Deoxyribonucleic acid damage induced by doxorubicin in peripheral blood mononuclear cells: possible roles for the stress response and the deoxyribonucleic acid repair process

Doxorubicin is an antineoplastic drug widely used in cancer treatment. However, many tumors are intrinsically resistant to the drug or show drug resistance after an initial period of response. Among the different molecules implicated with doxorubicin resistance are the heat shock proteins (Hsps). At present we do not know with certainty the mechanism(s) involved in such resistance. In the present study, to advance our knowledge on the relationship between Hsps and drug resistance, we have used peripheral blood mononuclear cells obtained from healthy nonsmoker donors to evaluate the capacity of a preliminary heat shock to elicit the Hsp response and to establish the protection against the deoxyribonucleic acid (DNA) damage induced by doxorubicin. DNA damage and repair were determined using the alkaline comet assay. We also measured the expression of Hsp27, Hsp60, Hsp70, Hsp90, hMLH1, hMSH2, and proliferating cell nuclear antigen by immunocytochemistry. The damage induced by doxorubicin was more efficiently repaired when the cells were previously heat shocked followed by a resting period of 24 hours before drug exposure, as shown by (1) the increased number of undamaged cells (P < 0.05), (2) the increased DNA repair capacity (P < 0.05), and (3) the high expression of the mismatch repair (MMR) proteins hMLH1 and hMSH2 (P < 0.05). In addition, in the mentioned group of cells, we confirmed by Western blot high expression levels of Hsp27 and Hsp70. We also noted a nuclear translocation of Hsp27 and mainly of Hsp70. Furthermore, inducible Hsp70 was more expressed in the nucleus than Hsc70, showing a possible participation of Hsp70 in the DNA repair process mediated by the MMR system

Phosphorylated hsp90 alfa as predictive and prognostic biomarker in tumors from patients treated with platinum analogs

The heat shock protein HSP90α is a ubiquitous molecular chaperone specially required for cancer cells as it chaperones proteins involved in oncogenesis, making it an attractive target for anticancer therapy. Phosphorylated HSP90α (P-HSP90α) on the threonine 7 (Thr-7) accumulates at the sites of DNA damage, involving this protein in DNA damage response. In addition, the basal level of P-HSP90α has been proposed as a surrogate biomarker for genetic instability in tumor cells. Platinum analogs (cisplatin, carboplatin) that are widely used for the treatment of many solid tumors damage DNA by forming covalent adducts. Platinum-DNA adducts are bulky lesions that interfere with DNA replication machinery, resulting in the formation of DNA double strand breaks. These lesions can lead to genomic instability and cell death. Unfortunately, the development of resistance to platinum-based agents may limit efficacy of the chemotherapy. Thus, it remains a need for biomarkers of cisplatin-response and prognosis for cancer patients. Our aim was to determine the predictive and prognostic ability of P-HSP90α in primary tumors from cancer patients who received platinum-based chemotherapy (cisplatin/carboplatin). P-HSP90α expression was determined by immunohistochemistry in paraffin-embedded tumor tissues from 51 cancer patients before chemotherapy, with a mean follow-up of 19.2 months. The expression of the protein was evaluated according to a staining intensity score and proportion of positive tumor cells. Clinical response was assessed after the third cycle of chemotherapy. Disease-free (DFS) and overall survival (OS) were periodically determined. Patients with complete clinical response or partial response to chemotherapy showed nuclear expression of P-HSP90α in contrast with tumors from patients with stable disease or progressive disease (P<0.01). In addition, patients with high cytoplasmic proportion of P-HSP90α had a significantly worse OS (P<0.05). No statistically significant relationship was found between P-HSP90α expression and DFS. Our preliminary results provide evidence that P-HSP90α could be a potentially valuable biomarker in predicting response to platinum-based chemotherapy and, may also be useful for defining the prognosis of the disease.Fil: Cuello Carrión, Fernando Darío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Semino, S.. Hospital Universitario Mendoza; ArgentinaFil: Ibarra, J.. Centro Oncológico de Integración Regional; ArgentinaFil: González, L.. Centro Oncológico de Integración Regional; ArgentinaFil: García, M. B.. Centro Oncológico de Integración Regional; ArgentinaFil: Vargas Roig, Laura Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Nadin, Silvia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaXXXVII Reunión Científica Anual de la Sociedad de Biología de CuyoSan LuisArgentinaSociedad de Biología de Cuy

