Quantitative Proteomic Analysis of Tumor Reversion in Multiple Myeloma Cells

Tumor reversion is defined as the process by which cancer cells lose their malignant phenotype. However, relatively little is known about the cellular proteome changes that occur during the reversion process. A biological model of multiple myeloma (MM) reversion was established by using the H-1 parvovirus as a tool to select for revertant cells from MM cells. Isolated revertant cells displayed a strongly suppressed malignant phenotype both in vitro and in vivo. To explore possible mechanisms of MM reversion, the protein profiles of the revertant and parental MM cells were compared using a quantitative proteomic strategy termed SILAC-MS. Our results revealed that 379 proteins were either activated or inhibited during the reversion process, with a much greater proportion of the proteins, including STAT3, TCTP, CDC2, BAG2, and PCNA, being inhibited. Of these, STAT3, which is significantly down regulated, was selected for further functional studies. Inhibition of STAT3 expression by RNA interference resulted in suppression of the malignant phenotype and concomitant down regulation of TCTP expression, suggesting that myeloma reversion operates, at least in part, through inhibition of STAT3. Our results provide novel insights into the mechanisms of tumor reversion and suggest new alternative approaches for MM treatment.

肿瘤逆转被定义为癌细胞丧失其恶性表型的过程。然而，关于逆转过程中发生的细胞蛋白质组变化，我们所知甚少。通过利用H-1细小病毒作为工具，从多发性骨髓瘤（MM）细胞中筛选逆转细胞，建立了一个MM逆转的生物学模型。分离的逆转细胞在体外和体内均表现出强烈的恶性表型受到显著抑制。为了探索MM逆转的可能机制，利用一种称为SILAC-MS的定量蛋白质组学策略，对比了逆转细胞和亲本MM细胞的蛋白质谱。我们的研究结果表明，在逆转过程中，有379种蛋白质被激活或抑制，其中蛋白质受到抑制的比例显著较高，包括STAT3、TCTP、CDC2、BAG2和PCNA等。在这些蛋白质中，STAT3的显著下调被选中进行进一步的功能研究。通过RNA干扰抑制STAT3的表达，导致恶性表型的抑制以及TCTP表达的伴随下调，这表明骨髓瘤逆转至少部分通过抑制STAT3来实现。我们的研究结果为肿瘤逆转的机制提供了新的见解，并暗示了MM治疗的新替代策略。