[Anticancer activity of N-(phenylacetyl) doxorubicin combined with folate-targeted PGA].
OBJECTIVE
To demonstrate the specific killing of folate receptor (FR)-positive tumor cells can be achieved by folate-targeted penicillin-G amidase (PGA) combined with its prodrug substrate N-(phenylacetyl) doxorubicin (DOXP).


METHODS
Folic acid was covalently linked to PGA and folate content value was determined by quantitative UV spectrophotometry. The ability of folate conjugated PGA to hydrolyze DOXP was measured by RP-HPLC. Visual demonstration of uptake by FR (+) HeLa and SKOV3 cells was detected by using FITC labeled folate-PGA and a fluorescence microscopy. The cytotoxicity of DOXP towards the cells in the presence or absence of folate-PGA was assayed by using MTT method.


RESULTS
The folate-PGA has a specific activity of 29. 8 U x mg(-1) (protein). FR selectivity was confirmed by fluorescence microscopy. The combination of DOXP prodrug with folate-PGA generated higher cytotoxicity towards the FR (+) cells than free doxorubicin. The IC50 was 0.72 micromol x L(-1) for HeLa cells and 0.75 micromol x L(-1) for SKOV3 cells, respectively. Further, the enhanced cytotoxicity reduced greatly with the addition of free folic acid.


CONCLUSIONS
Folate conjugated PGA did not significantly compromise PGA catalytic activity and enabled binding prodrug-activating enzyme PGA to folate receptor expressing cells, and increased the sensitivity of the cells to doxorubicin followed by administration of its prodrug substrate.
Zhang
Qi
Q
School of Pharmacy, Tongii Medical College of Huazhong University of Science and Technology, Wuhan 430030, China.
Xiang
Guang-ya
GY
Long
Na
N
Lin
Jia-liang
JL
Zeng
Fan-bo
FB
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000031:analogs & derivatives / Q000494:pharmacology*; D016503:Drug Delivery Systems; D005260:Female; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000737:chemistry / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D010051:Ovarian Neoplasms / Q000473:pathology; D010399:Penicillin Amidase / Q000737:chemistry / Q000494:pharmacology*; D011355:Prodrugs / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism
D000903:Antibiotics, Antineoplastic; D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D011355:Prodrugs; D011956:Receptors, Cell Surface; D004317:Doxorubicin; D005492:Folic Acid; D010399:Penicillin Amidase