Cross-syndrome: myasthenia gravis and the demyelinating diseases of the central nervous system combination. Systematic literature review and case reports.

Nowadays the problem of comorbidity is still relevant. In this review, we describe clinical cases of the disease of the neuromuscular junction (myasthenia gravis (MG) generalized form) and the demyelinating disease of the central nervous system (DD CNS) (multiple sclerosis, neuromyelitis optica spectrum disorder (NMOSD), etc.) combinations registered in our practice with precise pathogenetic analysis. Although the number of the described associations is growing every year, the exact development mechanisms of this cross syndrome as well as the nature of the association between the discussed autoimmune diseases remain unknown. At the beginning of both disorders there is a considerable loss of auto tolerance of the immune system and, as a result, an increased response from autoreactive T-lymphocytes to the structures of the nervous system: brain cells and neuromuscular synapses. There are three main theories for comorbidity: initial predisposition, direct case relationship with disease-modifying therapy (DMT) application, and coincidence. It is known that early diagnostics of MG and timely administration of necessary adequate treatment reduce the risk of process generalization and lead to a decline in mortality. Therefore, the offer to examine MS patients with atypical symptoms for possible MG identification seems very rational. Similarly, MG patients having uncharacteristic symptoms that can be indicative of other autoimmune nervous system diseases also demand special diagnostics. Considering the presence of similar pathogenetic links, several authors propose a possibility of a new nosological unit establishment, including described comorbidity.

Aberrant Splicing of INS Impairs Beta-Cell Differentiation and Proliferation by ER Stress in the Isogenic iPSC Model of Neonatal Diabetes.

One of the causes of diabetes in infants is the defect of the insulin gene (INS). Gene mutations can lead to proinsulin misfolding, an increased endoplasmic reticulum (ER) stress and possible beta-cell apoptosis. In humans, the mechanisms underlying beta-cell failure remain unclear. We generated induced pluripotent stem cells (iPSCs) from a patient diagnosed with neonatal diabetes mellitus carrying the INS mutation in the 2nd intron (c.188-31G>A) and engineered isogenic CRISPR/Cas9 mutation-corrected cell lines. Differentiation into beta-like cells demonstrated that mutation led to the emergence of an ectopic splice site within the INS and appearance of the abnormal RNA transcript. Isogenic iPSC lines differentiated into beta-like cells showed a clear difference in formation of organoids at pancreatic progenitor stage of differentiation. Moreover, MIN6 insulinoma cell line expressing mutated cDNA demonstrated significant decrease in proliferation capacity and activation of ER stress and unfolded protein response (UPR)-associated genes. These findings shed light on the mechanism underlying the pathogenesis of monogenic diabetes.

T-Cell Heterogeneity in Baseline Tumor Samples: Implications for Early Clinical Trial Design and Analysis.

Background: In early stage clinical trials, changes to levels of tumor infiltrating lymphocytes (TILs) in the tumor microenvironment (TME) are critical biomarkers of the mechanism of action of novel immunotherapies. However, baseline heterogeneity of tumor samples, both between and within patients, and the resultant impact on the validity of clinical trial data is not well defined. Here we identify and quantify the impact of baseline variables on the heterogeneity of FoxP3+ and proliferating CD8+ T-cells levels (MKi67+CD8A+) in the TME both between and within patients for the purpose of informing clinical trial design and analysis. Methods: We compared levels of FoxP3+ and MKi67+CD8+ cell densities (counts/mm2) from >1000 baseline tumor samples from clinical trials and commercially available sources. Using multivariate hierarchical regression techniques, we investigated whether inter-person heterogeneity of activated or regulatory T-cells could be attributed to baseline characteristics including demographics, indication, lesion type, tissue of excision, biopsy method, prior cancer treatment, and tissue type i.e., "fresh" or "archival" status. We also sought to characterize within-patient heterogeneity by lesion type and tissue type. Results: Prior cancer treatment with hormone therapy or chemotherapy that induces immunogenic cell death may alter the TME. Archival tissue is an unreliable substitute for fresh tissue for determining baseline TIL levels. Baseline and on treatment biopsies should be matched by lesion type to avoid bias.

Additive effect of frequent polymorphism and rare synonymous variant alters splicing in twin patients with Niemann-Pick disease type C.

