In preliminary findings, researchers have identified differences in the expression of two genes in normal breast tissue from African American and white women that could predispose the former to develop more aggressive tumors and poorer prognoses.
Postdoctoral fellow Lori Field, Ph.D., of the Windber Research Institute, and colleagues at Walter Reed Army Medical Center and Invitrogen Informatics, wanted to understand why breast cancer mortality rates are higher in African American women than in Caucasian, even though the overall incidence in white women is higher.
Breast tumors in black women are larger, more aggressive, and more likely to spread to the lymph node than those in white women.
Before comparing breast cancer tumors, the scientists first examined healthy breast tissue. They obtained samples from 26 African American and 22 Caucasian women enrolled in the Clinical Breast Care Project, a federally mandated breast research program with both military and civilian centers.
Using microarray technology to examine large numbers of genes at once, they found differences in the expression of 89 genes among the two groups. Two of these genes ? PSPH, phosphoserine phosphatase, which is involved in forming serine, and ACSM1, acyl-CoA synthetase medium chain family member 1, which is involved in fatty acid oxidation ? had a higher expression in the African American women.
Serine is an intermediate in the synthesis of other amino acids, as well as DNA and lipids. If more serine is being shunted into any of these pathways, Field said, it might enhance cellular division and growth. Increased ACSM1 expression could increase the rate of fatty acid oxidation in the cell, resulting in a rise in cellular energy production.
“Both conditions could promote cell growth and could potentially provide greater growth advantage to breast cells in African Americans compared to Caucasians and could increase the likelihood to potential cancer transformation,” Field said.
While the researchers continue to validate these initial findings, they currently are comparing breast tumors from African American and Caucasian women to look for differences in gene expression.
“If we see that there are differences in the breast tumors, we may find new molecular targets to which therapy can be tailored specifically to African American women,” Field said.