scholarly journals Dissecting Mechanisms of Melanoma Resistance to BRAF and MEK Inhibitors Revealed Genetic and Non-Genetic Patient- and Drug-Specific Alterations and Remarkable Phenotypic Plasticity

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 142 ◽  
Author(s):  
Mariusz L. Hartman ◽  
Malgorzata Sztiller-Sikorska ◽  
Anna Gajos-Michniewicz ◽  
Malgorzata Czyz
Keyword(s):  
Phenotypic Plasticity ◽  
Cell Lines ◽  
Mapk Pathway ◽  
Acquired Resistance ◽  
Resistance Mechanisms ◽  
Genetic Alterations ◽  
Resistant Cell ◽  
Cross Resistance ◽  
Preclinical Model ◽  
Development Of Resistance

The clinical benefit of MAPK pathway inhibition in BRAF-mutant melanoma patients is limited by the development of acquired resistance. Using drug-naïve cell lines derived from tumor specimens, we established a preclinical model of melanoma resistance to vemurafenib or trametinib to provide insight into resistance mechanisms. Dissecting the mechanisms accompanying the development of resistance, we have shown that (i) most of genetic and non-genetic alterations are triggered in a cell line- and/or drug-specific manner; (ii) several changes previously assigned to the development of resistance are induced as the immediate response to the extent measurable at the bulk levels; (iii) reprogramming observed in cross-resistance experiments and growth factor-dependence restricted by the drug presence indicate that phenotypic plasticity of melanoma cells largely contributes to the sustained resistance. Whole-exome sequencing revealed novel genetic alterations, including a frameshift variant of RBMX found exclusively in phospho-AKThigh resistant cell lines. There was no similar pattern of phenotypic alterations among eleven resistant cell lines, including expression/activity of crucial regulators, such as MITF, AXL, SOX, and NGFR, which suggests that patient-to-patient variability is richer and more nuanced than previously described. This diversity should be considered during the development of new strategies to circumvent the acquired resistance to targeted therapies.

scholarly journals Efficacy of the CDK4/6 Dual Inhibitor Abemaciclib in EGFR-Mutated NSCLC Cell Lines with Different Resistance Mechanisms to Osimertinib

Cancers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 6
Author(s):  
Silvia La Monica ◽  
Claudia Fumarola ◽  
Daniele Cretella ◽  
Mara Bonelli ◽  
Roberta Minari ◽  
...  
Keyword(s):  
Cell Lines ◽  
Kinase Inhibitor ◽  
Acquired Resistance ◽  
Growth Factor Receptor ◽  
Resistance Mechanisms ◽  
Resistant Cell ◽  
Nsclc Cell ◽  
Dual Inhibitor ◽  
Nsclc Patients ◽  
Egfr Mutated

Abemaciclib is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6 that inhibits the transition from the G1 to the S phase of the cell cycle by blocking downstream CDK4/6-mediated phosphorylation of Rb. The effects of abemaciclib alone or combined with the third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib were examined in a panel of PC9 and HCC827 osimertinib-resistant non-small cell lung cancer (NSCLC) cell lines carrying EGFR-dependent or -independent mechanisms of intrinsic or acquired resistance. Differently from sensitive cells, all the resistant cell lines analyzed maintained p-Rb, which may be considered as a biomarker of osimertinib resistance and a potential target for therapeutic intervention. In these models, abemaciclib inhibited cell growth, spheroid formation, colony formation, and induced senescence, and its efficacy was not enhanced in the presence of osimertinib. Interestingly, in osimertinib sensitive PC9, PC9T790M, and H1975 cells the combination of abemaciclib with osimertinib significantly inhibited the onset of resistance in long-term experiments. Our findings provide a preclinical support for using abemaciclib to treat resistance in EGFR mutated NSCLC patients progressed to osimertinib either as single treatment or combined with osimertinib, and suggest the combination of osimertinib with abemaciclib as a potential approach to prevent or delay osimertinib resistance in first-line treatment.

scholarly journals DDRE-07. DIPG HARBOUR ALTERATIONS TARGETABLE BY MEK INHIBITORS, WITH ACQUIRED RESISTANCE MECHANISMS OVERCOME BY COMBINATORIAL INHIBITION