Niemann-Pick disease type C (NP-C) (OMIM#257220) is a rare lysosomal storage disorder caused by pathogenic variants in either the NPC1 or NPC2 genes. It manifests with a wide spectrum of clinical symptoms and variable age of onset. We studied the impact of the frequent polymorphic variant c.2793 C > T (p.Asn931 = ), located in the donor splice site (SS) of NPC1 exon 18 on the penetrance of the rare synonymous variant c.2727 C > T (p.Cys909 = ), identified in two 55 y.o. twins with an adult onset form of NP-C. The patients' diagnosis was supported by biochemical analysis and positive filipin test. Analysis of the patients' cDNA showed that the c.2727 C > T variant leads to cryptic donor SS activation and frameshift deletion in the NPC1 exon 18. However, the minigene assay demonstrated that this exon shortening takes place only in the presence of the frequent polymorphic variant c.2793 C > T. Results of the transcript specific qPCR showed that only the presence in the NPC1 exon 18 of both variants leads to significant decrease of wild type (WT) transcript isoform.

In vivo profiling reveals immunomodulatory effects of sorafenib and dacarbazine on melanoma.

Sorafenib is a multi-kinase inhibitor used alone or in combination with dacarbazine to treat metastasized melanoma. Our study investigated the relationship between metabolic response assessed by PET-CT and global transcriptome changes during sorafenib and dacarbazine therapy in patients with advanced melanoma. We conducted an open-label, investigator-initiated study that enrolled 13 sorafenib-naïve Stage IV melanoma patients, whose metastases were accessible for repeated biopsies. Treatment regimen included orally administered sorafenib and intravenous dacarbazine. Biopsies of skin or superficial lymph node metastases were taken before treatment (baseline), during sorafenib and after dacarbazine therapy and used for transcriptional profiling and validation experiments. Serum samples were evaluated for cytokine production. Metabolic response to therapy was observed in 45.5% of patients. The study drugs were well tolerated. We observed a clear upregulation of interferon (IFN)-stimulated immune response genes in profiled metastases. The IFNγ-induced gene signature seemed to be enhanced after addition of dacarbazine to sorafenib. Serum IFNγ also increased during therapy, particularly after addition of dacarbazine. Induction of IFNγ stimulated genes correlating with increased serum IFNγ was predictive of better clinical outcome and responders who had significantly higher serum IFNγ levels lived longer. Our data reveal in situ changes in melanoma metastases during treatment with sorafenib and dacarbazine and suggest an additional mechanism of action through immunomodulation.

Methionine to isothreonine conversion as a source of false discovery identifications of genetically encoded variants in proteogenomics.

Searching deep proteome data for 9 NCI-60 cancer cell lines obtained earlier by Moghaddas Gholami et al. (Cell Reports, 2013) against a database from cancer genomes returned a variant tryptic peptide fragment 57-72 of molecular chaperone HSC70, in which methionine residue at 61 position is replaced by threonine, or isothreonine (homoserine), residue. However, no traces of the corresponding genetic alteration were found in the cell line genomes reported by Abaan et al. (Cancer Research, 2013). Studying on the background of this modification led us to conclude that a conversion of methionine into isothreonine resulted from iodoacetamide treatment of the probe during a sample preparation step. We found that up to 10% of methionine containing peptides experienced the above conversion for the datasets under study. The artifact was confirmed by model experiment with bovine albumin, where three of four methionine residues were partly converted to isothreonine by conventional iodoacetamide treatment. This experimental side reaction has to be taken into account when searching for genetically encoded peptide variants in the proteogenomics studies. BIOLOGICAL SIGNIFICANCE: A lot of effort is currently put into proteogenomics of cancer. Studies detect non-synonymous cancer mutations at protein level by search of high-throughput LC-MS/MS data against customized genomic databases. In such studies, much attention is paid to potential false positive identifications. Here we describe one possible cause of such false identifications, an artifact of sample preparation which mimics methionine to threonine nucleic acid-encoded variant. The methionine to isothreonine conversion should be taken into consideration for correct interpretation of proteogenomic data.

Exome-driven characterization of the cancer cell lines at the proteome level: the NCI-60 case study.

Cancer genome deviates significantly from the reference human genome, and thus a search against standard genome databases in cancer cell proteomics fails to identify cancer-specific protein variants. The goal of this Article is to combine high-throughput exome data [Abaan et al. Cancer Res. 2013] and shotgun proteomics analysis [Modhaddas Gholami et al. Cell Rep. 2013] for cancer cell lines from NCI-60 panel to demonstrate further that the cell lines can be effectively recognized using identified variant peptides. To achieve this goal, we generated a database containing mutant protein sequences of NCI-60 panel of cell lines. The proteome data were searched using Mascot and X!Tandem search engines against databases of both reference and mutant protein sequences. The identification quality was further controlled by calculating a fraction of variant peptides encoded by the own exome sequence for each cell line. We found that up to 92.2% peptides identified by both search engines are encoded by the own exome. Further, we used the identified variant peptides for cell line recognition. The results of the study demonstrate that proteome data supported by exome sequence information can be effectively used for distinguishing between different types of cancer cell lines.

