title: HDAC8 Inhibition Blocks SMC3 Deacetylation and Delays Cell Cycle Progression without Affecting Cohesin-dependent Transcription in MCF7 Cancer Cells.
abstract: Cohesin, a multi-subunit protein complex involved in chromosome organization, is frequently mutated or aberrantly expressed in cancer. Multiple functions of cohesin, including cell division and gene expression, highlight its potential as a novel therapeutic target. The SMC3 subunit of cohesin is acetylated (ac) during S phase to establish cohesion between replicated chromosomes. Following anaphase, ac-SMC3 is deacetylated by HDAC8. Reversal of SMC3 acetylation is imperative for recycling cohesin so that it can be reloaded in interphase for both non-mitotic and mitotic functions. We blocked deacetylation of ac-SMC3 using an HDAC8-specific inhibitor PCI-34051 in MCF7 breast cancer cells, and examined the effects on transcription of cohesin-dependent genes that respond to estrogen. HDAC8 inhibition led to accumulation of ac-SMC3 as expected, but surprisingly, had no influence on the transcription of estrogen-responsive genes that are altered by siRNA targeting of RAD21 or SMC3. Knockdown of RAD21 altered estrogen receptor α (ER) recruitment at SOX4 and IL20, and affected transcription of these genes, while HDAC8 inhibition did not. Rather, inhibition of HDAC8 delayed cell cycle progression, suppressed proliferation and induced apoptosis in a concentration-dependent manner. We conclude that HDAC8 inhibition does not change the estrogen-specific transcriptional role of cohesin in MCF7 cells, but instead, compromises cell cycle progression and cell survival. Our results argue that candidate inhibitors of cohesin function may differ in their effects depending on the cellular genotype and should be thoroughly tested for predicted effects on cohesin's mechanistic roles.
authors.affiliation: From the Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin 9016, and.
authors.forename: Tanushree
authors.initials: T
authors.lastname: Dasgupta
authors.affiliation: From the Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin 9016, and.
authors.forename: Jisha
authors.initials: J
authors.lastname: Antony
authors.affiliation: From the Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin 9016, and; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand.
authors.forename: Antony W
authors.initials: AW
authors.lastname: Braithwaite
authors.affiliation: From the Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin 9016, and; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand. Electronic address: julia.horsfield@otago.ac.nz.
authors.forename: Julia A
authors.initials: JA
authors.lastname: Horsfield
mesh_terms: D000107:Acetylation / Q000187:drug effects; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D059447:Cell Cycle Checkpoints / Q000187:drug effects / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics* / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006655:Histone Deacetylases / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D015151:Immunoblotting; D007211:Indoles / Q000494:pharmacology; D061986:MCF-7 Cells; D018613:Microscopy, Confocal; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects; D000097722:Cohesins
chemical_list: D018797:Cell Cycle Proteins; D011508:Chondroitin Sulfate Proteoglycans; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D004967:Estrogens; D006655:Histone Deacetylases; D006877:Hydroxamic Acids; D007211:Indoles; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011960:Receptors, Estrogen; D012097:Repressor Proteins; D000097722:Cohesins; C529435:PCI 34051; C429022:RAD21 protein, human; C492318:SMC3 protein, human; C409470:HDAC8 protein, human
keywords: HDAC8; SMC3; breast cancer; cell cycle; cohesin; estrogen receptor; gene expression; histone deacetylase inhibitor (HDAC inhibitor) (HDI)