an in vitro human tumor drug screen is used to evaluate compounds used in the method of the present invention . the screen employed has been described and the experimental details are taught in the text and bibliography of boyd , et al ., status of the nci preclinical antitumor drug discovery screen ; principles and practices of oncology , vol . 3 , no . 10 , october 1989 , lippincott . the screen is a disease - oriented primary screen that employs multiple disease - specific ( i . e . tumor - type specific ) models . the models are based on the availability of a wide variety of human tumor cell lines , representing many different forms of human cancer . these cell lines comprise a diverse panel of human tumor cell lines arrayed in disease - specific subpanels . the panel contains a total of 60 human tumor cell lines derived from seven cancer types ( lung , colon , melanoma , renal , ovarian , brain and leukemia ) that have been adapted to a single growth medium and that have reproducible profiles for growth and drug sensitivity . individual cell lines were initially photographed , expanded ( two passages maximum ) and cryo - preserved ( master stocks ) with growth medium and split - ratios recommended by their respective sources . only cell lines documented to be free of adventitious bacteria and pathogenic viruses ( nci - fcrf 3 diagnostic microbiology lab and animal health diagnostic lab ) were accepted for subsequent characterization . following recovery of master stocks , cell lines were adapted to a single , standard culture medium : rpmi 1640 ( quality biologicals , inc ., gaithersburg , md .) supplemented with 10 % heat - inactivated fetal bovine serum ( sterile systems hyclone , logan , utah ) and 2 mm l - glutamine ( nci - fcrf central medium laboratory ) without antibiotics and cultured under conventional culture conditions , that is , 37 ° c ., 5 % co 2 , 95 % air , 100 % relative humidity . cell lines were than expanded ( five passages maximum ) and cryopreserved for generation of seed stocks . established adherent cell monolayers approaching 80 % confluency were harvested with trypsin / edta ( nci - fcrf central medium laboratory ) whereas some early passage adherent cell lines were harvested with solution a and 2x - crystalized trypsin iii ( sigma chemical co .). leukemia cell lines were subcultured by trituration and dilution . small cell lung carcinoma cell lines ( which generally form large aggregates in suspension under conventional culture conditions ) were cultured and assayed in suspension as well as adherent monolayers utilizing poly - l - lysine pretreatment of culture vessels . following recovery of seed stock , cell lines were subjected to isoenzyme analysis as well as preliminary growth and drug sensitivity assays using one or more in vitro growth inhibition assays ( described below ). cell lines meeting basic quality assurance criteria ( mycoplasma - negative , map - negative , human isoenzymes only ) and exhibiting suitable growth profiles were expanded ( five serial passages from seed stock , maximum ) and cryopreserved as a large number of aliquots designated working seed stock . cell cryopreservation was achieved using a cryomed controller ( model 801 ) and a cryomed freezing chamber ( no . 2700 ) with a step rate of - 1 ° c ./ min followed by storage in vapor - phase liquid n 2 ( nci - fcrf central repository ). cell line seed stocks were tested also for in vivo tumorigenicity ( s . c . and i . p . inoculations ) in accordance with established protocols . cell lines recovered from working seed stocks were subjected to repeat mycoplasma tests and to more extensive in vitro growth characterization . cell lines subsequently were evaluated with respect to stability in drug sensitivity profiles over the course of 20 weekly passages . in addition , each cell line was expanded ( eight passages , maximum from seed stock thaw ) and cryopreserved as a large number of aliquots (&# 34 ; roller bottle &# 34 ; stock ) for in vivo characterization and assay development . tetrazolium / formazan reagents were purchased from sigma chemical co . ( st . louis , mo . ): mtt ( m2128 ), mtt formazan ( m2003 ), int ( 18377 ), int formazan ( i7375 ), and nbt ( n6876 ). dmso was purchased from sigma