Role of hypoxia and glycolysis in the development of multi-drug resistance in human tumor cells and the establishment of an orthotopic multi-drug resistant tumor model in nude mice using hypoxic pre-conditioning

Lara Milane,Mansoor Amiji,Zhenfeng Duan

doi:10.1186/1475-2867-11-3

Abstract

BackgroundThe development of multi-drug resistant (MDR) cancer is a significant challenge in the clinical treatment of recurrent disease. Hypoxia is an environmental selection pressure that contributes to the development of MDR. Many cancer cells, including MDR cells, resort to glycolysis for energy acquisition. This study aimed to explore the relationship between hypoxia, glycolysis, and MDR in a panel of human breast and ovarian cancer cells. A second aim of this study was to develop an orthotopic animal model of MDR breast cancer.MethodsNucleic and basal protein was extracted from a panel of human breast and ovarian cancer cells; MDR cells and cells pre-exposed to either normoxic or hypoxic conditions. Western blotting was used to assess the expression of MDR markers, hypoxia inducible factors, and glycolytic proteins. Tumor xenografts were established in the mammary fat pad of nu/nu mice using human breast cancer cells that were pre-exposed to either hypoxic or normoxic conditions. Immunohistochemistry was used to assess the MDR character of excised tumors.ResultsHypoxia induces MDR and glycolysis in vitro, but the cellular response is cell-line specific and duration dependent. Using hypoxic, triple-negative breast cancer cells to establish 100 mm3 tumor xenografts in nude mice is a relevant model for MDR breast cancer.ConclusionHypoxic pre-conditiong and xenografting may be used to develop a multitude of orthotopic models for MDR cancer aiding in the study and treatment of the disease.

Highlights

The basal protein and nucleic protein from cells exposed to hypoxic and normoxic conditions was extracted and western blotting was used to analyze the expression of hypoxic factors, multi-drug resistant (MDR) markers, and downstream proteins induced under hypoxic regulation
Nuclear protein analysis (Figure 2A) revealed that Hypoxia Inducible Factor (HIF)-1a expression was apparent in all cells but was elevated in the MDR cells, in cells exposed to hypoxic conditions for 3 days, and in cells exposed to hypoxic conditions for 5 days
Hypoxia alone is sufficient in transforming normal cancer cells into MDR cancer

Summary

Introduction

Angiogenesis and vascular destruction are dynamic, ongoing processes; as the tumor is established new blood vessels are formed, this process continues as the tumor grows, but as the tumor propagates and expands blood vessels may be destroyed or cut off [16,17,18]. This haphazard process of neo- and de-vascularization contributes to the evolving phenotype of a tumor. The development of multi-drug resistant (MDR) cancer is a significant challenge in the clinical treatment of recurrent disease. A second aim of this study was to develop an orthotopic animal model of MDR breast cancer

Objectives

Methods

Results

Discussion

Conclusion