RESUMO
Squamous cell carcinoma driven by human papillomavirus (HPV) is more sensitive to DNA-damaging therapies than its HPV-negative counterpart. Here, we show that p16, the clinically used surrogate for HPV positivity, renders cells more sensitive to radiotherapy via a ubiquitin-dependent signaling pathway, linking high levels of this protein to increased activity of the transcription factor SP1, increased HUWE1 transcription, and degradation of ubiquitin-specific protease 7 (USP7) and TRIP12. Activation of this pathway in HPV-positive disease led to decreased homologous recombination and improved response to radiotherapy, a phenomenon that can be recapitulated in HPV-negative disease using USP7 inhibitors in clinical development. This p16-driven axis induced sensitivity to PARP inhibition and potentially leads to "BRCAness" in head and neck squamous cell carcinoma (HNSCC) cells. Thus, these findings support a functional role for p16 in HPV-positive tumors in driving response to DNA damage, which can be exploited to improve outcomes in both patients with HPV-positive and HPV-negative HNSCC. SIGNIFICANCE: In HPV-positive tumors, a previously undiscovered pathway directly links p16 to DNA damage repair and sensitivity to radiotherapy via a clinically relevant and pharmacologically targetable ubiquitin-mediated degradation pathway.
Assuntos
Carcinoma de Células Escamosas , Neoplasias de Cabeça e Pescoço , Infecções por Papillomavirus , Carcinoma de Células Escamosas/patologia , Proteínas de Transporte , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Dano ao DNA , DNA Viral/genética , Neoplasias de Cabeça e Pescoço/genética , Humanos , Papillomaviridae/genética , Transdução de Sinais , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , Proteínas Supressoras de Tumor/metabolismo , Ubiquitina , Ubiquitina-Proteína Ligases/metabolismo , Peptidase 7 Específica de Ubiquitina/metabolismoRESUMO
Despite radiation forming the curative backbone of over 50% of malignancies, there are no genomically-driven radiosensitizers for clinical use. Herein we perform in vivo shRNA screening to identify targets generally associated with radiation response as well as those exhibiting a genomic dependency. This identifies the histone acetyltransferases CREBBP/EP300 as a target for radiosensitization in combination with radiation in cognate mutant tumors. Further in vitro and in vivo studies confirm this phenomenon to be due to repression of homologous recombination following DNA damage and reproducible using chemical inhibition of histone acetyltransferase (HAT), but not bromodomain function. Selected mutations in CREBBP lead to a hyperacetylated state that increases CBP and BRCA1 acetylation, representing a gain of function targeted by HAT inhibition. Additionally, mutations in CREBBP/EP300 are associated with recurrence following radiation in squamous cell carcinoma cohorts. These findings provide both a mechanism of resistance and the potential for genomically-driven treatment.
Assuntos
Proteína de Ligação a CREB/genética , Proteína de Ligação a CREB/metabolismo , Proteína p300 Associada a E1A/genética , Proteína p300 Associada a E1A/metabolismo , Mutação com Ganho de Função , Histona Acetiltransferases/metabolismo , Recombinação Homóloga , Acetilação , Animais , Apoptose , Proteína BRCA1/metabolismo , Biomarcadores Tumorais , Linhagem Celular Tumoral , Histona Acetiltransferases/química , Histona Acetiltransferases/genética , Humanos , Masculino , Camundongos Nus , Mutação , Neoplasias/genética , Neoplasias/terapia , Domínios Proteicos , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , Carcinoma de Células Escamosas de Cabeça e Pescoço/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
