Prognostic factors for hematologic cancers

New biomarkers in non-Hodgkin lymphoma and acute leukemias

Biomarkers play a critical role in the medical care of patients with cancer, including in early detection of the disease, diagnostic accuracy, risk stratification, treatment, and follow-up. Biomarkers in hematological malignancies can support the redefinition of the diagnosis and adjustments in the treatment plan. Biomarkers can be classified into 4 categories: (1) protein antigens, (2) cytogenetic abnormalities, (3) genetic polymorphisms, and (4) gene expression. Efforts in genomics, proteomics, and metabolomics to observe new biomarkers that contribute to the development of clinical medicine with greater precision in the strategies that improve prevention, diagnosis, and treatment of patients with malignant hematological disease. New biomarkers should accomplish several issues such as the biological plausibility, methodology used, analytical validation, intellectual property registry, and legal framework of application. This knowledge should be transferred to health professionals who can carry out the process of its implementation in clinical practice.

VH gene analysis of primary CNS lymphomas

Primary CNS lymphomas (PCNSL) are highly malignant non-Hodgkin's lymphomas of B cell origin associated with a poor prognosis. These neoplasms show variable sensitivity to radio- and chemotherapy. A molecular basis for these differences in treatment responses has not yet been established for primary CNS lymphomas in a comprehensive series of patients. Here, we performed PCR analyses of the immunoglobulin (Ig) gene rearrangements of 18 PCNSL, including nine patients who responded well to therapy and nine patients who showed resistance to treatment. Variable gene segment distribution, mutation frequency of variable region genes, and clinical course were analyzed. Our data suggest a tendency towards a higher mean mutation frequency (17.2%) in patients responding to treatment and a lower mutation frequency (11.8%) in patients exhibiting a poor response to therapy, respectively. Furthermore, a restricted usage of the VH4 gene family was observed in the majority of nonresponding patients. To further validate the prognostic impact of these molecular parameters, studies in a larger cohort of patients will be required.

Relationships between degree of binding, cytotoxicity and cytoagglutinating activity of plant-derived agglutinins in normal lymphocytes and cultured leukemic cell lines

PURPOSE

To clarify the relationships between the degree of lectin-cell binding, cytotoxicity and cytoagglutinating activity of plant-derived lectins in normal lymphocytes and cultured leukemic cell lines.

METHODS

Plant lectins with different quaternary structures and saccharide specificity were used: Dolichos biflorus agglutinin (DBA), Soybean agglutinin (SBA) and Wheat germ agglutinin (WGA). The leukemic cell lines used were: Jurkat, MOLT-4, RPMI-8402, HPB-ALL, CCR-HSB-2 and BALL-1 (derived from acute lymphoblastic leukemia); Raji and Daudi (derived from Burkitt's lymphoma); K-562 (derived from myelogenous leukemia). The lectin-cell binding was detected microscopically and fluorimetrically using FITC-conjugated lectins. Cytotoxicity was estimated by the CellTiter-Glo luminescent cell viability assay, and cytoagglutinating activity by a spectrophotometric method.

RESULTS

The binding of DBA and SBA to normal lymphocytes was negligible, while their binding to leukemic cells increased markedly with increasing lectin concentration. Analogous results were obtained for WGA. However, it was found that WGA also interacted to a significant degree with normal lymphocytes. The degree of lectin-cell binding increased in the order: DBA<SBA<WGA. The cytoagglutinating activity and cytotoxicity of lectins increased in the same order. DBA did not exhibit a cytotoxic effect against normal or leukemic cells, and showed a poor cytoagglutinating activity only in MOLT-4, CCR-HSB-2 and BALL-1 cells. SBA exhibited poor cytotoxicity against Jurkat, RPMI-8402, HPB-ALL and CCR-HSB-2 cells, but a well-defined cytotoxicity against Raji and Daudi cells. SBA showed poor cytoagglutinating activity in leukemic cells. In contrast, WGA at concentrations higher than 0.05 microM showed high cytotoxicity against all leukemic cell lines tested as well as against normal lymphocytes. WGA also showed a well-expressed cytoagglutinating effect in all cell lines except normal lymphocytes. There was a moderate inverse correlation between cell viability and the velocity of cytoagglutination ( r=-0.56, P<0.001), and a good correlation between cell viability and the degree of lectin-cell binding ( r=-0.75, P<0.001). There was a low positive correlation between the velocity of cytoagglutination and the degree of lectin-cell binding ( r=0.43, P<0.001).

