Differential expressions of MDM2 and TAP73 in cancer and cancer-adjacent tissues in patients with non-small-cell lung carcinoma

Aim: To investigate the differences in mRNA and protein expressions of MDM2 (mouse double minute 2 homolog) and P73 in cancer and cancer-adjacent tissues in patients with non-small-cell lung carcinoma (NSCLC). Materials and methods: We compared the protein expressions of MDM2 and P73 in lung cancer and cancer-adjacent tissues in NSCLC patients by IHC (immunohistochemistry) and WB (Western blot). We divided the NSCLC patients into two subgroups, adenocarcinoma and squamous carcinoma. The mRNA expressions of two main isoforms of P73, TAP73 and DNP73, as well as the ratio of DNP73/TAP73 were analyzed by qPCR (quantitative real-time PCR) in the two tissues in all NSCLC patients and in patients with adenocarcinoma or squamous carcinoma, respectively. Results: WB results did not show significant differences in MDM2 and P73 protein expressions in lung cancer and cancer-adjacent tissues. However, IHC results indicated that MDM2 expression significantly increased in cancer tissues in female patients, but not male patients. In addition, TAP73 mRNA expression significantly increased in cancer tissues in all NSCLC patients (p = 0.002) and in patients with adenocarcinoma (p = 0.01); while there was no significant difference in DNP73 mRNA expression. Hence the fold-change of DNP73/TAP73 ratio significantly decreased (p = 0.0003) in cancer tissues in all NSCLC patients and in patients with adenocarcinoma. Conclusions: TAP73 mRNA expression significantly increased in cancer tissues than cancer-adjacent tissues in all NSCLC patients and in patients with adenocarcinoma. Meanwhile, the fold-change of DNP73/TAP73 ratio was similar to TAP73. MDM2 protein expression significantly increased in cancer tissues in female NSCLC patients. Keywords: Lung cancer, Adenocarcinoma, Squamous carcinoma, TAP73, MDM2 (mouse double minute 2 homolog