PURPOSE: Head and neck cancers (HNSCC) are routinely treated with radiotherapy; however, normal tissue toxicity remains a concern. Therefore, it is important to validate treatment modalities combining molecularly targeted agents with radiotherapy to improve the therapeutic ratio. The aim of this study was to assess the ability of the PARP inhibitor niraparib (MK-4827) alone, or in combination with cell cycle checkpoint abrogating drugs targeting Chk1 (MK-8776) or Wee1 (MK-1775), to radiosensitize HNSCCs in the context of HPV status. MATERIALS AND METHODS: PARP1, PARP2, Chk1 or Wee1 shRNA constructs were analyzed from an in vivo shRNA screen of HNSCC xenografts comparing radiosensitization differences between HPV(+) and HPV(-) tumors. Radiosensitization by niraparib alone or in combination with MK-8776 or MK-1775 was assessed by clonogenic survival in HPV(-) and HPV(+) cells; and the role of p16 in determining response was explored. Relative expressions of DNA repair genes were compared by PCR array in HPV(+) and HPV(-) cells, and following siRNA-mediated knockdown of TRIP12 in HPV(-) cells. RESULTS: In vivo shRNA screening showed a modest preferential radiosensitization by Wee1 and PARP2 in HPV(-) and Chk1 in HPV(+) tumor models. Niraparib alone enhanced the radiosensitivity of all HNSCC cell lines tested. However, HPV(-) cells were sensitized to a greater degree, as suggested by the shRNA screen. When combined with MK-8776 or MK-1775, radiosensitization was further enhanced in an HPV dependent manner with HPV(+) cells enhanced by MK-8776 and HPV(-) cells enhanced by MK-1775. A PCR array for DNA repair genes showed PARP and HR proteins BRCA1 and RAD51 were much lower in HPV(+) cells than in HPV(-). Similarly, directly knocking down p16-dependent TRIP12 decreased expression of these same genes. Overexpressing p16 decreased TRIP12 expression and increased radiosensitivity in HPV(-) HN5. However, while PARP inhibition led to significant radiosensitization in the control, it led to no further significant radiosensitization in p16 overexpressing cells. Forced p16 expression in HPV(-) HN5 increased accumulation in G1 and subG1 and limited progression to S phase, thus reducing effectiveness of PARP inhibition. CONCLUSIONS: Niraparib effectively radiosensitizes HNSCCs with a greater benefit seen in HPV(-). HPV status also plays a role in response to MK-8776 or MK-1775 when combined with niraparib due to differences in DNA repair mechanisms. This study suggests that using cell cycle abrogators in combination with PARP inhibitors may be a beneficial treatment option in HNSCC, but also emphasizes the importance of HPV status when considering effective treatment strategies.
Assuntos
Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Dano ao DNA , Neoplasias de Cabeça e Pescoço/genética , Neoplasias de Cabeça e Pescoço/patologia , Pontos de Checagem do Ciclo Celular/efeitos da radiação , Linhagem Celular Tumoral , Humanos , Indazóis/farmacologia , Piperidinas/farmacologia , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Pirazóis/farmacologia , Pirimidinonas/farmacologia , Tolerância a Radiação/efeitos dos fármacosRESUMO
Radiotherapy is commonly used to treat a variety of solid tumors but improvements in the therapeutic ratio are sorely needed. The aim of this study was to assess the Chk1 kinase inhibitor, MK-8776, for its ability to radiosensitize human tumor cells. Cells derived from NSCLC and HNSCC cancers were tested for radiosensitization by MK-8776. The ability of MK-8776 to abrogate the radiation-induced G2 block was determined using flow cytometry. Effects on repair of radiation-induced DNA double strand breaks (DSBs) were determined on the basis of rad51, γ-H2AX and 53BP1 foci. Clonogenic survival analyses indicated that MK-8776 radiosensitized p53-defective tumor cells but not lines with wild-type p53. Abrogation of the G2 block was evident in both p53-defective cells and p53 wild-type lines indicating no correlation with radiosensitization. However, only p53-defective cells entered mitosis harboring unrepaired DSBs. MK-8776 appeared to inhibit repair of radiation-induced DSBs at early times after irradiation. A comparison of MK-8776 to the wee1 inhibitor, MK-1775, suggested both similarities and differences in their activities. In conclusion, MK-8776 radiosensitizes tumor cells by mechanisms that include abrogation of the G2 block and inhibition of DSB repair. Our findings support the clinical evaluation of MK-8776 in combination with radiation.
