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BACKGROUND: Failure-free survival (FFS) rates of low-risk patients with rhabdomyosarcoma improved in Intergroup Rhabdomyosarcoma Study IV after the escalation of cyclophosphamide total dose to 26.4 g/m2. However, this dose may increase the risk of adverse events, including infertility, in some patients. The JRS-I LRA0401 and LRB0402 protocols aimed to reduce the cyclophosphamide dose to 9.6 g/m2 and 17.6 g/m2, respectively, without decreasing the FFS rates. METHODS: Subgroup-A patients received eight cycles (24 weeks) of vincristine, actinomycin D, and 1.2 g/m2/cycle cyclophosphamide. Subgroup-B patients received eight cycles (24 weeks) of vincristine, actinomycin D, and 2.2 g/m2/cycle cyclophosphamide, followed by six cycles (24 weeks) of vincristine and actinomycin D. Group II/III patients in both subgroups received radiotherapy. RESULTS: In subgroup A (n = 12), the 3-year FFS rate was 83% (95% confidence interval [CI], 48-96), and the 3-year overall survival (OS) rate was 100%. Only one isolated local recurrence was observed (8.3%). There were no unexpected grade-4 toxicities and no deaths. In subgroup B (n = 16), the 3-year FFS and OS rates were 88% (95% CI, 59-97) and 94% (95% CI, 63-99), respectively. There were no unexpected grade 4 toxicities and no deaths. CONCLUSIONS: Shorter duration therapy using vincristine, actinomycin D, and lower dose cyclophosphamide with or without radiotherapy for patients with low-risk subgroup A rhabdomyosarcoma (JRS-I LRA0401 protocol) and moderate reduction of cyclophosphamide dose for patients with low-risk subgroup B rhabdomyosarcoma (JRS-I LRB0402 protocol) did not compromise FFS.
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Despite the potential of targeted epigenetic therapies, most cancers do not respond to current epigenetic drugs. The Polycomb repressive complex EZH2 inhibitor tazemetostat was recently approved for the treatment of SMARCB1-deficient epithelioid sarcomas, based on the functional antagonism between PRC2 and loss of SMARCB1. Through the analysis of tazemetostat-treated patient tumors, we recently defined key principles of their response and resistance to EZH2 epigenetic therapy. Here, using transcriptomic inference from SMARCB1-deficient tumor cells, we nominate the DNA damage repair kinase ATR as a target for rational combination EZH2 epigenetic therapy. We show that EZH2 inhibition promotes DNA damage in epithelioid and rhabdoid tumor cells, at least in part via its induction of the transposase-derived PGBD5. We leverage this collateral synthetic lethal dependency to target PGBD5-dependent DNA damage by inhibition of ATR but not CHK1 using elimusertib. Consequently, combined EZH2 and ATR inhibition improves therapeutic responses in diverse patient-derived epithelioid and rhabdoid tumors in vivo. This advances a combination epigenetic therapy based on EZH2-PGBD5 synthetic lethal dependency suitable for immediate translation to clinical trials for patients.
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Epigenetic dependencies have become evident in many cancers. On the basis of antagonism between BAF/SWI-SNF and PRC2 in SMARCB1-deficient sarcomas, we recently completed the clinical trial of the EZH2 inhibitor tazemetostat. However, the principles of tumor response to epigenetic therapy in general, and tazemetostat in particular, remain unknown. Using functional genomics and diverse experimental models, we define molecular mechanisms of tazemetostat resistance in SMARCB1-deficient tumors. We found distinct acquired mutations that converge on the RB1/E2F axis and decouple EZH2-dependent differentiation and cell-cycle control. This allows tumor cells to escape tazemetostat-induced G1 arrest, suggests a general mechanism for effective therapy, and provides prospective biomarkers for therapy stratification, including PRICKLE1. On the basis of this, we develop a combination strategy to circumvent tazemetostat resistance using bypass targeting of AURKB. This offers a paradigm for rational epigenetic combination therapy suitable for translation to clinical trials for epithelioid sarcomas, rhabdoid tumors, and other epigenetically dysregulated cancers. SIGNIFICANCE: Genomic studies of patient epithelioid sarcomas and rhabdoid tumors identify mutations converging on a common pathway for response to EZH2 inhibition. Resistance mutations decouple drug-induced differentiation from cell-cycle control. We identify an epigenetic combination strategy to overcome resistance and improve durability of response, supporting its investigation in clinical trials. See related commentary by Paolini and Souroullas, p. 903. This article is featured in Selected Articles from This Issue, p. 897.
