HOXB7 gene promotes tamoxifen resistance

December 10, 2010

A gene target for drug resistance, a triple-drug cocktail for triple negative breast cancer, and patients' risk for carpal tunnel syndrome are among study highlights scheduled to be presented by Johns Hopkins Kimmel Cancer Center scientists during the 33rd Annual CTRC-AACR San Antonio Breast Cancer Symposium, held Dec. 8-12. The information is embargoed for the time of presentation at the symposium.

HOXB7 GENE PROMOTES TAMOXIFEN RESISTANCE
(Presentation # PD05-10)

Many postmenopausal women with early-stage breast cancers who initially respond well to tamoxifen become resistant to the drug over time and develop recurrent tumors. Johns Hopkins Kimmel Cancer Center researchers have found that a gene called HOXB7 may be the culprit in tamoxifen resistance.

Taken by mouth, tamoxifen is used at every stage of breast cancer to treat existing tumors and prevent new ones from developing. The drug works only in women whose tumor cells have a protein, called the estrogen receptor, which binds to the estrogen hormone. Tamoxifen binds to this estrogen receptor and blocks estrogen's effect on fueling cancer cells.

In experiments on cancer cells, the scientists found that when the HOXB7 gene is overexpressed, as occurs in many breast cancers, tumors cells became resistant to tamoxifen. Overexpression of HOXB7 results in proteins that interact with a series of other estrogen-activated genes and proteins, including the HER2 gene, known to make breast cancers aggressive. When the scientists knocked out the HOXB7 gene in one group of breast cancer cells, HER2 activation decreased and the cells became more responsive to tamoxifen. The scientists then showed how the HOXB7-HER2 interaction works.

"HOXB7 appears crucial in orchestrating estrogen receptors, HER2 and other receptors that promote aggressive tumor growth in breast cancer cells," says senior author Saraswati Sukumar, PhD, professor of oncology and co-director of the Breast Cancer Program at Johns Hopkins. "Dialing down expression of the HOXB7 gene could stave off tamoxifen resistance."

Though it's not yet evident how to shut down HOXB7, Sukumar says that oncologists could potentially use the drug Herceptin to kill tumors in patients whose HER2 expression increases.
-end-
On the Web:
www.hopkinskimmelcancercenter.org
San Antonio Breast Cancer Symposium: http://www.sabcs.org/

Johns Hopkins Medicine

Related Breast Cancer Articles from Brightsurf:

Oncotarget: IGF2 expression in breast cancer tumors and in breast cancer cells
The Oncotarget authors propose that methylation of DVDMR represents a novel epigenetic biomarker that determines the levels of IGF2 protein expression in breast cancer.

Breast cancer: AI predicts which pre-malignant breast lesions will progress to advanced cancer
New research at Case Western Reserve University in Cleveland, Ohio, could help better determine which patients diagnosed with the pre-malignant breast cancer commonly as stage 0 are likely to progress to invasive breast cancer and therefore might benefit from additional therapy over and above surgery alone.

Partial breast irradiation effective treatment option for low-risk breast cancer
Partial breast irradiation produces similar long-term survival rates and risk for recurrence compared with whole breast irradiation for many women with low-risk, early stage breast cancer, according to new clinical data from a national clinical trial involving researchers from The Ohio State University Comprehensive Cancer Center - Arthur G.

Breast screening linked to 60 per cent lower risk of breast cancer death in first 10 years
Women who take part in breast screening have a significantly greater benefit from treatments than those who are not screened, according to a study of more than 50,000 women.

More clues revealed in link between normal breast changes and invasive breast cancer
A research team, led by investigators from Georgetown Lombardi Comprehensive Cancer Center, details how a natural and dramatic process -- changes in mammary glands to accommodate breastfeeding -- uses a molecular process believed to contribute to survival of pre-malignant breast cells.

Breast tissue tumor suppressor PTEN: A potential Achilles heel for breast cancer cells
A highly collaborative team of researchers at the Medical University of South Carolina and Ohio State University report in Nature Communications that they have identified a novel pathway for connective tissue PTEN in breast cancer cell response to radiotherapy.

Computers equal radiologists in assessing breast density and associated breast cancer risk
Automated breast-density evaluation was just as accurate in predicting women's risk of breast cancer, found and not found by mammography, as subjective evaluation done by radiologists, in a study led by researchers at UC San Francisco and Mayo Clinic.

Blood test can effectively rule out breast cancer, regardless of breast density
A new study published in PLOS ONE demonstrates that Videssa® Breast, a multi-protein biomarker blood test for breast cancer, is unaffected by breast density and can reliably rule out breast cancer in women with both dense and non-dense breast tissue.

Study shows influence of surgeons on likelihood of removal of healthy breast after breast cancer dia
Attending surgeons can have a strong influence on whether a patient undergoes contralateral prophylactic mastectomy after a diagnosis of breast cancer, according to a study published by JAMA Surgery.

Young breast cancer patients undergoing breast conserving surgery see improved prognosis
A new analysis indicates that breast cancer prognoses have improved over time in young women treated with breast conserving surgery.

Read More: Breast Cancer News and Breast Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.