Assuntos
Quinase 1 do Ponto de Checagem/antagonistas & inibidores , Pirazóis/farmacologia , Pirimidinas/farmacologia , Radiossensibilizantes/farmacologia , Proteína Supressora de Tumor p53/fisiologia , Linhagem Celular Tumoral , Quebras de DNA de Cadeia Dupla , Fase G2/efeitos da radiação , Histonas/análise , Humanos , Pirimidinonas , Proteína Supressora de Tumor p53/genéticaRESUMO
The aim of this study was to assess niraparib (MK-4827), a novel poly(ADP-Ribose) polymerase (PARP) inhibitor, for its ability to radiosensitize human tumor cells. Human tumor cells derived from lung, breast and prostate cancers were tested for radiosensitization by niraparib using clonogenic survival assays. Both p53 wild-type and p53-defective lines were included. The ability of niraparib to alter the repair of radiation-induced DNA double strand breaks (DSBs) was determined using detection of γ-H2AX foci and RAD51 foci. Clonogenic survival analyses indicated that micromolar concentrations of niraparib radiosensitized tumor cell lines derived from lung, breast, and prostate cancers independently of their p53 status but not cell lines derived from normal tissues. Niraparib also sensitized tumor cells to H2O2 and converted H2O2-induced single strand breaks (SSBs) into DSBs during DNA replication. These results indicate that human tumor cells are significantly radiosensitized by the potent and selective PARP-1 inhibitor, niraparib, in the in vitro setting. The mechanism of this effect appears to involve a conversion of sublethal SSBs into lethal DSBs during DNA replication due to the inhibition of base excision repair by the drug. Taken together, our findings strongly support the clinical evaluation of niraparib in combination with radiation.
Assuntos
Indazóis/farmacologia , Piperidinas/farmacologia , Inibidores de Poli(ADP-Ribose) Polimerases , Radiossensibilizantes/farmacologia , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Quebras de DNA de Cadeia Dupla/efeitos dos fármacos , Quebras de DNA de Cadeia Dupla/efeitos da radiação , Quebras de DNA de Cadeia Simples/efeitos dos fármacos , Quebras de DNA de Cadeia Simples/efeitos da radiação , Reparo do DNA/efeitos dos fármacos , Reparo do DNA/efeitos da radiação , Feminino , Histonas/metabolismo , Humanos , Peróxido de Hidrogênio/farmacologia , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Masculino , Microscopia de Fluorescência , Oxidantes/farmacologia , Poli(ADP-Ribose) Polimerases/metabolismo , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Rad51 Recombinase/metabolismo , Ensaio Tumoral de Célula-Tronco , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
BACKGROUND: Many prostate cancers demonstrate an increased expression of growth factor receptors such as vascular endothelial growth factor receptor (VEGFR) and platelet derived growth factor receptor (PDGFR) which have been correlated with increased resistance to radiotherapy and poor prognosis in other tumors. Therefore, response to radiation could potentially be improved by using inhibitors of these abnormally activated pathways. We have investigated the radiosensitizing effects of sunitinib, a potent, multi-tyrosine kinase inhibitor of the VEGFR and PDGFR receptors, on human prostate cancer cells. METHODS: The radiosensitizing effects of sunitinib were assessed on human prostate cancer cell lines DU145, PC3 and LNCaP by clonogenic assay. Sunitinib's ability to inhibit the activities of its key targets was determined by immunoblot analysis. The radiosensitizing effects of sunitinib in vivo were tested on human tumor xenografts growing in nude mice where response was assessed by tumor growth delay. RESULTS: Clonogenic survival curve assays for both DU145 and PC3 cells showed that the surviving fraction at 2 Gy was reduced from 0.70 and 0.52 in controls to 0.44 and 0.38, respectively, by a 24 hr pretreatment with 100 nM sunitinib. LNCaP cells were not radiosensitized by sunitinib. Dose dependent decreases in VEGFR and PDGFR activation were also observed following sunitinib in both DU145 and PC3 cells. We assessed the ability of sunitinib to radiosensitize PC3 xenograft tumors growing in the hind limb of nude mice. Sunitinib given concurrently with radiation did not prolong tumor growth delay. However, when animals were treated with sunitinib commencing the day after fractionated radiation was complete, tumor growth delay was enhanced compared to radiation alone. CONCLUSIONS: We conclude, based on the in vivo results, that sunitinib and radiation do not interact directly to radiosensitize the PC3 tumor cells in vivo as they did in vitro. The fact that tumor growth delay was enhanced when sunitinib was given after radiotherapy was completed suggests that sunitinib may be acting on the irradiated tumor stroma and suppressing its ability to sustain regrowth of the irradiated tumor. Based on these preclinical findings, we suggest that the combination of sunitinib and radiation for the treatment of prostate cancer deserves further development.
