2023
Lenvatinib or anti-VEGF in combination with anti-PD-1 differentially augments anti-tumor activity in melanoma
Tran T, Caulfield J, Zhang L, Schoenfeld D, Djureinovic D, Chiang V, Oria V, Weiss S, Olino K, Jilaveanu L, Kluger H. Lenvatinib or anti-VEGF in combination with anti-PD-1 differentially augments anti-tumor activity in melanoma. JCI Insight 2023, 8: e157347. PMID: 36821392, PMCID: PMC10132152, DOI: 10.1172/jci.insight.157347.Peer-Reviewed Original ResearchConceptsTumor microenvironmentAnti-VEGFCytokine/chemokine signalingCytokine/chemokine profilingBlood-brain barrier modelBlood vesselsLeukocyte transmigrationTumor-associated blood vesselsTumor-associated macrophagesIntratumoral blood vesselsAnti-angiogenesis effectAnti-tumor activityExtracranial diseasePlasmacytoid DCsImmune checkpointsPD-1Melanoma murine modelImmune infiltrationBBB modelChemokine profilingEndothelial stabilizationMurine modelLenvatinibCombined targetingMelanoma model
2021
KDM5B promotes immune evasion by recruiting SETDB1 to silence retroelements
Zhang SM, Cai WL, Liu X, Thakral D, Luo J, Chan LH, McGeary MK, Song E, Blenman KRM, Micevic G, Jessel S, Zhang Y, Yin M, Booth CJ, Jilaveanu LB, Damsky W, Sznol M, Kluger HM, Iwasaki A, Bosenberg MW, Yan Q. KDM5B promotes immune evasion by recruiting SETDB1 to silence retroelements. Nature 2021, 598: 682-687. PMID: 34671158, PMCID: PMC8555464, DOI: 10.1038/s41586-021-03994-2.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsCell Line, TumorDNA-Binding ProteinsEpigenesis, GeneticGene SilencingHeterochromatinHistone-Lysine N-MethyltransferaseHumansInterferon Type IJumonji Domain-Containing Histone DemethylasesMaleMelanomaMiceMice, Inbred C57BLMice, KnockoutNuclear ProteinsRepressor ProteinsRetroelementsTumor EscapeConceptsImmune checkpoint blockadeImmune evasionCheckpoint blockadeImmune responseAnti-tumor immune responseRobust adaptive immune responseTumor immune evasionAnti-tumor immunityAdaptive immune responsesType I interferon responseDNA-sensing pathwayMouse melanoma modelImmunotherapy resistanceMost patientsCurrent immunotherapiesTumor immunogenicityImmune memoryMelanoma modelCytosolic RNA sensingRole of KDM5BConsiderable efficacyInterferon responseImmunotherapyEpigenetic therapyBlockade
2020
Regulation of eIF2α by RNF4 Promotes Melanoma Tumorigenesis and Therapy Resistance
Avitan-Hersh E, Feng Y, Oknin Vaisman A, Abu Ahmad Y, Zohar Y, Zhang T, Lee JS, Lazar I, Sheikh Khalil S, Feiler Y, Kluger H, Kahana C, Brown K, Ruppin E, Ronai ZA, Orian A. Regulation of eIF2α by RNF4 Promotes Melanoma Tumorigenesis and Therapy Resistance. Journal Of Investigative Dermatology 2020, 140: 2466-2477. PMID: 32360601, PMCID: PMC8081033, DOI: 10.1016/j.jid.2020.04.008.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsCarcinogenesisCell Line, TumorDrug Resistance, NeoplasmEukaryotic Initiation Factor-2FemaleGene Expression Regulation, NeoplasticHumansKaplan-Meier EstimateMelanomaMiceMitogen-Activated Protein KinasesNuclear ProteinsOncogenesPrognosisProtein Kinase InhibitorsProtein StabilityProto-Oncogene Proteins B-rafSkinSkin NeoplasmsTranscription FactorsUbiquitinationXenograft Model Antitumor AssaysConceptsUbiquitin ligase RNF4Elongation factor alphaPatient-derived melanomasIntegrated stress responseTherapy resistancePositive feed-forward loopTranscription factor 4Feed-forward loopOncogenic translationMolecular machineryMajor clinical challengePhosphorylated eIF2αHallmark of melanomaXenograft mouse modelHomologous proteinsStress responseMAPK inhibitorProtein stabilizationMelanoma tumorigenesisTumorigenic propertiesPoor prognosisFactor alphaClinical challengeMouse modelRNF4
