Cell experiment:

Cells are incubated with 1 μM MKT-077 and 100 nM Mitotracker Green FM in culture medium for 30 minutes at 37℃ in the dark, washed with PBS, switched into phenol-red free medium before visualizing fluorescence under a microscope. Pictures are acquired and processed with software. For flow cytometric measurement, MKT-077-treated cells are resuspended in 0.1% bovine serum albumin/PBS and analyzed by flow cytometry. Data from 20,000 cells are analyzed using FCS Express software[1].

Animal experiment:

The 1×107 TT cells in 200 μL Hank's balanced salt solution are inoculated subcutaneously into the rear flanks of 6-week-old female athymic nude (nu/nu) mice. Once palpable, tumors are measured using calipers at intervals indicated in the text. When tumor volume reaches 100 mm3, mice are sorted into groups of 8 to achieve equal distribution of tumor size in all treatment groups. Group 1 receives only the vehicle (1:9 mixture of DMSO/saline) and group 2 receives MKT-077 (10 mg/kg body weight/dose). A 200 μL of ether solution is administered by intraperitoneal injection every 2 days (total 10 doses). At the end of the experiments, animals are euthanized by CO2 asphyxiation[1].

MKT-077 is a rhodacyanine dye and also a heat shock protein 70 (Hsp70) inhibitor which exhibits significant antitumor activity.

MKT-077 is a rhodacyanine dye and also a heat shock protein 70 (Hsp70) inhibitor which exhibits significant antitumor activity. MKT-077 treatment (0.1 to 10 μM dose ranges) for 48 hours can effectively decrease TT cell viability. MKT-077 treatment results in accumulation of cells in the G0/G1 phase in a dose-dependent manner, and also increases sub-G0/G1 phase population in TT cell culture in a dose-dependent manner. MKT-077 also downregulates cellular levels of the proliferation marker, Ki67, and the S-phase transcription factor, E2F-1, in TT and MZ-CRC-1 cells. Moreover, flow cytometry using different doses of MKT-077 reveales that TT cells can uptake and retain MKT-077 at significantly higher levels than MZ-CRC-1 cells[1]. MKT-077 has EC50 values of 1.4±0.2 and 2.2±0.2 μM against MDA-MB-231 and MCF7 breast cancer cells, respectivelyl[2].

Systemic administration of MKT-077 significantly delays the growth of TT xenografts in mice throughout the treatment. At the end of MKT-077 treatment, it is found that tumor weights are about two-times less in MKT-077-treated group than in control group. MKT-077 treatment also results in weight loss and general toxicity in animals[1]. Results show that the succinate-induced, ADP-stimulated respiratory rate in mitochondria isolated from the liver of rats treated with a bolus i.v. injection of 15 mg MKT-077 1kg body weight each day for 5 days is significantly lower than that of untreated controls[3].

References:
[1]. Starenki D, et al. Selective Mitochondrial Uptake of MKT-077 Can Suppress Medullary Thyroid Carcinoma Cell Survival In Vitro and In Vivo. Endocrinol Metab (Seoul). 2015 Dec;30(4):593-603.
[2]. Li X, et al. Analogs of the Allosteric Heat Shock Protein 70 (Hsp70) Inhibitor, MKT-077, as Anti-Cancer Agents. ACS Med Chem Lett. 2013 Nov 14;4(11).
[3]. Weisberg EL, et al. In vivo administration of MKT-077 causes partial yet reversible impairment of mitochondrial function. Cancer Res. 1996 Feb 1;56(3):551-5.