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Shibu MA, Chen YJ, Yang HS, He YH, Lo YH, Lin WT. Principle active metabolites of Pinus morrisonicola Hayata synergistically inhibit cell proliferation and autophagy to elevate apoptosis in hepatocellular carcinoma cells. ENVIRONMENTAL TOXICOLOGY 2023; 38:3018-3025. [PMID: 37615216 DOI: 10.1002/tox.23935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 06/22/2023] [Accepted: 07/29/2023] [Indexed: 08/25/2023]
Abstract
Hepatocellular carcinoma (HCC), a common primary tumor of liver is a leading cause of cancer-associated deaths. Improving cellular apoptosis and enhancing autophagic clearance is been considered to improve treatment outcomes of HCC. Polyphenols from Pinus morrisonicola (Hayata) have shown various physiological and therapeutic benefits and the flavonoid chrysin is been known for their anticancer effects. However, the main bioactive principle and the mechanism underlying the antitumor activity of pine needle extract are not clear yet. In this study, the effects of ethanol extract from pine needle on HCC cells were determined. The results show that when compared with administration of chrysin alone, a fraction containing pinocembrin, chrysin, and tiliroside significantly reduced autophagy and increased apoptosis. The results also correlated with decrease in cell cycle regulators and the autophagic proteins like LC3-II. Collectively, the results imply the fraction containing pinocembrin, chrysin, and tiliroside as an ideal complementary medicine for an effective antitumor activity.
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Affiliation(s)
| | - Yi-Ju Chen
- Department of Surgery, Taichung Veterans General Hospital, Taichung, Taiwan
- Department of Animal Science and Biotechnology, Tunghai University, Taichung, Taiwan
| | - Hong-Siang Yang
- Department of Food Science College of Agriculture and Health, Tunghai University, Taichung, Taiwan
| | - Yen-Hua He
- Department of Hospitality Management College of Agriculture and Health, Tunghai University, Taichung, Taiwan
- R&D Division, Utopia Holiday Hotel Corporation, Taichung, Taiwan
| | - Yun-Hsin Lo
- Department of Hospitality Management College of Agriculture and Health, Tunghai University, Taichung, Taiwan
- R&D Division, Utopia Holiday Hotel Corporation, Taichung, Taiwan
| | - Wan-Teng Lin
- Department of Hospitality Management College of Agriculture and Health, Tunghai University, Taichung, Taiwan
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Targeting RAS–RAF–MEK–ERK signaling pathway in human cancer: Current status in clinical trials. Genes Dis 2022; 10:76-88. [PMID: 37013062 PMCID: PMC10066287 DOI: 10.1016/j.gendis.2022.05.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 04/23/2022] [Accepted: 05/05/2022] [Indexed: 12/12/2022] Open
Abstract
Molecular target inhibitors have been regularly approved by Food and Drug Administration (FDA) for tumor treatment, and most of them intervene in tumor cell proliferation and metabolism. The RAS-RAF-MEK-ERK pathway is a conserved signaling pathway that plays vital roles in cell proliferation, survival, and differentiation. The aberrant activation of the RAS-RAF-MEK-ERK signaling pathway induces tumors. About 33% of tumors harbor RAS mutations, while 8% of tumors are driven by RAF mutations. Great efforts have been dedicated to targeting the signaling pathway for cancer treatment in the past decades. In this review, we summarized the development of inhibitors targeting the RAS-RAF-MEK-ERK pathway with an emphasis on those used in clinical treatment. Moreover, we discussed the potential combinations of inhibitors that target the RAS-RAF-MEK-ERK signaling pathway and other signaling pathways. The inhibitors targeting the RAS-RAF-MEK-ERK pathway have essentially modified the therapeutic strategy against various cancers and deserve more attention in the current cancer research and treatment.
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Yeom H, Hwang SH, Kim HG, Lee M. Increase in the sensitivity to PLX4720 through inhibition of transcription factor EB-dependent autophagy in BRAF inhibitor-resistant cells. Toxicol Res 2022; 38:35-44. [PMID: 35070939 PMCID: PMC8748576 DOI: 10.1007/s43188-021-00109-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 09/08/2021] [Accepted: 09/22/2021] [Indexed: 01/03/2023] Open
Abstract
Long-term treatment with oncogenic BRAF inhibitors confers resistance to BRAF inhibitor monotherapy. In this study, a combination treatment strategy with autophagy inhibitors was proposed to increase the sensitivity of BRAF mutant containing A375P melanoma cells that have developed resistance to BRAF inhibitors. We found that the A375P/Multi-drug resistance (A375P/Mdr) cells, which are resistant to both BRAF inhibitors and MEK inhibitors, exhibited a higher basal autophagic flux compared to their parental A375P cells, as determined by tandem mRFP-GFP-tagged LC3 imaging assay and LC3 conversion. In addition, transcription factor EB (TFEB), which acts as a transcription factor regulating the transcription of autophagy-related genes, was much more localized in the nucleus in A375P/Mdr cells than in A375P cells, indicating that the increase in basal autophagic flux was TFEB-dependent. In particular, the overexpression of an activated form of TFEB (TFEBAA) caused a modest increase in PLX4720 resistance in A375P/Mdr cells. Interestingly, treatment with early stage autophagy inhibitors reversed BRAF inhibitor-induced resistance, whereas late autophagy inhibition did not. In contrast, inhibition of ER stress by 4-phenylbutyric acid suppressed basal autophagic flux. Moreover, ER stress inhibition significantly remarkably inhibited the nuclear localization of TFEB, resulting in an increase in the sensitivity of A375P/Mdr cells to PLX4720. Taken together, these results suggest that autophagy may be an important mechanism of acquired resistance to BRAF inhibitors. Thus, targeting autophagy may be suitable for the treatment of tumors resistant to BRAF inhibitor.
