Autoři popsali případ 64-letého muže, u kterého byla zjištěna chronická lymfatické leukémie (CLL) před pěti lety. V současné době byl pacient přijat pro nádor kůže v lumbální oblasti vlevo. Histologické a imunohistologické vyšetření ukázalo, že jde o karcinom z Merkelových buněk (MCC). Elektronově mikroskopické vyšetření ukázalo charakteristické paranukleární globule tvořené intermediálními filamenty. Koincidence MCC a CLL je poměrně vzácná a cytogenetická vyšetření zde nebyla publikována. Vyšetřovali jsme RB1 gen pomocí interfázové FISH metody. Cytogenetické vyšetření RB1 genu ukázalo bialelickou deleci u nádorových buněk CLL; u MCC byla bialelická delece u 33 % a monoalelická delece u 57 % buněk. Současně byla prokázána trizomie 6 a delece 1p36. Vyšetření nenádorové kůže ukázalo přítomnost RB1 genu v obou alelách. Podle literárních údajů má vyšetření RB1 genu u CLL význam při stanovení prognózy onemocnění. Vztah mezi delecí RB1 genu a prognózou onemocnění nebyl dosud u MCC stanoven a vyžaduje vyšetření dalších případů.

The authors report a case of a 64-year-old man with chronic lymphocytic leukaemia (CLL) diagnosed 5 years ago. Recently, the patient was admitted with a tumour of the skin in the left lumbar region. Histological and immunohistochemical examinations established the diagnosis of Merkel cell carcinoma (MCC). Electron-microscopic examination revealed the formation of spherical aggregates of intermediate-sized filaments in the perinuclear region. The coincidence of MCC and CLL is rather rare and in published cases, no cytogenetic examinations were performed. We examined the RB1 gene using the interphase FISH method. A biallelic deletion in CLL tumour cells was detected; in MCC tumour cells, biallelic deletion was found in 33 % of the cells and monoallelic deletion in 57 % of the cells. In addition, chromosome 6 trisomy and 1p36 deletion were detected. Examination of non-neoplastic cells of the patient’s skin showed a biallelic presence of the RB1 gene. According to the relevant literature, examination of the RB1 gene in CLL has informational value as a prognostic factor. The relationship between deletion of the RB1 gene and prognosis in MCC has not yet been determined and needs more research.

• Klíčová slova
• RB1 gen,
• MeSH
• chromozomální delece MeSH
• chronická lymfatická leukemie diagnóza   genetika   komplikace   MeSH
• elektronová mikroskopie MeSH
• geny retinoblastomu MeSH
• hybridizace in situ fluorescenční MeSH
• imunohistochemie metody   využití   MeSH
• komorbidita MeSH
• lidé středního věku MeSH
• lidé MeSH
• Merkelův nádor diagnóza   genetika   komplikace   MeSH
• retinoblastomový protein genetika   izolace a purifikace   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• kazuistiky MeSH

Here, we focus on epigenetic changes in leukaemia and MM (multiple myeloma) cells. We show how the histone signature, DNA methylation and levels of select tumour-suppressor proteins can be affected by inhibitors of HDACs (histone deacetylases) and Dnmts (DNA methyltransferases). Both inhibitors, TSA (trichostatin A) and 5-AZA (5-azacytidine), have the ability to change the histone signature in a tumour-specific manner. In MM cells, we observed changes in H3K4 methylation, while in leukaemia cells, H3K9 methylation was especially affected by select inhibitors. Compared with normal peripheral blood lymphocytes, tumour cell samples were characterized by increased H3K9 acetylation, increased H3K4me2, H3K9me2 and HP1α (heterochromatin protein 1α) levels and specific changes were also observed for DNA methylation. Additionally, we showed that the tumour suppressor pRb1 (retinoblastoma protein) is more sensitive to epigenetic-based anti-cancer stimuli than p53. We have found significant decrease in the levels of pRb1 and p53 in both myeloma and leukaemia cells after HDAC inhibition.