Coexpression of SOX10/CD271 (p75(NTR)) and ß-Galactosidase in Large to Giant Congenital Melanocytic Nevi of Pediatric Patients.

BACKGROUND: Congenital melanocytic nevi (CMNs) are melanocytic neoplasms that can transform into melanoma. However, this development is impeded in the majority of cases and mostly affects patients with large or giant CMNs. METHODS: To elucidate mechanisms that keep CMNs from malignant transformation, CMN tissue biopsies were investigated for p-ERK and senescence markers by immunohistochemistry and for SOX10/CD271 (p75(NTR)) by immunofluorescence. CMN cells were cultivated, and MTT assays were performed for evaluating cell viability. Mutation status for NRAS and BRAF was performed by real-time PCR. RESULTS: 13 CMNs (from patients aged 0.5-11.8 years, mean: 2.7) showed immunoreactivity for SOX10/CD271 (p75(NTR)) in 34.2%. p-ERK was immunoreactive in 80% (4/5); ß-galactosidase was significantly stronger expressed in CMNs compared to melanocytic nevi of patients over 70 years (p = 0.0085). The 5 CMN cultures were immunoreactive for SOX10/CD271 (p75(NTR)) in 36.7%. By silencing SOX10 by siRNA in 2 CMN cell cultures, cell viability decreased significantly. NRAS(Q61K) mutation was found in 91.7% (11/12) and BRAF(V600E) in 6.3% of all analyzable CMNs (1/16). CONCLUSIONS: Oncogene-induced senescence might prevent malignant transformation through activation of the mitogen-activated protein kinase pathway. SOX10 is necessary for the viability of human CMN cell cultures and may be responsible for clinical changes during aging.

Complete absence of the αGal xenoantigen and isoglobotrihexosylceramide in α1,3galactosyltransferase knock-out pigs.

BACKGROUND: Anti-Galα1,3Galß-R natural antibodies are responsible for hyperacute rejection in pig-to-primate xenotransplantation. Although the generation of pigs lacking the α1,3galactosyltransferase (GalT) has overcome hyperacute rejection, antibody-mediated rejection is still a problem. It is possible that other enzymes synthesize antigens similar to Galα1,3Gal epitopes that are recognized by xenoreactive antibodies. The glycosphingolipid isoglobotrihexosylceramide (iGb3) represents such a candidate expressing an alternative Galα1,3Gal epitope. The present work determined whether the terminal Galα1,3Gal disaccharide is completely absent in Immerge pigs lacking the GalT using several different highly sensitive methods. METHODS: The expression of Galα1,3Gal was evaluated using a panel of antibodies and lectins by flow cytometry and fluorescent microscopy; GalT activity was detected by an enzymatic assay; and ion trap mass spectroscopy of neutral cellular membranes extracted from aortic endothelial was used for the detection of sugar structures. Finally, the presence of iGb3 synthase mRNA was tested by RT-PCR in pig thymus, spleen, lymph node, kidney, lung, and liver tissue samples. RESULTS: Aortic endothelial cells derived from GalT knockout pigs expressed neither Galα1,3Gal nor iGb3 on their surface, and GalT enzymatic activity was also absent. Lectin staining showed an increase in the blood group H-type sugar structures present in GalT knockout cells as compared to wild-type pig aortic endothelial cells (PAEC). Mass spectroscopic analysis did not reveal Galα1,3Gal in membranes of GalT knockout PAEC; iGb3 was also totally absent, whereas a fucosylated form of iGb3 was detected at low levels in both pig aortic endothelial cell extracts. Isoglobotrihexosylceramide 3 synthase mRNA was expressed in all pig tissues tested whether derived from wild-type or GalT knockout animals. CONCLUSIONS: These results confirm unequivocally the absence of terminal Galα1,3Gal disaccharides in GalT knockout endothelial cells. Future work will have to focus on other mechanisms responsible for xenograft rejection, in particular non-Galα1,3Gal antibodies and cellular responses.

Sorafenib in melanoma.

