Characterization of the anticancer effects of S115, a novel heteroaromatic thiosemicarbazone compound, in vitro and in vivo

Abstract

Aim: To investigate the anticancer effects of S115, a novel heteroaromatic thiosemicarbazone compound in vitro and in vivo.

Methods: The anti-proliferative action of S115 was analyzed in 12 human and mouse cancer cell lines using MTT assay. Autograft and xenograft cancer models were made by subcutaneous inoculation of cancer cells into mice or nude mice. The mice were orally treated with S115 (2, 8, 32 mg·kg(-1)·d(-1)) for 7 d, and the tumor size was measured every 3 d. Cell apoptosis and cell cycle distribution were examined using flow cytometry, gene expression profile analyses, Western blots and RT-PCR.

Results: The IC50 values of S115 against 12 human and mouse cancer cell lines ranged from 0.3 to 6.6 μmol/L. The tumor growth inhibition rate caused by oral administration of S115 (32 mg·kg(-1)·d(-1)) were 89.7%, 81.7%, 78.4% and 77.8%, respectively, in mouse model of B16 melanoma, mouse model of Colon26 colon cancer, nude mouse model of A549 lung cancer and nude mouse model of SK-OV-3 ovarian cancer. Furthermore, oral administration of S115 (7.5 mg·kg(-1)·d(-1)) synergistically enhanced the anticancer effects of cyclophosphamide, cisplatin, or 5-fluorouracil in mouse model of S180 sarcoma. Treatment of A549 human lung cancer cells with S115 (1.5 μmol/L) induced G0/G1 cell cycle arrest, and increased apoptosis. Furthermore, S115 downregulated the level of ubiquitin, and upregulated the level of Tob2 in A549 cells.

Conclusion: S115 exerts anticancer effects against a variety of cancer cells in vitro and in grafted cancer models by inducing apoptosis, downregulating ubiquitin and upregulating Tob2.

Figure 1

Chemical structure of S115.

Figure 2

Inhibitory effects of multi-daily gavage of S115 on B16 (A) and Colon26 (B) tumor growth in the allografted B16-C57BL/6 or BALB/c mouse model. B16 mouse melanoma cells or Colon26 colon cells were injected into C57BL/6 or BALB/c mice. Immediately after inoculation, mice were given multi-daily gavage of saline (0.5 mL/d) or S115 (2, 8, or 32 mg·kg⁻¹·d⁻¹) for 7 d. Images of the excised B16 tumors from all mice in each group are shown. Data are presented as mean±SD. (n=10 in each group).

Figure 3

Inhibitory effects of multi-daily gavage of S115 on A549 tumor growth in the xenografted A549-BALB/c nude mouse model. A549 human lung carcinoma cells were injected into BALB/c nude mice. After solid tumors grew to about 100 mm³, mice were given multi-daily gavage of saline (0.5 mL/d) or S115 (2, 8, or 32 mg·kg⁻¹·d⁻¹) for 7 d. (A) Tumor growth is shown as measured by tumor volume over a time-course. (B) Images are shown for the isolated tumors from the mice from each group following 12 d treatment. Data are presented as mean±SD. n=6 per group.

Figure 4

Inhibitory effects of multi-daily gavage of S115 on SK-OV-3 tumor growth in xenografted SK-OV-3-BALB/c nude mouse model. SK-OV-3 human hepatoma cells were injected into BALB/c nude mice. After solid tumors grew to about 100 mm³, mice were given multi-daily gavage of saline (0.5 mL/d) or S115 (2, 8, or 32 mg/kg) for 7 d. (A) Tumor growth was measured by tumor volume and is graphed over time. (B) Images are isolated tumors from the mice from each group after 12 d of treatment. Data are presented as mean±SD. n=6 per group.

Figure 5

Inhibitory effects of multi-daily gavage of S115 on Bcap-37 tumor growth in xenografted Bcap-37-BALB/c nude mouse model. Bcap-37 human breast cancer cells were injected into BALB/c nude mice. After solid tumors grew to about 100 mm³, mice were given multi-daily gavage of saline (0.5 mL/d) or S115 (2, 8, or 32 mg/kg) for 7 d. (A) Tumor growth was measured by tumor volume and is graphed over time. (B) Images are isolated tumors from the mice from each group after 12 d of treatment. Data are presented as mean±SD. (n=6 per group).

Figure 6

S115 (1.5 μmol/L) promotes progressive apoptosis and G₀–G₁ cell cycle arrest in A549 human lung carcinoma cells (A). The apoptotic cells were stained with propidium iodide and the cell cycle distribution was evaluated using a flow cytometry (B).

Figure 7

Changes in the gene expression of human non-small cell lung carcinoma A549 cells under the action of 1.5 μmol/L of S115 at different time points: 0, 3, 6, 12, 24, 48, and 72 h with 3 chips per point. The network of differentially expressed genes included those involved in the UPS obtained from microarray analysis.

Figure 8

Tob2 status of the human non-small cell lung carcinoma A549 cell line under the action of 1.5 μmol/L of S115 measured at 3 points in time: 0, 3, and 24 h. The status of Tob2 was upregulated by S115 as indicated by Western blot analysis and RT-PCR. ^bP<0.05, ^cP<0.01 vs 0 h.