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Affiliation(s)
- Hojin Yeom
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, 22012 Republic of Korea
| | - Sung-Hee Hwang
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, 22012 Republic of Korea
| | - Hye-Gyo Kim
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, 22012 Republic of Korea
| | - Michael Lee
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, 22012 Republic of Korea
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4
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Shim D, Duan L, Maki CG. P53-regulated autophagy and its impact on drug resistance and cell fate. CANCER DRUG RESISTANCE (ALHAMBRA, CALIF.) 2021; 4:85-95. [PMID: 34532654 PMCID: PMC8443158 DOI: 10.20517/cdr.2020.85] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Wild-type p53 is a stress-responsive transcription factor and a potent tumor suppressor. P53 inhibits the growth of incipient cancer cells by blocking their proliferation or inducing their death through apoptosis. Autophagy is a self-eating process that plays a key role in response to stress. During autophagy, organelles and other intracellular components are degraded in autophagolysosomes and the autophagic breakdown products are recycled into metabolic and energy producing pathways needed for survival. P53 can promote or inhibit autophagy depending on its subcellular localization, mutation status, and the level of stress. Blocking autophagy has been reported in several studies to increase p53-mediated apoptosis, revealing that autophagy can influence cell-fate in response to activated p53 and is a potential target to increase p53-dependent tumor suppression.
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Affiliation(s)
- Daeun Shim
- Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Lei Duan
- Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Carl G Maki
- Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, IL 60612, USA
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5
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Yeom H, Hwang SH, Han BI, Lee M. Differential Sensitivity of Wild-Type and BRAF-Mutated Cells to Combined BRAF and Autophagy Inhibition. Biomol Ther (Seoul) 2021; 29:434-444. [PMID: 33551379 PMCID: PMC8255135 DOI: 10.4062/biomolther.2020.203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 01/07/2023] Open
Abstract
BRAF inhibitors are insufficient monotherapies for BRAF-mutated cancer; therefore, we investigated which inhibitory pathway would yield the most effective therapeutic approach when targeted in combination with BRAF inhibition. The oncogenic BRAF inhibitor, PLX4720, increased basal autophagic flux in BRAF-mutated cells compared to wild-type (WT) BRAF cells. Interestingly, early autophagy inhibition improved the effectiveness of PLX4720 regardless of BRAF mutation, whereas late autophagy inhibition did not. Although ATG5 knockout led to PLX4720 resistance in both WT and BRAF-mutated cells, the MEK inhibitor trametinib exhibited a synergistic effect on PLX4720 sensitivity in WT BRAF cells but not in BRAF-mutated cells. Conversely, the prolonged inhibition of endoplasmic reticulum (ER) stress reduced basal autophagy in BRAF-mutated cells, thereby increasing PLX4720 sensitivity. Taken together, our results suggest that the combined inhibition of ER stress and BRAF may simultaneously suppress both pro-survival ER stress and autophagy, and may therefore be suitable for treatment of BRAF-mutated tumors whose autophagy is increased by chronic ER stress. Similarly, for WT BRAF tumors, therapies targeting MEK signaling may be a more effective treatment strategy. Together, this study presents a rational combination treatment strategy to improve the efficacy of BRAF inhibitors depending on BRAF mutation status.
