Researchers Study Impact Of Galectin-3 On Breast Cancer

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Researchers at the Barbara Ann Karmanos Cancer Institute in Detroit have been studying racial disparities related to cancer patients. Today, at the American Association for Cancer Research (AACR) Annual Meeting, Karmanos researchers Vitaly Balan, Ph.D., Pratima Nangia-Makker, Ph.D., and Avraham Raz, Ph.D., presented their abstract, Galectin-3 nsSNP rs4644 Foretells Human Breast Cancer Risk Associated with Racial Disparity, exploring factors that suggest why Caucasian women have a significantly higher risk of developing breast cancer than Asian women. This research was done in collaboration with investigators from Karmanos Cancer Institute, in Michigan; Mayo Clinic, in Minnesota; and Zhengzhou University, in China.

Breast cancer is the most common cancer among women, according to the American Cancer Society, and it is the second leading cause of cancer deaths among women in the United States, estimated at more than 40,000 this year alone. It's estimated that in 2007 there were 178,480 new cases of invasive breast cancer and another 62,000 of in situ breast cancer, and Caucasian women are far more prone to develop breast cancer than Asian women, for reasons unknown.

Although the mutations in BRCA1 and BRCA2 were identified as genetic risk factors for breast cancer more than a decade ago, they only account for five percent of the breast cancer cases. The discovery of additional genes that might also prove significant for breast cancer has been limited especially as related to racial differences in the breast cancer incidences.

Researchers studied galectin-3 which is widely expressed in various tumor cells and its expression is correlated with tumorigenesis, tumor progression and metastasis.

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Analysis of galectin-3 variants in the DNA of blood, normal and cancerous tissues of Asian and Caucasian women revealed that galectin-3 is expressed as either histidine at position 64 (H64) or proline (P64) and is associated in part with increased risk for the development of breast cancer.

The breakdown of the data revealed that 64% of the disease-free control Caucasian women were either homozygous (12%) or heterozygous (52%) for H64 and the remaining 36% were homozygous for P64. In contrast, 30% of the disease-free control Asian women carried at least one H64 allele, of which 5% were homozygous and 25% were heterozygous and the remaining 70% were homozygous for P64.

The analysis distribution of the polymorphism of galectin-3 in Caucasian and Asian breast cancer patients showed that about 70% and 90% of the tumor samples from Caucasians and Asians, respectively, harbor the H64 allele, of which approximately 35% of the Caucasians and 70% of the Asians were homozygous for the H64 allele.

"This study suggests that a gene(s) is responsible for the racial disparity between Caucasian and Asian women breast cancer incidence, so we need to look beyond lifestyle influences, such as diet, exercise and environment and consider other genetic markers like Galectin-3 H64 as a possible contributor to breast cancer," said Avraham Raz, Ph.D.

Dr. Raz added, "Further research is needed but the suggestion of Galectin-3-H64 as a contributor in breast cancer is significant."

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