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii62-ii62
Author(s):  
Elisa Izquierdo ◽  
Diana Carvalho ◽  
Alan Mackay ◽  
Sara Temelso ◽  
Jessica K R Boult ◽  
...  
Keyword(s):  
Drug Exposure ◽  
Mapk Pathway ◽  
Synergistic Effects ◽  
Acquired Resistance ◽  
Mek Inhibitor ◽  
Resistance Mechanisms ◽  
Genetic Alterations ◽  
Mesenchymal Transition

Abstract The survival of children with diffuse intrinsic pontine glioma (DIPG) remains dismal, with new treatments desperately needed. In the era of precision medicine, targeted therapies represent an exciting treatment opportunity, yet resistance can rapidly emerge, playing an important role in treatment failure. In a prospective biopsy-stratified clinical trial, we combined detailed molecular profiling (methylation BeadArray, exome, RNAseq, phospho-proteomics) linked to drug screening in newly-established patient-derived models of DIPG in vitro and in vivo. We identified a high degree of in vitro sensitivity to the MEK inhibitor trametinib (GI50 16-50nM) in samples, which harboured genetic alterations targeting the MAPK pathway, including the non-canonical BRAF_G469V mutation, and those affecting PIK3R1 and NF1. However, treatment of PDX models and of a patient with trametinib at relapse failed to elicit a significant response. We generated trametinib-resistant clones (62-188-fold, GI50 2.4–5.2µM) in the BRAF_G469V model through continuous drug exposure, and identified acquired mutations in MEK1/2 (MEK1_K57N, MEK1_I141S and MEK2_I115N) with sustained pathway up-regulation. These cells showed the hallmarks of mesenchymal transition, and expression signatures overlapping with inherently trametinib-insensitive primary patient-derived cells that predicted an observed sensitivity to dasatinib. Combinations of trametinib with dasatinib and the downstream ERK inhibitor ulixertinib showed highly synergistic effects in vitro. These data highlight the MAPK pathway as a therapeutic target in DIPG, and show the importance of parallel resistance modelling and rational combinatorial treatments likely to be required for meaningful clinical translation.

Genetic alterations in HRAS gene in relation to outcome and response to cetuximab in head and neck squamous cell carcinoma.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 5574-5574
Author(s):  
Theodoros Rampias ◽  
Athina Giagini ◽  
Hiroumi Matsuzaki ◽  
Valentina Bartzi ◽  
Spyros Siolos ◽  
...  
Keyword(s):  
Cell Lines ◽  
Mapk Pathway ◽  
Small Sample Size ◽  
Mutant Cell ◽  
Disease Free Survival ◽  
Genetic Alterations ◽  
Resistant Cell ◽  
Small Sample ◽  
The Impact ◽  
Hras Gene

5574 Background: Aberrant signaling through RAS/MAPK pathway is implicated in resistance to EGFR-targeted agents in cancer. Genetic alterations in Hras gene such as mutations and specific polymorphisms are associated with aggressive phenotype in several smoking-related malignancies. We sought to determine the impact of Hras genetic alterations on response to cetuximab and prognosis in HNSCC. Methods: Clinical outcome according to Hras status was investigated in a retrospective cohort of 140 HNSCC specimens. Primary endpoints were overall survival (OS) and disease-free survival (DFS) and secondary endpoint was treatment response. For statistical analysis, T-test was used for continuous data and x2 –test for categorical data. Cetuximab-resistant cell lines harboring mutant Hras (BB49, T24) were infected with lentivirus expressing shRNA targeting the Hras or a scrambled- shRNA. MTT assay was used to determine the effect of cetuximab on growth of lentivirus infected cells. Biochemical analysis involved immunoblotting for pERK1/2. Results: Mutationanalysis of tumor samples showed that 5.7% participants harbored Hras mutations and 16.42% harbored Hras polymorphisms (rs12628, rs41258054) that are associated with tumorigenesis. Patients bearing tumors with mutated Hras had inferior mean OS ( 22.13vs 35.20, p=0.02) and a non-significant trend for inferior mean DFS. Patients with tumors containing Hras genetic alterations (mutation or polymorphism) had significantly inferior mean OS (p=0.02) compared to those harboring wt Hras and trended towards inferior DFS (p=0.07). Patients had received various treatments such as surgery plus/minus RT and various chemotherapy regimens. A subgroup analysis of 38 patients treated with cetuximab-based regimens showed that wt Hras was associated with higher likelihood of attaining CR or PR to treatment of borderline significance (p=0.06) due to small sample size. Silencing of Hras in Hras-mutant cell lines restored sensitivity to cetuximab and caused a direct downregulation of pERK1/2 levels. Conclusions: Hras genetic alterations are associated with aggressive clinical course and may affect response to cetuximab in HNSCC.

