Peroxiredoxin V: A candidate breast tumor marker of population specificity.

Breast and cervical cancers account for approximately 50% of all types of cancer in Sudanese women. In a previous preliminary proteomic study aimed to identify proteins that were differentially expressed between tumors and control tissues (n=24), we identified peroxiredoxin V (PrdxV) as a candidate tumor marker. Peroxiredoxins (Prdxs) are a family of multifunctional proteins that are involved in the cell protection against oxidative stress, modulation of intracellular signaling, and regulation of cell proliferation. Knockout animal models suggest that the regulation of these proteins may be a novel target for therapeutic interventions. A total of 91 tumors and 79 normal breast tissues obtained from a panel of 106 Sudanese breast cancer patients, as well as 31 paired tissue samples (tumors and controls) from Chinese cancer patients were included in this study. Tissue sections were examined using immunohistochemistry (IHC) for PrdxI, V and VI antibodies. The PrdxV mRNA pattern of expression was also investigated using in situ hybridization (ISH). The overall expression of the same Prdx family members was also examined in a panel of Chinese breast carcinoma and control samples. Statistical comparisons were performed between Prxds antibodies, and between available demographic and pathological parameters. The studied Prdxs were found to be overexpressed in both Sudanese and Chinese breast cancer and control samples. PrdxV was the only member of the Prdxs family to be significantly down-regulated in Sudanese tumor samples, with only a few cases being immunoreactive for PrdxV (11%). Significant elevation was demonstrated between tumors and controls at both the protein (using IHC) (P=0.000) and mRNA (using ISH) (P= 0.044) levels. However, the finding was more apparent and statistically significant at the protein level, suggesting the presence of post-translational modification. These findings suggest that PrdxV is a tumor marker of population specificity. However, more studies are needed to investigate the applicability of PrdxV as a marker in Sudanese breast cancer patients and its potential implications in therapy.