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Resistencia a Medicamentos Antineoplásicos , Proteína Potenciadora do Homólogo 2 de Zeste , Epigênese Genética , Piridonas , Humanos , Proteína Potenciadora do Homólogo 2 de Zeste/antagonistas & inibidores , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Piridonas/uso terapêutico , Piridonas/farmacologia , Resistencia a Medicamentos Antineoplásicos/genética , Morfolinas/farmacologia , Morfolinas/uso terapêutico , Animais , Camundongos , Compostos de Bifenilo/uso terapêutico , Compostos de Bifenilo/farmacologia , Linhagem Celular Tumoral , Proteína SMARCB1/genética , Benzamidas/uso terapêutico , Benzamidas/farmacologia , MutaçãoRESUMO
Genetic information encoded by DNA is packaged in the nucleus using the chromatin structure. The accessibility of transcriptional elements in DNA is controlled by the dynamic structural changes of chromatin for the appropriate regulation of gene transcription. Chromatin structure is regulated by two general mechanisms, one is histone modification and the other is chromatin remodeling in an ATP-dependent manner. Switch/sucrose nonfermentable (SWI/SNF) complexes utilize the energy from ATP hydrolysis to mobilize nucleosomes and remodel the chromatin structure, contributing to conformational changes in chromatin. Recently, the inactivation of encoding genes for subunits of the SWI/SNF complexes has been documented in a series of human cancers, accounting for up to almost 20% of all human cancers. For example, human SNF5 (hSNF5), the gene that encodes a subunit of the SWI/SNF complexes, is the sole mutation target that drives malignant rhabdoid tumors (MRT). Despite remarkably simple genomes, the MRT has highly malignant characteristics. As a key to understanding MRT tumorigenesis, it is necessary to fully examine the mechanism of chromatin remodeling by the SWI/SNF complexes. Herein, we review the current understanding of chromatin remodeling by focusing on SWI/SNF complexes. In addition, we describe the molecular mechanisms and influences of hSNF5 deficiency in rhabdoid tumors and the prospects for developing new therapeutic targets to overcome the epigenetic drive of cancer that is caused by abnormal chromatin remodeling.
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Tumor Rabdoide , Fatores de Transcrição , Humanos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Tumor Rabdoide/genética , Tumor Rabdoide/patologia , Proteínas Cromossômicas não Histona/genética , Nucleossomos , DNA , Trifosfato de Adenosina , Montagem e Desmontagem da CromatinaRESUMO
Essential epigenetic dependencies have become evident in many cancers. Based on the functional antagonism between BAF/SWI/SNF and PRC2 in SMARCB1-deficient sarcomas, we and colleagues recently completed the clinical trial of the EZH2 inhibitor tazemetostat. However, the principles of tumor response to epigenetic therapy in general, and tazemetostat in particular, remain unknown. Using functional genomics of patient tumors and diverse experimental models, we sought to define molecular mechanisms of tazemetostat resistance in SMARCB1-deficient sarcomas and rhabdoid tumors. We found distinct classes of acquired mutations that converge on the RB1/E2F axis and decouple EZH2-dependent differentiation and cell cycle control. This allows tumor cells to escape tazemetostat-induced G1 arrest despite EZH2 inhibition, and suggests a general mechanism for effective EZH2 therapy. This also enables us to develop combination strategies to circumvent tazemetostat resistance using cell cycle bypass targeting via AURKB, and synthetic lethal targeting of PGBD5-dependent DNA damage repair via ATR. This reveals prospective biomarkers for therapy stratification, including PRICKLE1 associated with tazemetostat resistance. In all, this work offers a paradigm for rational epigenetic combination therapy suitable for immediate translation to clinical trials for epithelioid sarcomas, rhabdoid tumors, and other epigenetically dysregulated cancers.