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Affiliation(s)
- Hojin Yeom
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 22012, Republic of Korea
| | - Sung-Hee Hwang
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 22012, Republic of Korea
| | - Byeal-I Han
- Institute for New Drug Development, Incheon National University, Incheon 22012, Republic of Korea
| | - Michael Lee
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 22012, Republic of Korea.,Institute for New Drug Development, Incheon National University, Incheon 22012, Republic of Korea
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Proietti I, Skroza N, Bernardini N, Tolino E, Balduzzi V, Marchesiello A, Michelini S, Volpe S, Mambrin A, Mangino G, Romeo G, Maddalena P, Rees C, Potenza C. Mechanisms of Acquired BRAF Inhibitor Resistance in Melanoma: A Systematic Review. Cancers (Basel) 2020; 12:E2801. [PMID: 33003483 PMCID: PMC7600801 DOI: 10.3390/cancers12102801] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/21/2020] [Accepted: 09/25/2020] [Indexed: 12/18/2022] Open
Abstract
This systematic review investigated the literature on acquired v-raf murine sarcoma viral oncogene homolog B1 (BRAF) inhibitor resistance in patients with melanoma. We searched MEDLINE for articles on BRAF inhibitor resistance in patients with melanoma published since January 2010 in the following areas: (1) genetic basis of resistance; (2) epigenetic and transcriptomic mechanisms; (3) influence of the immune system on resistance development; and (4) combination therapy to overcome resistance. Common resistance mutations in melanoma are BRAF splice variants, BRAF amplification, neuroblastoma RAS viral oncogene homolog (NRAS) mutations and mitogen-activated protein kinase kinase 1/2 (MEK1/2) mutations. Genetic and epigenetic changes reactivate previously blocked mitogen-activated protein kinase (MAPK) pathways, activate alternative signaling pathways, and cause epithelial-to-mesenchymal transition. Once BRAF inhibitor resistance develops, the tumor microenvironment reverts to a low immunogenic state secondary to the induction of programmed cell death ligand-1. Combining a BRAF inhibitor with a MEK inhibitor delays resistance development and increases duration of response. Multiple other combinations based on known mechanisms of resistance are being investigated. BRAF inhibitor-resistant cells develop a range of 'escape routes', so multiple different treatment targets will probably be required to overcome resistance. In the future, it may be possible to personalize combination therapy towards the specific resistance pathway in individual patients.
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Affiliation(s)
- Ilaria Proietti
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
| | - Nevena Skroza
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
| | - Nicoletta Bernardini
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
| | - Ersilia Tolino
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
| | - Veronica Balduzzi
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
| | - Anna Marchesiello
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
| | - Simone Michelini
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
| | - Salvatore Volpe
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
| | - Alessandra Mambrin
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
| | - Giorgio Mangino
- Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, 00185 Rome, Italy; (G.M.); (G.R.)
| | - Giovanna Romeo
- Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, 00185 Rome, Italy; (G.M.); (G.R.)
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, 00185 Rome, Italy
- Institute of Molecular Biology and Pathology, Consiglio Nazionale delle Ricerche, 00185 Rome, Italy
| | - Patrizia Maddalena
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
| | | | - Concetta Potenza
- Dermatology Unit “Daniele Innocenzi”, Department of Medical-Surgical Sciences and Bio-Technologies, Sapienza University of Rome, Fiorini Hospital, Polo Pontino, 04019 Terracina, Italy; (N.S.); (N.B.); (E.T.); (V.B.); (A.M.); (S.M.); (S.V.); (A.M.); (P.M.); (C.P.)
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Hwang SH, Ahn JH, Lee M. Upregulation of S100A9 contributes to the acquired resistance to BRAF inhibitors. Genes Genomics 2019; 41:1273-1280. [PMID: 31388978 DOI: 10.1007/s13258-019-00856-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 07/24/2019] [Indexed: 01/18/2023]
Abstract
BACKGROUNDS Acquired resistance is a significant clinical challenge in targeted therapy of melanomas using BRAF inhibitors. We previously identified that downregulation of miR-92a-1-5p confers acquired resistance to BRAF inhibition using an miRNA array platform. OBJECTIVE In this study, we investigated the target genes of miR-92a-1-5p and their functional significance in BRAF inhibitor resistance. METHODS The miRNA target prediction data were combined with RNA-Seq data to identify possible target genes for miR-92a-1-5p. Cellular effects of target genes were further examined using siRNA knockdown, WST-1 assay, and immunoblotting analysis. RESULTS We selected S100 calcium-binding protein A9 (S100A9) as a possible target gene for functional validation. S100A9 knockdown abrogated resistance to PLX4720 in A375P/Mdr cells. This result was similar to those described earlier for miR-92a-1-5p, indicating that miR-92a-1-5p inhibits cell viability by targeting S100A9. S100A9 overexpression partially conferred PLX4720 resistance to A375P cells. We also demonstrated that MAPK re-activation does not contribute to the promotion of BRAF inhibitor resistance by S100A9. CONCLUSION Taken together, our results indicate that S100A9 might be functionally involved in development of resistance to BRAF inhibitors and might be a target for melanoma therapy in the future.
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Affiliation(s)
- Sung-Hee Hwang
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, 22012, Republic of Korea
| | - Jun-Ho Ahn
- System Toxicology Research Center, Korea Institute of Toxicology, Daejeon, 34114, Republic of Korea
| | - Michael Lee
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, 22012, Republic of Korea.
