhibitory action of CTS is largely attributed to the inhibition of STAT3 Tyr705 phosphorylation with a novel mechanism of upregulating the tyrosine phosphatase activity of SHP-2 protein.
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Project description:Multidrug resistance (MDR) is the major obstruction in the successful treatment of breast cancer (BCa). The elucidation of molecular events that confer chemoresistance of BCa is of major therapeutic importance. Several studies have elucidated the correlation of TRPS1 and BCa. Here we focused on the role of TRPS1 in acquisition of chemoresistance, and reported a unique role of TRPS1 renders BCa cells resistant to chemotherapeutic drugs via the regulation of BCRP expression. Bioinformation analysis based on publicly available BCa data suggested that TRPS1 overexpression linked to chemoresistance. Mechanistically, TRPS1 regulated BCRP expression and efflux transportation. Overexpression of TRPS1 led to upregulation of BCRP while its inhibition resulted in repression of BCRP. The correlation of TRPS1 and BCRP was further confirmed by immunohistochemistry in 180 BCa samples. MTT assay demonstrated that manipulation of TRPS1 expression affects the chemosensitivity of BCa cells. In total, high expression of TRPS1 confers MDR of BCa which is mediated by BCRP. Our data demonstrated a new insight into mechanisms and strategies to overcome chemoresistance in BCa.
| S-EPMC7338551 | biostudies-literature
Project description:Reverse translational research takes a bedside-to-bench approach, using sophisticated basic research to explain the biological mechanisms behind observed clinical data. For transporters, which play a role in human disease and drug response, this approach offers a distinct advantage over the typical translational research, which often falters due to inadequate in vitro and preclinical animal models. Research on ABCG2, which encodes the Breast Cancer Resistance Protein, has benefited immensely from a reverse translational approach due to its broad implications for disease susceptibility and both therapeutic and adverse drug response. In this review, we describe the success of reverse translational research for ABCG2 and opportunities for further studies.
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Project description:To influence energy homeostasis and reproduction, 17β-estradiol (E2) controls the arcuate nucleus (ARC) through multiple receptor-mediated mechanisms, but primarily via estrogen receptor (ER) α, which signals through both estrogen response element (ERE)-dependent and -independent mechanisms. To determine ERα-mediated, ERE-dependent, and ERE-independent E2 signaling in the ARC, we examined the differential regulation of the mouse arcuate transcriptome by E2 using three mice genotypes: (1) wild-type, (2) ERα knock-in/knockout (ERE-independent mechanisms), and (3) total ERα knockout (ERα-independent mechanisms). Females were ovariectomized and injected with oil or E2, and RNA sequencing on the ARC was used to identify E2-regulated genes in each genotype. Our results show that E2 regulates numerous genes involved in cell signaling, cytoskeleton structure, inflammation, neurotransmission, neuropeptide production, and transcription. Furthermore, ERE-independent signaling regulates ARC genes expressed in kisspeptin neurons and transcription factors that control the hypothalamic/pituitary/gonadal axis. Interestingly, a few genes involved in mitochondrial oxidative respiration were regulated by E2 through ERα-independent signaling. A comparison within oil- and E2-treated females across the three genotypes suggests that genes involved in cell growth and proliferation, extracellular matrices, neuropeptides, receptors, and transcription are differentially expressed across the genotypes. Comparing with previously published chromatin immunoprecipitation sequencing analysis, we found that ERE-independent regulation in the ARC is mainly mediated by tethering of ERα, which is consistent with previous findings. We conclude that the mouse arcuate estrogen-regulated transcriptome is regulated by multiple receptor-mediated mechanisms to modulate the central control of energy homeostasis and reproduction, including novel E2-responsive pathways.
| S-EPMC5460777 | biostudies-literature
Project description:BACKGROUND: S100B is a dimeric protein that can form tetramers, hexamers and higher order oligomers. These forms have been suggested to play a role in RAGE activation. METHODOLOGY/PRINCIPAL FINDINGS: Oligomerization was found to require a low molecular weight trigger/cofactor and could not be detected for highly pure dimer, irrespective of handling. Imidazol was identified as a substance that can serve this role. Oligomerization is dependent on both the imidazol concentration and pH, with optima around 90 mM imidazol and pH 7, respectively. No oligomerization was observed above pH 8, thus the protonated form of imidazol is the active species in promoting assembly of dimers to higher species. However, disulfide bonds are not involved and the process is independent of redox potential. The process was also found to be independent of whether Ca(2+) is bound to the protein or not. Tetramers that are purified from dimers and imidazol by gel filtration are kinetically stable, but dissociate into dimers upon heating. Dimers do not revert to tetramer and higher oligomer unless imidazol is again added. Both tetramers and hexamers bind the target peptide from p53 with retained stoichiometry of one peptide per S100B monomer, and with high affinity (lgK?=?7.3±0.2 and 7.2±0.2, respectively in 10 mM BisTris, 5 mM CaCl(2), pH 7.0), which is less than one order of magnitude reduced compared to dimer under the same buffer conditions. CONCLUSION/SIGNIFICANCE: S100B oligomerization requires protonated imidazol as a trigger/cofactor. Oligomers are kinetically stable after imidazol is removed but revert back to dimer if heated. The results underscore the importance of kinetic versus thermodynamic control of S100B protein aggregation.
| S-EPMC3060798 | biostudies-literature