A novel class of C14-sulfonate-tetrandrine derivatives as potential chemotherapeutic agents for hepatocellular carcinoma

Abstract

Hepatocellular carcinoma (HCC), the most common malignancy of the liver, exhibits high recurrence and metastasis. Structural modifications of natural products are crucial resources of antitumor drugs. This study aimed to synthesize C-14 derivatives of tetrandrine and evaluate their effects on HCC. Forty C-14 sulfonate tetrandrine derivatives were synthesized and their in vitro antiproliferative was evaluated against four hepatoma (HepG-2, SMMC-7721, QGY-7701, and SK-Hep-1) cell lines. For all tested cells, most of the modified compounds were more active than the lead compound, tetrandrine. In particular, 14-O-(5-chlorothiophene-2-sulfonyl)-tetrandrine (33) exhibited the strongest antiproliferative effect, with half-maximal inhibitory concentration values of 1.65, 2.89, 1.77, and 2.41 μM for the four hepatoma cell lines, respectively. Moreover, 33 was found to induce apoptosis via a mitochondria-mediated intrinsic pathway via flow cytometry and western blotting analysis. In addition, colony formation, wound healing, and transwell assays demonstrated that 33 significantly inhibited HepG-2 and SMMC-7721 cell proliferation, migration, and invasion, indicating that it might potentially be a candidate for an anti-HCC therapy in the future.

Keywords: anti-HCC; anti-migration; apoptosis; sulfonate derivatives; tetrandrine derivatives.

SCHEME 1

General synthetic route of tetrandrine derivatives. (i) Mixed acid HNO₃: (CH₃CO)₂O = 3:5, v/v), CH₂Cl₂, 0°C, 45 min (ii) Pd/C (10%), N₂H₄⋅H₂O, MeOH, 80°C, 1 h (iii) 1) 2 M H₂SO₄, NaNO₂, 0°C, 10 min; 2) 10 M H₂SO₄, 110°C, 1 h (iv) Sulfonyl chloride (RSO2Cl), 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDCI), 4-dimethylaminopyridine (DMAP), CH2Cl2, 0°C, 8 h.

FIGURE 1

Compound 33 inhibits hepatocellular carcinoma (HCC) cell proliferation in vitro. (A) HepG-2 and SMMC-7721 cells were treated with different concentrations (0, 1, 2, and 4 μM) of compound 33 to analyze colony formation. (B) Data are represented as the mean ± standard error of the mean (SEM) of three independent experiments. *p < 0.05, **p < 0.01.

FIGURE 2

Compound 33 suppresses the motility of HCC cells in vitro. (A,B) HepG-2 and SMMC-7721 cells were treated with different concentrations (0, 1, 2, and 4 μM) of 33 to analyze wound healing. (C) Invasion cell numbers were analyzed using a transwell assay in HepG-2 and SMMC-7721 cells treated with different concentrations (0, 1, 2, and 4 μM) of compound 33. *p < 0.05, **p < 0.01, ***p < 0.001.

FIGURE 3

Compound 33 induces the apoptosis of HCC cells in vitro. (A) Apoptosis of HepG-2 and SMMC-7721 cells with different concentrations (0, 1, 2, and 4 μM) of 33 was analyzed via flow cytometry. (B). Based on three independent experiments, GraphPad Prism software (version 8.0.2) was used to quantify the percentage of apoptotic cells. Results of three independent experiments are presented as the mean ± SEM. *p < 0.05, **p < 0.01.

FIGURE 4

Compound 33 induces the apoptosis of HepG-2 and SMMC-7721 cells via the mitochondrial pathway. (A) Western blotting revealed that 33 increases the mitochondrial pathway protein expression in HepG-2 and SMMC-7721 cells. (B) Western blot results statistics were performed using GraphPad Prim software (version 8.0.2). Results of three independent experiments are presented as the mean ± SEM. *p < 0.05, **p < 0.01.