title: Synthesis, characterization, and antitumor evaluation of the albumin-SN38 conjugate.
abstract: 7-Ethyl-10-hydroxycamptothecin (SN38), the active metabolite of irinotecan, exerts a 100-fold to 1000-fold higher effect than irinotecan itself against several tumor cell lines. However, the water insolubility of SN38 has prevented its direct use as an antitumor drug in the clinic. To improve the water solubility and antitumor efficacy, SN38 was covalently attached to the only free sulfhydryl at cysteine-34 on the BSA site specifically through a thiol-binding linker to form a prodrug BSA-SN38 conjugate (BSA : SN38=1 : 1). The water solubility of this conjugate was similar to albumin using the current method. Also, SN38 loading in this conjugate became controllable. Size-exclusion chromatography purification and UV characterization of the SDS-PAGE electrophoresis product were carried out. Then, an MTT assay was carried out to test the antitumor effect of this conjugate on five colon cancer cell lines in vitro. The 72 h IC50 values of the BSA-SN38 conjugate ranged from 1.5 to 6.1 μmol/l. A colorectal peritoneal carcinomatosis model in mice was established to determine the intraperitoneal chemotherapy effect of the BSA-SN38 conjugate. The BSA-SN38 conjugate at an SN38 equivalent dose of 10 mg/kg/day was administrated every 4 days. Eighteen days after manipulation, the mice were euthanized and the tumors in the abdominal cavity were collected and weighed. Tumors in the BSA-SN38 conjugate treatment group (m=0.21 ± 0.15 g) were found to be significantly (P=5) lighter than those in the NS control group (m=4.74±0.73 g). The results indicated that this water-soluble BSA-SN38 conjugate exerted a strong antitumor effect on colorectal carcinoma.
authors.affiliation: State Key Laboratory of Biotherapy, West China Medical School, West China Hospital, Sichuan University, Keyuan Prad 4, Gaopeng Street, Chengdu 610041, China.
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Yao
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Su
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Xie
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Wang
authors.forename: Tairan
authors.initials: T
authors.lastname: Kang
authors.forename: Lantu
authors.initials: L
authors.lastname: Gou
authors.forename: Chen
authors.initials: C
authors.lastname: Yi
authors.forename: Jinliang
authors.initials: J
authors.lastname: Yang
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000138:chemical synthesis* / Q000494:pharmacology*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000737:chemistry; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000188:drug therapy; D004354:Drug Screening Assays, Antitumor / Q000379:methods; D005260:Female; D045325:HCT116 Cells; D006801:Humans; D000077146:Irinotecan; D051379:Mice; D008807:Mice, Inbred BALB C; D010534:Peritoneal Neoplasms / Q000188:drug therapy; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012995:Solubility; D023041:Xenograft Model Antitumor Assays
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D012710:Serum Albumin, Bovine; D000077146:Irinotecan; D002166:Camptothecin