scholarly journals Characterization of newly established Pralatrexate-resistant cell lines and the mechanisms of resistance

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kana Oiwa ◽  
Naoko Hosono ◽  
Rie Nishi ◽  
Luigi Scotto ◽  
Owen A. O’Connor ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Lines ◽  
Acquired Resistance ◽  
3D Culture ◽  
Resistance Mechanisms ◽  
Resistant Cell ◽  
Gene Set Enrichment Analysis ◽  
Synergistic Activity ◽  
Mechanisms Of Resistance ◽  
Resistant Cells

Abstract Background Pralatrexate (PDX) is a novel antifolate approved for the treatment of patients with relapsed/refractory peripheral T-cell lymphoma, but some patients exhibit intrinsic resistance or develop acquired resistance. Here, we evaluated the mechanisms underlying acquired resistance to PDX and explored potential therapeutic strategies to overcome PDX resistance. Methods To investigate PDX resistance, we established two PDX-resistant T-lymphoblastic leukemia cell lines (CEM and MOLT4) through continuous exposure to increasing doses of PDX. The resistance mechanisms were evaluated by measuring PDX uptake, apoptosis induction and folate metabolism-related protein expression. We also applied gene expression analysis and methylation profiling to identify the mechanisms of resistance. We then explored rational drug combinations using a spheroid (3D)-culture assay. Results Compared with their parental cells, PDX-resistant cells exhibited a 30-fold increase in half-maximal inhibitory concentration values. Induction of apoptosis by PDX was significantly decreased in both PDX-resistant cell lines. Intracellular uptake of [14C]-PDX decreased in PDX-resistant CEM cells but not in PDX-resistant MOLT4 cells. There was no significant change in expression of dihydrofolate reductase (DHFR) or folylpolyglutamate synthetase (FPGS). Gene expression array analysis revealed that DNA-methyltransferase 3β (DNMT3B) expression was significantly elevated in both cell lines. Gene set enrichment analysis revealed that adipogenesis and mTORC1 signaling pathways were commonly upregulated in both resistant cell lines. Moreover, CpG island hypermethylation was observed in both PDX resistant cells lines. In the 3D-culture assay, decitabine (DAC) plus PDX showed synergistic effects in PDX-resistant cell lines compared with parental lines. Conclusions The resistance mechanisms of PDX were associated with reduced cellular uptake of PDX and/or overexpression of DNMT3B. Epigenetic alterations were also considered to play a role in the resistance mechanism. The combination of DAC and PDX exhibited synergistic activity, and thus, this approach might improve the clinical efficacy of PDX.

scholarly journals Molecular Alterations Associated with Acquired Drug Resistance during Combined Treatment with Encorafenib and Binimetinib in Melanoma Cell Lines

Cancers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 6058
Author(s):  
Vikas Patel ◽  
István Szász ◽  
Viktória Koroknai ◽  
Tímea Kiss ◽  
Margit Balázs
Keyword(s):  
Drug Resistance ◽  
Cell Lines ◽  
Melanoma Cell ◽  
Acquired Resistance ◽  
Resistance Mechanisms ◽  
Resistant Cell ◽  
Differentially Expressed ◽  
Molecular Alterations ◽  
Melanoma Cell Lines ◽  
Resistant Cells

Combination treatment using BRAF/MEK inhibitors is a promising therapy for patients with advanced BRAFV600E/K mutant melanoma. However, acquired resistance largely limits the clinical efficacy of this drug combination. Identifying resistance mechanisms is essential to reach long-term, durable responses. During this study, we developed six melanoma cell lines with acquired resistance for BRAFi/MEKi treatment and defined the molecular alterations associated with drug resistance. We observed that the invasion of three resistant cell lines increased significantly compared to the sensitive cells. RNA-sequencing analysis revealed differentially expressed genes that were functionally linked to a variety of biological functions including epithelial-mesenchymal transition, the ROS pathway, and KRAS-signalling. Using proteome profiler array, several differentially expressed proteins were detected, which clustered into a unique pattern. Galectin showed increased expression in four resistant cell lines, being the highest in the WM1617E+BRes cells. We also observed that the resistant cells behaved differently after the withdrawal of the inhibitors, five were not drug addicted at all and did not exhibit significantly increased lethality; however, the viability of one resistant cell line (WM1617E+BRes) decreased significantly. We have selected three resistant cell lines to investigate the protein expression changes after drug withdrawal. The expression patterns of CapG, Enolase 2, and osteopontin were similar in the resistant cells after ten days of “drug holiday”, but the Snail protein was only expressed in the WM1617E+BRes cells, which showed a drug-dependent phenotype, and this might be associated with drug addiction. Our results highlight that melanoma cells use several types of resistance mechanisms involving the altered expression of different proteins to bypass drug treatment.

