Pyronaridine exerts potent cytotoxicity on human breast and hematological cancer cells through induction of apoptosis

The potent antimalarial drug pyronaridine (PND) was tested for its potential as an anticancer drug. After exposing cancerous (17) and non-cancerous (2) cells to PND for 72 hr, PND was found to exhibit consistent and potent cytotoxic activity at low micromolar (μM) concentrations that ranged from 1.6 μM to 9.4 μM. Moreover, PND exerted a significant selective cytotoxicity index (SCI) on five out of seven breast cancer cell lines tested, with favorable values of 2.5 to 4.4, as compared with the non-cancerous breast MCF-10A cell line. By using the same comparison, PND exhibited a significant SCI on three out of four leukemia/lymphoma cell lines with promising values of 3.3 to 3.5. One breast cancer and one leukemia cell line were tested further in order to determine the likely mode of action of PND. PND was found to consistently elicit phosphatidylserine externalization, mitochondrial depolarization, and DNA fragmentation, in both the triple negative MDA-MB-231 breast cancer and HL-60 leukemia cell lines. In addition, PND treatment altered cell cycle progression in both cancer cells. Subsequent DNA mobility-shift assays, UV-Visible spectroscopic titrations, and circular dichroism (CD) experiments revealed that PND intercalates with DNA. The findings presented in this study indicates that PND induces apoptosis and interfered with cell cycle progression of cancer cell lines and these results indicate that this drug has the potential as a repurposed drug for cancer therapy.

Use of non-selective β-blockers is associated with decreased tumor proliferative indices in early stage breast cancer

Previous studies suggest beta-adrenergic receptor (β-AR) antagonists (β-blockers) decrease breast cancer progression, tumor metastasis, and patient mortality; however the mechanism for this is unknown. Immunohistochemical analysis of normal and malignant breast tissue revealed overexpression of β1-AR and β3-AR in breast cancer. A retrospective cross-sectional study of 404 breast cancer patients was performed to determine the effect of β-blocker usage on tumor proliferation. Our analysis revealed that non-selective β-blockers, but not selective β-blockers, reduced tumor proliferation by 66% (p < 0.0001) in early stage breast cancer compared to non-users. We tested the efficacy of propranolol on an early stage breast cancer patient, and quantified the tumor proliferative index before and after treatment, revealing a propranolol-mediated 23% reduction (p = 0.02) in Ki67 positive tumor cells over a three-week period. The anti-proliferative effects of β-blockers were measured in a panel of breast cancer lines, demonstrating that mammary epithelial cells were resistant to propranolol, and that most breast cancer cell lines displayed dose dependent viability decreases following treatment. Selective β-blockers alone or in combination were not as effective as propranolol at reducing breast cancer cell proliferation. Molecular analysis revealed that propranolol treatment of the SK-BR-3 breast cancer line, which showed high sensitivity to beta blockade, led to a reduction in Ki67 protein expression, decreased phosphorylation of the mitogenic signaling regulators p44/42 MAPK, p38 MAPK, JNK, and CREB, increased phosphorylation of the cell survival/apoptosis regulators AKT, p53, and GSK3β. In conclusion, use of non-selective β-blockers in patients with early stage breast cancer may lead to decreased tumor proliferation.

Tumor-selective cytotoxicity of a novel pentadiene analogue on human leukemia/ lymphoma cells

BACKGROUND

A novel series of structurally divergent 1,5-diaryl-3-oxo-1,4-pentadiene analogues 1-10 displayed marked cytotoxic potencies towards a number of human leukemia/lymphoma cells.

OBJECTIVE

To identify novel selective cytotoxic compounds that induce apoptosis.

METHODS

The Differential Nuclear Staining (DNS) screening protocol was utilized to measure the cytotoxicity of all experimental dienones on several cancerous cells. Additionally, the selective cytotoxicity index was calculated by comparing the dienone's cytotoxicity between leukemia/lymphoma cells vs. non-cancerous cells. Furthermore, to discern whether a selected dienone induced cell death via apoptosis or necrosis on T-lymphocyte leukemia cells, diverse approaches were utilized to detect individual biochemical facets of apoptosis.

RESULTS

The dienones were tested for their anti-neoplastic efficiency on human leukemia/lymphoma-derived cell lines. Special emphasis was applied on dienone 1, on the basis of its sub-micromolar cytotoxicity (CC₅₀=0.43+0.02 μM) and high selective cytotoxicity index (11.1) exerted on T-leukemia cells. In general, dienone 1 showed the most potent cytotoxic properties as compared to other dienones and a related reference cytotoxin curcumin as well as the EF-24 curcumin analogue. Dienone 1 caused cell death by apoptosis in Jurkat cells as evidenced by inducing phosphatidylserine externalization, mitochondrial depolarization and caspase-3/7. These effects were mainly attributed to the induction of apoptotic pathways.

CONCLUSION

The novel dienone 1 was found to exhibit potent anti-leukemia activity by inducing programmed cell death/apoptosis. Consequently, dionone 1 should be developed further to examine its potential efficacy to combat malignancies in a pre-clinical animal model.