Lenalidomide inhibits the proliferation of CLL cells via a cereblon/p21WAF1/Cip1-dependent mechanism independent of functional p53

Abstract

Lenalidomide has demonstrated clinical activity in patients with chronic lymphocytic leukemia (CLL), even though it is not cytotoxic for primary CLL cells in vitro. We examined the direct effect of lenalidomide on CLL-cell proliferation induced by CD154-expressing accessory cells in media containing interleukin-4 and -10. Treatment with lenalidomide significantly inhibited CLL-cell proliferation, an effect that was associated with the p53-independent upregulation of the cyclin-dependent kinase inhibitor, p21 WAF1/Cip1 (p21).Silencing p21 with small interfering RNA impaired the capacity of lenalidomide to inhibit CLL-cell proliferation. Silencing cereblon, a known molecular target of lenalidomide, impaired the capacity of lenalidomide to induce expression of p21, inhibit CD154-induced CLL-cell proliferation, or enhance the degradation of Ikaros family zinc finger proteins 1 and 3. We isolated CLL cells from the blood of patients before and after short-term treatment with low-dose lenalidomide (5 mg per day) and found the leukemia cells were also induced to express p21 in vivo. These results indicate that lenalidomide can directly inhibit proliferation of CLL cells in a cereblon/p21-dependent but p53-independent manner, at concentrations achievable in vivo, potentially contributing to the capacity of this drug to inhibit disease-progression in patients with CLL. (Blood. 2014;124(10):1637-1644 IntroductionLenalidomide is a second-generation immunomodulatory drug (IMiD) 1-3 that has both direct tumoricidal, as well as immunomodulatory activity in patients with multiple myeloma. 4 This drug also has clinical activity in patients with chronic lymphocytic leukemia (CLL), even though it is not directly cytotoxic to CLL cells in vitro. 5,6 As such, its clinical activity in CLL is presumed to be secondary to its immune modulatory activity. 7 Indeed, lenalidomide indirectly modulates CLL-cell survival in vitro by affecting supportive cells, such as nurse-like cells, 8 found in the microenvironment of lymphoid tissues. Lenalidomide also can enhance T-cell proliferation 1 and interferon-g production 9 in response to CD3-crosslinking in vitro and dendritic-cell-mediated activation of T cells. 10 Moreover, lenalidomide can reverse noted functional defects of T cells in patients with CLL. 11,12 Finally, lenalidomide can also induce CLL B cells to express higher levels of immunostimulatory molecules such as CD80, CD86, HLA-DR, CD95, and CD40 in vitro, 5,13 thereby potentially enhancing their capacity to engage T cells in cognate interactions that lead to immune activation in response to leukemia-associated antigen(s). 14 However, lenalidomide may also have direct antiproliferative effects on CLL cells that account in part for its clinical activity in patients with this disease. This drug can inhibit proliferation of B-cell lymphoma lines 15 and induce growth arrest and apoptosis of mantlecell lymphoma cells. 16 Although originally considered an accumulative disease of resting G 0/1 lymphocytes, CLL increasingly is being reco...

Wnt5a induces ROR1/ROR2 heterooligomerization to enhance leukemia chemotaxis and proliferation

“…Equal amounts of total protein from each sample were fractionated by SDS-PAGE and blotted onto Cell proliferation assay. Primary CLL cell proliferation assay was performed as described (55). CLL cells were labeled by CFSE (Life Technologies) and plated at 1.5 × 10 6 /well/ml in a 24-well tray on a layer of irradiated HeLa CD154 cells (80 Gy) at a CLL/HeLa CD154 cell ratio of 15:1 in complete RPMI-1640 medium supplemented with 5 ng/ml of recombinant human IL-4 (R&D Systems) and 15 ng/ml of recombinant human IL-10 (R&D Systems).…”

Lenalidomide improvement of cisplatin antitumor efficacy on triple-negative breast cancer cells in�vitro

“…In the present study, cisplatin significantly reduced MDA-MB-231 cell viability at an IC 50 value of 7.8 µM. On the other hand, it is controversy and debatable whether lenalidomide can be used to control solid tumors (14,16), although lenalidomide significantly inhibited growth of the chronic lymphocytic leukemia cells (19). In the present study, we further confirmed that lenalidomide alone had only a minimal effect on MDA-MB-231 cell viability, even at a very high dose of 320 µM, far beyond the clinically achievable concentration in humans (20).…”

Cereblon in health and disease

“…Subsequently, the use of lenalidomide in combination with dexamethasone was approved for MM patients who have received at least one previous treatment. Lenalidomide was also shown to inhibit chronic lymphocytic leukemia (CLL) cell proliferation via cereblon-p21-dependent manner [18]. More recently, pomalidomide, which has greater in vitro activity than thalidomide or lenalidomide [9], received approval for the treatment of relapsed and refractory MM.…”