Establishment and Indentification of Genetic Alterations in Chemotherapy-Resistant T-ALL Cell Lines.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4423-4423
Author(s):  
David A. Estes ◽  
Rahul Poria ◽  
Debbie M. Lovato ◽  
Hadya M. Khawaja ◽  
Claudia L. Quan ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Cell Line ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Acquired Resistance ◽  
Genetic Alterations ◽  
Resistant Cell ◽  
Multi Drug Resistance ◽  
Growth Media ◽  
Drug Resistant

Abstract Acquisition of drug resistance in tumor cells in children with T-cell acute lymphoblastic leukemia (T-ALL) during chemotherapy results in relapse and poor outcome. T-ALL cell lines that have acquired resistance to chemotherapeutics are therefore critical tools for the study of acquired resistance, yet there is a paucity of cell lines available for study. In this study, we hypothesize that drug resistant T-ALL cells can be produced by prolonged exposure to chemotherapeutics and that microarray analysis can be employed to identify the gene products responsible for acquired drug resistance. By incrementally increasing the drug concentration in growth media, we have produced T-ALL cell lines (Jurkat and Sup T1) that grow well in the presence of therapeutic concentrations of L-asparaginase (ASNase) and daunorubicin (DNR). The genetic profiles of the drug-resistant cell lines were compared to their parental progenitors using the Affymetrix HG-U133Plus2 GeneChip platform, capable of hybridizing ~54,000 genes and ESTs/chip. Signal intensity was normalized using the robust multi-array average (RMA) technique in GeneSpring 7.2. The Sup T1 and Jurkat ASNase-resistant cell lines increased their IC50s 26-fold (0.044 IU/mL to 1.14 IU/mL) and 320-fold (0.003 IU/mL to 0.96 IU/mL), respectively. The IC50 of the Jurkat DNR resistant cell line increased 77-fold (30 nM to 2300 nM), and 4.0-fold, (0.46 nM to 1.85 nM), respectively. Notably, DNR resistant Jurkat cells were also resistant to therapeutic concentrations of vincristine and prednisolone, but not ASNase. In contrast, the ASNase resistant cell lines remained sensitive to DNR, vincristine, and prednisolone. Microarray data comparing DNR-resistant and parental cell lines showed 288 genes upregulated >1.5-fold in the resistant line. Two sets of genes were the most upregulated in the drug resistant cells in comparison to parental cells. ABCB1 (ABC transporter P-glycoprotein) was upregulated ~940-fold and genes coding for 6 different killer-cell immunoglobulin-like receptors (KIRs) were upregulated >6-fold. In the case of the ASNase-resistant cell lines, 96 genes were found to be upregulated >1.5-fold in both Jurkat and Sup T1 lines. The most highly upregulated gene in both cell lines was argininosuccinate synthase (ASS), 32-fold upregulated in Jurkat and 6.5-fold in Sup T1. All expression results were confirmed by qRT-PCR. These genes have previously been implicated in the acquisition of drug resistance: ASS is critical for responding to asparagine depletion caused by ASNase. ABCB1 acts as a molecular pump capable of lowering intracellular concentrations of substrate chemotherapeutics such as DNR, vincristine, and prednisolone, consistent with our observation of multi-drug resistance in that cell line. To our knowledge, this is the first description of DNR and ASNase resistant Jurkat and Sup T1 T-ALL cell lines. In addition, our results suggest that microarray technology is a valid method for elucidating the genetic nature of drug resistance in T-ALL cell lines, making it a productive approach to identify mechanisms of chemotherapy resistance. Finally, these cell lines will serve as useful tools for studying mechanisms of chemotherapeutic resistance in T-ALL.

scholarly journals Drivers of AR indifferent anti-androgen resistance in prostate cancer cells