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Malignant rhabdoid tumor (MRT) is a highly aggressive pediatric malignancy with no effective therapy. Therefore, it is necessary to identify a target for the development of novel molecule-targeting therapeutic agents. In this study, we report the importance of the runt-related transcription factor 1 (RUNX1) and RUNX1-Baculoviral IAP (inhibitor of apoptosis) Repeat-Containing 5 (BIRC5/survivin) axis in the proliferation of MRT cells, as it can be used as an ideal target for anti-tumor strategies. The mechanism of this reaction can be explained by the interaction of RUNX1 with the RUNX1-binding DNA sequence located in the survivin promoter and its positive regulation. Specific knockdown of RUNX1 led to decreased expression of survivin, which subsequently suppressed the proliferation of MRT cells in vitro and in vivo. We also found that our novel RUNX inhibitor, Chb-M, which switches off RUNX1 using alkylating agent-conjugated pyrrole-imidazole polyamides designed to specifically bind to consensus RUNX-binding sequences (5'-TGTGGT-3'), inhibited survivin expression in vivo. Taken together, we identified a novel interaction between RUNX1 and survivin in MRT. Therefore the negative regulation of RUNX1 activity may be a novel strategy for MRT treatment.
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Subunidade alfa 2 de Fator de Ligação ao Core , Tumor Rabdoide , Survivina , Humanos , Apoptose , Sequência de Bases , Linhagem Celular Tumoral , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Tumor Rabdoide/tratamento farmacológico , Tumor Rabdoide/genéticaRESUMO
Malignant rhabdoid tumors (MRTs) are rare and highly aggressive pediatric cancers with no standard of care. MRTs are characterized by loss of SMARCB1, which results in upregulated expression of enhancer of zeste homolog 2 (EZH2), which is responsible for the methylation of lysine 27 of histone H3 (H3K27me3), leading to the repression of gene expression. Although previous reports suggest EZH2 as an effective therapeutic target, the functions of EZH1, the other homolog of EZH, in MRT remain unknown. Here, we show that EZH1, as well as EZH2, contributes to MRT cell growth and H3K27 methylation. Depletion or selective inhibition of EZH2 led to a compensatory increase in EZH1 expression, and depletion of EZH1 enhanced the effect of EZH2 inhibition. EZH1/2 dual inhibitors suppressed MRT cell growth markedly, reflecting the reduction of H3K27me3 accumulation at one of the EZH1/2 targets, the CDKN2A locus. Dual inhibition of EZH1/2 in vivo suppressed tumor growth completely, with no significant adverse effects. These findings indicate that both EZH1 and EZH2 are potential targets for MRT therapy, and that EZH1/2 dual inhibitors may be promising therapeutic strategies for MRT.
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Runtrelated transcription factor 1 (RUNX1), which is also known as acute myeloid leukemia 1 (AML1), has been frequently found with genomic aberrations in human leukemia. RUNX1 encodes a transcription factor that can regulate the expression of hematopoietic genes. In addition, tumor necrosis factorrelated apoptosisinducing ligand (TRAIL) performs an important function for malignant tumors in immune surveillance. However, the regulatory mechanism of TRAIL expression remain to be fully elucidated. In the present study, tetradecanoylphorbol 13acetatetreated megakaryocytic differentiated K562 cells was used to examine the effect of RUNX1 on TRAIL expression. Luciferase assay series of TRAIL promoters for the cells cotransfected with RUNX1 and corebinding factor ß (CBFß) expression vectors were performed to evaluate the nature of TRAIL transcriptional regulation. Electrophoresis mobility shift assay of the RUNX1 consensus sequence of the TRAIL promoter with recombinant RUNX1 and CBFß proteins was also performed. BloodSpot database analysis for TRAIL expression in patients with acute myeloid leukemia were performed. The expression of TRAIL, its receptor Death receptor 4 and 5 and RUNX1 in K562 cells transfected with the RUNX1 expression vector and RUNX1 siRNA were evaluated by reverse transcriptionquantitative PCR (RTqPCR). TRAIL and RUNX1ETO expression was also measured in Kasumi1 cells transfected with RUNX1ETO siRNA and in KG1 cells transfected with RUNX1ETO expression