Synthesis and evaluation of fluoromycin: a novel fluorescence-labeled derivative of talisomycin S10b.
We have synthesized fluoromycin (FLM), a novel fluorescein-labeled derivative of talisomycin S10b (TLM S10b), and used it to evaluate cellular drug accumulation and distribution in bleomycin (BLM)-sensitive and -resistant cell lines. The fluorescence intensity of FLM was 300- to 400-fold greater than that of BLM A2, TLM S10b, or the lipophilic BLM analogue, liblomycin. FLM possessed an antiproliferative potency similar to liblomycin in BLM-sensitive human A-253 squamous carcinoma cells but was less potent than BLM A2 or TLM S10b. C-10E cells, a clone of A-253 cells with 40- to 50-fold resistance to BLM A2 and TLM S10b, were 50-fold resistant to FLM. A partially revertant cell population (C-10E ND) regained sensitivity to BLM A2, TLM S10b, and FLM. FLM like BLM cleaved pGEM-3Z plasmid DNA in vitro in a concentration-dependent manner. Flow cytometric analysis of FLM content in C-10E and C-10E ND cell lines showed 4-fold and 2-fold lower fluorescence intensity, respectively, compared with A-253 cells. Similar results were seen by fluorescence spectrophotometry with cell extracts. Fluorescence microscopy indicated heterogeneous distribution among A-253 cells with at least 50% of the cells exhibiting marked nuclear fluorescence localization. In contrast, C-10E cells displayed lower cellular fluorescence and predominantly cytoplasmic localization. C-10E ND cells exhibited a mixed population of nuclear and cytoplasmic vesicular localization with fluorescence levels that were intermediate between A-253 and C-10E cells. Thus, BLM-resistant cells have reduced levels of FLM and appear to have a lower nuclear:cytoplasmic ratio of FLM. FLM may be useful in studying the intracellular fate of BLM-like drugs as well as providing a tool to detect and isolate BLM-resistant cells.
Department of Pharmacology, University of Pittsburgh, School of Medicine, Pennsylvania 15261.
J S
JS
Mistry
J P
JP
Jani
G
G
Morris
R B
RB
Mujumdar
I J
IJ
Reynolds
S M
SM
Sebti
J S
JS
Lazo
D000970:Antineoplastic Agents / Q000138:chemical synthesis*; D001761:Bleomycin / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology / Q000031:analogs & derivatives; D002294:Carcinoma, Squamous Cell; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D004354:Drug Screening Assays, Antitumor; D005452:Fluoresceins / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D005456:Fluorescent Dyes; D006258:Head and Neck Neoplasms; D006801:Humans; D007202:Indicators and Reagents; D015394:Molecular Structure; D010957:Plasmids / Q000187:drug effects
D000970:Antineoplastic Agents; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D001761:Bleomycin; C072391:fluoromycin