2019
B cell depletion or absence does not impede anti-tumor activity of PD-1 inhibitors
Damsky W, Jilaveanu L, Turner N, Perry C, Zito C, Tomayko M, Leventhal J, Herold K, Meffre E, Bosenberg M, Kluger HM. B cell depletion or absence does not impede anti-tumor activity of PD-1 inhibitors. Journal For ImmunoTherapy Of Cancer 2019, 7: 153. PMID: 31200747, PMCID: PMC6567557, DOI: 10.1186/s40425-019-0613-1.Peer-Reviewed Original ResearchConceptsPD-1 inhibitorsB cell contentB-cell depletionAnti-tumor activityB cellsMuMT miceCell depletionAnti-PD-1 inhibitorsAnti-PD-1 responseB-cell depleting drugsTumor-infiltrating B cellsImpaired B-cell functionT cell-dependent tumor rejectionPD-1 inhibitionMC38 colon cancerB cell functionAnti-tumor effectsB-cell malignanciesMurine cancer modelsCell contentOverall survivalTumor rejectionCD20 antibodyAutoimmune disordersTumor shrinkageA First-in-Human Study and Biomarker Analysis of NKTR-214, a Novel IL2Rβγ-Biased Cytokine, in Patients with Advanced or Metastatic Solid Tumors
Bentebibel SE, Hurwitz ME, Bernatchez C, Haymaker C, Hudgens CW, Kluger HM, Tetzlaff MT, Tagliaferri MA, Zalevsky J, Hoch U, Fanton C, Aung S, Hwu P, Curti BD, Tannir NM, Sznol M, Diab A. A First-in-Human Study and Biomarker Analysis of NKTR-214, a Novel IL2Rβγ-Biased Cytokine, in Patients with Advanced or Metastatic Solid Tumors. Cancer Discovery 2019, 9: 711-721. PMID: 30988166, DOI: 10.1158/2159-8290.cd-18-1495.Peer-Reviewed Original ResearchConceptsNKTR-214Tumor biopsiesDurable disease stabilizationImmuno-oncology agentsMulticenter phase IPathway-targeted agentsTreatment tumor biopsiesPhase II doseActivation of CD8Metastatic solid tumorsNatural killer cellsOutpatient regimenCheckpoint inhibitorsDisease stabilizationRegulatory cellsEffector phenotypeKiller cellsTreatment algorithmImmune activationTumor shrinkagePharmacodynamic markersImmune cellsClinical activityIL2 receptorHuman studies
2017
SHARPIN-mediated regulation of protein arginine methyltransferase 5 controls melanoma growth
Tamiya H, Kim H, Klymenko O, Kim H, Feng Y, Zhang T, Han JY, Murao A, Snipas SJ, Jilaveanu L, Brown K, Kluger H, Zhang H, Iwai K, Ronai Z. SHARPIN-mediated regulation of protein arginine methyltransferase 5 controls melanoma growth. Journal Of Clinical Investigation 2017, 128: 517-530. PMID: 29227283, PMCID: PMC5749505, DOI: 10.1172/jci95410.Peer-Reviewed Original ResearchMeSH KeywordsCell Line, TumorHEK293 CellsHumansMelanomaNeoplasm ProteinsProtein-Arginine N-MethyltransferasesSOXE Transcription FactorsUbiquitinsConceptsLinear ubiquitin chain assembly complexType II protein arginine methyltransferaseProtein arginine methyltransferase 5Protein arginine methyltransferaseTranscription factor Sox10Cyclin-dependent kinase inhibitor 2ATranscriptional corepressor SKIArginine dimethylationArginine methyltransferasePRMT5 activityAssembly complexMelanoma growthMethyltransferase activityPRMT5PRMT5 inhibitionRegulatory axisInhibitor 2ASHARPINNF-κB signalingHuman cancersMethylthioadenosine phosphorylaseMultiproteinImportant roleDimethylationMethyltransferase
2015
The transcription factor ATF2 promotes melanoma metastasis by suppressing protein fucosylation