plasmid, both by RTqPCR. Cell counting, lactate dehydrogenase assay and cell cycle analysis by flow cytometry were performed on Kasumi1, KG1, SKNO1 and K562 cells treated with TRAIL and HDAC inhibitors sodium butyrate or valproic acid. The present study demonstrated that RUNX1 is a transcriptional regulator of TRAIL. It was initially found that the induction of TRAIL expression following the megakaryocytic differentiation of human leukemia cells was RUNX1dependent. Subsequently, overexpression of RUNX1 was found to increase TRAIL mRNA expression by activating its promoter activity. Additional analyses revealed that RUNX1 regulated the expression of TRAIL in an indirect manner, because RUNX1 retained its ability to activate this promoter following the mutation of all possible RUNX1 consensus sites. Furthermore, TRAIL expression was reduced in leukemia cells carrying the t(8;21) translocation, where the RUNX1ETO chimeric protein interfere with normal RUNX1 function. Exogenous treatment of recombinant TRAIL proteins was found to induce leukemia cell death. To conclude, the present study provided a novel mechanism, whereby TRAIL is a target gene of RUNX1 and TRAIL expression was inhibited by RUNX1ETO. These results suggest that TRAIL is a promising agent for the clinical treatment of t(8;21) AML.
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Subunidade alfa 2 de Fator de Ligação ao Core/farmacologia , Ligante Indutor de Apoptose Relacionado a TNF/efeitos dos fármacos , Animais , Subunidade alfa 2 de Fator de Ligação ao Core/metabolismo , Modelos Animais de Doenças , Humanos , Células K562/efeitos dos fármacos , Células K562/metabolismo , Camundongos , Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Transcrição Gênica/genéticaRESUMO
Rhabdoid tumors (RTs) are a rare and aggressive pediatric cancer that commonly presents with alterations in the tumor suppressor gene SMARCB1. However, RT prognosis is still poor, with no standard treatment available. Moreover, no predictive biomarkers have been identified for determining its aggressiveness or chemo- and radio-sensitivities. Herein, four cases of extra-cranial RTs (ERTs) are described, two of whom are long-term survivors. These two surviving patients were positive for p16, whereas the other two were p16-negative. Our findings suggest that biologically distinct types of ERTs exist and that p16 expression may be a potential positive prognostic biomarker of ERTs. Nevertheless, further studies are required to confirm our findings.
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Tumor Rabdoide , Criança , Humanos , Prognóstico , Tumor Rabdoide/genética , Tumor Rabdoide/metabolismo , Tumor Rabdoide/terapia , Proteína SMARCB1/genéticaRESUMO
The fusion protein RUNX1-ETO is an oncogenic transcription factor generated by t(8;21) chromosome translocation, which is found in FAB-M2-type acute myeloid leukemia (AML). RUNX1-ETO is known to dysregulate the normal RUNX1 transcriptional network, which should involve essential factors for the onset of AML with t(8;21). In this study, we screened for possible transcriptional targets of RUNX1 by reanalysis of public data in silico, and identified C11orf21 as a novel RUNX1 target gene because its expression was down-regulated in the presence of RUNX1-ETO. The expression level of C11orf21 was low in AML patient samples with t(8;21) and in Kasumi-1 cells, which carry RUNX1-ETO. Knockdown of RUNX1-ETO in Kasumi-1 cells restored C11orf21 expression, whereas overexpression of RUNX1 up-regulated C11orf21 expression. In addition, knockdown of RUNX1 in other human leukemia cells without RUNX-ETO, such as K562, led to a decrease in C11orf21 expression. Of note, the C11orf21 promoter sequence contains a consensus sequence for RUNX1 binding and it was activated by exogenously expressed RUNX1 based on our luciferase reporter assay. This luciferase signal was trans-dominantly suppressed by RUNX1-ETO and site-directed mutagenesis of the consensus site abrogated the reporter activity. This study demonstrated that C11orf21 is a novel transcriptional target of RUNX1 and RUNX1-ETO suppressed C11orf21 transcription in t(8;21) AML. Thus, through this in silico approach, we identified a novel transcriptional target of RUNX1, and the depletion of C11orf21, the target gene, may be associated with the onset of t(8;21) AML.