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Ahn JH, Hwang SH, Cho HS, Lee M. Differential Gene Expression Common to Acquired and Intrinsic Resistance to BRAF Inhibitor Revealed by RNA-Seq Analysis. Biomol Ther (Seoul) 2019; 27:302-310. [PMID: 30293252 PMCID: PMC6513187 DOI: 10.4062/biomolther.2018.133] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 08/14/2018] [Accepted: 08/16/2018] [Indexed: 12/18/2022] Open
Abstract
Melanoma cells have been shown to respond to BRAF inhibitors; however, intrinsic and acquired resistance limits their clinical application. In this study, we performed RNA-Seq analysis with BRAF inhibitor-sensitive (A375P) and -resistant (A375P/Mdr with acquired resistance and SK-MEL-2 with intrinsic resistance) melanoma cell lines, to reveal the genes and pathways potentially involved in intrinsic and acquired resistance to BRAF inhibitors. A total of 546 differentially expressed genes (DEGs), including 239 up-regulated and 307 down-regulated genes, were identified in both intrinsic and acquired resistant cells. Gene ontology (GO) analysis revealed that the top 10 biological processes associated with these genes included angiogenesis, immune response, cell adhesion, antigen processing and presentation, extracellular matrix organization, osteoblast differentiation, collagen catabolic process, viral entry into host cell, cell migration, and positive regulation of protein kinase B signaling. In addition, using the PANTHER GO classification system, we showed that the highest enriched GOs targeted by the 546 DEGs were responses to cellular processes (ontology: biological process), binding (ontology: molecular function), and cell subcellular localization (ontology: cellular component). Ingenuity pathway analysis (IPA) network analysis showed a network that was common to two BRAF inhibitor-resistant cells. Taken together, the present study may provide a useful platform to further reveal biological processes associated with BRAF inhibitor resistance, and present areas for therapeutic tool development to overcome BRAF inhibitor resistance.
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Affiliation(s)
- Jun-Ho Ahn
- System Toxicology Research Center, Korea Institute of Toxicology, Daejeon 34114, Republic of Korea
| | - Sung-Hee Hwang
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 22012, Republic of Korea
| | - Hyun-Soo Cho
- Stem Cell Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea.,Department of Functional Genomics, Korea University of Science and Technology, Daejeon 34113, Republic of Korea
| | - Michael Lee
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 22012, Republic of Korea
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Kim JH, Ahn JH, Lee M. Upregulation of MicroRNA-1246 Is Associated with BRAF Inhibitor Resistance in Melanoma Cells with Mutant BRAF. Cancer Res Treat 2017; 49:947-959. [PMID: 28052651 PMCID: PMC5654168 DOI: 10.4143/crt.2016.280] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Accepted: 12/19/2016] [Indexed: 12/17/2022] Open
Abstract
Purpose Intrinsic and acquired resistance limit the therapeutic benefits of inhibitors of oncogenic BRAF in melanoma. To identify microRNAs (miRNAs) associated with resistance to a BRAF inhibitor, we compared miRNA expression levels in three cell lines with different BRAF inhibitor sensitivity. Materials and Methods miRNA microarray analysis was conducted to compare miRNA expression levels. Real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was performed to confirm the expression of differentially expressed miRNAs. The cellular effects of miR-1246 were further examined by MTT assay, immunoblotting analysis, cell cycle analysis, flow cytometric assay of apoptosis, and autophagy assay. Results The miRNA microarray analysis and qRT-PCR identified five miRNAs (miR-3617, miR-92a-1, miR-1246, miR-193b-3p, and miR-17-3p) with expression that was consistently altered in two BRAF inhibitor-resistant cell lines. Among the five miRNAs, a miR-1246 mimic significantly reduced the antiproliferative effects of the BRAF inhibitor PLX4720 in BRAF inhibitor–resistant A375P (A375P/Mdr) cells, suggesting that miR-1246 upregulation confers acquired resistance to BRAF inhibition. In particular, apoptosis was identified as a major type of cell death in miR-1246–transfected cells; however, necrosis predominated in mimic-control-transfected cells, indicating that the resistance to PLX4720 in miR-1246 mimic-transfected cells is predominantly due to a reduction in necrosis. Furthermore, we found that miR-1246 promoted G2/M arrest through autophagy as a way to escape cell death by necrosis and apoptosis in response to PLX4720. The promotion of BRAF inhibitor resistance by miR-1246 was associated with lowered levels of p-ERK. Conclusion These results suggest that miR-1246 may be a potential therapeutic target in melanoma with acquired resistance to BRAF inhibitors.
