Human mammary microenvironment better regulates the biology of human breast cancer in humanized mouse model

Biological effect of ribosomal protein L32 on human breast cancer cell behavior

Breast cancer (BC) is the most common malignancy among women worldwide. However, identifying effective biomarkers for the diagnosis and treatment of BC is challenging. Based on our previously developed 'humanized' mouse model of BC, microarray expression analysis was performed and multiple differentially expressed genes, including ribosomal protein (RP) L32, were screened. Recent reports have revealed that RPs are relevant to the development and progression of cancer. However, the expression and function of RPL32 in BC remains unknown. Therefore, in the present study, the role of RPL32 in the development of BC was explored. Immunohistochemical staining and reverse transcription‑quantitative PCR were used, and it was found that RPL32 was upregulated in human BC tissues and cells. Cell Counting Kit‑8, cell invasion and migration assays were performed, which demonstrated that RPL32 knockdown using lentivirus‑delivered small interfering RNA inhibited the migration and invasion of BC cells in vitro and in vivo (nude mouse model). Moreover, western blotting showed that RPL32 knockdown decreased the expression levels of matrix metalloproteinase (MMP)‑2 and MMP‑9. Thus, the present findings indicated a potential oncogenic role of RPL32, suggesting that it may be a novel target for molecular targeted therapy in patients with BC.

Peptide-based gene delivery vectors

Gene therapy as a strategy for disease treatment requires safe and efficient gene delivery systems that encapsulate nucleic acids and deliver them to effective sites in the cell.

Breast Organotypic Cancer Models

Breast cancer is the most common cancer type diagnosed in women, it represents a critical public health problem worldwide, with 1,671,149 estimated new cases and nearly 571,000 related deaths. Research on breast cancer has mainly been conducted using two-dimensional (2D) cell cultures and animal models. The usefulness of these models is reflected in the vast knowledge accumulated over the past decades. However, considering that animal models are three-dimensional (3D) in nature, the validity of the studies using 2D cell cultures has recently been questioned. Although animal models are important in cancer research, ethical questions arise about their use and usefulness as there is no clear predictivity of human disease outcome and they are very expensive and take too much time to obtain results. The poor performance or failure of most cancer drugs suggests that preclinical research on cancer has been based on an over-dependence on inadequate animal models. For these reasons, in the last few years development of alternative models has been prioritized to study human breast cancer behavior, while maintaining a 3D microenvironment, and to reduce the number of experiments conducted in animals. One way to achieve this is using organotypic cultures, which are being more frequently explored in cancer research because they mimic tissue architecture in vivo. These characteristics make organotypic cultures a valuable tool in cancer research as an alternative to replace animal models and for predicting risk assessment in humans. This chapter describes the cultures of multicellular spheroids, organoids, 3D bioreactors, and tumor slices, which are the most widely used organotypic models in breast cancer research.

Screening and analysis of breast cancer genes regulated by the human mammary microenvironment in a humanized mouse model

Tumor microenvironments play critical regulatory roles in tumor growth. Although mouse cancer models have contributed to the understanding of human tumor biology, the effectiveness of mouse cancer models is limited by the inability of the models to accurately present humanized tumor microenvironments. Previously, a humanized breast cancer model in severe combined immunodeficiency mice was established, in which human breast cancer tissue was implanted subcutaneously, followed by injection of human breast cancer cells. It was demonstrated that breast cancer cells showed improved growth in the human mammary microenvironment compared with a conventional subcutaneous mouse model. In the present study, the novel mouse model and microarray technology was used to analyze changes in the expression of genes in breast cancer cells that are regulated by the human mammary microenvironment. Humanized breast and conventional subcutaneous mouse models were established, and orthotopic tumor cells were obtained from orthotopic tumor masses by primary culture. An expression microarray using Illumina HumanHT-12 v4 Expression BeadChip and database analyses were performed to investigate changes in gene expression between tumors from each microenvironment. A total of 94 genes were differentially expressed between the primary cells cultured from the humanized and conventional mouse models. Significant upregulation of genes that promote cell proliferation and metastasis or inhibit apoptosis, such as SH3-domain binding protein 5 (BTK-associated), sodium/chloride cotransporter 3 and periostin, osteoblast specific factor, and genes that promote angiogenesis, such as KIAA1618, was also noted. Other genes that restrain cell proliferation and accelerate cell apoptosis, including tripartite motif containing TRIM36 and NES1, were downregulated. The present results revealed differences in various aspects of tumor growth and metabolism between the two model groups and indicated the functional changes specific to the human mammary microenvironment.