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SMARCB1 is mutated in most rhabdoid tumors (RTs) developing in the kidney (RTK) and various other organs. Focal deletions found in patients with 22q11.2 deletion syndrome show breakpoints within clusters of segmental duplications (SDs), and those in some RTs show breakpoints in the 22q11-q12 region. SDs are known to cause focal deletion mediated by non-allelic homologous recombination. The present study identified SMARCB1 alterations in all 30 RTKs, using SNP array CGH, MLPA, and sequence analyses. Twenty-eight tumors had a total of 51 breakpoints forming focal 22q deletion and/or uniparental disomy (22qUPD), and the other two had compound mutation with no breakpoints in 22q. Twenty-four (47.1%) of the 51 breakpoints were within SDs, and occurred in 16 (53.3%) of the 30 tumors. The association of breakpoints with SDs was found not only in focal deletion, but also in 22qUPD, indicating that SDs mediate the first and second hits (focal deletion) and the second hit (22qUPD) of SMARCB1 alteration. Of the 51 breakpoints, 14 were recurrent, and 10 of the 14 were within SDs, suggesting the presence of hotspots in the 22q11.2 region. One recurrent breakpoint outside SDs resided in SMARCB1, suggesting inactivation of the gene by out-of-frame fusion. The association between SDs and focal deletion has been reported in two other types of cancer. RTKs may be the third example of SD-associated tumors. Thus, the present study indicated that RTKs exploit genomic instability in the 22q11.1-11.2 SDs region, and 22qUPD caused by mitotic recombination may also be mediated by SDs.
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Pontos de Quebra do Cromossomo , Cromossomos Humanos Par 22/genética , Neoplasias Renais/genética , Tumor Rabdoide/genética , Carcinogênese/genética , Pré-Escolar , Deleção Cromossômica , Duplicação Cromossômica , Feminino , Humanos , Lactente , Neoplasias Renais/patologia , Masculino , Tumor Rabdoide/patologia , Proteína SMARCB1/genética , Dissomia Uniparental/genéticaRESUMO
Malignant rhabdoid tumor (MRT) is a rare and highly aggressive pediatric malignancy primarily affecting infants and young children. Intensive multimodal therapies currently given to MRT patients are not sufficiently potent to control this highly malignant tumor. Therefore, additive or alternative therapy for these patients with a poor prognosis is necessary. We herein demonstrated that the inhibition of runt-related transcription factor 1 (RUNX1) by novel alkylating conjugated pyrrole-imidazole (PI) polyamides, which specifically recognize and bind to RUNX-binding DNA sequences, was highly effective in the treatment of rhabdoid tumor cell lines in vitro as well as in an in vivo mouse model. Therefore, suppression of RUNX1 activity may be a novel strategy for MRT therapy.
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Antineoplásicos Alquilantes/uso terapêutico , Clorambucila/uso terapêutico , Subunidade alfa 2 de Fator de Ligação ao Core/antagonistas & inibidores , Tumor Rabdoide/tratamento farmacológico , Animais , Linhagem Celular Tumoral , Clorambucila/análogos & derivados , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Modelos Animais de Doenças , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Interferência de RNA , RNA Interferente Pequeno/genética , Proteína SMARCB1/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
A 46-year-old man with a history of ulcerative colitis (UC) for over 25 years was treated with infliximab for 7 years. He noticed gradually spreading erythema on his right lower abdomen, femur, and buttocks. Skin biopsy from the right lower abdomen revealed massive invasion of lymphocytes in the papillary dermis and epidermal layer. In conjunction with the findings of immunohistochemistry, the skin lesion was diagnosed as mycosis fungoides (MF) at infiltration stage. Infliximab was discontinued, and narrow-band ultraviolet light B therapy was initiated to treat the skin lesion. The patient achieved remission for MF following treatment and UC has not relapsed for more than 1 year with 5-aminosalicylic acid treatment alone. This is the first case of MF in a UC patient treated with anti-tumor necrosis factor-alpha (anti-TNFα). Lymphoma occurrence is a complication of treatment with anti-TNFα agent or thiopurine. However, there is no evidence regarding the relationship between MF and UC. Hence, these immunomodulatory agents may have triggered the occurrence of MF in this case. When treating UC patients with immunomodulatory agents, the possibility of MF or other types of lymphoma as rare complications must be considered.