CONCLUSION

The results suggest that the lectins that bound most strongly to leukemic cells expressed higher cytotoxic and cytoagglutinating activities.

Interaction of soybean agglutinin with leukemic T-cells and its use for their in vitro separation from normal lymphocytes by lectin-affinity chromatography

A procedure for separation of leukemic T-cells from normal lymphocytes, using lectin-affinity column chromatography, is described. CNBr-activated Sepharose 6MB was used as a non-mobile phase. The gel was covalently coupled with soybean agglutinin (SBA), then served as an affinity probe for fractionation of mixture of normal lymphocytes and leukemic cells. Leukemic cell lines, derived from acute lymphoblastic leukemia (Jurkat, MOLT-4, RPMI-8402), were tested. The elution of normal lymphocytes was carried out by PBS(-). The leukemic T-cells, interacting with SBA, were removed by N-acetyl-D-galactosamine or low-concentration acetic acid. The type and viability of the separated cell fractions were analyzed by flow cytometry and fluorescent microscopy, using adequate fluorescent antibodies. The interaction of leukemic T-cells with free SBA, as well as with SBA-conjugated Sepharose beads, was examined fluorimetrically and visualized by fluorescent microscopy, using FITC-SBA as a marker. The rate of cell elution on SBA-affinity column decreased in order: normal > leukemic T-cells. Both normal lymphocytes and leukemic T-cells were removed in a mixture from SBA-free Sepharose 6MB by PBS(-) and were not fractionated discretely. The leukemic T-cells specifically interacted with SBA as well as with SBA-affinity adsorbent. In contrast, the normal lymphocytes did not interact with free SBA as well as with SBA-conjugated Sepharose beads in the concentrations applied. The method potentially combines a discrete cell fractionation with manifestation of a specific target cytotoxicity of SBA against leukemic T-cells, without any influence on normal lymphocytes.

Flow cytometric detection of total and serine 473 phosphorylated Akt

The evaluation of regulatory proteins is important for biological studies and is also established as a prognostic marker for cancer diagnosis. Very recently, it has been highlighted that the serine/threonine kinase Akt plays a fundamental role in survival pathways and is also involved in the onset of resistance to anti-neoplastic drugs and ionizing radiation in cell lines derived from solid tumors. For its full activation Akt needs to be phosphorylated on Serine 473 residue. Molecules that are fundamental in determining resistance to therapeutic treatments might serve in the future as clinical markers to tailor therapy and/or predict treatment response. The aim of this study was to ascertain whether or not flow cytometric analysis of total Akt and of its form phosphorylated on Serine 473 could be related to standard techniques such as Western blotting with phosphospecific antibodies and in vitro kinase assay. To this end, we employed as experimental models HL-60 and PC-12 lines in which there is an enhancement of Akt activity. Our results showed that flow cytometry analysis, performed on fixed and permeabilized cells, correlated well with the results provided by in vitro activity assays and Western blots. Therefore, our findings might indicate that flow cytometric study of Akt (both total and phosphorylated) content may be applied in routine work for phenotyping of hematological and non-hematological neoplasias, and allow for its use as a useful marker for the classification and the prognosis of neoplastic diseases.