• MeSH
• antitumorózní látky farmakologie   MeSH
• azacytidin farmakologie   MeSH
• DNA modifikační methylasy genetika   metabolismus   MeSH
• epigeneze genetická MeSH
• histondeacetylasy metabolismus   MeSH
• histony genetika   metabolismus   MeSH
• inhibitory histondeacetylas farmakologie   MeSH
• kyseliny hydroxamové farmakologie   MeSH
• leukemie farmakoterapie   genetika   MeSH
• lidé MeSH
• metylace DNA MeSH
• mnohočetný myelom farmakoterapie   genetika   MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• retinoblastomový protein genetika   metabolismus   MeSH
• umlčování genů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• buněčné jádro chemie   MeSH
• finanční podpora výzkumu jako téma MeSH
• geny abl genetika   MeSH
• lidé MeSH
• protoonkogenní proteiny c-myc genetika   MeSH
• retinoblastomový protein genetika   MeSH
• Check Tag
• lidé MeSH

The retinoblastoma (pRb)-related p130 pocket protein is a regulator of cell growth and differentiation, and a candidate tumour suppressor. Both pRb and p130 operate through interactions with cellular proteins, including the E2F transcription factors. While such interactions are controlled by phosphorylation of multiple sites of pRb, regulation of p130 remains poorly understood. We now identify 22 in vivo phosphorylation sites of p130, targeted by diverse kinases, and present evidence for three cyclin-dependent kinase 4(6) [Cdk4(6)] specific phosphorylations, which appear critical for controlling the growth-restraining activity of p130. When expressed in U2OS cells, the phosphorylation-deficient mutant p130(Delta)(CDK4), in which the Cdk4 specific sites were mutated to alanine residues, imposed a more sustained G1 arrest than a constitutively active pRb(Delta)(CDK), known to repress all cellular E2F activity. Experiments using p130(Delta)(Cdk4) and another phosphorylation-deficient mutant, p130(PM19A), with 19 phosphorylation sites mutated, revealed that the p130-imposed G1 block reflects cooperative growth-suppressive effects of phosphorylation-regulated E2F binding and phosphorylation-independent sequestration of cyclin E(A)-Cdk2 through the N-terminal cyclin binding motif of p130.

• MeSH
• buněčné linie MeSH
• cyklin D MeSH
• cyklin E metabolismus   MeSH
• cyklin-dependentní kinasy metabolismus   MeSH
• cykliny metabolismus   MeSH
• DNA vazebné proteiny * MeSH
• fosfoproteiny * genetika   chemie   metabolismus   MeSH
• fosforylace MeSH
• G1 fáze * fyziologie   MeSH
• lidé MeSH
• mutageneze cílená MeSH
• peptidové mapování MeSH
• protein p130 podobný retinoblastomu MeSH
• proteiny buněčného cyklu * MeSH
• proteiny * MeSH
• retinoblastomový protein * genetika   chemie   metabolismus   MeSH
• transkripční faktor DP1 MeSH
• transkripční faktory E2F MeSH
• transkripční faktory metabolismus   MeSH
• transportní proteiny * MeSH
• vazebná místa genetika   MeSH
• vazebný protein 1 retinoblastomu MeSH
• Check Tag
• lidé MeSH

p16ink4 and pRb, two components of a key G1/S regulatory pathway, and tumor suppressors commonly targeted in oncogenesis, are among the candidates for gene therapy of cancer. Wild-type p16 and a constitutively active pRb(delta cdk) mutant both blocked G1 in short-term experiments, but only p16 imposed a sustained G1 arrest. Unexpectedly, cells conditionally exposed to pRb(delta cdk) entered S phase after 2 days, followed by endoreduplication between days 4-6. The distinct phenotypes evoked by p16 vs pRb(delta cdk) appear mediated by cyclin E/CDK2 which, while active in the pRb(delta cdk)-expressing cells, became rapidly inhibited through restructuring diverse cyclin/CDK/p21 complexes by p16. These results provide novel insights into the roles of p16, pRb and cyclin E in G1/S control and multistep oncogenesis, with implications for gene therapy strategies.

