Acquired platinum resistance involves epithelial to mesenchymal transition through ubiquitin ligase FBXO32 dysregulation.
To identify the molecules involved in epithelial to mesenchymal transition (EMT) in urothelial carcinoma (UC) after acquisition of platinum resistance, here we examined the changes in global gene expression before and after platinum treatment. Four invasive UC cell lines, T24, 5637, and their corresponding sublines T24PR and 5637PR with acquired platinum resistance, were assessed by microarray, and the ubiquitin E3 ligase FBXO32 was newly identified as a negative regulator of EMT in UC tumors after acquisition of platinum resistance. In vitro and in vivo studies showed an intimate relationship between FBXO32 expression and EMT, demonstrating that FBXO32 dysregulation in T24PR cells results in elevated expression of the mesenchymal molecules SNAIL and vimentin and decreased expression of the epithelial molecule E-cadherin. The association between FBXO32 expression and EMT was further validated using clinical samples. Knockdown of MyoD expression, a specific target of FBXO32 polyubiquitination, revealed upregulation of E-cadherin expression and downregulation of SNAIL and vimentin expression in T24PR cells. Comparative genomic hybridization array analysis demonstrated loss of heterozygosity at 8q24.13 in T24PR cells, which harbors FBXO32. Our findings suggest the importance of the association between EMT and ubiquitin-proteasome regulation when tumors develop acquired platinum resistance.
Department of Urology, Keio University School of Medicine, Tokyo, Japan.
Nobuyuki
N
Tanaka
Department of Urology, Keio University School of Medicine, Tokyo, Japan.
Takeo
T
Kosaka
Department of Urology, Keio University School of Medicine, Tokyo, Japan.
Yasumasa
Y
Miyazaki
Division of Diagnostic Pathology, Keio University Hospital, Tokyo, Japan.
Shuji
S
Mikami
Department of Urology, Keio University School of Medicine, Tokyo, Japan.
Naoya
N
Niwa
Department of Molecular Biology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
Yutaro
Y
Otsuka
Department of Biochemistry, Keio University School of Medicine, and Japan Agency for Science and Technology (JST), Exploratory Research for Advanced Technology (ERATO), Suematsu Gas Biology Project, Tokyo, Japan.
Yoji Andrew
YA
Minamishima
Department of Urology, Keio University School of Medicine, Tokyo, Japan.
Ryuichi
R
Mizuno
Department of Urology, Keio University School of Medicine, Tokyo, Japan.
Eiji
E
Kikuchi
Department of Urology, Keio University School of Medicine, Tokyo, Japan.
Akira
A
Miyajima
Department of Molecular Biology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
Hisataka
H
Sabe
Department of Pathology, Keio University School of Medicine, Tokyo, Japan.
Yasunori
Y
Okada
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
Per
P
Uhlén
Department of Biochemistry, Keio University School of Medicine, and Japan Agency for Science and Technology (JST), Exploratory Research for Advanced Technology (ERATO), Suematsu Gas Biology Project, Tokyo, Japan.
Makoto
M
Suematsu
Department of Urology, Keio University School of Medicine, Tokyo, Japan.
Mototsugu
M
Oya
D000368:Aged; D000818:Animals; D015703:Antigens, CD; D015820:Cadherins / Q000378:metabolism; D045744:Cell Line, Tumor; D055028:Comparative Genomic Hybridization; D019008:Drug Resistance, Neoplasm; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D006801:Humans; D008297:Male; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009124:Muscle Proteins / Q000378:metabolism*; D010984:Platinum / Q000494:pharmacology*; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism*; D000071250:Snail Family Transcription Factors / Q000378:metabolism; D014571:Urologic Neoplasms / Q000188:drug therapy*; D019459:Urothelium / Q000473:pathology; D023041:Xenograft Model Antitumor Assays
D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D009124:Muscle Proteins; D000071250:Snail Family Transcription Factors; D010984:Platinum; C440907:FBXO32 protein, human; D044843:SKP Cullin F-Box Protein Ligases