Topoisomerase II alpha mRNA and tumour cell proliferation in non-Hodgkin's lymphoma

A systems medicine approach for finding target proteins affecting treatment outcomes in patients with non-Hodgkin lymphoma

Autoantibody profiling with a systems medicine approach can help identify critical dysregulated signaling pathways (SPs) in cancers. In this way, immunoglobulins G (IgG) purified from the serum samples of 92 healthy controls, 10 pre-treated (PR) non-Hodgkin lymphoma (NHL) patients, and 20 NHL patients who underwent chemotherapy (PS) were screened with a phage-displayed random peptide library. Protein-protein interaction networks of the PR and PS groups were analyzed and visualized by Gephi. The results indicated AXIN2, SENP2, TOP2A, FZD6, NLK, HDAC2, HDAC1, and EHMT2, in addition to CAMK2A, PLCG1, PLCG2, GRM5, GRIN2B, GRIN2D, CACNA2D3, and SPTAN1 as hubs in 11 and 7 modules of PR and PS networks, respectively. PR- and PS-specific hubs were evaluated in the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Reactome databases. The PR-specific hubs were involved in Wnt SP, signaling by Notch1 in cancer, telomere maintenance, and transcriptional misregulation. In contrast, glutamate receptor SP, Fc receptor-related pathways, growth factors-related SPs, and Wnt SP were statistically significant enriched pathways, based on the pathway analysis of PS hubs. The results revealed that the most PR-specific proteins were associated with events involved in tumor development, while chemotherapy in the PS group was associated with side effects of drugs and/or cancer recurrence. As the findings demonstrated, PR- and PS-specific proteins in this study can be promising therapeutic targets in future studies.

High expression of Bcl-2 predicts poor outcome in diffuse large B-cell lymphoma patients with low international prognostic index receiving R-CHOP chemotherapy

The prognostic significance of Bcl-2, Bcl-6, p53, topoisomerase II, and β-tubulin expression was evaluated in diffuse large B-cell lymphoma (DLBCL) patients treated with cyclophosphamide, doxorubicin, vincristine, prednisolone, and rituximab. Eight-year progression-free survival (PFS, P = 0.006) and overall survival (OS, P = 0.001) of patients with high Bcl-2 expression were significantly inferior to those of patients with low expression without prognostic significance of Bcl-6, p53, topoisomerase II, and β-tubulin expression. High expression of Bcl-2 was associated with poor PFS (P = 0.045) and OS (P = 0.004) only in patients with low international prognostic index (IPI). In multivariate analysis, high expression of Bcl-2 was a significant independent prognostic factor of poor PFS (P = 0.026) and OS (P = 0.007) along with high IPI. In conclusion, the expression of Bcl-2 may be a useful prognostic factor, especially in DLBCL patients with low IPI.

High levels of topoisomerase IIalpha protein expression in diffuse large B-cell lymphoma are associated with high proliferation, germinal center immunophenotype, and response to treatment

Gene copy number and protein expression of topoisomerase IIalpha were correlated to benefit from anthracyclines in various tumors. A retrospective series of 69 patients with DLBCL managed with CHOP chemotherapy were studied for immunohistochemical TopoIIalpha expression and numerical gene abnormalities by fluorescent in situ hybridization (FISH). The results were analyzed in relation to the expression of cell cycle proteins (Ki67, p53, HDM2, p21, p14, pRb, p16, and cyclins A, B1, D1, D2, D3, and E) and BCL6/CD10/MUM1/CD138 B-cell differentiation immunophenotype and outcome. High levels of TopoIIalpha protein were found in 91% of DLBCL cases. No evidence of TopoIIalpha gene amplification or deletion was found. The TopoIIalpha expression showed significant positive correlations with the proliferation index Ki67 (p = 0.002), cell cycle proteins pRb and cyclin D2 (p = 0.018 and p = 0.028, respectively), and the germinal center proteins bcl6 and CD10 (p = 0.010 and p < 0.0001, respectively). TopoIIalpha expression was significantly higher in germinal center B-cell like (GCB) DLBCL than in non-germinal center B-cell like (non-GCB) DLBCL (p = 0.048). TopoIIalpha protein was significantly associated with response to chemotherapy (chi(2), p = 0.024), but not with relapse-free or overall survival (p = 0.5). On multivariate analysis, only stage of disease retained independent prognostic significance (HR 0.33 for early stage, p = 0.008). Although TopoIIa gene copy number abnormalities were not found in DLBCL, high levels of protein expression are associated with GCB-cell differentiation immunophenotype, high proliferation, and response to treatment.

DNA topoisomerase IIalpha protein and mRNA expression in intracranial meningiomas

We examined the expression of DNA topoisomerase IIalpha (Topo IIalpha) immunohistochemically using a monoclonal antibody and compared its proliferative potential [MIB-1 labeling index (LI)] and recurrence to verify the possible influence of Topo IIalpha on the progress of meningiomas. The reverse transcription-polymerase chain reaction (RT-PCR) assay was also performed to evaluate the expression of Topo IIalpha mRNA. Formalin-fixed, paraffin-embedded tissue sections of 52 meningiomas (18 meningothelial types, 16 fibrous types, 4 transitional types, 4 psammomatous types, 1 angiomatous type, 1 secretory type, 5 atypical types, and 3 anaplastic types) were used for immunostaining. The Topo IIalpha labeling index (LI) was 1.4 +/- 1.9% (mean +/- SE) in benign meningiomas and 4.5 +/- 1.6% in atypical or anaplastic meningiomas, representing significant differences between them (P < 0.0001). RT-PCR assay revealed that Topo IIalpha mRNA expression was associated with Topo IIalpha LI. A significant correlation was seen between Topo IIalpha LI and MIB-1 LI (r = 0.517; P < 0.01). Recurrence was significantly more frequent in patients with more than 1.5% of Topo IIalpha LI than in those with 1.5% or less (P < 0.005). In conclusion, Topo IIalpha protein and mRNA expression correlated with clinical malignancy and the potential for predicting the regrowth of meningiomas.

