Table 1.

Cytotoxicity profile of MAC-321 in a panel of PTX-sensitive and -resistant tumor cell lines^a

Cell Line	Tumor Origin	P-glycoprotein Expression^b	IC₅₀ (nm)
Cell Line	Tumor Origin	P-glycoprotein Expression^b				MAC-321	PTX	DTX	Vinblastine
A549	NSCLC	0	1.2 ± 0.7	7.5 ± 1.8	1.9 ± 0.7	3.7 ± 0.9
HCT-116	colon	0	3.1 ± 0.7	8.2 ± 1.4	5.4 ± 0.8	2.3 ± 1.5
NCI-H838	NSCLC	0	3.3 ± 0.3	2.1 ± 0.9	6.3 ± 0.7	0.9 ± 0.6
KB-3-1	epidermoid	0	1.3 ± 0.5	3.9 ± 1.3	1.1 ± 0.6	0.8 ± 0.4
1A9 (A2780 subclone)	ovarian	0	1.7 ± 0.6	5.1 ± 0.9	1.9 ± 1.0	1.9 ± 0.2
Average ± SD			2.1 ± 1.00	5.4 ± 2.50	3.3 ± 2.40	1.9 ± 1.20
MX-1W	breast	+	2.6 ± 1.4	15.4 ± 2.9	5.78 ± 2.37	n.d.
NCI-H1299	NSCLC	++	5.3 ± 1.8	37.7 ± 2.3	12.9 ± 0.98	6.33 ± 1.24
DLD-1	colon	+++	1.2 ± 0.9	32.5 ± 2.4	14.29 ± 1.18	15.38 ± 0.62
HCT-15	colon	++++	3.3 ± 0.2	438.6 ± 1.9	54.62 ± 0.19	15.81 ± 1.97
Average ± SD			3.1 ± 1.70	131.0 ± 205.30	21.9 ± 22.10	9.4 ± 7.75
COLO 205	colon	n.d.	0.6 ± 0.1	7.0 ± 2.3	0.6 ± 0.2	1.3 ± 1.0
LOX	melanoma	n.d.	4.3 ± 2.4	17.4 ± 1.4	6.9 ± 0.6	2.8 ± 1.7
Panc-1	pancreatic	n.d.	1.2 ± 0.9	6.2 ± 1.7	1.9 ± 1.2	n.d.
AsPc-1	pancreatic	n.d.	1.2 ± 0.3	2.4 ± 0.3	1.9 ± 0.7	n.d.
Capan-1	pancreatic	n.d.	1.2 ± 1.0	2.6 ± 0.8	1.5 ± 0.9	n.d.
Average ± SD			2.7 ± 1.50	7.1 ± 6.10	2.6 ± 2.50	0.8 ± 1.20

↵a Cell toxicity was measured using the SRB protein stain as an assessment of protein content and survival after a 72-h incubation period with MAC-321, PTX, DTX, or vinblastine as described in “Materials and Methods.” IC₅₀ ± SD values are representative of three independent experiments.
↵b P-glycoprotein expression was determined by Western blotting and quantitative real-time RT-PCR using MDR-specific antibodies and probes, respectively, as described in “Materials and Methods.” Scoring code based on Western blotting: 0, not detected; + to ++++, low to high expression; n.d., not determined.