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Affiliation(s)
- Jae-Hyeon Kim
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon, Korea
| | - Jun-Ho Ahn
- Genome Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea
| | - Michael Lee
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon, Korea
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Han BI, Lee M. Paclitaxel-Induced G2/M Arrest via Different Mechanism of Actions in Glioma Cell Lines with Differing p53 Mutational Status. INT J PHARMACOL 2015. [DOI: 10.3923/ijp.2016.19.27] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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11
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Verma N, Manna SK. Advanced Glycation End Products (AGE) Potently Induce Autophagy through Activation of RAF Protein Kinase and Nuclear Factor κB (NF-κB). J Biol Chem 2015; 291:1481-91. [PMID: 26586913 DOI: 10.1074/jbc.m115.667576] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Indexed: 11/06/2022] Open
Abstract
Advanced glycation end products (AGE) accumulate in diabetic patients and aging people because of high amounts of three- or four-carbon sugars derived from glucose, thereby causing multiple consequences, including inflammation, apoptosis, obesity, and age-related disorders. It is important to understand the mechanism of AGE-mediated signaling leading to the activation of autophagy (self-eating) that might result in obesity. We detected AGE as one of the potent inducers of autophagy compared with doxorubicin and TNF. AGE-mediated autophagy is inhibited by suppression of PI3K and potentiated by the autophagosome maturation blocker bafilomycin. It increases autophagy in different cell types, and that correlates with the expression of its receptor, receptor for AGE. LC3B, the marker for autophagosomes, is shown to increase upon AGE stimulation. AGE-mediated autophagy is partially suppressed by inhibitor of NF-κB, PKC, or ERK alone and significantly in combination. AGE increases sterol regulatory element binding protein activity, which leads to an increase in lipogenesis. Although AGE-mediated lipogenesis is affected by autophagy inhibitors, AGE-mediated autophagy is not influenced by lipogenesis inhibitors, suggesting that the turnover of lipid droplets overcomes the autophagic clearance. For the first time, we provide data showing that AGE induces several cell signaling cascades, like NF-κB, PKC, ERK, and MAPK, that are involved in autophagy and simultaneously help with the accumulation of lipid droplets that are not cleared effectively by autophagy, therefore causing obesity.
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Affiliation(s)
- Neeharika Verma
- From the Laboratory of Immunology, Centre for DNA Fingerprinting and Diagnostics, Nampally, Hyderabad 500001, India and Graduate Studies, Manipal University, Manipal, Karnataka 576104, India
| | - Sunil K Manna
- From the Laboratory of Immunology, Centre for DNA Fingerprinting and Diagnostics, Nampally, Hyderabad 500001, India and
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Ahn JH, Han BI, Lee M. Induction of Resistance to BRAF Inhibitor Is Associated with the Inability of Spry2 to Inhibit BRAF-V600E Activity in BRAF Mutant Cells. Biomol Ther (Seoul) 2015; 23:320-6. [PMID: 26157547 PMCID: PMC4489825 DOI: 10.4062/biomolther.2015.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 04/06/2015] [Accepted: 04/08/2015] [Indexed: 12/05/2022] Open
Abstract
The clinical benefits of oncogenic BRAF inhibitor therapies are limited by the emergence of drug resistance. In this study, we investigated the role of a negative regulator of the MAPK pathway, Spry2, in acquired resistance using BRAF inhibitor-resistant derivatives of the BRAF-V600E melanoma (A375P/Mdr). Real-time RT-PCR analysis indicated that the expression of Spry2 was higher in A375P cells harboring the BRAF V600E mutation compared with wild-type BRAF-bearing cells (SK-MEL-2) that are resistant to BRAF inhibitors. This result suggests the ability of BRAF V600E to evade feedback suppression in cell lines with BRAF V600E mutations despite high Spry2 expression. Most interestingly, Spry2 exhibited strongly reduced expression in A375P/Mdr cells with acquired resistance to BRAF inhibitors. Furthermore, the overexpression of Spry2 partially restored sensitivity to the BRAF inhibitor PLX4720 in two BRAF inhibitor-resistant cells, indicating a positive role for Spry2 in the growth inhibition induced by BRAF inhibitors. On the other hand, long-term treatment with PLX4720 induced pERK reactivation following BRAF inhibition in A375P cells, indicating that negative feedback including Spry2 may be bypassed in BRAF mutant melanoma cells. In addition, the siRNA-mediated knockdown of Raf-1 attenuated the rebound activation of ERK stimulated by PLX4720 in A375P cells, strongly suggesting the positive role of Raf-1 kinase in ERK activation in response to BRAF inhibition. Taken together, these data suggest that RAF signaling may be released from negative feedback inhibition through interacting with Spry2, leading to ERK rebound and, consequently, the induction of acquired resistance to BRAF inhibitors.
