Frequent inactivation of the cyclin-dependent kinase inhibitor p18 by homozygous deletion in multiple myeloma cell lines: ectopic p18 expression inhibits growth and induces apoptosis

Kulkarni, Manas; Daggett, J L; Bender, Timothy P.; Kuehl, W. Michael; Bergsagel, P. Leif; Williams, M. E.

doi:10.1038/sj.leu.2402328

Cited by 57 publications

(37 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The multiple myeloma-derived cell line RPMI-8226 failed to amplify either M or U bands, a finding consistent with the previously described sporadic homozygous deletion of the p18 INK4c gene in myeloma cell lines. 24 The existence of this deletion in RPMI-8226, but not in any of the other cell lines, was confirmed by multiplex PCR using unmodified genomic DNA as a template (data not shown).As might be expected, this hypermethylated status of the p18 INK4c promoter correlated with loss of protein expression as demonstrated by Western blot and IHC ( Figure 1C). p18 INK4c protein expression was almost completely absent from the L-540 cell line, and clearly reduced in HDLM-2 and KM-H2 compared with the L-428 cell line.…”

supporting

confidence: 65%

“…[16][17][18][19] Although in normal lymphoid B cells the p18 INK4c protein has been implicated in key functions such as cell cycle control and terminal (plasma cell) differentiation, 19,20 most studies performed in lymphoid neoplasms have shown preservation of the gene and its expression, 21,22 except for myeloma-derived cell lines and, more rarely, tumors, where occasional homozygous deletions have been demonstrated. 23,24 These findings could be considered unexpected due to the structural and functional homology of p18 INK4c to p16 INK4a and p15 INK4b , and its key role in cell cycle control. Nevertheless, all of these previous analyses largely ignored HL and HL-derived cell lines.…”

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Silencing of the p18INK4c gene by promoter hypermethylation in Reed-Sternberg cells in Hodgkin lymphomas

Sánchez-Aguilera

Delgado

Camacho

et al. 2004

Blood

View full text Add to dashboard Cite

IntroductionCyclin-dependent kinase inhibitors (CKIs) are a group of lowmolecular-weight proteins that associate with cyclin-dependent kinases (CDKs), blocking their activity. 1,2 The inhibitors of CDK4 (INK4) family of CKIs is composed of p16 INK4a , p15 INK4b , p18 INK4c , and p19 INK4d , which specifically bind and inhibit CDK4 and CDK6, thereby preventing cyclin D-dependent phosphorylation of Rb. 1 Inactivation of the genes comprising the INK4 family of cell-cycle inhibitors is a frequent phenomenon in human cancer, although it seems to be mostly restricted to p16 INK4a and p15 INK4b silencing through genetic 3 and epigenetic 4 mechanisms. Alterations of both p16 INK4a and p15 INK4b have been described in non-Hodgkin lymphoma (NHL) [5][6][7] and Hodgkin lymphoma (HL). 8,9 In these hematologic neoplasias, hypermethylation of the 5Ј cytidine-phosphateguanosine (CpG) island of these genes seems to be a frequent event, whereas the incidence of homozygous deletion and mutations is relatively low. 10,11 Unsurprisingly, this hypermethylation status of the promoter region correlates with transcriptional repression of these genes and constitutes an alternative inactivating mechanism. 6,12 The human p18 INK4c gene was first identified in a yeast interaction screen that searched for CDK6-interacting proteins. 13 p18 INK4c was demonstrated to interact with CDK6 and more weakly with CDK4 (but not with other CDKs) both in vivo and in vitro, and to inhibit the kinase activity of cyclin D-CDK6 complexes. Ectopic expression of p18 INK4c was shown to suppress cell growth in a wild-type Rb-dependent manner. 13 p18 INK4c has been proposed to function as a tumor suppressor gene, based on the observation that p18 INK4c -null mice display an increased susceptibility to developing spontaneous and induced tumors, such as pituitary adenomas and others. 14,15 However, alterations in the p18 INK4c gene are strikingly less frequent than those affecting p16 INK4a or p15 INK4b , having been observed in human cancer only sporadically. [16][17][18][19] Although in normal lymphoid B cells the p18 INK4c protein has been implicated in key functions such as cell cycle control and terminal (plasma cell) differentiation, 19,20 Patients, materials, and methods Tumor samples and cell linesThere were 316 retrospective cases of HL collected by collaborating members of the Spanish Hodgkin Lymphoma Study Group. 25 The histologic confirmation of HL and subtype was determined by central review using standard tissue sections, and diagnoses were made according to the criteria of the WHO classification. 28 Cases included 171 cases of nodular sclerosis HL, 112 cases of mixed-cellularity HL, 14 cases of lymphocyterich classical HL, 9 cases of lymphocyte-depletion HL, and 10 cases of nodular lymphocyte-predominant HL. All of the samples included represent at-diagnosis biopsies and all of the patients were treated following standard protocols: patients with advanced HL were mainly treated with 6 to 10 courses of combination chemotherapy (adriamycin, bleom...

show abstract

supporting

confidence: 65%

Section: Introductionmentioning

confidence: 98%

Silencing of the p18INK4c gene by promoter hypermethylation in Reed-Sternberg cells in Hodgkin lymphomas

Sánchez-Aguilera

Delgado

Camacho

et al. 2004

Blood

View full text Add to dashboard Cite

show abstract

“…Gene expression profile analysis suggests that cyclin D1, D2, or D3 RNA is elevated in most multiple myeloma cases (15,17,18). In addition, the p18 INK4c gene is deleted in some multiple myeloma cell lines (19), and the p16 INK4a and p15 INK4b genes are inactivated by methylation in multiple myeloma cells (20,21). These observations suggest that gain of D cyclin or loss of CKI function might promote cell cycle reentry and progression in multiple myeloma pathogenesis.…”

