Daily or weekly dosing with EGFR inhibitors, gefitinib and lapatinib, and AKt inhibitor MK2206 in mammary cancer models

Eupalinolide O Induces Apoptosis in Human Triple-Negative Breast Cancer Cells via Modulating ROS Generation and Akt/p38 MAPK Signaling Pathway

Background

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with limited therapeutic options. Eupalinolide O (EO) was reported to inhibit tumor growth. This study is aimed at exploring the role of EO on TNBC both in vivo and in vitro. Methods. In in vitro experiments, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and clonogenic assay were conducted to measure the impact of EO on TNBC cell growth at different concentrations and time points. Flow cytometry was conducted to evaluate cell apoptosis. Mitochondrial membrane potential (MMP) loss, caspase-3 activity, and reactive oxygen species (ROS) generation were assessed. The expressions of apoptosis-related mRNAs and Akt/p38 MAPK signaling pathway-related proteins were measured. In in vivo experiments, by injecting TNBC cells into the nude mice to induce xenograft tumor, mice were treated with EO for 20 days. Then, in vivo bioluminescence imaging system was utilized to monitor the growth and distribution of TNBC cells. Tumor volume and weight were also recorded. Hematoxylin-eosin (HE) staining and ELISA assay were applied to observe tumor tissue morphology and ROS levels. Furthermore, western blotting was conducted to observe the expression of apoptosis-related proteins and Akt/p38 MAPK signaling pathway-associated proteins.

Results

EO inhibited the cell viability and proliferation of TNBC cells but not normal epithelial cells. Furthermore, EO induced apoptosis, decreased MMP, and elevated caspase-3 activity and ROS content in TNBC cells. Meanwhile, the expression of apoptosis-related mRNAs and Akt/p38 MAPK pathway-related proteins was regulated by EO treatment. Besides, in vivo experiments demonstrated EO not only suppressed tumor growth, Ki67 expression, ROS generation, and Akt phosphorylation but also upregulated caspase-3 expression and p-38 phosphorylation.

Conclusion

EO may induce cell apoptosis in TNBC via regulating ROS generation and Akt/p38 MAPK pathway, indicating EO may be a candidate drug for TNBC.

Cancer Chemoprevention: Preclinical In Vivo Alternate Dosing Strategies to Reduce Drug Toxicities

Cancer chemopreventive agents inhibit the formation of precursor lesions and/or the progression of these lesions to late stage disease. This approach to disease control has the potential to reduce the physical and financial costs of cancer in society. Several drugs that have been approved by the FDA for other diseases and have been extensively evaluated for their safety and pharmacokinetic/pharmacodynamic characteristics have the potential to be repurposed for use as cancer chemopreventive agents. These agents often mechanistically inhibit signaling molecules that play key roles in the carcinogenic process. The safety profile of agents is a primary concern when considering the administration of drugs for chemoprevention, as the drugs will be given chronically to high-risk, asymptomatic individuals. To decrease drug toxicity while retaining efficacy, several approaches are currently being explored. In this short review, we describe studies that use preclinical in vivo models to assess efficacy of alternative drug dosing strategies and routes of drug administration on chemopreventive drug efficacy. In vivo drug dosing strategies that reduce toxicity while retaining efficacy will pave the way for future cancer prevention clinical trials.