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Affiliation(s)
- Jun-Ho Ahn
- Genome Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806
| | - Byeal-I Han
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 406-772, Republic of Korea
| | - Michael Lee
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 406-772, Republic of Korea
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Bu XF, Wang MB, Zhang ZJ, Zhao YH, Li M, Yan YL. Autophagy is involved in recombinant Newcastle disease virus (rL-RVG)-induced cell death of stomach adenocarcinoma cells in vitro. Int J Oncol 2015; 47:679-89. [PMID: 26058483 DOI: 10.3892/ijo.2015.3039] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 05/11/2015] [Indexed: 11/06/2022] Open
Abstract
Oncolytic viruses can kill malignant cells while sparing normal cells. Multiple pathways are involved in this action. The antitumor effects of viral infection on SGC-7901 and AGS cells were investigated. We measured endoplasmic reticulum stress and autophagy caused by the recombinant avirulent Newcastle disease virus (NDV) LaSota strain expressing the rabies virus glycoprotein (rL-RVG) and the NDV wild-type strain. The dose-response curves were analyzed using the MTT assay. The expression of RVG was detected by western blotting, RT-PCR and immunofluorescence analyses. Cell death and autophagy were observed using transmission electron microscopy, TUNEL and western blotting. Endoplasmic reticulum stress and the mitochondrial transmembrane potential were detected by western blotting and immunofluorescence, respectively. Immunofluorescence, western blot and RT-PCR analyses indicated that RVG gene and protein were expressed in SGC-7901 and AGS cells infected by rL-RVG. MTT and TUNEL analyses showed that the growth of SGC-7901 and AGS cells in the rL-RVG-infected group was significantly inhibited compared with the wild-type NDV-infected group (p<0.05). Western blot analysis indicated that rL-RVG and NDV induced increases in apoptosis, endoplasmic reticulum stress, and autophagy in the SGC-7901 and AGS cells. However, apoptosis and autophagy decreased in these cells after the application of the autophagy pathway inhibitor 3-MA or ATG-5-specific siRNA. Immunofluorescence analysis showed that the mitochondrial membrane potential collapsed. Taken together, these results indicate that the rL-RVG virus group is much more powerful compared with the NDV-infected group (p<0.05). rL-RVG and NDV are potent antitumor agents that induce autophagy.
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Affiliation(s)
- Xu-Feng Bu
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, Jiangsu, P.R. China
| | - Mu-Bing Wang
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, Jiangsu, P.R. China
| | - Zhi-Jian Zhang
- Clinical Medicine College of Jiangsu University, Zhenjiang, Jiangsu, P.R. China
| | - Ying-Hai Zhao
- Clinical Medicine College of Jiangsu University, Zhenjiang, Jiangsu, P.R. China
| | - Mi Li
- Clinical Medicine College of Jiangsu University, Zhenjiang, Jiangsu, P.R. China
| | - Yu-Lan Yan
- Department of Internal Medicine, Affiliated People's Hospital of Jiangsu University, Zhenjiang, Jiangsu, P.R. China
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Jang GH, Kim NY, Lee M. Low inducible expression of p21Cip1 confers resistance to paclitaxel in BRAF mutant melanoma cells with acquired resistance to BRAF inhibitor. Mol Cell Biochem 2015; 406:53-62. [PMID: 25912549 DOI: 10.1007/s11010-015-2423-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/22/2015] [Indexed: 12/11/2022]
Abstract
The therapeutic efficacy of oncogenic BRAF inhibitor is limited by the onset of acquired resistance. In this study, we investigated the potential therapeutic effects of the mitotic inhibitor paclitaxel on three melanoma cell lines with differing sensitivity to the BRAF inhibitor. Of the two BRAF inhibitor-resistant cell lines, A375P/Mdr cells harboring the BRAF V600E mutant were resistant and the wild-type BRAF SK-MEL-2 cells were sensitive to paclitaxel. In particular, paclitaxel caused the growth inhibition of SK-MEL-2 cells to a much greater extent than it caused growth inhibition of A375P cells. Paclitaxel exhibited no significant effect on the phosphorylation of MEK-ERK in any cell lines tested, regardless of both the BRAF mutation and the drug resistance, implying that paclitaxel activity is independent of MEK-ERK inhibition. In A375P cells, paclitaxel treatment resulted in a marked emergence of apoptotic cells after mitotic arrest, concomitant with a remarkable induction of p21(Cip1). However, paclitaxel only moderately increased the levels of p21(Cip1) in A375P/Mdr cells, which exhibited a strong resistance to paclitaxel. The p21(Cip1) overexpression partially conferred paclitaxel sensitivity to A375P/Mdr cells. Interestingly, we found an extremely low background expression level of p21(Cip1) in SK-MEL-2 cells lacking normal p53 function, which caused much greater G2/M arrest than that seen in A375P cells. Taken together, these results suggest that paclitaxel may be an effective anticancer agent through regulating the expression of p21(Cip1) for the treatment of BRAF mutant melanoma cells resistant to BRAF inhibitors.