chemical co . ( d5879 ), j . t . baker chemical co . ( 9194 - 3 , phillipsburg , n . j . ), and american burdick and jackson laboratories ( spectrophotometric grade product 081 , muskegan , mich .). these chemicals were stored in unopened bottles at room temperature in the dark or in 50 - ml sterile plastic tubes at - 20 ° c . in the dark . anhydrous isopropanol ( 505 - 7 ) and propylene glycol ( p - 1009 ) were purchased from sigma chemical co . reagent grade hydrochloric acid ( a - 744 ) and hexane ( h - 302 - 1 ) were purchased from fisher scientific co . dimethylformamide ( 27 , 054 - 7 ) was purchased from aldrich chemical co . ( milwaukee , wis .) propanol ( spectrophotometric grade 9068 - 1 ) was purchased from american burdick and jackson laboratories . crystalline stock materials were stored at - 20 ° c . solvent - reconstituted chemotherapeutic agents were prepared at high concentration , partitioned into multiple aliquots , and stored at - 70 ° c . just prior to culture application the contents of frozen vials were thawed and mixed . measured aliquots ( 20 - 200 μl ) were transferred by micropipet ( gilson pipetman , models p200 and p1000 ) equipped with polypropylene tips to standard culture medium within polypropylene tubes ( sarstedt 62 . 554 / 002 or falcon 2098 ) and serially diluted in culture medium containing an appropriate concentration of vehicle . in principle , the viable cell number / well is directly proportional to the production of formazan , which following solubilization , can be measured spectrophotometrically . in brief , cells were harvested from exponential - phase maintenance cultures ( t - 75 cm 2 flasks ; falcon plastics 3023 ), counted by trypan blue exclusion , and dispensed within replicate 96 - well culture plates ( falcon plastics 3075 ) in 100 - μl volumes using a repeating pipet ( eppendorf repeater 4780 ) or multichannel pipet ( flow labs , titertek ). following a 24 - h incubation at 37 ° c ., 5 % co 2 , 100 % relative humidity ( heraeus b5060eko 2 incubators or napco 5300 incubators ), 100 μl of culture medium , culture medium containing drug or culture medium containing drug vehicle was dispersed within appropriate wells ( vehicle control group , n = 6 ; each drug treatment group , n = 3 ). peripheral wells of each plate ( lacking cells ) were utilized for drug blank ( n = 2 ) and medium / tetrazolium reagent blank ( n = 6 ) &# 34 ; background &# 34 ; determinations . culture plates were then incubated for 1 to 11 days prior to the addition of tetrazolium reagent . mtt stock solution was prepared as follows : 5 mg mtt / ml pbs ( quality biologicals , inc .) was sterile filtered with 0 . 45 - μm filter units ( nalgene type scn ) and stored at 4 ° c . for a maximum of 1 month . mtt working solution was prepared just prior to culture application by diluting mtt stock solution 1 : 5 ( v / v ) in prewarmed standard culture medium . alternatively , other tetrazolium reagents ( namely , int or nbt ) were prepared and utilized in a similar fashion for selected experiments . under standard mta conditions 50 μl of mtt working solution was added to each culture well ( resulting in 50 μg mtt / 250 μl to total medium volume ) and cultures were incubated at 37 ° c . for 4 to 24 h depending upon individual cell line requirements . following incubation cell monolayers and formazan were inspected microscopically : culture plates containing suspension lines or any detached cells were centrifuged at low speed for 5 min . all but 10 - 20 μl of culture medium supernatant was removed from wells by slow aspiration through a blunt 18 - gauge needle and replaced with 150 μl of dmso ( burdick & amp ; jackson ) using a multichannel pipet . following thorough formazan solubilization ( trituration by pipet or vibration on a plate shaker ), the absorbance of each well was measured using a microculture plate reader ( dynatech mr600 ; alexandria , va .) at 540 nm ( single wavelength , calibration factor = 1 . 