title: Adenovirus-mediated ribonucleotide reductase R1 gene therapy of human colon adenocarcinoma.
abstract: Ribonucleotide reductase is the enzyme responsible for the reduction of ribonucleotides to their corresponding deoxyribonucleotides for DNA synthesis. Ribonucleotide reductase is a multisubunit complex containing two polypeptides, R1 and R2. In addition to catalytic and allosteric regulatory functions, the R1 subunit appears to act as a novel tumor suppressor. Previous studies demonstrated that overexpression of mouse R1 resulted in suppression of tumorigenicity and metastatic potential, whereas expression of antisense RNA, complementary to R1 mRNA, increased anchorage-independent growth of ras-transformed NIH 3T3 cells. The current study investigated the potential of R1 gene therapy for human cancer using a recombinant adenovirus encoding the human R1 gene (rAd5-R1). Recombinant viruses were constructed by FLP-mediated site-specific recombination and demonstrated high infectivity of a human colon carcinoma cell line (Colo320 HRS), as assessed by expression of a viral encoded beta-Gal gene (rAd5-LacZ). R1mRNA and protein were overexpressed in Colo320 HRS cells infected with rAd5-R1 compared with untreated or rAd5-LacZ-infected cells. Infection with rAd5-R1 inhibited Colo320 HRS cell proliferation, in vitro, in a time- and dose-dependent manner. When Colo320 HRS cells were treated with rAd5-R1, before injection into CD-1 mice, there was complete inhibition of tumor growth compared with treatment with rAd5-LacZ. Furthermore, intratumoral injection of rAd5-R1 into Colo320 HRS tumor xenografts inhibited tumor growth in CD-1 mice compared with rAd5-LacZ treated mice (P = 0.0001). These results demonstrate gene-specific antitumor effects of R1 and suggest that rAd5-R1 gene therapy has the potential to improve currently available treatments for colon cancer.
authors.affiliation: Lorus Therapeutics Inc., Toronto, Ontario M9W 4Z7, Canada. mcao@lorusthera.com
authors.forename: Ming-Yu
authors.initials: MY
authors.lastname: Cao
authors.forename: Yoon
authors.initials: Y
authors.lastname: Lee
authors.forename: Ning-Ping
authors.initials: NP
authors.lastname: Feng
authors.forename: Keyong
authors.initials: K
authors.lastname: Xiong
authors.forename: Hongnan
authors.initials: H
authors.lastname: Jin
authors.forename: Ming
authors.initials: M
authors.lastname: Wang
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Vassilakos
authors.forename: Stéphane
authors.initials: S
authors.lastname: Viau
authors.forename: Jim A
authors.initials: JA
authors.lastname: Wright
authors.forename: Aiping H
authors.initials: AH
authors.lastname: Young
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology / Q000473:pathology / Q000628:therapy*; D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D015152:Blotting, Northern; D003110:Colonic Neoplasms / Q000201:enzymology / Q000473:pathology / Q000628:therapy*; D005260:Female; D015316:Genetic Therapy; D005822:Genetic Vectors; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012262:Ribonucleoside Diphosphate Reductase; D012264:Ribonucleotide Reductases / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D012333:RNA, Messenger; D012264:Ribonucleotide Reductases; D012262:Ribonucleoside Diphosphate Reductase; C498690:Rrm1 protein, mouse