Lau E, Feng Y, Claps G, Fukuda MN, Perlina A, Donn D, Jilaveanu L, Kluger H, Freeze HH, Ronai ZA. The transcription factor ATF2 promotes melanoma metastasis by suppressing protein fucosylation. Science Signaling 2015, 8: ra124. PMID: 26645581, PMCID: PMC4818095, DOI: 10.1126/scisignal.aac6479.Peer-Reviewed Original ResearchConceptsProtein fucosylationFucose salvage pathwayTranscription factor ATF2Tumor microarray analysisProtein kinase CεTranscription factor 2Human melanoma specimensTranscriptional repressionPrimary melanoma growthPrimary melanocytesGenetic manipulationActive ATF2Cell motilityElucidation of mechanismsMicroarray analysisSalvage pathwayATF2Cell adhesionHigh abundanceCellular adhesionReduced motilityInvasive behaviorCell linesFactor 2Melanoma specimensCharacterization of PD-L1 Expression and Associated T-cell Infiltrates in Metastatic Melanoma Samples from Variable Anatomic Sites
Kluger HM, Zito CR, Barr ML, Baine MK, Chiang VL, Sznol M, Rimm DL, Chen L, Jilaveanu LB. Characterization of PD-L1 Expression and Associated T-cell Infiltrates in Metastatic Melanoma Samples from Variable Anatomic Sites. Clinical Cancer Research 2015, 21: 3052-3060. PMID: 25788491, PMCID: PMC4490112, DOI: 10.1158/1078-0432.ccr-14-3073.Peer-Reviewed Original ResearchConceptsPD-L1 expressionT-cell contentPD-1/PD-L1 inhibitorsHigher T-cell contentT-cell infiltratesPD-L1 inhibitorsAnatomic sitesBrain metastasesMetastatic melanomaTissue microarrayHigh PD-L1 expressionLess PD-L1 expressionLow PD-L1 expressionTumor PD-L1 expressionHigher TIL contentImproved overall survivalT cell infiltrationLess T cellsMetastatic melanoma samplesExtracerebral metastasesCerebral metastasesOverall survivalDermal metastasesImproved survivalPD-L1PLEKHA5 as a Biomarker and Potential Mediator of Melanoma Brain Metastasis
Jilaveanu LB, Parisi F, Barr ML, Zito CR, Cruz-Munoz W, Kerbel RS, Rimm DL, Bosenberg MW, Halaban R, Kluger Y, Kluger HM. PLEKHA5 as a Biomarker and Potential Mediator of Melanoma Brain Metastasis. Clinical Cancer Research 2015, 21: 2138-2147. PMID: 25316811, PMCID: PMC4397107, DOI: 10.1158/1078-0432.ccr-14-0861.Peer-Reviewed Original ResearchMeSH KeywordsAdultAgedAged, 80 and overBiomarkers, TumorBrain NeoplasmsCell Line, TumorFemaleFluorescent Antibody TechniqueGene Expression ProfilingHumansImage Processing, Computer-AssistedIntracellular Signaling Peptides and ProteinsMaleMelanomaMiddle AgedNeoplasm InvasivenessTissue Array AnalysisTranscriptomeYoung AdultConceptsCell line modelsBlood-brain barrierBrain metastasesGene expression profilesGene expression profilingExpression profilingExpression profilesPLEKHA5Brain metastasis-free survivalA375P cellsQuantitative immunofluorescenceEarly brain metastasisMelanoma brain metastasesMetastasis-free survivalProfile of patientsPotential mediatorsProtein levelsMetastatic melanoma casesEarly developmentMelanoma cellsKnockdownDecrease proliferationBBB transmigrationExtracerebral sitesMetastatic sitesRole of Chitinase 3–like-1 and Semaphorin 7a in Pulmonary Melanoma Metastasis
Ma B, Herzog EL, Lee CG, Peng X, Lee CM, Chen X, Rockwell S, Koo JS, Kluger H, Herbst RS, Sznol M, Elias JA. Role of Chitinase 3–like-1 and Semaphorin 7a in Pulmonary Melanoma Metastasis. Cancer Research 2015, 75: 487-496. PMID: 25511377, PMCID: PMC4321965, DOI: 10.1158/0008-5472.can-13-3339.Peer-Reviewed Original ResearchConceptsMelanoma lung metastasisPulmonary melanoma metastasesPulmonary metastasesLung metastasesMelanoma metastasesGenetic deletionBreast cancer cellsPlexin C1 receptorsPulmonary microenvironmentPoor prognosisSemaphorin 7AMelanoma spreadChitinase 3MetastasisCHI3L1Cancer progressionSema7AInhibitory wayCancer cellsReceptorsSignificant reductionΒ1 integrinNovel pathwayCritical roleIL13Rα2Identification of Novel Radiosensitizers in a High-Throughput, Cell-Based Screen for DSB Repair Inhibitors