00 ) interfaced with an apple iie computer . subsequently , data were stored and analyzed through use of apple soft , apple turnover , and lotus symphony software . cell line growth and growth inhibition were expressed in terms of mean (± 1 sd ) absorbance units and / or percentage of control absorbance (± 1 sd %) following subtraction of mean &# 34 ; background &# 34 ; absorbance . linearity and reproducibility of instrument measurements were verified by the use of formazan reagents in appropriate solvent systems . absorption spectra of formazan reagents as well as cell - generated formazans were measured with a uv / visible scanning spectrophotometer ( perkin - elmer lambda v ; perkin - elmer corp ., norwalk , conn .). samples were placed in 1 - cm pathlength disposable polystyrene cuvets ( fisher scientific co . 14 - 385 - 942 ) except those solubilized in dimethylformamide solvent which were evaluated in 1 - cm pathlength glass spectrophotometer cells ( coleman s7300 - 4 ). freshly prepared material was analyzed in dual beam mode with 2 - nm slit width , at 120 nm / min . 0 . 02 a threshold , and 0 . 5 s response . instrument wavelength calibration was verified by examination of deuterium emission spectra to be 653 . 1 ± 0 . 3 nm . following 1 - 11 days &# 39 ; incubation , supernatant culture medium was removed and 200 μl of methylene blue ( sigma mb - 1 ) solution [ 5 g / liter in ethanol : water ( 50 %, v / v )] was added without delay . following incubation at room temperature for 45 min , unbound stain was removed by plate inversion on absorbant paper and subsequent emersion / dilution in four , 1 - liter washes with distilled deionized water . bound protein stain was solubilized by the addition of 100 μl sds ( sigma l4509 ) solution ( 1 %, v / v in water ) to each well . absorbances of wells were measured at 630 nm ( single wavelengths , calibration factor = 1 . 00 ) using equipment and computerized analysis procedures described above for the mta . a more preferred method uses the anionic dye sulforhodamine b ( srb ). srb is a bright pink anionic dye that , in dilute acetic acid , binds electrostatically to the basic amino acids of fixed monolayers of cells . srb can detect about 1000 cells at 560 nm and 200 - 300 cells fluorescently . supermaximal concentration and staining time were determined by dose - response and kinetic analyses . a more preferred medium comprises beta - glycerophosphate as the buffering agent , and the medium has a stable physiological ph of 7 . 4 in atmospheric co 2 . the medium includes biotin , l - asparagine , pyruvate and oxaloacetate for metabolic stimulation of intracellular co 2 production . measures of relative cell line sensitivities are done by comparing relative drug concentrations required to produce the same level of response in each cell line visually . this is presented by a mean graph . two mean graphs appear at fig1 and 2 . the mean graph , derived from total growth inhibition ( tgi ) values , is centered at the arithmetic mean of the logarithm of the tgi values for all cell live responses measured for a given compound . the mean graph is construed by projecting bars , one for each cell line ( listed by identified on the left of the graph ) to either the right or the left of the mean , depending on whether cell sensitivity to the test drug is greater or less than average . the length of a bar is proportional to the difference between the logarithm of the cell line tgi and the mean . for example , for a given cell line , a bar projecting three log units to the right of the mean would reflect an individual cellular sensitivity 1 , 000 times that of the average of all the cellular responses to the given compound represented on the graph . fig1 and 2 demonstrate that compounds 4 and 19 , respectively have especially good antitumor activity against colon cancer cells , renal cancer cells , melanoma cells , lung cancer cells ( non - small cells ) and leukemia cells . more limited activity is also shown against the other cell lines . the extrapolation of positive results in the above - described assays to utility as antitumor agents is supported by boyd , m . r ., status of the nci preclinical antitumor drug discovery screen ; principles and practices of oncology , vol . 3 , no . 10 , october 1989 , lippincott , the entire disclosure of which is incorporated herein by reference .
inhibition of renal cancer , melanoma , colon cancer , lung cancer and leukemia cells by administration of compounds from the bafilomycin and hygrolidin groups of compounds .