Anticancer Potential and Safety Profile of β-Lapachone In Vitro

Abstract

Ipê is a plant of the Bignoniaceae family. Among the compounds extracted from this tree, lapachol is notable because its structural modification allows the production of β-lapachone, which has anticancer properties. The objective of this work was to test this hypothesis at a cellular level in vitro and assess its potential safety for use. The following tests were performed: MTT cell viability assay, apoptotic index determination, comet assay, and micronucleus test. The results showed that β-lapachone had a high cytotoxic capacity for all cell lines tested: ACP02 (gastric adenocarcinoma cells), MCF7 (breast carcinoma cells), HCT116 (colon cancer cells) and HEPG2 (hepatocellular carcinoma cells). Regarding genotoxicity, the exposure of cells to sublethal doses of β-lapachone induced DNA damage (assessed by the comet assay) and nuclear abnormalities, such as nucleoplasmic bridges and nuclear buds (assessed by the micronucleus test). All tested cell lines responded similarly to β-lapachone, except for ACP02 cells, which were relatively resistant to the cytotoxic effects of the compound in the MTT test. Our results collectively indicate that although β-lapachone showed antiproliferative activity against cancer cell lines, it also caused harmful effects in these cells, suggesting that the use of β-lapachone in treating cancer should be carried out with caution.

Keywords: Ipê; antiproliferative activity; apoptosis; genotoxicity; mutagenicity.

Figure 1

The survival of neoplastic cell lines under β-lapachone treatment was evaluated using the MTT test. The tested cell lines were (A) ACP02, (B) MCF7, (C) HCT116, and (D) HEPG2. Statistical analysis was performed using ANOVA parametric test (multiple comparisons—Tukey); * indicates a significant difference relative to the other treatments.

Figure 2

IC50 values of β-lapachone in four neoplastic cell lines. Statistical analysis was performed using ANOVA parametric test (multiple comparisons—Tukey); * indicates a significant difference relative to the other cell lines.

Figure 3

Apoptosis in neoplastic cells treated with β-lapachone for 24 h. (A) The cell lines were exposed to different concentrations of β-lapachone and the apoptotic index was determined. (B) The percentage of apoptotic cells seen at the highest concentration tested (1.5 µg/mL) was compared across the cell lines. NC: negative control; PC: positive control. Statistical analysis was performed using ANOVA parametric test (multiple comparisons—Tukey); * indicates a significant difference with respect to the NC, 0.5 µg/mL, and 1 µg/mL groups.

Figure 4

DNA damage index in HepG2 cells treated for 3 h with various doses of β-lapachone. NC: negative control; PC: positive control. Statistical analysis was performed using ANOVA parametric test (multiple comparisons—Tukey); * indicates a significant difference relative to the NC.

Figure 5

Micronucleus test results for cells exposed for 24 h to different concentrations of β-lapachone and control treatments. (A) Cytokinesis block proliferation index (CBPI). (B) Frequency of micronuclei (MN). (C) Frequency of nuclear abnormalities (NAs). NC: negative control; PC: positive control. Statistical analysis was performed using ANOVA parametric test (multiple comparisons—Tukey); ^a indicates a significant difference relative to the NC group; ^b indicates a significant difference relative to all other treatments.

Figure 6

Parameters analyzed in the micronucleus test of cells exposed for 24 h to β-lapachone. (A) Binucleated cell without any change (negative control cells). (B) Binucleated cell with micronucleus (arrow) from the positive control group. (C) Cell treated with 0.5 µg/mL of β-lapachone, exhibiting a nuclear bud (arrow). (D) Cell treated with 1 µg/mL of β-lapachone, exhibiting a nucleoplasmic bridge (arrow).