Goglia AG, Delsite R, Luz AN, Shahbazian D, Salem AF, Sundaram RK, Chiaravalli J, Hendrikx PJ, Wilshire JA, Jasin M, Kluger HM, Glickman JF, Powell SN, Bindra RS. Identification of Novel Radiosensitizers in a High-Throughput, Cell-Based Screen for DSB Repair Inhibitors. Molecular Cancer Therapeutics 2015, 14: 326-342. PMID: 25512618, PMCID: PMC4326563, DOI: 10.1158/1535-7163.mct-14-0765.Peer-Reviewed Original ResearchConceptsDSB repair inhibitorsDouble-strand breaksDSB repairHomologous recombinationRepair inhibitorsCell-based small molecule screenSuccessful DSB repairDNA-damaging agentsPlate-based formatCell-based screenSmall-molecule screenGenomic integrityTumor cell survivalMammalian cellsHR repairDNA repairMolecule screenReporter systemSecondary assaysCell survivalDNA damageCancer cell linesTumor cellsNovel hitsMost cancer therapies
2013
Genetic inactivation or pharmacological inhibition of Pdk1 delays development and inhibits metastasis of BrafV600E::Pten–/– melanoma
Scortegagna M, Ruller C, Feng Y, Lazova R, Kluger H, Li JL, De SK, Rickert R, Pellecchia M, Bosenberg M, Ronai ZA. Genetic inactivation or pharmacological inhibition of Pdk1 delays development and inhibits metastasis of BrafV600E::Pten–/– melanoma. Oncogene 2013, 33: 4330-4339. PMID: 24037523, PMCID: PMC3955742, DOI: 10.1038/onc.2013.383.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsCarcinogenesisCell Line, TumorForkhead Box Protein O3Forkhead Transcription FactorsGene Knockout TechniquesHumansIndazolesLung NeoplasmsLymphatic MetastasisMelanoma, ExperimentalMiceMice, KnockoutMutation, MissenseProtein Serine-Threonine KinasesProto-Oncogene Proteins B-rafPTEN PhosphohydrolasePyrimidinesPyruvate Dehydrogenase Acetyl-Transferring KinaseSignal TransductionSkin NeoplasmsTissue Array AnalysisConceptsPhosphoinositide-dependent kinase 1Protein kinase CAGC kinasesSerine/threonine protein kinasePDK1 expressionThreonine protein kinaseImportant cellular processesDirect genetic evidenceGene expression analysisActivity of AktCellular processesProtein kinaseGenetic evidenceExpression analysisPDK1 deletionKinase 1Kinase CElevated phosphorylationGenetic inactivationKinaseMelanoma invasionMelanoma developmentColony formationPharmacological inhibitionInhibits metastasisRadiation sensitivity and sensitization in melanoma
Shahbazian D, Bindra RS, Kluger HM, Glazer PM. Radiation sensitivity and sensitization in melanoma. Pigment Cell & Melanoma Research 2013, 26: 928-930. PMID: 23870422, PMCID: PMC3866027, DOI: 10.1111/pcmr.12147.Peer-Reviewed Original Research
2012
c-Met is a prognostic marker and potential therapeutic target in clear cell renal cell carcinoma
Gibney GT, Aziz SA, Camp RL, Conrad P, Schwartz BE, Chen CR, Kelly WK, Kluger HM. c-Met is a prognostic marker and potential therapeutic target in clear cell renal cell carcinoma. Annals Of Oncology 2012, 24: 343-349. PMID: 23022995, PMCID: PMC3551486, DOI: 10.1093/annonc/mds463.Peer-Reviewed Original ResearchMeSH KeywordsAdultAgedAged, 80 and overAntineoplastic AgentsBiomarkers, TumorCarcinoma, Renal CellCell Line, TumorCell ProliferationFemaleHepatocyte Growth FactorHumansIndolesKidney NeoplasmsMaleMiddle AgedPiperazinesPrognosisProto-Oncogene Proteins c-metPyrrolidinonesQuinolinesSulfonamidesTissue Array AnalysisConceptsRenal cell carcinomaClear cell renal cell carcinomaC-Met expressionCell renal cell carcinomaHigh c-Met expressionAdjacent normal renal tissuesNormal renal tissueARQ 197Cell carcinomaRenal tissueRCC tumorsTissue microarrayWorse disease-specific survivalC-MetClear cell RCC cell linesC-Met protein expressionCell linesPoor pathologic featuresCell subset analysisDisease-specific survivalPapillary renal cell carcinomaRange of malignanciesC-Met pathwayC-Met inhibitionPotential therapeutic targetIntegrated analysis of tumor samples sheds light on tumor heterogeneity.
