Lenalidomide and CC-4047 Inhibit the Proliferation of Malignant B Cells while Expanding Normal CD34+ Progenitor Cells

Abstract

Clinical studies involving patients with myelodysplastic syndromes or multiple myeloma have shown the efficacy of lenalidomide by reducing and often eliminating malignant cells while restoring the bone marrow function. To better understand these clinical observations, we investigated and compared the effects of lenalidomide and a structurally related analogue, CC-4047, on the proliferation of two different human hematopoietic cell models: the Namalwa cancer cell line and normal CD34 + progenitor cells. Both compounds had antiproliferative effects on Namalwa cells and pro-proliferative effects on CD34 + cells, whereas p21WAF-1 expression was up-regulated in both cell types. In Namalwa cells, the up-regulation of p21 WAF-1 correlated well with the inhibition of cyclin-dependent kinase (CDK) 2, CDK4, and CDK6 activity leading to pRb hypophosphorylation and cell cycle arrest, whereas in CD34 + progenitor cells the increase of p21 WAF-1 did not inhibit proliferation. Similarly, antiproliferation results were observed in two B lymphoma cell lines (LP-1 and U266) but interestingly not in normal B cells where a protection of apoptosis was found. Finally, CC-4047 and lenalidomide had synergistic effects with valproic acid [a histone deacetylase (HDAC) inhibitor] by increasing the apoptosis of Namalwa cells and enhancing CD34 + cell expansion. Our results indicate that lenalidomide and CC-4047 have opposite effects in tumor cells versus normal cells and could explain, at least in part, the reduction of malignant cells and the restoration of bone marrow observed in patients undergoing lenalidomide treatment. Moreover, this study provides new insights on the cellular pathways affected by lenalidomide and CC-4047, proposes new potential clinical uses, such as bone marrow regeneration, and suggests that the combination of lenalidomide or CC-4047 with certain HDAC inhibitors may elevate the therapeutic index in the treatment of hematologic malignancies. [Cancer Res 2007;67(2):746-55]

Pomalidomide and Lenalidomide Induce p21WAF-1 Expression in Both Lymphoma and Multiple Myeloma through a LSD1-Mediated Epigenetic Mechanism

“…3A). Sp1 binding site enrichment was also found in genes up-regulated by pomalidomide in the multiple myeloma cell line LP-1 cells, described to be responsive to pomalidomide (11). Based on this in silico analysis of promoters, we conclude that pomalidomide preferentially up-regulates genes whose promoters contain Sp1 binding sites.…”

“…The up-regulation of p21 WAF-1 by pomalidomide and lenalidomide is not restricted to Namalwa cells, as we have previously shown that p21 WAF-1 was up-regulated in the multiple myeloma cell lines LP-1 and U266 (11). Figure 6C shows that this up-regulation of p21 WAF-1 is also decreased in LP-1 cells silenced for LSD1, extending the role of this demethylase in the mechanism of action of pomalidomide and lenalidomide in a myeloma cell line.…”

“…We previously reported that p21 WAF-1 RNA expression was induced by pomalidomide and lenalidomide in Namalwa cells after 8 hours of treatment (11). To investigate the early mechanistic events involved, we first analyzed the regulation of p21 WAF-1 RNA expression and the recruitment of RNA polymerase II on p21 WAF-1 gene in response to pomalidomide and lenalidomide in timecourse experiments.…”

“…An increase in p21 WAF-1 expression was also observed in patient primary multiple myeloma cells on treatment with IMiDs immunomodulatory compounds (1). In addition, we presented evidence that p21 WAF-1 up-regulation inhibits cyclin-dependent kinase (CDK)-2, CDK4, and CDK6 kinase activity, which leads to the loss of pRb phosphorylation and the inability of these cells to progress into S phase (11). In this report, we investigate the mechanism by which lenalidomide and pomalidomide up-regulate p21 WAF-1 expression.…”

Pathogenetic insight and prognostic information from standard and molecular cytogenetic studies in the BCR-ABL-negative myeloproliferative neoplasms (MPNs)

“…163 The mechanism of lenalidomide's action remains unclear but it may relate to the induction of G0-G1 growth arrest in malignant rather than normal cells. 164 Finally, detailed molecular profiling may provide additional prognostic information. For example, a recent Italian study reported that expression levels of both CD9 and DLK1 are associated with platelet count, whereas high WT1 expression identifies PMF cases with more active disease, as evidenced by elevated CD34 þ cell count and a higher severity score.…”