Decreased Thymosin Beta 4 Expression Results in Poor Prognosis and Decreased Survival in Multiple Myeloma.

Thymosin beta 4 (Tβ4) is a small cytoplasmic and nuclear protein involved in different cellular processes including differentiation, migration and proliferation. It is overexpressed in several malignant cells, resulting in an increased angiogenic respons and metastatic potential of tumor cells. In the current study we wanted to evaluate the expression of Tβ4 in primary human multiple myeloma cells (MM) and murine 5TMM cells. Microarray analysis and qRT-PCR of 171 MM patients treated with high dose therapy and autologous stem cell transplantation, showed that MM cells display a decreased Tβ4 expression compared to plasma cells from healthy individuals. We investigated whether Tβ4 expression in MM cells influences the event free (EFS) and overall survival (OAS) of these patients. As Tβ4 was expressed in all MM cells, we compared survival of patients with Tβ4 expression in MM cells in the upper thirtile (Tβ4high MMC) against the lowest thirtile (Tβ4low MMC). Patients with Tβ4high MMC had an increased EFS (P