The patient information is described in Table 1. Cu/Zn
SOD was included in this experiment as a positive control. Abbreviations: Cu/Zn SOD, copper/zinc superoxide dismutase; see more M, metastatic cancer; N, normal; P, primary cancer; Prx I, peroxiredoxin I; Prx II, peroxiredoxin II; SDS-PAGE, sodium dodecyl sulfate polyacrylamide gel; Trx1, thioredoxin 1. These Western data shown in Figures 7, 8, 9 indicate that Prx I protein was overexpressed in 7 of 8 cases (87.5%) of breast cancer but in none of the 6 cases of normal breast tissue. Thioredoxin1 protein was overexpressed in 6 of 8 cases (75.0%) of breast cancer. Discussion To our knowledge, there has been only one previous report suggesting overexpression of Prx I protein in human breast
cancer. Overexpression of Prx I was detected in 21 of 24 patients (87.5%) with breast cancer, but no significant relationship was found between overexpression of Prx I and progress in breast cancer [13]. Anlotinib research buy Their finding of overexpression of Prx I protein in breast cancer tissue by Western immunoblotting agrees with our observations (7 of 8 cases, 87.5%; 0 of 6 normal, 0%). One study has examined the association of overexpression of Prx I protein with clinicopathological parameters in oral cancer [15]. Low Prx I expression in oral cancer was associated with larger tumor mass and poorly differentiated cancer cells. In our study, all samples of breast cancer stage IV, which belonged to metastatic breast cancers, were found to overexpress Prx I at the highest level. Moreover, in our study of 204 samples, Prx I expression was significantly associated with increasing cancer progress. We examined all six members of the Prx family in eight human cancers (breast, colon, kidney, liver, lung, ovary,
prostate, and thyroid) and found that Prx I was preferentially induced only in breast cancer, not in other cancer tissues. The isoforms Prx GNAT2 I and II were highly expressed in breast cancer. The expression level of Prx II was slightly higher than that of Prx I in breast cancer, but the induction fold of Prx I was significantly higher than that of Prx II. This apparent inconsistency seems to be caused by the lower level of Prx I mRNA in normal breast tissue compared with that of Prx II. At present, few studies have been conducted on all six Prx members in various human cancers [13, 16]. In contrast to our observations, other results have shown high protein expression of Prxs III, IV, and V in breast cancer, but not Prxs I, II, V, and VI. Immunoreactive protein and mRNA levels do not necessarily correspond with each other, as previously seen in a study of Prx V in rat tissues [30]. This suggests that both translational and posttranslational mechanisms probably have effects on Prx protein expression in human tissues. For example, destabilizing Prx proteins by overoxidation or phosphorylation leads to degradation, which results in reduced protein levels in cancer tissue [31, 32].