Parisi F, Micsinai M, Strino F, Ariyan S, Narayan D, Bacchiocchi A, Cheng E, Xu F, Li P, Kluger H, Halaban R, Kluger Y. Integrated analysis of tumor samples sheds light on tumor heterogeneity. The Yale Journal Of Biology And Medicine 2012, 85: 347-61. PMID: 23012583, PMCID: PMC3447199.Peer-Reviewed Original ResearchMeSH KeywordsCell Line, TumorChromosome MappingChromosomes, HumanDNA Copy Number VariationsEvolution, MolecularGene Expression ProfilingGene Expression Regulation, NeoplasticGenes, NeoplasmHumansIntercellular Signaling Peptides and ProteinsKaryotypingMelanomaMutationOligonucleotide Array Sequence AnalysisPolymorphism, Single NucleotideProto-Oncogene Proteins B-rafConceptsHigh-throughput profilingGene expression levelsExpression levelsDifferent gene expression levelsGene expression profilingCopy number analysisExpression profilingSNP arrayPathway analysisCopy number statusWnt pathwayTumor samplesNumber alteration profilesTumor heterogeneityTumor evolutionCopy number alteration profilesGenomic aberrationsIntegrated analysisCell linesTumor subclonesNumber analysisNumber statusProfilingDriver mutationsRecurrent associationMulti-Level Targeting of the Phosphatidylinositol-3-Kinase Pathway in Non-Small Cell Lung Cancer Cells
Zito CR, Jilaveanu LB, Anagnostou V, Rimm D, Bepler G, Maira SM, Hackl W, Camp R, Kluger HM, Chao HH. Multi-Level Targeting of the Phosphatidylinositol-3-Kinase Pathway in Non-Small Cell Lung Cancer Cells. PLOS ONE 2012, 7: e31331. PMID: 22355357, PMCID: PMC3280285, DOI: 10.1371/journal.pone.0031331.Peer-Reviewed Original ResearchMeSH KeywordsAdenocarcinomaAdultAgedAged, 80 and overAntineoplastic AgentsBlotting, WesternCarcinoma, Non-Small-Cell LungCarcinoma, Squamous CellCell Line, TumorCell ProliferationClass Ia Phosphatidylinositol 3-KinaseDrug SynergismFemaleFluorescent Antibody TechniqueHumansImmunoenzyme TechniquesLung NeoplasmsMaleMiddle AgedPhosphoinositide-3 Kinase InhibitorsProtein Kinase InhibitorsProto-Oncogene Proteins c-aktSignal TransductionTissue Array AnalysisTOR Serine-Threonine KinasesConceptsNon-small cell lung cancerNSCLC cell linesDual PI3K/mTOR inhibitorPI3K/AKT/mTOR pathwayPI3K/mTOR inhibitorAKT/mTOR pathwayPI3K inhibitorsNVP-BEZ235MTOR inhibitorsNVP-BKM120MTOR expressionAdvanced stageCell linesMTOR pathwayPI3K subunitsNon-small cell lung cancer cellsK inhibitorsCell lung cancer cellsCell lung cancerSquamous cell carcinomaP85 expressionSynergistic growth inhibitionRegulation of pAktExpression of p85Lung cancer cellsPKCε Promotes Oncogenic Functions of ATF2 in the Nucleus while Blocking Its Apoptotic Function at Mitochondria
