Studies on the association of malondialdehyde as a biomarker for oxidative stress and degree of malignancy in dogs with mammary adenocarcinomas.

BACKGROUND: Mammary adenocarcinomas are one of the most common tumour diseases in bitches. The relationship between oxidative stress and the degree of malignancy of the tumour has not been sufficiently researched in veterinary medicine. OBJECTIVES: The main objective was to investigate the potential role of MDA as a practice-relevant biomarker for the assessment of systemic oxidative stress and to determine whether this parameter can indicate the malignancy grade of a mammary adenocarcinoma. METHODS: In the present pilot study, MDA plasma concentrations were analysed in 55 bitches with (n = 28) and without (n027) malignant adenocarcinomas of the mammary gland using two different measurement methods and the relationship to tumour size was investigated. RESULTS: The mean MDA concentration measured by enzyme-linked immunosorbent assay (ELISA) was 289 ng/mL (range 365-634 ng/mL) in dogs with grade 1 adenocarcinoma (n = 13), 288.5 ng/mL (range 85-752 ng/mL) in dogs with grade 2 adenocarcinoma (n = 10), 332 ng/mL (range 239-947 ng/mL) in dogs with grade 3 (n = 5) adenocarcinoma and 293 ng/mL (range 175-549 ng/mL) in dogs without a mammary tumour (n = 27). When MDA was measured by HPLC, the average MDA concentration in the study group (n = 11) was 0.24 µmol/L (range 0.16-0.37) and that of the control group (n = 15) was 0.27 µmol/L (range 0.16-1.62). Thus, there were no significant differences between the study group with malignant adenocarcinomas and the control group in both examination methods (p > 0.05). Furthermore, there was no correlation between the MDA concentrations and the approximate volume of the mammary tumour. CONCLUSION: The results highlight the challenges of providing a prognosis for the malignancy of a mammary adenocarcinoma based on MDA concentrations in plasma using ELISA or HPLC. As a result, histopathological examination remains the gold standard for diagnosing and differentiating adenocarcinomas of the mammary gland.

MDM2 SNP309 modifies the prognostic significance of the p53 mutational status in patients with ovarian cancer.

A single nucleotide polymorphism (SNP309) of MDM2 causes elevated MDM2 levels and an attenuation of p53 function. The aim of the present study was to examine the clinical relevance of the MDM2 SNP309 in ovarian cancer.MDM2 SNP309 genotype was analyzed in 198 patients with primary ovarian cancer. MDM2 expression was investigated using immunohistochemistry. A functional yeast-based assay and subsequent sequencing were performed to determine p53 mutational status. Of the patients, 44.4% (88 of 198) exhibited the common variant (T/T), 40.9% (81 of 198) the heterozygous variant (T/G) and 14.7% (29 of 198) the homozygous variant (G/G) MDM2 SNP309 genotype. MDM2 SNP309 was not associated with p53 mutational status, MDM2 expression, clinicopathological parameters or prognosis. In patients with the T allele (T/T and T/G genotype), p53 wild type carcinomas were associated with significantly improved recurrence-free (p<0.001) and overall survival (p<0.001) as compared to p53 mutant carcinomas. In contrast, p53 mutational status did not possess prognostic relevance in G/G carriers. A possible functional impairment of the p53 pathway caused by the G/G genotype of the MDM2 SNP309 may modify the association between p53 mutational status and prognosis in ovarian cancer.