• MeSH
• cyklin-dependentní kinasa 2 MeSH
• cyklin-dependentní kinasy biosyntéza   metabolismus   MeSH
• G1 fáze genetika   fyziologie   MeSH
• inhibitor p16 cyklin-dependentní kinasy biosyntéza   genetika   fyziologie   MeSH
• inhibitory růstu genetika   fyziologie   MeSH
• kinasy CDC2-CDC28 * MeSH
• krysa rodu rattus MeSH
• lidé MeSH
• nádorová transformace buněk genetika   metabolismus   MeSH
• nádorové buňky kultivované MeSH
• osteosarkom MeSH
• protein-serin-threoninkinasy biosyntéza   metabolismus   MeSH
• retinoblastomový protein biosyntéza   genetika   fyziologie   MeSH
• S fáze genetika   MeSH
• technika přenosu genů MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

The members of the 'pocket protein' family, comprising the retinoblastoma tumor suppressor (pRB) and its relatives, p107 and p130, negatively regulate cell proliferation and modulate fundamental biological processes including embryonic development, differentiation, homeostatic tissue renewal, and defense against cancer. The large, multidomain pocket proteins act by binding a plethora of cell fate-determining and growth-stimulatory proteins, the most prominent of which are the E2F/DP transcription factors. These protein-protein interactions are in turn regulated by carefully orchestrated phosphorylation events on multiple serine and threonine residues of pRB, p107, and p130, events which are carried out, at least in part, by the cyclin-dependent kinases that form the key elements of the cell cycle machinery. Here we discuss the recently obtained new insights into the diverse functions of the pRB family, and show examples of how integration of genetic, cell biology, and a range of electrophoretic approaches help to advance our understanding of the biological roles played by the pocket proteins in both normal and cancer cells.

• MeSH
• 2D gelová elektroforéza MeSH
• elektroforéza v polyakrylamidovém gelu MeSH
• fosfoproteiny genetika   fyziologie   MeSH
• jaderné proteiny genetika   fyziologie   MeSH
• lidé MeSH
• molekulární sekvence - údaje MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• nádorové buňky kultivované MeSH
• protein p107 podobný retinoblastomu MeSH
• protein p130 podobný retinoblastomu MeSH
• proteiny * MeSH
• retinoblastomový protein genetika   fyziologie   MeSH
• sekvence aminokyselin MeSH
• tumor supresorové geny MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The Rho family of GTPases plays an important and diverse role in reorganization of the actin cytoskeleton, transcriptional regulation, and multiple aspects of cell growth. Our study has examined their potential links to the cell cycle machinery. We find that constitutively active mutants of Rac and Cdc42, but not Rho, are potent inducers of E2F transcriptional activity in NIH 3T3 fibroblasts. Furthermore, activated Rac and Cdc42, but again not Rho, are capable of inducing cyclin D1 accumulation and pRB hyperphosphorylation in serum-deprived cells, outlining one route leading to enhanced E2F-mediated transcription. The inhibitory effect of the cyclin-dependent kinase inhibitors, p16(ink4), p21(cip1), and p27(cip) on Rac/Cdc42-mediated E2F transcription corroborates a role for pRB family members and their functional inactivation by cyclin-dependent kinases in generating E2F activity. While the up-regulation of E2F transcriptional activity by Rac or Cdc42, not Rho, suffices for entry into S phase and DNA synthesis in Rat-1 R12 cells, this is clearly not the case in NIH 3T3, where additional requirements must exist.

