Figure 4 from ZSTK3744, a Novel Aryl Hydrocarbon Receptor Agonist, Exhibits Efficacy against Chemotherapy-Resistant Triple-Negative Breast Cancer

Evaluation of the antitumor activity of ZSTK3744 on various TNBC cell lines. MM468 (A), MM453 (B), DU4475 (C), and Hs578T (D) cells were treated with ZSTK3744, paclitaxel, adriamycin, or eribulin at the indicated concentrations for 72 hours. Cell viability was assessed using the Cell Counting Kit-8 assay (mean ± SD of quadruplicate experiments). E, AhR and GAPDH protein expression levels were analyzed using Western blotting in wild-type T47D, MM468, MM453, DU4475, and Hs578T cells. GAPDH was used as a loading control. F and G, Evaluation of the antitumor activity of ZSTK3744 was conducted in mouse xenograft models. NOD/SCID mice were subcutaneously implanted with slices of tumors from MM468 (F) and injected with MM453 cells mixed with Matrigel (G). Drug administration was initiated when the tumor volume reached 100–300 mm3. ZSTK3744 was administered intravenously at doses of 1, 2.5, and 5 mg/kg for MM468 and 2.5, 5, and 10 mg/kg for MM453 on days 0, 4, and 8. Tumor volumes for MM468 and MM453 were measured from day 0 to day 32 (mean ± SD, n = 5). Statistical analysis was performed using the Kruskal–Wallis test, followed by the Steel–Dwass test (*, P < 0.05 vs. vehicle-treated group on day 32 of administration).