Expression of DNA topoisomerase I, IIalpha, and IIbeta in human brain tumors

We investigated the expression of DNA topoisomerase I (Topo I), IIalpha (Topo IIalpha), and IIbeta (Topo IIbeta) mRNA using reverse transcription-polymerase chain reaction (RT-PCR) assay in 31 human brain tumors, and examined the relationship between DNA topoisomerase mRNA expression and Topo IIalpha and MIB-1 positive index (PI) as a cell proliferation marker. Topo IIalpha mRNA was expressed in 11 of 31 cases, and Topo I and IIbeta were each expressed in 18 of 31 cases. A significant correlation was seen between the MIB-1 PI and Topo IIalpha PI (P < 0.001). The cases with overexpression of Topo IIalpha mRNA had significantly high MIB-1 and Topo IIalpha PI (P < 0.0001). There was no significant correlation between Topo I and IIbeta mRNA expression and MIB-1 PI. We concluded that it was useful as a cell proliferation marker to analyze the expression of Topo IIalpha mRNA using RT-PCR in human brain tumors.

Topoisomerase II alpha and II beta expression in childhood acute lymphoblastic leukaemia: relation to prognostic factors and clinical outcome

BACKGROUND/AIMS

Many regimens used in the treatment of childhood acute lymphoblastic leukaemia (ALL) include Daunorubicin or Etoposide, which act as topoisomerase poisons. It has been suggested that there may be a relation between topoisomerase expression and response to topoisomerase poisons, based mainly on results from in vitro studies. Therefore, the aim of this study was to investigate this relation in a clinical setting and determine whether topoisomerase II alpha and II beta might be of predictive value in ALL.

METHODS

Cellular expression of topoisomerases II alpha and II beta was assessed in 177 cases of ALL by immunohistochemistry using monoclonal antibodies to the two enzymes. The percentages of cell nuclei showing positive staining for topoisomerase II alpha and II beta expression were assessed.

RESULTS

Taking the series as a whole, a clear separation of survival curves was seen with the established prognostic markers white blood cell (WBC) count, CD10 status, and sex. However, topoisomerase II alpha and II beta expression showed no relation to survival. No association was found between the topoisomerases and the prognostic markers CD10 and WBC count; however, topoisomerase II alpha expression was found to be related to sex, with expression being lower in girls (p = 0.002).

CONCLUSIONS

These results suggest that the response to topoisomerase poisons cannot be predicted by the assessment of topoisomerase II alpha and II beta expression as defined by immunohistochemistry.

Cyclins D1 and D3 and topoisomerase II alpha in inactive pituitary adenomas

The oncogenes cyclin D1 and D3 are overexpressed in many tumors. Topoisomerase II alpha is found in proliferating cells. The immunohistological expression of cyclin D1, cyclin D3, and Topoisomerase II alpha was studied in a collection of 60 clinically inactive surgically removed pituitary adenomas of the follicle-stimulating hormone/luteinizing hormone (FSH/LH) cell complex (20 null cell adenomas, 20 oncocytomas, and 20 FSH/LH cell adenomas) for correlation with other proliferation markers (Ki-67, PCNA) and with clinical data. Whereas cyclin D1 was positive only in one invasive null cell adenoma (1.7%) with some p53-positive nuclei, cyclin D3 was overexpressed in the nuclei of 41 tumors (68%). Topoisomerase II alpha was demonstrated in the nuclei of 42 adenomas (70%) with no significant differences discernible between the three adenoma subtypes. There was no significant correlation to the time of development of tumor symptoms, but a correlation of Topoisomerase II alpha with cyclin D3 and the proliferation marker Ki-67 (Mib1). From these data we conclude that cyclin D3 and Topoisomerase II alpha appear to be additional markers for proliferation which can be used for prognosis index in surgical pathology of the pituitary.

Clinical resistance to topoisomerase-targeted drugs

This review describes topoisomerase (topo)-mediated drug resistance and topo expression in human tissues and cancers. In some in vitro studies a relation has been observed between topo I, IIalpha or IIbeta expression and sensitivity to topo inhibitors. Drug resistance to topo inhibitors may, however, be multifactorial. Several topo inhibitors are substrates for drug membrane transporters. As most topo inhibitors are cell cycle specific, disturbances in cell cycle regulation can also confer resistance, and downstream events following DNA damage induced by topo inhibitors may be involved in regulating cell death or survival. Several studies in patient specimens have shown a relation between topo IIalpha expression and the proliferative state of the tumor, higher topo IIalpha levels being seen in more highly proliferating tumor types. In contrast, topo IIbeta appears to be expressed in both proliferating and quiescent cells. Furthermore, higher topo I levels were observed in some tumors when compared to their normal counterparts. In some studies a reduced topo IIalpha level was seen in samples taken after chemotherapy treatment, as compared with specimens prior to treatment. No unequivocal relation was observed, however, between expression or activity of the topo genes and response to chemotherapy; nonetheless only a few studies have properly addressed this question. This review summarizes the results of the clinical studies performed so far, and analyzes the critical issues in performing studies on patient material.