METHODS: Pharmacokinetics of KKA was studied after intravenous and oral administration in SD rats using HPLC. Anti-angiogenic efficacy of KKA was investigated in rat aorta, human endothelial cells (EA.hy926) and nude mice implanted with matrigel.
RESULTS: Pharmacokinetic study revealed that KKA was readily absorbed into blood and stayed for a long time in the body with Tmax 2.89 ± 0.12 h, Cmax 7.24 ± 0.36 μg/mL and T1/2 1.46 ± 0.03 h. The pharmacological results showed that KKA significantly suppressed sprouting of microvessels in rat aorta with IC50 18.4 ± 4.2 μM and demonstrated remarkable inhibition of major endothelial functions such as migration, differentiation and VEGF expression in endothelial cells. Further, KKA significantly inhibited vascularization in matrigel plugs implanted in nude mice.
CONCLUSIONS: The results indicate that bioabsorption of KKA from oral route was considerably efficient with longer retention in body than compared to that of the intravenous route. Further, improved antiangiogenic activity of KKA was recorded which could probably be due to its increased solubility and bioavailability. The results revealed that KKA inhibits angiogenesis by suppressing endothelial functions and expression of VEGF.
EXPERIMENTAL APPROACH: KKA was produced by a semi-synthetic method. A human apoptosis proteome profiler array was applied to determine the protein targets responsible for the stimulation of apoptosis. Three doses of KKA were studied in athymic nude mice models to examine the in vivo anti-tumorigenic ability of KKA.
FINDINGS/RESULTS: The results of this study demonstrated that KKA regulates the activities of various proteins. It downregulates the expression of several antiapoptotic proteins and negative regulators of apoptosis including HSP60, HSP90, Bcl-2, and IGF-1 in HCT 116 cells with consequent upregulation of TRAILR-1 and TRAILR-2, p27, CD40, caspase 3, and caspase 8 proteins. Additionally, KKA showed an in vitro antimetastatic effect against HCT 116 cells. These results are feasibly related to the down-regulation of Notch, Wnt, hypoxia, and MAPK/JNK and MAPK/ERK signalling pathways in HCT 116 cells besides the up-regulation of a transcription factor for cell cycle (pRb-E2F) pathways. In addition, KKA revealed potent inhibition of tumor growth.
CONCLUSION AND IMPLICATIONS: In sum, the findings indicate that KKA can be a promising candidate as a chemotherapeutic agent against colorectal cancer.