INTRODUCTION: Sorafenib is an orally available multi-kinase inhibitor that inhibits tumor proliferation by targeting multiple kinases including the vascular endothelial growth factor receptors VEGFR1, VEGFR2, VEGFR3 and the platelet-derived growth factor receptor PDGFR, and it targets tumor progression by inhibiting FLT3, C-Kit and BRAF. Since BRAF mutations are frequent in melanoma, sorafenib was investigated in various Phase I, II and III clinical trials. The drug is well tolerated with mild to moderate adverse effects, which are mostly limited to cutaneous toxicity, diarrhea and fatigue. AREAS COVERED: Systematic literature review of the randomized trials using PubMed was performed. Original articles were reviewed and citations from those were also considered. Additionally, clinical trial databases were examined to identify and summarize ongoing trials of sorafenib in melanoma patients. EXPERT OPINION: Sorafenib as a monotherapy or in combination with chemotherapy is of limited use. Combining it with dacarbazine doubled the response rate and the progression-free survival in metastatic melanoma patients. Unfortunately, these results have never been evaluated in large randomized Phase III clinical trials. According to the trials conducted so far a subpopulation of patients experience substantial benefit, therefore it is essential to identify biomarkers to select the subgroups of patients that are more likely to respond to sorafenib. Furthermore, other less frequent subtypes such as mucosal or ocular melanoma still constitute promising targets; academic institutions are currently launching investigator-initiated trials in these indications.

Cutaneous lymphomas: molecular pathways leading to new drugs.

Currently, cutaneous lymphomas represent a paradigm for the heterogeneity and the dynamic variability of neoplastic disorders resulting in the accumulation of clonal lymphocytes in the skin, and thus mirror the complexity of lymphocytic populations. Increasing knowledge and insight in pathobiology offer new opportunities for targeted interventions to selectively hit the tumor populations. mAbs, rexinoids, small kinase inhibitors, or molecules interfering with methylation or histone acetylation contribute to disease control. The rational and well-coordinated application of these tools, together with improved chemotherapeutic options, will hopefully further improve treatment success in the near future.

Characterization of the DNA copy-number genome in the blood of cutaneous T-cell lymphoma patients.

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous non-Hodgkin's lymphoma that may variably involve the skin, lymph nodes, and peripheral blood. Malignant burden ranges from cutaneous patches and plaques with little evidence of blood involvement to erythroderma often in association with frank leukemia, as in Sézary syndrome. Toward a better understanding of the pathogenesis of this CD4+ T-cell malignancy, we conducted a high-resolution genomic analysis combining DNA (23 samples) and mRNA (12 samples) data of peripheral blood isolates from CTCL patients across a spectrum of stages. Strikingly, even patients with limited involvement, e.g., normal CD4 counts, contained significant copy-number alterations. Defining genomic characteristics of CTCL blood involvement included gains on 8q and 17q, and deletions on 17p and chromosome 10. A consensus analysis of 108 leukemic CTCL samples demonstrated global similarities among patients with varied blood involvement, narrowing 38 of 62 loci. Toward an annotated framework for in vitro testing, we also characterized genomic alterations in five CTCL cell lines (HH, HUT78, PNO, SeAx, and Sez4), revealing intact core features of leukemic CTCL. Together, these studies produce the most comprehensive view of the leukemic CTCL genome to date, with implications for pathogenesis, molecular classification, and potential future therapeutic developments.

Proteome and cytokine serum profiling to diagnose a mycosis fungoides.

PURPOSE: The aim of this study was to estimate a possibility of mycosis fungoides (MF) diagnostics based on protein profiling in blood serum. EXPERIMENTAL DESIGN: We obtained and analysed samples of blood serum from 23 patients with MF, and 29 psoriasis patients and 22 healthy donors as controls. Protein profiling was carried out using SELDI TOF MS SELDI-TOF and also profiling of 27 cytokines with multiplex immunoassay technology was implemented. RESULTS: MS data analysis of sera did not give satisfactory statistical discrimination between the groups. Antibody-based cytokine profiling revealed a number of cytokines with a change in their concentrations in both MF and psoriasis (IL-1Ra, IL-4, G-CSF). The C-X-C motif chemokine 10 (IP-10, CXCL10) cytokine had a significantly increased concentration (p<0,001) in samples from MF patients as compared with the other groups. CONCLUSIONS AND CLINICAL RELEVANCE: IP-10 may be considered as a promising biomarker for the differentiation between MF and other skin conditions.

High-throughput mutation profiling of CTCL samples reveals KRAS and NRAS mutations sensitizing tumors toward inhibition of the RAS/RAF/MEK signaling cascade.