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Colite Ulcerativa , Micose Fungoide , Neoplasias Cutâneas , Colite Ulcerativa/complicações , Colite Ulcerativa/tratamento farmacológico , Humanos , Infliximab/efeitos adversos , Masculino , Pessoa de Meia-Idade , Micose Fungoide/tratamento farmacológico , PeleRESUMO
BACKGROUND/AIM: Malignant rhabdoid tumor (MRT) is a rare, aggressive neoplasm found in young children, caused by inactivation of a single gene, SNF5 (INI1, SMARCB1). MRT cases with multifocal tumors at diagnosis are categorized as synchronous MRT, often with a germline mutation of SNF5. The aim of this study was to establish new models useful in clarifying the biological basis of synchronous MRT. MATERIALS AND METHODS: We established two novel MRT cell lines, designated as KP-MRT-KS and KP-MRT-KSa, derived from different lesions and at a different time from a synchronous multifocal 7-month-old female MRT patient. RESULTS: Both cells showed typical morphology of MRT, with a compound genomic mutation in exons 2 and 5 of the SNF5 gene. The exon 2 mutation was found in the germline. CONCLUSION: These cell lines could serve as powerful tools for unveiling the molecular mechanism of refractory synchronous MRT.
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Neoplasias Primárias Múltiplas/patologia , Tumor Rabdoide/patologia , Sequência de Bases , Carcinogênese/genética , Carcinogênese/patologia , Linhagem Celular Tumoral , Proliferação de Células/genética , Análise por Conglomerados , Metilação de DNA/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Lactente , Neoplasias Primárias Múltiplas/genética , Tumor Rabdoide/diagnóstico por imagem , Tumor Rabdoide/genética , Proteína SMARCB1/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Rhabdoid tumor is an aggressive, early childhood tumor. Biallelic inactivation of the SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1)/integrase interactor 1 (INI1) gene is the only common genetic feature in rhabdoid tumors. Loss of SMARCB1 function results in downregulation of several tumor suppressor genes including p16, p21, and NOXA The novel histone deacetylase inhibitor, OBP-801, induces p21 and has shown efficacy against various cancers. In our study, OBP-801 strongly inhibited the cell growth of all rhabdoid tumor cell lines in WST-8 assay. However, Western blotting and cell-cycle analysis revealed that OBP-801 did not activate the P21-RB pathway in some cell lines. p21 knockout indicated that p21 did not dominate the OBP-801 antitumor effect in rhabdoid tumor cell lines. We discovered that OBP-801 induced NOXA expression and caspase-dependent apoptosis in rhabdoid tumor cell lines independent of TP53. Chromatin immunoprecipitation assay showed that OBP-801 acetylated histone proteins and recruited RNA polymerase II to the transcription start site (TSS) of the NOXA promotor. Moreover, OBP-801 recruited BRG1 and BAF155, which are members of the SWI/SNF complex, to the TSS of the NOXA promotor. These results suggest that OBP-801 epigenetically releases the silencing of NOXA and induces apoptosis in rhabdoid tumors. OBP-801 strongly inhibited tumor growth in human rhabdoid tumor xenograft mouse models in vivo Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and cleaved caspase-3 were stained in tumors treated with OBP-801. In conclusion, OBP-801 induces apoptosis in rhabdoid tumor cells by epigenetically releasing the silencing of NOXA, which is a key mediator of rhabdoid tumor apoptosis. The epigenetic approach for NOXA silencing with OBP-801 is promising for rhabdoid tumor treatment.
