RESUMEN
BACKGROUND: DNA damage is accumulated in the cells over time as the result of both exogenous and endogenous factors. The objective of this study was to analyze the immunohistochemical expression of the repair proteins in oral leukoplakia (OL) and oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: Paraffin blocks were selected from the archives of the Laboratory of Hospital Clinico Universitario de Santiago de Compostela, Spain. The sample was composed of 16 cases of OL without dysplasia, 14 cases of OL with dysplasia, and 15 cases of OSCC. The patients' clinical data were collected and immunohistochemical analysis was performed for MLH1, MSH2, MRE11, and XRCC1. The data were submitted to the χ2 and the Kruskal-Wallis (P≤0.05) tests. RESULTS: MSH2 was overexpressed in OSCC (P=0.020) and was positive in 100% of patients with OL with dysplasia or OSCC (P=0.019). Positivity for MLH1 was significantly associated with comorbidity (P=0.040), especially in patients who presented with 2 or more pathologies (P=0.028). XRCC1 positivity was also associated with comorbidity (P=0.039). No significant associations were found for the MRE11A expression. Although the simultaneous positivity for the 4 markers was observed in presence of comorbidities (P=0.006). CONCLUSIONS: This study supports the effect of the overexpression of MSH2 protein in samples of OL with dysplasia and OSCC, most notably in patients who present with comorbidities and negativity for OL without dysplasia.
Asunto(s)
Carcinoma de Células Escamosas/metabolismo , Regulación Neoplásica de la Expresión Génica , Leucoplasia Bucal/metabolismo , Proteína Homóloga de MRE11/biosíntesis , Homólogo 1 de la Proteína MutL/biosíntesis , Proteína 2 Homóloga a MutS/biosíntesis , Proteína 1 de Reparación por Escisión del Grupo de Complementación Cruzada de las Lesiones por Rayos X/biosíntesis , Anciano , Carcinoma de Células Escamosas/patología , Estudios Transversales , Femenino , Humanos , Leucoplasia Bucal/patología , Masculino , Persona de Mediana EdadRESUMEN
Chemoresistance is the primary obstacle in the treatment of locally advanced and metastatic nasopharyngeal carcinoma (NPC). Recent evidence suggests that the transcription factor forkhead box M1 (FoxM1) is involved in chemoresistance. Our group previously confirmed that FoxM1 is overexpressed in NPC. In this study, we investigated the role of FoxM1 in cisplatin resistance of the cell lines 5-8F and HONE-1 and explored its possible mechanism. Our results showed that FoxM1 and NBS1 were both overexpressed in NPC tissues based on data from the GSE cohort (GSE12452). Then, we measured FoxM1 levels in NPC cells and found FoxM1 was overexpressed in NPC cell lines and could be stimulated by cisplatin. MTT and clonogenic assays, flow cytometry, γH2AX immunofluorescence, qRT-PCR, and western blotting revealed that downregulation of FoxM1 sensitized NPC cells to cisplatin and reduced the repair of cisplatin-induced DNA double-strand breaks via inhibition of the MRN (MRE11-RAD50-NBS1)-ATM axis, which might be related to the ability of FoxM1 to regulate NBS1. Subsequently, we demonstrated that enhanced sensitivity of FoxM1 knockdown cells could be reduced by overexpression of NBS1. Taken together, our data demonstrate that downregulation of FoxM1 could improve the sensitivity of NPC cells to cisplatin through inhibition of MRN-ATM-mediated DNA repair, which could be related to FoxM1-dependent regulation of NBS1. [BMB Reports 2019; 52(3): 208-213].
Asunto(s)
Proteínas de la Ataxia Telangiectasia Mutada/antagonistas & inhibidores , Cisplatino/farmacología , Reparación del ADN , Proteína Forkhead Box M1/genética , Carcinoma Nasofaríngeo/tratamiento farmacológico , Carcinoma Nasofaríngeo/metabolismo , Ácido Anhídrido Hidrolasas , Antineoplásicos/farmacología , Proteínas de la Ataxia Telangiectasia Mutada/biosíntesis , Proteínas de la Ataxia Telangiectasia Mutada/genética , Proteínas de Ciclo Celular/antagonistas & inhibidores , Proteínas de Ciclo Celular/biosíntesis , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Línea Celular Tumoral , Enzimas Reparadoras del ADN/antagonistas & inhibidores , Enzimas Reparadoras del ADN/biosíntesis , Enzimas Reparadoras del ADN/genética , Proteínas de Unión al ADN/antagonistas & inhibidores , Proteínas de Unión al ADN/biosíntesis , Proteínas de Unión al ADN/genética , Regulación hacia Abajo , Resistencia a Antineoplásicos , Proteína Forkhead Box M1/biosíntesis , Proteína Forkhead Box M1/metabolismo , Humanos , Proteína Homóloga de MRE11/antagonistas & inhibidores , Proteína Homóloga de MRE11/biosíntesis , Proteína Homóloga de MRE11/genética , Carcinoma Nasofaríngeo/genética , Proteínas Nucleares/antagonistas & inhibidores , Proteínas Nucleares/biosíntesis , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismoRESUMEN
Adenovirus-mediated sensitization of cancer cells to cytotoxic drugs depends on simultaneous interactions of early viral genes with cell death and survival pathways. It is unclear what cellular factors mediate these interactions in the presence of DNA-damaging drugs. We found that adenovirus prevents Chk1-mediated checkpoint activation through inactivation of Mre11 and downregulation of the pChk1 adaptor-protein, Claspin, in cells with high levels of DNA-damage induced by the cytotoxic drugs gemcitabine and irinotecan. The mechanisms for Claspin downregulation involve decreased transcription and increased degradation, further attenuating pChk1-mediated signalling. Live cell imaging demonstrated that low doses of gemcitabine caused multiple mitotic aberrations including multipolar spindles, micro- and multi-nucleation and cytokinesis failure. A mutant virus with the anti-apoptotic E1B19K-gene deleted (AdΔ19K) further enhanced cell killing, Claspin downregulation, and potentiated drug-induced DNA damage and mitotic aberrations. Decreased Claspin expression and inactivation of Mre11 contributed to the enhanced cell killing in combination with DNA-damaging drugs. These results reveal novel mechanisms that are utilised by adenovirus to ensure completion of its life cycle in the presence of cellular DNA damage. Taken together, our findings reveal novel cellular targets that may be exploited when developing improved anti-cancer therapeutics.