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Florian Handle ◽  
Stefan Prekovic ◽  
Christine Helsen ◽  
Thomas Van den Broeck ◽  
Elien Smeets ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cell Lines ◽  
Parp Inhibitor ◽  
Resistance Mechanisms ◽  
Resistant Cell ◽  
Cross Resistance ◽  
Castration Resistant Prostate Cancer ◽  
Tissue Samples ◽  
Cellular Models ◽  
Castration Resistant

Abstract Inhibition of the androgen receptor (AR) by second-generation anti-androgens is a standard treatment for metastatic castration resistant prostate cancer (mCRPC), but it inevitably leads to the development of resistance. Since the introduction of highly efficient AR signalling inhibitors, approximately 20% of mCRPC patients develop disease with AR independent resistance mechanisms. In this study, we generated two anti-androgen and castration resistant prostate cancer cell models that do not rely on AR activity for growth despite robust AR expression (AR indifferent). They are thus resistant against all modern AR signalling inhibitors. Both cell lines display cross-resistance against the chemotherapeutic drug docetaxel due to MCL1 upregulation but remain sensitive to the PARP inhibitor olaparib and the pan-BCL inhibitor obatoclax. RNA-seq analysis of the anti-androgen resistant cell lines identified hyper-activation of the E2F cell-cycle master regulator as driver of AR indifferent growth, which was caused by deregulation of cyclin D/E, E2F1, RB1, and increased Myc activity. Importantly, mCRPC tissue samples with low AR activity displayed the same alterations and increased E2F activity. In conclusion, we describe two cellular models that faithfully mimic the acquisition of a treatment induced AR independent phenotype that is cross-resistant against chemotherapy and driven by E2F hyper-activation.

scholarly journals TDP1 and TOP1 Modulation in Olaparib-Resistant Cancer Determines the Efficacy of Subsequent Chemotherapy

Cancers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 334 ◽  
Author(s):  
Jin Won Kim ◽  
Ahrum Min ◽  
Seock-Ah Im ◽  
Hyemin Jang ◽  
Yu Jin Kim ◽  
...  
Keyword(s):  
Cell Lines ◽  
Brca2 Mutation ◽  
Acquired Resistance ◽  
Xenograft Model ◽  
Underlying Mechanism ◽  
Resistant Cell ◽  
Cross Resistance ◽  
Topoisomerase 1 ◽  
Underlying Mechanisms ◽  
Resistant Cells

The aim of this study was to elucidate the carryover effect of olaparib to subsequent chemotherapy and its underlying mechanisms. We generated olaparib-resistant SNU-484, SNU-601, SNU-668, and KATO-III gastric cancer cell lines and confirmed their resistance by cell viability and colony forming assays. Notably, olaparib-resistant cell lines displayed cross-resistance to cisplatin except for KATO-III. Inversely, olaparib-resistant SNU-484, SNU-668, and KATO-III were more sensitive to irinotecan than their parental cells. However, sensitivity to paclitaxel remained unaltered. There were compensatory changes in the ATM/ATR axis and p-Chk1/2 protein expression. ERCC1 was also induced in olaparib-resistant SNU-484, SNU-601, and SNU-668, which showed cross-resistance to cisplatin. Olaparib-resistant cells showed tyrosyl-DNA phosphodiesterase 1 (TDP1) downregulation with higher topoisomerase 1 (TOP1) activity, which is a target of irinotecan. These changes of TOP1 and TDP1 in olaparib-resistant cells was confirmed as the underlying mechanism for increased irinotecan sensitivity through manipulated gene expression of TOP1 and TDP1 by specific plasmid transfection and siRNA. The patient-derived xenograft model established from the patient who acquired resistance to olaparib with BRCA2 mutation showed increased sensitivity in irinotecan. In conclusion, the carryover effects of olaparib to improve antitumor effect of subsequent irinotecan were demonstrated. These effects should be considered when determining the subsequent therapy with olaparib.

scholarly journals Comparative Study of the Effect of Solvents on the Efficacy of Neonicotinoid Insecticides Against Malaria Vector Populations Across Africa

