Table 4.

In vitro data for inhibitors of cell proliferation by selected lead compounds in the development of CYP26 Inhibitors. (GI₅₀ is the concentration at which growth is inhibited by 50%). The structures of compounds 1–13 are shown in figures 3, 4 and 5.

Compound	ATRA Conc.	Cell Line	Effects on Cell Growth	Ref
Liarazole	1 – 10 nM	MCF-7	LRZ concentration-dependent growth inhibition up to >90% inhibition (0.01 – 10 μM liarozole)	[109]
	Not supplemented	MCF-7 DU145 LNCaP	No cytostatic properties at 10 μM LRZ	[91]
	10 pM – 1 μM	MCF-7	Enhances antiproliferative effects of ATRA at 1 μM LRZ	[66, 195]
	1 nM – 1 μM	C3H/10T1/2	10 μM LRZ shifted the RA concentration required to inhibit MCA-induced transformation from 1 μM to 1 nM	[110]
R116010	10 pM – 10 μM	T47D	10 nM R116010 decreased ATRA GI50 1.25-fold to 1.6 nM	[142]
			100 nM R116010 decreased ATRA GI50 2.6-fold to 0.77 nM
			1 μM R116010 decreased ATRA GI50 3-fold to 0.6 nM
1a	Not supplemented	MCF-7	GI50 = 0.49 μM	[157]
		T47D	GI50 = 0.003 μM
		MDA-MB-231	No inhibition of growth up to 10 μM I
		LNCaP	GI50 = 10 μM
		PC-3	GI50= 7.7 μM
1a	Not supplemented	LNCaP	GI50 = 10 μM	[159, 161]
2			GI50 = 6 μM
3			GI50 = 4.5 to 5.5 μM
4			GI50 = 5 μM
1a	0.01 – 1 μM	LNCaP	1 μM compound 1a decreased ATRA GI50 to 92 nM	[159]
2			1 μM compound 2 decreased ATRA GI50 to 71 nM
3			1 μM compound 3 decreased ATRA GI50 to 61 nM
4			1 μM compound 4 decreased ATRA GI50 to 66 nM
1b	Not supplemented	MCF-7	GI50 = 0.57 μM	[189]
		SKBR-3	GI50 = 5.38 μM
		MDA-MB-231	GI50 = 7.37 μM
5	0.001 – 1 μM	T47D	GI50 = 300 nM	[169]
		AT6.1	GI50 = 125 nM