Pharmacogenetics in breast cancer: steps toward personalized medicine in breast cancer management

Unraveling the Role of PCDH9 in Breast Cancer and Identifying Therapeutic Strategies for PCDH9-Deficient Tumors

Introduction

Protocadherin 9 (PCDH9), a member of the cadherin superfamily of transmembrane proteins, plays a role in cell adhesion and neural development. Recent studies suggest that PCDH9 may function as a tumor suppressor in certain cancers, though its specific role in breast cancer remains unclear.

Methods

UALCAN database to retrieve information on PCDH9 expression in breast cancer tissues compared with that in normal tissues. The biological effects of PCDH9 in breast cancer cells were analyzed using the DepMap database. Stable knockdown or overexpression of PCDH9 in breast cancer cell lines and subsequently assessed tumor cell proliferation and migration. Synthetic lethal screening was conducted for breast cancer cells with low PCDH9 expression or deficiency.

Results

In this study, we observed significant downregulation of PCDH9 in breast cancer tissues, with its expression negatively correlated with progression-free survival. Further investigations revealed that decreased PCDH9 expression promotes breast cancer cell proliferation and migration, while overexpression of PCDH9 has the opposite effect. Subsequently, we identified the TAS-102, an approved drug for metastatic colorectal cancer, exhibited selective cytotoxicity against breast cancer cells with low PCDH9 expression.

Conclusion and discussion

In summary, our study identified PCDH9 as a tumor suppressor in breast cancer and highlighted TAS-102 as a potential therapeutic option for tumors with low PCDH9 expression or deficiency. The specific interaction between TAS-102 and PCDH9 warrants further exploration, providing deeper insights into its mode of action in treating PCDH9-deficient breast cancer.

Return of research results from pharmacogenomic versus disease susceptibility studies: what's drugs got to do with it?

One of the most controversial ethical issues in genomics research is the return of individual research results to research subjects. As new technologies, including whole-genome sequencing, provide an increased opportunity for researchers to find clinically relevant research results, the questions related to if, when and how individual research results should be returned become more central to the ethical conduct of genomic research. In the absence of federal guidance on this issue, many groups and individuals have developed recommendations and suggestions to address these questions. Most of these recommendations have focused on the return of individual results from disease susceptibility studies. However, in addition to predicting the development of disease, genomic research also includes predicting an individual's response to drugs, especially the risk of developing adverse events. This article evaluates and compares the return of individual research results from disease susceptibility studies versus pharmacogenomic studies.