2022 ◽  
Author(s):  
Magellan Tchouakui ◽  
Tatiane Assatse ◽  
Leon M. J. Mugenzi ◽  
Benjamin D. Menze ◽  
Daniel Nguiffo-Nguete ◽  
...  
Keyword(s):  
Democratic Republic Of Congo ◽  
Natural Populations ◽  
Resistance Mechanisms ◽  
Lower Mortality ◽  
Malaria Vectors ◽  
Cross Resistance ◽  
Metabolic Resistance ◽  
Resistance Development ◽  
Development Of Resistance ◽  
Bottle Test

Abstract Background New insecticides with a novel mode of action such as neonicotinoids have recently been recommended for public health by WHO. Resistance monitoring of such novel insecticides requires a robust protocol to monitor the development of resistance in natural populations. In this study, we comparatively used three different solvents to assess the susceptibility of malaria vectors to neonicotinoids across Africa.MethodsMosquitoes were collected from May to July 2021 from three agricultural settings in Cameroon (Njombe-Penja, Nkolondom, and Mangoum), the Democratic Republic of Congo (Ndjili-Brasserie), Ghana (Obuasi), and Uganda (Mayuge). Using the CDC bottle test, we compared the effect of three different solvents (ethanol, acetone, MERO) on the efficacy of neonicotinoids against Anopheles gambiae s.l. In addition, TaqMan assays were used to genotype key pyrethroid-resistant markers in An. gambiae and to evaluate potential cross-resistance between pyrethroids and clothianidin.ResultsLower mortality were observed when using absolute ethanol or acetone alone as solvent (11.4- 51.9% mortality in Nkolondom, 31.7- 48.2% in Mangoum, 34.6- 56.1% in Mayµge, 39.4- 45.6% in Obuasi, 83.7- 89.3% in Congo and 71.05- 95.9% in Njombe pendja) compared to acetone + MERO for which 100% mortality were observed for all the populations. Synergist assays (PBO, DEM and DEF) revealed a significant increase of mortality suggesting that metabolic resistance mechanisms are contributing to the reduced susceptibility. A negative association was observed between the L1014F-kdr mutation and clothianidin resistance with a greater frequency of homozygote resistant mosquitoes among the dead than among survivors (OR=0.5; P=0.02). However, the I114T-GSTe2 was in contrast significantly associated with a greater ability to survive clothianidin with a higher frequency of homozygote resistant among survivors than other genotypes (OR=2.10; P=0.013). ConclusionsThis study revealed a contrasted susceptibility pattern depending on the solvents with ethanol/acetone resulting to lower mortality, thus possibly overestimating resistance, whereas the MERO consistently showed a greater efficacy of neonicotinoids but it could prevent to detect early resistance development. Therefore, we recommend monitoring the susceptibility using both acetone alone and acetone+MERO (8-10µg/ml for clothianidin) to capture the accurate resistance profile of the mosquito populations.

scholarly journals Oxidative Stress-Related Mechanisms in Melanoma and in the Acquired Resistance to Targeted Therapies

Antioxidants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1942
Author(s):  
Stefania Pizzimenti ◽  
Simone Ribero ◽  
Marie Angele Cucci ◽  
Margherita Grattarola ◽  
Chiara Monge ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Targeted Therapies ◽  
Current Knowledge ◽  
Mapk Pathway ◽  
Acquired Resistance ◽  
Genetic Alterations ◽  
Advanced Melanoma ◽  
Braf Mutations ◽  
Downstream Signaling ◽  
Activating Mutations

Melanoma is a highly aggressive cancer with the poorest prognosis, representing the deadliest form of skin cancer. Activating mutations in BRAF are the most frequent genetic alterations, present in approximately 50% of all melanoma cases. The use of specific inhibitors towards mutant BRAF variants and MEK, a downstream signaling target of BRAF in the MAPK pathway, has significantly improved progression-free and overall survival in advanced melanoma patients carrying BRAF mutations. Nevertheless, despite these improvements, resistance still develops within the first year of therapy in around 50% of patients, which is a significant problem in managing BRAF-mutated advanced melanoma. Understanding these mechanisms is one of the mainstreams of the research on BRAFi/MEKi acquired resistance. Both genetic and epigenetic mechanisms have been described. Moreover, in recent years, oxidative stress has emerged as another major force involved in all the phases of melanoma development, from initiation to progression until the onsets of the metastatic phenotype and chemoresistance, and has thus become a target for therapy. In the present review, we discuss the current knowledge on oxidative stress and its signaling in melanoma, as well as the oxidative stress-related mechanisms in the acquired resistance to targeted therapies.

Sign in / Sign up

Export Citation Format

Share Document