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Affiliation(s)
- Gun-Hee Jang
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, 406-772, Republic of Korea
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Lee SW, Kim HK, Lee NH, Yi HY, Kim HS, Hong SH, Hong YK, Joe YA. The synergistic effect of combination temozolomide and chloroquine treatment is dependent on autophagy formation and p53 status in glioma cells. Cancer Lett 2015; 360:195-204. [PMID: 25681668 DOI: 10.1016/j.canlet.2015.02.012] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 01/14/2015] [Accepted: 02/06/2015] [Indexed: 11/27/2022]
Abstract
Temozolomide (TMZ) is an alkylating agent used for the treatment of glioblastoma. The late autophagy inhibitor chloroquine (CQ) inhibits glioblastoma tumors in a p53-independent and p53-dependent manner. We addressed a possible beneficial effect of combination treatment with TMZ and CQ by examining the molecular and cellular mechanism of co-treatment. Combination treatment of U87 cell (wild type p53) with TMZ and CQ synergistically reduced cell proliferation and enhanced apoptosis, with increased sub-G1 hypodiploid cells and caspase activation. This effect was abolished by a pan-caspase inhibitor, Z-VAD-FMK. TMZ induced autophagy, and the addition of CQ further increased autophagic vacuoles. Inhibition of early stages of autophagy by Beclin 1 knockdown and 3-methyladenine pretreatment prevented the enhanced effect of the combination treatment. The combination treatment also upregulated p53 and phospho-p53 levels, whereas p53 knockdown or overexpression of mutant p53 abolished the combination effect. In contrast, combination therapy had no enhanced effect on U373 cell (mutant p53) proliferation and apoptosis within 3 d, although TMZ induced autophagy and co-treatment with CQ increased autophagic vacuole accumulation. However, long term combination treatment for 9-10 d effectively decreased clonal and cellular growth with increased G2-M arrest. This effect was also abolished by Beclin 1 knockdown. Our data support the beneficial effect of combination treatment with TMZ and CQ in glioma via differential autophagy-associated mechanisms, depending on p53 status.
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Affiliation(s)
- Seung Woo Lee
- Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Hyun-Kyung Kim
- Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Na-Hyeon Lee
- Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Hee-Yeon Yi
- Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Hong-Sug Kim
- Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Sung Hee Hong
- Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, 215-4, Gongneung-Dong, Nowon-Gu, Seoul 139-706, Republic of Korea
| | - Yong-Kil Hong
- Department of Neuro-Surgery, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Young Ae Joe
- Cancer Research Institute, Department of Medical Lifescience, and Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea.
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16
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Concurrent MEK and autophagy inhibition is required to restore cell death associated danger-signalling in Vemurafenib-resistant melanoma cells. Biochem Pharmacol 2015; 93:290-304. [DOI: 10.1016/j.bcp.2014.12.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 12/08/2014] [Accepted: 12/08/2014] [Indexed: 12/28/2022]
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17
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Liu Q, Shi X, Zhou X, Wang D, Wang L, Li C. Effect of autophagy inhibition on cell viability and cell cycle progression in MDA‑MB‑231 human breast cancer cells. Mol Med Rep 2014; 10:625-30. [PMID: 24898397 DOI: 10.3892/mmr.2014.2296] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 05/22/2014] [Indexed: 11/06/2022] Open
Abstract
Atg7 is an autophagy‑related gene, and is involved in two ubiquitin‑like conjugation systems in the process of autophagy. It is well established that 3‑methyladenine (3Ma) is an autophagy inhibitor. The present study aimed to investigate the effect of autophagy inhibition on the cell viability and cell cycle progression of human breast cancer cells. MDA‑MB‑231 human breast cancer cells were cultured in Dulbecco's modified Eagle's medium (DMEM) with high glucose, then divided into six groups. The six groups included the three fundamental groups as follows: The control group (untreated); the starvation group (high‑glucose DMEM replaced with glucose‑free minimal essential medium); and the starvation 3Ma group (maintained in glucose‑free culture medium and treated with the autophagy inhibitor 3Ma). The three fundamental groups were further divided into Atg7 siRNA‑transfected and non‑transfected groups. The cell viability and apoptosis of each group was determined by MTT assay and flow cytometry. The results of the current study demonstrated that Atg7 deficiency alone had no statically significant effect on the cell viability of MDA‑MB‑231 human breast cancer cells, while 3Ma reduced the cell viability and its effect was potentiated by Atg7 deficiency. Atg7 deficiency was more intense than 3Ma in the promotion of apoptosis and cell arrest in G0/G1‑phase in the absence of glucose and its effect was reduced by 3Ma. In conclusion, 3Ma and Atg7 may be involved in different pathways in the process of autophagy. Inhibition of autophagy may influence the cell viability and cell cycle through different pathways in MDA‑MB‑231 human breast cancer cells.
