title: HOXB13 contributes to G1/S and G2/M checkpoint controls in prostate.
abstract: HOXB13 is a homeobox protein that is expressed in normal adult prostate and colon tissues; however, its deregulated expression was evidenced in various malignancies. To characterize the putative role of HOXB13 in cell cycle progression, we performed overexpression and siRNA-mediated knockdown studies in PC-3 and LNCaP cells. Immunohistochemistry (IHC) analyses were also performed using formalin-fixed, paraffin-embedded tissues containing normal, H-PIN and PCa sections from 20 radical prostatectomy specimens. Furthermore, when the role of HOXB13 during cell cycle progression, association with cyclins, cell growth and colony formation using real-time cell proliferation were assessed, we observed that ectopic expression of HOXB13 accumulated cells at G1 through decreasing the cyclin D1 level by promoting its ubiquitination and degradation. This loss slowed S phase entry in both cell lines examined, with an associated decrease in pRb((S780) and (S795)) phosphorylations. Contrary, siRNA-mediated depletion of HOXB13 expression noticeably increased cyclin levels, stabilized E2F1 and CDC25C, subsequent to increased pRb phosphorylations. This increase in Cyclin B1 and CDC25C both together facilitated activation of cyclin B complex via dephosphorylating CDK1((T14Y15)), and resumed the G2/M transition after nocodazole synchronization. Despite an increase in the total expression level and cytoplasmic retention of HOXB13 in H-PIN and PCa samples that were observed via IHC evaluation of prostate tissues, HOXB13 depletion facilitated to an increase in PC-3 and LNCaP cell proliferation. Thus, we suggest that HOXB13 expression is required for cell cycle regulation, and increases by an unknown mechanism consequent to its functional loss in cancer.
authors: Department of Bioengineering, Cancer Biology Laboratory and Faculty of Pharmacy, Ege University, Faculty of Engineering, Bornova, Izmir, Turkey.
authors: Syed Muhammad
authors: SM
authors: Hamid
authors: Department of Bioengineering, Cancer Biology Laboratory and Faculty of Pharmacy, Ege University, Faculty of Engineering, Bornova, Izmir, Turkey.
authors: Seher
authors: S
authors: Cicek
authors: Department of Bioengineering, Cancer Biology Laboratory and Faculty of Pharmacy, Ege University, Faculty of Engineering, Bornova, Izmir, Turkey.
authors: Selda
authors: S
authors: Karamil
authors: Department of Bioengineering, Cancer Biology Laboratory and Faculty of Pharmacy, Ege University, Faculty of Engineering, Bornova, Izmir, Turkey.
authors: Mert Burak
authors: MB
authors: Ozturk
authors: Department of Bioengineering, Cancer Biology Laboratory and Faculty of Pharmacy, Ege University, Faculty of Engineering, Bornova, Izmir, Turkey; Department of Biotechnology, Ege University, Faculty of Engineering, Bornova, Izmir, Turkey.
authors: Bilge
authors: B
authors: Debelec-Butuner
authors: Department of Bioengineering, Cancer Biology Laboratory and Faculty of Pharmacy, Ege University, Faculty of Engineering, Bornova, Izmir, Turkey.
authors: Burcu
authors: B
authors: Erbaykent-Tepedelen
authors: Department of Bioengineering, Cancer Biology Laboratory and Faculty of Pharmacy, Ege University, Faculty of Engineering, Bornova, Izmir, Turkey.
authors: Lokman
authors: L
authors: Varisli
authors: Department of Pharmacology, Bornova, Izmir, Turkey.
authors: Ceren
authors: C
authors: Gonen-Korkmaz
authors: Dokuz Eylul University, Faculty of Medicine, Department of Pathology, Inciralti, Izmir, Turkey.
authors: Kutsal
authors: K
authors: Yorukoglu
authors: Department of Bioengineering, Cancer Biology Laboratory and Faculty of Pharmacy, Ege University, Faculty of Engineering, Bornova, Izmir, Turkey. Electronic address: ks_korkmaz@yahoo.com.
authors: Kemal Sami
authors: KS
authors: Korkmaz
mesh_terms: D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D056744:Cyclin B1 / Q000235:genetics / Q000378:metabolism; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D050687:E2F1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D059585:G1 Phase Cell Cycle Checkpoints / Q000235:genetics*; D059565:G2 Phase Cell Cycle Checkpoints / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D010766:Phosphorylation; D011467:Prostate / Q000378:metabolism / Q000473:pathology; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D059748:Proteolysis; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D054875:Ubiquitination; D020687:cdc25 Phosphatases / Q000235:genetics / Q000378:metabolism
chemical_list: D056744:Cyclin B1; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C484414:HOXB13 protein, human; D018398:Homeodomain Proteins; D016160:Retinoblastoma Protein; D019938:Cyclin D1; D016203:CDC2 Protein Kinase; C517009:CDC25C protein, human; D020687:cdc25 Phosphatases
keywords: Cell cycle; Cyclin D1; E2F regulation; Homeobox protein; Prostate tissues; Rb phosphorylation