Table 1.
PA-L1/LF, PA/LF, and PA/FP59 cytotoxicity to human melanoma cells. Twenty five melanoma cell lines were tested for PA-L1/LF sensitivity as described in the Methods section. Assays were performed in triplicate with IC50 variability between assays less than 30% and the IC50s were subsequently tabulated. (a) Twelve cell lines were sensitive to PA-L1/LF as well as PA/LF (IC50 < 200 pM with < 10% of control 3H thymidine incorporation at 10 nM PA-L1/1 nM LF) while 13 melanomas were resistant to PA-L1/LF. (b) The PA-L1/LF resistant cell lines G361, A375, A101D, SK-MEL-28, 451Lu, WM902B were sensitive to PA/LF (IC50 < 200 pM with < 10% of control 3H thymidine incorporation at 10 nM PA/1 nM) LF and thus exhibited MAPK dependency. (c) The PA-L1 resistant SK-MEL-2 demonstrated resistance to PA/FP59, which suggested low LeTx receptor expression. The PA/FP59 sensitive WM1361A, SK-MEL-173, A2058, WM1158, WM239A, and WM3211 were not sensitive to PA/LF, which indicated tolerance for LF-mediated MAPK inhibition.
| Cell Line | PA-L1/LF ([3H]thymidine, pmol/L) |
PA/LF IC50 ([3H]thymidine, pmol/L) |
PA/FP59 IC50 ([3H]thymidine, pmol/L) |
MAP Kinase Pathway Mutational Status |
Reference |
|---|---|---|---|---|---|
| a PA-L1/LF senstive melanoma cell lines | |||||
| SK-MEL-24 | 7 | 2 | 2 | V600E B-RAF | 10 |
| WM793B | 11 | 7 | 1 | V600E B-RAF | 29 |
| C32 | 11 | 8 | 1 | V600E B-RAF | 10 |
| WM115 | 19 | 8.7 | 0.65 | V600E B-RAF | 25 |
| WM46 | 55 | 12 | 7.8 | V600E B-RAF | |
| Malme-3M | 64 | 54 | 25 | V600E B-RAF | 10 |
| HT-144 | 104 | 25 | 2 | V600E B-RAF | 10 |
| WM983A | 109 | 16 | 5.1 | V600E B-RAF | 10 |
| WM-266–4 | 119 | 58 | 5 | V600E B-RAF | 10 |
| 1205Lu | 147 | 14 | 2 | V600E B-RAF | 29 |
| WM852 | 159 | 14 | 0.7 | Q61R NRAS | |
| WM51 | 177 | 54 | 15 | V600E B-RAF | |
| b PA-L1/LF resistant, PA/LF sensitive melanoma cell lines | |||||
| G361 | 225 | 44 | 9 | V600E B-RAF | 10 |
| A375 | 247 | 93 | 4 | V600E B-RAF | 10 |
| A101D | 335 | 30 | 3 | V600E B-RAF | |
| SK-MEL-28 | 359 | 15 | 2 | V600E B-RAF | 10 |
| 451Lu | 841 | 57 | 5.7 | V600E B-RAF | 30 |
| WM902B | 1010 | 33 | 10 | V600E B-RAF | |
| c PA/LF resistant melanoma cell lines | |||||
| SK-MEL-2 | 407 | 319 | 130 | Q61K NRAS | 10 |
| WM1361A | 419 | 248 | 4.7 | Q61R NRAS | 29 |
| SK-MEL-173 | 757 | 286 | 6.4 | Wild-type B-RAF | |
| A2058 | >10,000 | >10,000 | 1.9 | Heterozygous V600E B-RAF | |
| WM1158 | >10,000 | >10,000 | 0.5 | V600E B-RAF | |
| WM239A | >10,000 | >10,000 | 0.4 | Wild-type B-RAF | |
| WM3211 | >10,000 | >10,000 | 1 | Wild-type B-RAF/NRAS | |