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Affiliation(s)
- Qiujun Liu
- Department of Biochemistry and Molecular Biology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Xinli Shi
- Department of Pathobiology and Immunology, Hebei University of Traditional Chinese Medicine, Shijiazhuang, Hebei 050200, P.R. China
| | - Xianyao Zhou
- Department of Biochemistry and Molecular Biology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Da Wang
- Department of Biochemistry and Molecular Biology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Li Wang
- Research Center of Traditional Chinese and Western Medicine, Affiliated Traditional Hospital, Luzhou Medical College, Luzhou, Sichuan 646000, P.R. China
| | - Changlong Li
- Department of Biochemistry and Molecular Biology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, P.R. China
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Progesterone increases apoptosis and inversely decreases autophagy in human hepatoma HA22T/VGH cells treated with epirubicin. ScientificWorldJournal 2014; 2014:567148. [PMID: 24971383 PMCID: PMC4055367 DOI: 10.1155/2014/567148] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 05/01/2014] [Indexed: 01/11/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is the leading cause of cancer-related deaths worldwide. Epirubicin can induce intracellular reactive oxygen species and is widely used to treat unresectable HCC. Progesterone has been found to inhibit the proliferation of hepatoma cells. This study was designed to test the combined effects of epirubicin and progesterone on human hepatoma cell line, HA22T/VGH. These cells were treated with different concentrations of epirubicin with or without the coaddition of 30 μM progesterone and then analyzed for apoptosis, autophagy, and expressions of apoptotic-related proteins and multidrug-resistant gene. Epirubicin treatment dose-dependently inhibited the growth of HA22T/VGH cells. Addition of 30 μM progesterone, which was inactive alone, augmented the effect of epirubicin on the inhibition of growth of HA22T/VGH cells. Cotreatment with progesterone enhanced epirubicin-induced apoptosis, as evidenced by greater increase in caspase-3 activity and in the ratio of the apoptosis-regulating protein, Bax/Bcl-XL. The combination also caused a decrease in autophagy and in the expression of multidrug resistance-related protein 1 mRNA compared to epirubicin alone. This study shows the epirubicin/progesterone combination was more effective in increasing apoptosis and inversely decreasing autophagy on HA22T/VGH cells treated with epirubicin alone, suggesting that this combination can potentially be used to treat HCC.
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Jang GH, Lee M. BH3-mimetic gossypol-induced autophagic cell death in mutant BRAF melanoma cells with high expression of p21Cip1. Life Sci 2014; 102:41-8. [DOI: 10.1016/j.lfs.2014.02.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 01/24/2014] [Accepted: 02/21/2014] [Indexed: 02/06/2023]
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Ahn JH, Lee M. The siRNA-mediated downregulation of N-Ras sensitizes human melanoma cells to apoptosis induced by selective BRAF inhibitors. Mol Cell Biochem 2014; 392:239-47. [PMID: 24671490 DOI: 10.1007/s11010-014-2034-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 03/14/2014] [Indexed: 01/06/2023]
Abstract
The clinical benefit of selective BRAF inhibitor therapies is limited by the emergence of drug resistance. Here, we investigated the molecular basis underlying the acquired resistance to a BRAF inhibitor by comparing the signaling pathways in the parental A375P cells and the resistant subline (A375P/Mdr). We demonstrate that MAPK re-activation does not contribute to the mechanism of resistance to UAI-201 of A375P/Mdr cells. The relative quantitative analysis using the 2(-ΔΔCt) method revealed that the BRAF inhibitor resistance observed in A375P/Mdr cells is not mediated through the overexpression of MDR proteins. In particular, we found that the expression of N-Ras was upregulated in BRAF inhibitor-resistant A375P/Mdr cells compared with A375P cells. In fact, siRNA-mediated N-Ras knockdown partially conferred UAI-201 sensitivity to A375P/Mdr cells, implying that N-Ras upregulation confers acquired resistance to BRAF inhibition. Notably, the flow cytometric analysis of the N-Ras-knockdown A375P/Mdr cells revealed that UAI-201 causes a significant accumulation of cells in the G 0/G 1 phase with a concomitant decrease in the number of cells in the S and G 2/M phases. However, platelet-derived growth factor receptor β (PDGFRβ) knockdown failed to sensitize A375P/Mdr cells to growth suppression by UAI-201, although a remarkable increase in PDGFRβ was observed in the A375P cells after UAI-201 treatment. Taken together, our results suggest that N-Ras is worth targeting to improve the therapeutic outcome of melanomas with acquired resistance to BRAF inhibitors.
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Affiliation(s)
- Jun-Ho Ahn
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, 12-1 Songdo-dong, Yeonsu-gu, Incheon, 406-772, Republic of Korea
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