Assuntos
Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Indóis/farmacologia , Neoplasias da Próstata/tratamento farmacológico , Inibidores de Proteínas Quinases/farmacologia , Pirróis/farmacologia , Radiossensibilizantes/farmacologia , Ensaios Antitumorais Modelo de Xenoenxerto , Animais , Western Blotting , Imunofluorescência , Humanos , Masculino , Camundongos , Camundongos Nus , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Proteínas Proto-Oncogênicas c-kit/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-kit/metabolismo , Receptor beta de Fator de Crescimento Derivado de Plaquetas/antagonistas & inibidores , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Sunitinibe , Células Tumorais Cultivadas , Ensaio Tumoral de Célula-Tronco , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Tirosina Quinase 3 Semelhante a fms/antagonistas & inibidores , Tirosina Quinase 3 Semelhante a fms/metabolismoRESUMO
PURPOSE: Radiotherapy is commonly used to treat a variety of solid tumors. However, improvements in the therapeutic ratio for several disease sites are sorely needed, leading us to assess molecularly targeted therapeutics as radiosensitizers. The aim of this study was to assess the wee1 kinase inhibitor, MK-1775, for its ability to radiosensitize human tumor cells. EXPERIMENTAL DESIGN: Human tumor cells derived from lung, breast, and prostate cancers were tested for radiosensitization by MK-1775 using clonogenic survival assays. Both p53 wild-type and p53-defective lines were included. The ability of MK-1775 to abrogate the radiation-induced G2 block, thereby allowing cells harboring DNA lesions to prematurely progress into mitosis, was determined using flow cytometry and detection of γ-H2AX foci. The in vivo efficacy of the combination of MK-1775 and radiation was assessed by tumor growth delay experiments using a human lung cancer cell line growing as a xenograft tumor in nude mice. RESULTS: Clonogenic survival analyses indicated that nanomolar concentrations of MK-1775 radiosensitized p53-defective human lung, breast, and prostate cancer cells but not similar lines with wild-type p53. Consistent with its ability to radiosensitize, MK-1775 abrogated the radiation-induced G2 block in p53-defective cells but not in p53 wild-type lines. MK-1775 also significantly enhanced the antitumor efficacy of radiation in vivo as shown in tumor growth delay studies, again for p53-defective tumors. CONCLUSIONS: These results indicate that p53-defective human tumor cells are significantly radiosensitized by the potent and selective wee1 kinase inhibitor, MK-1775, in both the in vitro and in vivo settings. Taken together, our findings strongly support the clinical evaluation of MK-1775 in combination with radiation.
Assuntos
Proteínas de Ciclo Celular/antagonistas & inibidores , Neoplasias , Proteínas Nucleares/antagonistas & inibidores , Proteínas Tirosina Quinases/antagonistas & inibidores , Pirazóis/farmacologia , Pirimidinas/farmacologia , Radiossensibilizantes/farmacologia , Proteína Supressora de Tumor p53/deficiência , Animais , Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/radioterapia , Linhagem Celular Tumoral , Terapia Combinada , Feminino , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos dos fármacos , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos da radiação , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/radioterapia , Masculino , Camundongos , Camundongos Nus , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Neoplasias/radioterapia , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/radioterapia , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Pirimidinonas , Transplante Heterólogo , Proteína Supressora de Tumor p53/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
PURPOSE: This study assessed the role of oxidative stress and loss of glutathione in ABT-737-induced apoptosis. METHODS: Jurkat human acute lymphocytic leukemia cells and HeLa cells transfected with a tet-regulated Bcl-2 expression system were treated with ABT-737 or its less active stereoisomer. GSH concentrations, intracellular reactive oxygen species (ROS), caspase activation and apoptotic DNA fragmentation were measured. RESULTS: ABT-737 induced oxidative stress through decreased GSH and increased intracellular hydrogen peroxide and superoxide levels. Apoptotic DNA fragmentation and caspase activation were the consequences of this oxidative stress. Combining ABT-737 with ROS-inducing agents such as adaphostin or etoposide enhanced cell death. CONCLUSIONS: These results demonstrate that inhibition of Bcl-2 causes a loss of GSH, an increase in ROS, caspase activation and subsequent apoptosis. Clinically, redox alterations as a consequence of Bcl-2 inhibition by ABT-737 should be considered in devising combination therapies with this novel agent or its derivatives.