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Inibidores de Histona Desacetilases/uso terapêutico , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Tumor Rabdoide/tratamento farmacológico , Animais , Apoptose , Feminino , Inibidores de Histona Desacetilases/farmacologia , Humanos , Camundongos , Camundongos NusRESUMO
BACKGROUND: Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma. There are two subtypes, fusion gene-positive RMS (FP-RMS) and fusion gene-negative RMS (FN-RMS), depending on the presence of a fusion gene, either PAX3-FOXO1 or PAX7-FOXO1. These fusion genes are thought to be oncogenic drivers of FP-RMS. By contrast, the underlying mechanism of FN-RMS has not been thoroughly investigated. It has recently been shown that HMGA2 is specifically positive in pathological tissue from FN-RMS, but the role of HMGA2 in FN-RMS remains to be clarified. METHODS: In this study, we used FN-RMS cell lines to investigate the function of HMGA2. Gene expression, cell growth, cell cycle, myogenic differentiation, tumor formation in vivo, and cell viability under drug treatment were assessed. RESULTS: We found that HMGA2 was highly expressed in FN-RMS cells compared with FP-RMS cells and that knockdown of HMGA2 in FN-RMS cells inhibited cell growth and induced G1 phase accumulation in the cell cycle and myogenic differentiation. Additionally, we showed using both gain-of-function and loss-of-function assays that HMGA2 was required for tumor formation in vivo. Consistent with these findings, the HMGA2 inhibitor netropsin inhibited the cell growth of FN-RMS. CONCLUSIONS: Our results suggest that HMGA2 has important role in the oncogenicity of FP-RMS and may be a potential therapeutic target in patients with FN-RMS.
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INTRODUCTION: Cunninghamella bertholletiae although rarely causing mucormycosis, is responsible for the highest mortality among mucormycetes. The diagnosis of mucormycosis is challenged by the absence of specific biomarkers. Herein, we report a fatal case of C. bertholletiae infection and detection of its DNA in the serum by polymerase chain reaction (PCR). PRESENTATION OF CASE: A 23-year-old male with refractory osteosarcoma was admitted with multiple lung metastases. He was on oral voriconazole prophylaxis after pulmonary aspergillosis. He suffered from fever during temporary neutropenia following chemotherapy and showed several neurological and respiratory symptoms. Despite liposomal-amphotericin B administration, the symptoms rapidly progressed, and he died five days after the onset of neurological symptoms.We retrospectively evaluated the filamentous fungus isolated after his death from gastric juices. Based on the sequence of the internal transcribed spacer (ITS) region we identified the fungal isolate as C. bertholletiae. A 146-bp portion of the D1/D2 region was quantified by quantitative-PCR using DNA extracted from the serum. C. bertholletiae DNA load in the serum was 18.0 copies/µL on the day of onset of neurological symptoms, with the highest (101.0 copies/µL) on the day of his death. DISCUSSION: Detection of circulating DNA of mucormycetes in the blood would greatly enhance the diagnosis of mucormycosis. Rapid diagnosis might alleviate mortality due to mucormycosis. CONCLUSION: The present case-report suggests that the quantification of C. bertholletiae DNA in the serum could be useful for the diagnosis and evaluation of mucormycosis pathogenesis in patients.
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The new paradigm of mutations in chromatin-modifying genes as driver events in the development of cancers has proved challenging to resolve the complex influences over disease phenotypes. In particular, impaired activities of members of the SWI/SNF chromatin remodeling complex have appeared in an increasing variety of tumors. Mutations in SNF5, a member of this ubiquitously expressed complex, arise in almost all cases of malignant rhabdoid tumor in the absence of additional genetic alterations. Therefore, we studied how activation of additional oncogenic pathways might shift the phenotype of disease driven by SNF5 loss. With the use of a genetically engineered mouse model, we examined the effects of a hypomorphic Vhl2B allele on disease phenotype, with a modest up-regulation of the hypoxia response pathway. Snf5+/-;Vhl2B/+ mice did not demonstrate a substantial difference in overall survival or a change in malignant rhabdoid tumor development. However, a high percentage of female mice showed complex hemorrhagic ovarian cysts, a phenotype rarely found in either parental mouse strain. These lesions also showed mosaic expression of SNF5 by immunohistochemistry. Therefore, our studies implicate that modest changes in angiogenic regulation interact with perturbations of SWI/SNF complex activity to modulate disease phenotypes.
