Breast Cancer Neoadjuvant Chemotherapy Response with miRNA

Institution: Beckman Research Institute of the City of Hope
Investigator(s): Shizhen Emily Wang, Ph.D. -
Award Cycle: 2010 (Cycle 16) Grant #: 16IB-0081 Award: $249,000
Award Type: IDEA
Research Priorities
Detection, Prognosis and Treatment>Innovative Treatment Modalities: search for a cure

Initial Award Abstract (2010)

Pre-operative chemotherapy, also referred to as neoadjuvant chemotherapy (NCT), is increasingly being used to treat patients with late-stage breast cancers, with the expectation that the treatment can reduce the size or extent of the cancer before surgery, thus making the surgical procedures easier and more likely to be successful. However, only a minority of the patients who have receive NCT show optimal response. The underlying reasons remain unclear; therefore, it is critical to develop clinical markers to better predict patients’ NCT response and to determine the causes of drug resistance at the molecular level.

This project focuses on the detection of a novel type of biomarker, microRNAs (miRNAs), from the blood of breast cancer patients. These, recently discovered, small molecules play crucial functions in various physiological mechanisms and are aberrantly expressed in cancer. MiRNAs can be secreted by cancer cells and readily detected from blood, since they are so stable. Our project is a study to assess circulating miRNAs in breast cancer patients, and on their correlation with tumor NCT response.

Our approach, first, is to collect RNA fractions enriched for small RNAs from paired breast cancer tissue and serum samples prior to and after NCT. These samples will be analyzed by “deep sequencing” (i.e., DNA sequencing at very high throughput) with the Solexa platform. We will characterize changes in the miRNA profiles after NCT, and will identify miRNA signatures associated with drug response and resistance. In parallel, growth media will be prepared from a panel of breast cancer cell lines and normal cells cultured in the presence/absence of the chemotherapy agent cisplatin. Deep sequencing analyses will be carried out and the profiles of miRNAs secreted by cancer and normal cells. Secreted miRNAs with cancer specificity and correlated to clinical features, and those for which level is changed upon drug treatment will be validated and selected for additional study. Taken together, we hope to relate the changes in the miRNA “signature” to clinically-relevant mechanistic/ molecular-level changes that predict a patients’ successful NCT response.

Identification of blood-based miRNA “signature” that predicts response to NCT, as an immediate outcome of this study, will enhance our ability to develop individualized NCT, which will result in higher drug efficacy with reduced side effects. This study may also reveal novel mechanisms of drug action/resistance.

Final Report (2012)

Although pre-operative chemotherapy, also referred to as neoadjuvant chemotherapy (NCT), is increasingly being used to treat patients with late-stage breast cancers (BC), only a minority of the patients who have received the treatment show regression of the disease and improved survival. The goals of this study are to identify the blood-borne microRNA (miRNA) “signature” associated with BC response and resistance to NCT (Aim 1), and to determine the function of identified miRNAs (Aim 2). MiRNAs are known to play crucial functions in cancer, and can be secreted by cancer cells and readily detected from blood. The proposed project on assessment of circulating miRNAs in BC patients and the correlation of miRNAs with tumor traits (e.g., drug response) is therefore of great clinical interest for its potential to guide future treatments.

During the 1.5-year funding period, we have completed the studies proposed in Aim 1 and Aim 2. In Aim 1, we identified the miRNA signature associated with chemotherapy response. By deep sequencing small RNAs in the pre-treatment serum specimens from BC patients with or without pathological complete response to NCT, we determined 19 circulating miRNAs that are differentially expressed between the two groups of patients. We encountered but eventually overcame several technical challenges from the highly innovative Solexa deep sequencing technique, and were able to acquire high-quality sequencing data from 42 out of 60 serum samples. As this is the first study to profile miRNAs using de novo sequencing approach from ~1 milliliter of patient serum, the current successful rate is highly promising, and will be further improved in our future studies based on the experiences we have gained. These results have been accepted for publication in the Journal of Translational Medicine.

In Aim 2, we determined the function of several selected miRNAs. We found that two miRNAs readily detected in the blood of BC patients, miR-21 and miR-181, can be induced by transforming growth factor beta (TGF-beta), and are related to chemotherapy resistance by regulating the expression of MSH2 and ATM, two genes that play important role in the cancer-killing effects of DNA damaging chemotherapy drug. These results have been published in Oncogene and Molecular Cancer Research.

We have also investigated the potential function of selected circulating miRNAs outside of cancer cells via their secretion by cancer cells and uptake by various types of niche cells, such as epithelial and endothelial cells. Both niche cell types can efficiently internalize miRNAs secreted by cancer cells, and exhibit altered expression of the corresponding miRNA target genes. Through the successful completion of this project, we have gained important insight into the role of blood-borne miRNAs as potential biomarkers and therapeutic targets. Our study revealed the global patterns of circulating miRNAs in breast cancer patients, and led to the identification of miRNA markers that can predict clinical outcome in primary stage II–III breast cancer.

Transforming growth factor-ß regulates the sphere-initiating stem cell-like feature in breast cancer through miRNA-181 and ATM.
Index Medicus: Oncogene
Authors: Wang Y, Yu Y, Tsuyada A, Ren X, Wu X, Stubblefield K, Rankin-Gee EK, Wang SE
Yr: 2010 Vol: 30 Nbr: 12 Abs: Pg:1470-80

Context-dependent bidirectional regulation of the MutS homolog 2 by transforming growth factor ß contributes to chemoresistance in breast cancer cells.
Periodical:Molecular Cancer Research
Index Medicus: Mol Cancer Res
Authors: Yu Y, Wang Y, Ren X, Tsuyada A, Li A, Liu LJ, Wang SE
Yr: 2010 Vol: 8 Nbr: 12 Abs: Pg:1633-42

De novo sequencing of circulating miRNAs identifies novel markers predicting clinical outcome of locally advanced breast cancer.
Periodical:Journal of Translational Medicine
Index Medicus: J Transl Med
Authors: Wu X, Somlo G, Yu Y, Palomares MR, et al and Wang SE
Yr: 2012 Vol: 10 Nbr: Abs: Pg:42