• MeSH
• buňky 3T3 MeSH
• cdc42 protein vázající GTP MeSH
• cykliny metabolismus   MeSH
• DNA vazebné proteiny * MeSH
• fosforylace MeSH
• genetická predispozice k nemoci MeSH
• genetická transkripce * MeSH
• inhibitor p16 cyklin-dependentní kinasy metabolismus   MeSH
• inhibitor p21 cyklin-dependentní kinasy MeSH
• myši MeSH
• proteiny buněčného cyklu metabolismus   MeSH
• proteiny vázající GTP metabolismus   MeSH
• rac proteiny vázající GTP MeSH
• replikace DNA MeSH
• retinoblastomový protein genetika   MeSH
• transkripční faktor DP1 MeSH
• transkripční faktory E2F MeSH
• transkripční faktory metabolismus   MeSH
• transportní proteiny * MeSH
• upregulace MeSH
• vazebný protein 1 retinoblastomu MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• exprese genu MeSH
• nádory jater genetika   MeSH
• retinoblastomový protein genetika   MeSH
• virus hepatitidy B MeSH

The mammalian D-type cyclins promote progression through a G1 checkpoint by phosphorylating the retinoblastoma protein (pRB), and can contribute to oncogenesis via their deregulated expression achieved through gene amplification, chromosomal rearrangement, or retroviral integration. We now report a novel mechanism of tumour-associated D-cyclin over-abundance, resulting from enhanced protein stability. In two human cell lines established from a single uterine sarcoma biopsy, pRB-positive SK-UT-1B and pRB-deficient SK-UT-1, aberrant accumulation of functional cyclins D1, and D2 and D3 occurred in the absence of gene amplification and/or elevated mRNA expression. The abundance of D-cyclin proteins remained elevated throughout the cell cycle, and pulse-chase experiments revealed six to 10-fold prolongation of their protein half-lives as compared with either diploid fibroblasts or control U-2-OS sarcoma cells. These results point to a critical regulatory role of D-type cyclin turnover, and contribute to refinement of current views of the role played by the cyclin D-CDK-p16-pRB pathway in cell cycle control and tumorigenesis.

• MeSH
• aktivace enzymů MeSH
• amplifikace genu MeSH
• cyklin D MeSH
• cyklin-dependentní kinasa 4 MeSH
• cyklin-dependentní kinasy metabolismus   MeSH
• cykliny genetika   metabolismus   MeSH
• imunoblotting MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• nádorové buňky kultivované MeSH
• nádorové proteiny genetika   metabolismus   MeSH
• nádory dělohy genetika   metabolismus   MeSH
• protoonkogenní proteiny * MeSH
• retinoblastomový protein genetika   metabolismus   MeSH
• sarkom metabolismus   MeSH
• stabilita léku MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

The product of the retinoblastoma susceptibility gene, pRb, is a negative regulator of cell growth. It functions by regulating the activity of transcription factors. Rb represses some genes by sequestering or inactivating the positive transcription factor E2F and seems to activate some others by interacting with factors like Sp1 or ATF-2. However, there are only a few examples of genes which are positively regulated by pRb. In order to find out if there are common mechanisms for promoter regulation by pRb, we were interested to identify more genes which are either stimulated or repressed by pRb. Using the method of differential display (DDRT-PCR) in combination with nuclear run-on analyses we were able to detect a number of genes which are upregulated by ectopic expression of the Rb gene in Rb-deficient mammary carcinoma cells. We could demonstrate not only stimulation of the endogenous mutant Rb gene but also positive regulation of genes coding for diverse classes of proteins, including the endothelial growth regulator endothelin-1 and the proteoglycans versican and PG40. As a second approach, we investigated gene expression in cell lines established from Rb deficient heterozygous and homozygous knockout mouse embryos and normal mice. We have identified several genes the expression of which correlates positively or negatively with the presence of Rb. These data provide further evidence for pRb being a master regulator of a complex network of gene activities defining the difference between dividing and resting or differentiated cells.

• MeSH
• endoteliny biosyntéza   genetika   MeSH
• geny retinoblastomu fyziologie   MeSH
• lidé MeSH
• molekulární sekvence - údaje MeSH
• myši knockoutované MeSH
• myši MeSH
• nádorové buňky kultivované MeSH
• polymerázová řetězová reakce metody   MeSH
• proteoglykany biosyntéza   genetika   MeSH
• regulace genové exprese * MeSH
• retinoblastomový protein genetika   fyziologie   MeSH
• sekvence nukleotidů MeSH
• transfekce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH