Expression of peroxisome‐proliferator activated receptor‐gamma (PPARγ) and the PPARγ co‐activator, PGC‐1, in human breast cancer correlates with clinical outcomes

Peroxisome‐proliferator activated receptor‐gamma (PPARγ) belongs to a family of nuclear receptors and acts as receptor for peroxisome‐proliferators, steroids, retinoic acids, and polyunsaturated fatty acids. Our study examined the transcript levels of peroxisome‐proliferator activated receptor‐gamma (PPARγ) and its co‐activator (PGC‐1) in a cohort of patients with breast cancer. An invasive breast cancer cell, MDA MB 231 exhibited lower level of expression of PPARγ, compared to non‐invasive MCF‐7. Breast cancer tissues (n = 120) exhibited a lower level of PPARγ mRNA compared to normal tissues (n = 25, p = 0.05). No difference, however, was seen with PGC‐1. Although the levels of PPARγ and PGC‐1 did not correlate with nodal involvement and grade, significantly lower levels of PPARγ were seen in TNM3 and TNM4 tumors and from patients with local recurrence and those who died of breast cancer. Lowest level of PGC‐1 was also seen in TNM3 and TNM4 tumors and patients who died of breast cancer. We conclude that there is aberrant expression of PPARγ and its co‐activator, PGC‐1, in human breast cancer and low levels of these molecules in cancer tissues are associated with poor clinical outcomes. © 2003 Wiley‐Liss, Inc.