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Hemorragia/patologia , Mutação , Cistos Ovarianos/patologia , Proteína SMARCB1/fisiologia , Proteína Supressora de Tumor Von Hippel-Lindau/fisiologia , Animais , Feminino , Hemorragia/etiologia , Hemorragia/metabolismo , Camundongos , Camundongos Knockout , Cistos Ovarianos/etiologia , Cistos Ovarianos/metabolismo , FenótipoRESUMO
Despite intense efforts, the cure rates of childhood and adult solid tumors are not satisfactory. Resistance to intensive chemotherapy is common, and targets for molecular therapies are largely undefined. We have found that the majority of childhood solid tumors, including rhabdoid tumors, neuroblastoma, medulloblastoma, and Ewing sarcoma, express an active DNA transposase, PGBD5, that can promote site-specific genomic rearrangements in human cells. Using functional genetic approaches, we discovered that mouse and human cells deficient in nonhomologous end joining (NHEJ) DNA repair cannot tolerate the expression of PGBD5. In a chemical screen of DNA damage signaling inhibitors, we identified AZD6738 as a specific sensitizer of PGBD5-dependent DNA damage and apoptosis. We found that expression of PGBD5, but not its nuclease activity-deficient mutant, was sufficient to induce sensitivity to AZD6738. Depletion of endogenous PGBD5 conferred resistance to AZD6738 in human tumor cells. PGBD5-expressing tumor cells accumulated unrepaired DNA damage in response to AZD6738 treatment and underwent apoptosis in both dividing and G1-phase cells in the absence of immediate DNA replication stress. Accordingly, AZD6738 exhibited nanomolar potency against most neuroblastoma, medulloblastoma, Ewing sarcoma, and rhabdoid tumor cells tested while sparing nontransformed human and mouse embryonic fibroblasts in vitro. Finally, treatment with AZD6738 induced apoptosis and regression of human neuroblastoma and medulloblastoma tumors engrafted in immunodeficient mice in vivo. This effect was potentiated by combined treatment with cisplatin, including substantial antitumor activity against patient-derived primary neuroblastoma xenografts. These findings delineate a therapeutically actionable synthetic dependency induced in PGBD5-expressing solid tumors.
Assuntos
Reparo do DNA/efeitos dos fármacos , Terapia de Alvo Molecular , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Pirimidinas/uso terapêutico , Sulfóxidos/uso terapêutico , Transposases/antagonistas & inibidores , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Criança , Dano ao DNA , Reparo do DNA por Junção de Extremidades/efeitos dos fármacos , Sinergismo Farmacológico , Humanos , Indóis , Camundongos , Camundongos Nus , Modelos Biológicos , Morfolinas , Pirimidinas/farmacologia , Transdução de Sinais , Sulfonamidas , Sulfóxidos/farmacologia , Transposases/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND: It remains unclear whether a residual tumor mass following therapy influences the prognosis of neuroblastoma. METHODS: We retrospectively reviewed 20 patients with intermediate-risk tumors treated at our institution between 1993 and 2012 to elucidate whether additional treatment is required for residual tumors. RESULTS: The patient ages at diagnosis ranged from 0 days to 7 years. The 5-year overall survival rate was 94.4%. Thirteen patients had Stage 3 disease and seven patients had Stage 4 disease. Nine patients showed intraspinal extension. Twelve patients had a residual tumor mass at the completion of therapy, and eight showed intraspinal extension. Five of these 12 patients showed metaiodobenzylguanidine (MIBG) uptake at the end of treatment, but the uptake disappeared during the follow-up period. Except for one patient who died due to treatment complications, the rest are all alive, and nine are alive with a residual mass. We examined the residual mass in four patients and found that these tissues had differentiated into a ganglioneuroma or changed to a necrotic tissue. For the three patients with neurological symptoms at the end of treatment, some slight neurological symptoms still remained during the follow-up. Five patients with an intraspinal mass eventually presented with new symptoms. CONCLUSIONS: The presence of a residual mass at the end of treatment did not influence the patients' prognosis. Therefore, an invasive radical surgical resection and additional treatment may not be necessary. Cases with a residual intraspinal mass also require a long-term follow-up to assess the neurological prognosis.The presence of a residual mass in cases of intermediate-risk neuroblastoma at the end of treatment did not influence the patients' prognosis.