[Expression and clinical significance of beta-catenin in multiple myeloma]

beta-catenin is the pivotal regulator in Wnt pathway and in charge of cellular adhesion and signal conduction. Overexpression of beta-catenin has been observed in various human tumors. This study was to investigate the expression and clinical significance of beta-catenin in multiple myeloma (MM).

Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were used to detect mRNA and protein expression of beta-catenin in bone marrow samples from 12 newly diagnosed MM patients, 14 relapsed/refractory MM patients, and 11 healthy donors. The clinical data and treatment outcomes of the MM patient were also analyzed.

The positive rate and the expression level of beta-catenin mRNA were significantly lower in healthy donors than in newly diagnosed patients and relapsed/refractory patients (27.3% vs. 75.0% and 100%, P=5.01e(-4); 0.35+/-0.17 vs. 0.72+/-0.11 and 0.85+/-0.16, P=5.88e(-5)); the mRNA level of beta-catenin was significantly lower in newly diagnosed patients than in relapsed/refractory patients (P=0.045). beta-catenin protein was not detected in healthy donors; while the positive rate and the expression level of beta-catenin protein were significantly lower in newly diagnosed patients than in relapsed/refractory patients (50.0% vs. 85.7%, 0.32+/-0.11 vs. 0.21+/-0.08, P=0.039). In the 10 newly diagnosed MM patients with evaluable treatment outcomes, the positive rate of beta-catenin protein was significant lower in the 7 patients without response than in the 3 patients showed response (14.3% vs. 100%, P=0.033). The positive rate of beta-catenin protein was significant higher in the 16 Durie/Salmon stage III patients than in the 10 stage II patients (87.5% vs. 40.0%, P=0.026), and significant higher in ISS stage III patients than in stage I and II patients (100% vs. 45.5% and 33.3%, P=0.006, P=0.032). The protein level of beta-catenin was positively correlated to serum levels of beta2-MG (r=0.688, P=0.002) and lactate dehydrogenase (LDH) (r=0.502, P=0.034).

The expression of beta-catenin is related with treatment outcome, Durin-Salmon stage and ISS stage of MM, and is positively correlated to serum levels of LDH and beta2-MG.