DNA methylation index and methylation profile of invasive ductal breast tumors

Breast carcinogenesis is a multistep process that involves both genetic and epigenetic alterations. Identification of aberrantly methylated genes in breast tumors and their relation to clinical parameters can contribute to improved diagnostic, prognostic, and therapeutic decision making. Our objective in the present study was to identify the methylation status of 34 cancer-involved genes in invasive ductal carcinomas (IDC). Each of the 70 IDC cases analyzed had a unique methylation profile. The highest methylation frequency was detected in the WT1 (95.7%) and RASSF1 (71.4%) genes. Hierarchical cluster analysis revealed three clusters with different distribution of the prognostic factors tumor grade, lymph node metastasis, and proliferation rate. Methylation of TP73 was associated with high histological grade and high proliferation rate; methylation of RARB was associated with lymph node metastasis. Concurrent methylation of TP73 and RARB was associated with high histological grade, high proliferation rate, increased tumor size, and lymph node metastasis. Patients with more than six methylated genes had higher rates of relapse events and cancer deaths. In multivariate analysis, TP73 methylation and the methylation index were associated with disease outcome. Our results indicate that methylation index and methylation of TP73 and/or RARB are related to unfavorable prognostic factors in patients with IDC. These epigenetic markers should be validated in further studies to improve breast cancer management. © 2012 American Society for Investigative Pathology and the Association for Molecular Pathology.Fil: Marzese, Diego Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Hoon, Dave S.B.. Saint John's Health Center; Estados UnidosFil: Chong, Kelly K.. Saint John's Health Center; Estados UnidosFil: Gago, Francisco E.. Universidad Nacional de Cuyo; Argentina. Centro Médico de Mendoza; ArgentinaFil: Orozco, Javier Dario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo; Argentina. Centro Médico de Mendoza; ArgentinaFil: Tello, Olga M.. Universidad Nacional de Cuyo; ArgentinaFil: Vargas Roig, Laura Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Roque Moreno, Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; Argentina. Universidad Nacional de Cuyo; Argentin

TP73 DNA methylation and upregulation of ΔNp73 are associated with an adverse prognosis in breast cancer

AIM: Accumulated evidence suggests that aberrant methylation of the METHODS: RESULTS: We observed that the methylation of diverse CpG islands of CONCLUSIONS: Our findings suggest that high expression of ΔNp73 could be used to determine the aggressiveness of IDCs and could be incorporated in the pathologist\u27s report

TP73 DNA methylation and upregulation of ΔNp73 are associated with an adverse prognosis in breast cancer

Aim: Accumulated evidence suggests that aberrant methylation of the TP73 gene and increased levels of ΔNp73 in primary tumours correlate with poor prognosis. However, little is known regarding the transcriptional and functional regulation of the TP73 gene in breast cancer. The aim of the present study was to determine the expression of the ΔNp73 isoform, its relationship with DNA methylation of TP73 and their clinical prognostic significance in breast cancer patients. Methods: TP73 gene methylation was studied in TCGA datasets and in 70 invasive ductal breast carcinomas (IDCs). The expression of p73 isoforms was evaluated by immunohistochemistry (IHC) and Western blot and correlated with clinicopathological variables and clinical outcome. Results: We observed that the methylation of diverse CpG islands of TP73 differed significantly between molecular subtypes. An inverse correlation was found between p73 protein expression and the methylation status of the TP73 gene. The expression of exon 3′ of p73 (only expressed in ΔNp73) was significantly higher in patients with wild-type p53. Immunohistochemical analysis revealed that all p73 isoforms were localised in both the nuclear and cytoplasmic compartments. We confirmed a positive association between the expression of ΔNp73 and high histological grade. Conclusions: Our findings suggest that high expression of ΔNp73 could be used to determine the aggressiveness of IDCs and could be incorporated in the pathologist's report.Fil: Gomez, Laura Constanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Sottile Fleury, Mayra Lis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Guerrero Gimenez, Martin Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Zoppino, Felipe Carlos Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Redondo, Analia Lourdes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Gago, Francisco E.. Instituto Gineco-mamario; ArgentinaFil: Orozco, Javier I.. Ginecomamario Institute, Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas; Argentina. John Wayne Cancer Institute at Providence Saint John’s Health Center; Estados UnidosFil: Tello, Olga M.. Ginecomamario Institute, Mendoza; ArgentinaFil: Roqué, María. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Nadin, Silvina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Marzese, Diego Matías. John Wayne Cancer Institute; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vargas Roig, Laura Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; Argentin

Facilitating Akt Clearance via Manipulation of Hsp70 Activity and Levels*

Members of the 70-kDa heat shock family can control and manipulate a host of oncogenic client proteins. This role of Hsp70 in both the folding and degradation of these client proteins makes it a potential drug target for certain forms of cancer. The phenothiazine family of compounds, as well as the flavonoid myricetin, was recently shown to inhibit Hsp70-ATPase activity, whereas members of the dihydropyrimidine family stimulated ATPase function. Akt, a major survival kinase, was found to be under the regulation of Hsp70, and when the ATPase activity of Hsp70 was increased or decreased by these compounds, Akt levels were also increased or decreased. Also, increasing Hsp70 levels concurrent with inhibition of its ATPase function synergistically reduced Akt levels to a greater extent than either manipulation alone, providing new insights about client fate decisions. Akt reductions mediated by Hsp70 inhibitors were prevented when Hsp70 expression was silenced with small interfering RNA. Inhibiting Hsp70 ATPase function produced cytotoxic events only in breast cancer cell lines where Akt dysfunction was previously shown, suggesting therapeutic specificity depending on the Hsp70 client profile. Thus, increasing Hsp70 levels combined with inhibiting its ATPase function may serve to dramatically reduce Akt levels and facilitate cell death in certain types of cancer