Lau E, Kluger H, Varsano T, Lee K, Scheffler I, Rimm DL, Ideker T, Ronai ZA. PKCε Promotes Oncogenic Functions of ATF2 in the Nucleus while Blocking Its Apoptotic Function at Mitochondria. Cell 2012, 148: 543-555. PMID: 22304920, PMCID: PMC3615433, DOI: 10.1016/j.cell.2012.01.016.Peer-Reviewed Original ResearchConceptsTumor suppressor functionGenotoxic stressNuclear exportSuppressor functionTranscription factor ATF2Tumor suppressor activityApoptotic functionSubcellular localizationMelanoma tumor samplesNuclear localizationMitochondrial permeabilityOncogenic functionOncogenic activityATF2MitochondriaPKCε levelsSuppressor activityMembrane permeabilityMelanoma cellsPKCεApoptosisTumor samplesLocalization
2011
Characterization and targeting of phosphatidylinositol-3 kinase (PI3K) and mammalian target of rapamycin (mTOR) in renal cell cancer
Elfiky AA, Aziz SA, Conrad PJ, Siddiqui S, Hackl W, Maira M, Robert CL, Kluger HM. Characterization and targeting of phosphatidylinositol-3 kinase (PI3K) and mammalian target of rapamycin (mTOR) in renal cell cancer. Journal Of Translational Medicine 2011, 9: 133. PMID: 21834980, PMCID: PMC3173341, DOI: 10.1186/1479-5876-9-133.Peer-Reviewed Original ResearchMeSH KeywordsApoptosisAutomationBiomarkers, TumorCarcinoma, Renal CellCell Line, TumorChromonesDrug SynergismHumansImidazolesInhibitory Concentration 50Kidney NeoplasmsMolecular Targeted TherapyMorpholinesMultivariate AnalysisPhosphatidylinositol 3-KinasePhosphoinositide-3 Kinase InhibitorsProtein Kinase InhibitorsQuinolinesSirolimusTOR Serine-Threonine KinasesConceptsRenal cell carcinomaRCC cell linesNVP-BEZ235PI3KMTOR expressionMetastatic renal cell carcinomaPI3K subunitsHigh mTOR expressionAutomated Quantitative AnalysisRCC cell growthRenal cell cancerExpression of p85PI3K inhibitor LY294002Cell linesWarrants further investigationK inhibitor LY294002PI3K inhibitorsMulti-variable analysisCell cancerCell carcinomaClinical trialsSitu protein expressionNephrectomy casesTissue microarrayMTOR inhibitorsIn vitro studies of dasatinib, its targets and predictors of sensitivity
Jilaveanu LB, Zito CR, Aziz SA, Chakraborty A, Davies MA, Camp RL, Rimm DL, Dudek A, Sznol M, Kluger HM. In vitro studies of dasatinib, its targets and predictors of sensitivity. Pigment Cell & Melanoma Research 2011, 24: 386-389. PMID: 21320292, PMCID: PMC4431976, DOI: 10.1111/j.1755-148x.2011.00835.x.Peer-Reviewed Original Research
2010
A Role for ATF2 in Regulating MITF and Melanoma Development
Shah M, Bhoumik A, Goel V, Dewing A, Breitwieser W, Kluger H, Krajewski S, Krajewska M, DeHart J, Lau E, Kallenberg DM, Jeong H, Eroshkin A, Bennett DC, Chin L, Bosenberg M, Jones N, Ronai ZA. A Role for ATF2 in Regulating MITF and Melanoma Development. PLOS Genetics 2010, 6: e1001258. PMID: 21203491, PMCID: PMC3009656, DOI: 10.1371/journal.pgen.1001258.Peer-Reviewed Original ResearchConceptsMelanoma developmentMouse melanoma modelHuman melanoma cell linesMITF expressionMelanoma tissue microarrayMelanoma cell linesMetastatic diseasePoor prognosisTissue microarrayXenograft modelMelanoma modelPrimary specimensPrimary human melanocytesOncogenic BRAFMiceGene expression profilingHigh MITF expressionDependent suppressionATF2 knockdownCell linesSoft agarHuman melanocytesMelanocytesMelanoma susceptibilityPrimary melanocytes