Comparative genomic hybridization of 49 primary retinoblastoma tumors identifies chromosomal regions associated with histopathology, progression, and patient outcome

Forty-nine primary retinoblastoma (Rb) tumors were analyzed by the use of comparative genomic hybridization (CGH), and clinical/histological correlations were performed. Adverse histological factors were present in 13 patients. Chromosomal imbalance was a frequent phenomenon, seen in 96% of the tumors. Gain of 6p represented the most frequent event (69% of the tumors), whereas +1q was observed in 57%, confirming that these abnormalities are key secondary events in retinoblastoma tumor progression. Loss of 13q and 16 was significantly associated with tumors displaying adverse histo-prognostic factors, whereas -16q was significantly associated with tumors without adverse features. In three patients who developed an extra-ocular relapse, the tumors showed -13q and 2/3 had -5q, suggesting that these abnormalities may be associated with metastasis. Children >or= 36 months of age at enucleation tended to have more CGH abnormalities per tumor than children < 12 months (median numbers 11 vs. 3). In addition, +1q, +13q, -16, and -16q were more frequent in children with an older age at enucleation. Identical CGH changes were found in both tumors from one patient with bilateral tumors, suggesting a common origin. It is possible that tumors displaying loss of 13q and 5q indicate those patients who may suffer an adverse outcome and who would require alternative or more intensive therapy. CGH analysis on larger cohorts and in prospective clinical trials will be invaluable in determining whether a genetic classification of retinoblastoma represents a reliable measure of prognosis.

Cytoagglutination and cytotoxicity of Wheat Germ Agglutinin isolectins against normal lymphocytes and cultured leukemic cell lines--relationship between structure and biological activity

The relationships between degree of lectin-cell binding, cytotoxicity and cytoagglutinating activity of three Wheat Germ Agglutinin isolectins (WGA-1, WGA-2, WGA-3) against normal lymphocytes and cultured leukemic cell lines (Jurkat, MOLT-4, Raji, Daudi, K-562) were studied. All WGA-isolectins interacted in a similar degree with normal lymphocytes, while in the case of leukemic cells, the degree of isolectin-cell binding increased in the order: WGA-1< or =WGA-3<WGA-2 at isolectin concentrations 0.5 microM and higher, and WGA-3<WGA-2< or =WGA-1 at 0.25 microM isolectin concentration. The WGA interacted in higher degree with Jurkat, Raji, Daudi and K-562, followed by MOLT-4 and normal lymphocytes. The velocity of cytoagglutination in the presence of 0.25 microM WGA-isolectins increased in the order: WGA-3<WGA-2< or =WGA-1, and was better expressed in Jurkat, Raji, Daudi and K-562, followed by MOLT-4 and normal lymphocytes. The cytotoxicity of isolectins was very well expressed against Jurkat, MOLT-4, Raji and Daudi, and less expressed against K-562 and normal lymphocytes. In the case of leukemic cells, the cytotoxic effect of WGA-isolectins increased in the order: WGA-3<WGA-2=WGA-1. A very good positive correlation was determined between velocity of cytoagglutination and degree of lectin-cell binding (r=0.77, P<0.001). A good inverse correlation was found between cytotoxicity and degree of lectin-cell binding (r=-0.34, P<0.001), and poor correlation was observed between cytotoxicity and cytoagglutinating activity of WGA-isolectins (r=0.16, P<0.01). The results suggest that the WGA-isolectins, structurally distinguishable in only several amino acid sequences, interacted in different degrees with leukemic cells and manifested different cytoagglutinating and cytotoxic activity.

High level amplification of N-MYC is not associated with adverse histology or outcome in primary retinoblastoma tumours

Twenty-five primary retinoblastoma tumours were analysed by real-time quantitative polymerase chain reaction to determine the genomic copy number of the N-MYC gene (2p24) relative to the copy number for REL, B2M, ALB, AF10 and MLL. Twenty-one of these tumours were shown by Comparative Genomic Hybridization to contain variable copy number increases of chromosomal material mapping to 2p. High level amplification (>30-fold) of N-MYC was found in three tumours, none of which showed adverse histological features and all patients are surviving at between 54 and 108 months post enucleation. Furthermore, the three tumours associated with metastasis and adverse patient outcome showed normal N-MYC copy number. Although high level amplification of N-MYC is an unfavourable prognostic indicator in neuroblastoma, these data show no evidence of a correlation between amplification of N-MYC and adverse outcome in retinoblastoma.