Section: Introductionmentioning

confidence: 99%

Mutually Exclusive Cyclin-Dependent Kinase 4/Cyclin D1 and Cyclin-Dependent Kinase 6/Cyclin D2 Pairing Inactivates Retinoblastoma Protein and Promotes Cell Cycle Dysregulation in Multiple Myeloma

Ely¹,

Liberto²,

Niesvizky

et al. 2005

Cancer Research

102

View full text Add to dashboard Cite

Multiple myeloma, the second most common hematopoietic cancer, ultimately becomes refractory to treatment when selfrenewing multiple myeloma cells begin unrestrained proliferation by unknown mechanisms. Here, we show that one, but not more than one, of the three early G 1 D cyclins is elevated in each case of multiple myeloma. Cyclin D1 or D3 expression does not vary in the clinical course, but that alone is insufficient to promote cell cycle progression unless cyclindependent kinase 4 (cdk4) is also elevated, in the absence of cdk6, to phosphorylate the retinoblastoma protein (Rb). By contrast, cyclin D2 and cdk6 are coordinately increased, thereby overriding the inhibition by cdk inhibitors p18 INK4c and p27 Kip1 and phosphorylating Rb in conjunction with the existing cdk4. Thus, cyclin D1 pairs exclusively with cdk4 and cdk6 pairs only with cyclin D2, although cyclin D2 can also pair with cdk4 in multiple myeloma cells. The basis for this novel and specific cdk/D cyclin pairing lies in differential transcriptional activation. In addition, cyclin D1-or cyclin D3-expressing multiple myeloma cells are uniformly distributed in the bone marrow, whereas cdk6-specific phosphorylation of Rb occurs in discrete foci of bone marrow multiple myeloma cells before proliferation early in the clinical course and is then heightened with proliferation and disease progression. Mutually exclusive cdk4/cyclin D1 and cdk6/ cyclin D2 pairing, therefore, is likely to be a critical determinant for cell cycle reentry and progression and may play a pivotal role in the expansion of self-renewing multiple myeloma cells. (Cancer Res 2005; 65(24): 11345-53)

show abstract

“…p15 1NK4b is unique in that it can be induced by cytokines (Hannon and Beach, 1994;Reynisdottir et al, 1995) and its upregulation is correlated with specific biological responses such as differentiation of myeloid cells into macrophages and granulocytes (Teofili et al, 1998(Teofili et al, , 2000. Recently, another INK4 inhibitor, p18 INK4c was found to be deleted in 38% of multiple myeloma and its ectopic expression caused growth suppression and apoptosis, which raises the possibility that it also acts as a tumor suppressor (Kulkarni et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Consistent inactivation of p19Arf but not p15Ink4b in murine myeloid cells transformed in vivo by deregulated c-Myc

Haviernik

Schmidt

et al. 2003

Oncogene

View full text Add to dashboard Cite

Cyclin-dependent kinase inhibitors p16 INK4a and p15 INK4b , encoded by the CDKN2A and B loci, play an important role in negative regulation of the cell cycle. Furthermore, p19 ARF also encoded by the CDKN2A locus, has been shown to regulate positively the p53 pathway leading to growth arrest and apoptosis. All three genes have been inactivated in human tumors. In myeloid cells, p15 INK4b mRNA is upregulated during cytokine-induced differentiation and/or growth arrest, and hypermethylation of the p15 INK4b gene promoter region is a common event in acute myeloid leukemia. In the present study, we examined murine monocyte/macrophage tumors with deregulated cmyc for evidence of Ink4 gene inactivation. p15 Ink4b mRNA and protein were detected in the majority of leukemias, and p16 Ink4a mRNA and protein were highly expressed in two of them. pRb was in a hypophosphorylated state in most of the neoplasms indicating that the Cdk inhibitors that were expressed in the cells were functional. The observed expression of p15 Ink4b is inconsistent with their proliferation state, although it might be expected to be expressed owing to the maturity of the cells. These data suggest, therefore, that deregulated cMyc bypasses the pRb restriction point and cell cycle arrest in these tumors. An examination of p19 Arf exons revealed deletions of the gene in up to 94% of the tumors. Since this gene shares exon 2 with p16 Ink4a , it is often difficult to determine which gene is the relevant tumor suppressor. However, the loss of only the p19 Arf -specific exon 1b was observed in a tumor that had normal p16 Ink4a protein expression. In addition, the p19 Arf -specific exon was deleted in another tumor that expressed a functional chimeric protein, p15Ex1-p16Ex2-3; it was demonstrated here that this fusion protein is capable of inducing G1 arrest. These data overall supports the hypothesis that the critical inactivation event in these hematopoietic neoplasms is elimination of p19 Arf , and not Ink4 function.

show abstract

Frequent inactivation of the cyclin-dependent kinase inhibitor p18 by homozygous deletion in multiple myeloma cell lines: ectopic p18 expression inhibits growth and induces apoptosis

Cited by 57 publications

References 30 publications

Silencing of the p18INK4c gene by promoter hypermethylation in Reed-Sternberg cells in Hodgkin lymphomas

Silencing of the p18INK4c gene by promoter hypermethylation in Reed-Sternberg cells in Hodgkin lymphomas

Mutually Exclusive Cyclin-Dependent Kinase 4/Cyclin D1 and Cyclin-Dependent Kinase 6/Cyclin D2 Pairing Inactivates Retinoblastoma Protein and Promotes Cell Cycle Dysregulation in Multiple Myeloma

Consistent inactivation of p19Arf but not p15Ink4b in murine myeloid cells transformed in vivo by deregulated c-Myc

Contact Info

Product

Resources

About