Cutaneous T-cell lymphomas (CTCLs) are malignancies of skin-homing lymphoid cells, which have so far not been investigated thoroughly for common oncogenic mutations. We screened 90 biopsy specimens from CTCL patients (41 mycosis fungoides, 36 Sézary syndrome, and 13 non-mycosis fungoides/Sézary syndrome CTCL) for somatic mutations using OncoMap technology. We detected oncogenic mutations for the RAS pathway in 4 of 90 samples. One mycosis fungoides and one pleomorphic CTCL harbored a KRAS(G13D) mutation; one Sézary syndrome and one CD30(+) CTCL harbored a NRAS(Q61K) amino acid change. All mutations were found in stage IV patients (4 of 42) who showed significantly decreased overall survival compared with stage IV patients without mutations (P = .04). In addition, we detected a NRAS(Q61K) mutation in the CTCL cell line Hut78. Knockdown of NRAS by siRNA induced apoptosis in mutant Hut78 cells but not in CTCL cell lines lacking RAS mutations. The NRAS(Q61K) mutation sensitized Hut78 cells toward growth inhibition by the MEK inhibitors U0126, AZD6244, and PD0325901. Furthermore, we found that MEK inhibitors exclusively induce apoptosis in Hut78 cells. Taken together, we conclude that RAS mutations are rare events at a late stage of CTCL, and our preclinical results suggest that such late-stage patients profit from MEK inhibitors.

Evaluation of lymphangiogenic markers in Sézary syndrome.

Sézary syndrome (SS) is regarded as a leukemic, aggressive subtype of cutaneous T-cell lymphoma (CTCL) characterized by the accumulation of malignant T-cells in the skin, as well as by blood and lymph node involvement. To date there have been no data on the extent of lymphangiogenesis in SS or erythrodermic mycosis fungoides (eMF). Lymphangiogenesis represents the de novo formation of lymphatic vasculature and has been associated with the occurrence of metastatic disease and poor prognosis. In this study we investigated lymphangiogenesis in skin biopsies from patients with SS and eMF. The expression of VEGFR-3 was significantly higher in patients with SS (p = 0.0285) as compared to patients with eMF. LYVE-1, podoplanin (PDPN), and VEGF-C stainings showed a similar tendency. The number of PDPN-expressing lymphatic vessels (p = 0.025) as well as CD31-positive blood vessels (p = 0.0065) correlated with disease progression in patients with SS. We show for the first time a non-vascular pattern of VEGF-C and VEGFR-3, i.e. their epidermal expression in erythrodermic CTCLs, suggesting their role in lymphocyte trafficking to the skin.

Oligonucleotide array-CGH identifies genomic subgroups and prognostic markers for tumor stage mycosis fungoides.

Mycosis fungoide (MF) patients who develop tumors or extracutaneous involvement usually have a poor prognosis with no curative therapy available so far. In the present European Organization for Research and Treatment of Cancer (EORTC) multicenter study, the genomic profile of 41 skin biopsies from tumor stage MF (MFt) was analyzed using a high-resolution oligo-array comparative genomic hybridization platform. Seventy-six percent of cases showed genomic aberrations. The most common imbalances were gains of 7q33.3q35 followed by 17q21.1, 8q24.21, 9q34qter, and 10p14 and losses of 9p21.3 followed by 9q31.2, 17p13.1, 13q14.11, 6q21.3, 10p11.22, 16q23.2, and 16q24.3. Three specific chromosomal regions, 9p21.3, 8q24.21, and 10q26qter, were defined as prognostic markers showing a significant correlation with overall survival (OS) (P=0.042, 0.017, and 0.022, respectively). Moreover, we have established two MFt genomic subgroups distinguishing a stable group (0-5 DNA aberrations) and an unstable group (>5 DNA aberrations), showing that the genomic unstable group had a shorter OS (P=0.05). We therefore conclude that specific chromosomal abnormalities, such as gains of 8q24.21 (MYC) and losses of 9p21.3 (CDKN2A, CDKN2B, and MTAP) and 10q26qter (MGMT and EBF3) may have an important role in prognosis. In addition, we describe the MFt genomic instability profile, which, to our knowledge, has not been reported earlier.

MEK1 mutations confer resistance to MEK and B-RAF inhibition.

Genetic alterations that activate the mitogen-activated protein kinase (MAP kinase) pathway occur commonly in cancer. For example, the majority of melanomas harbor mutations in the BRAF oncogene, which are predicted to confer enhanced sensitivity to pharmacologic MAP kinase inhibition (e.g., RAF or MEK inhibitors). We investigated the clinical relevance of MEK dependency in melanoma by massively parallel sequencing of resistant clones generated from a MEK1 random mutagenesis screen in vitro, as well as tumors obtained from relapsed patients following treatment with AZD6244, an allosteric MEK inhibitor. Most mutations conferring resistance to MEK inhibition in vitro populated the allosteric drug binding pocket or alpha-helix C and showed robust ( approximately 100-fold) resistance to allosteric MEK inhibition. Other mutations affected MEK1 codons located within or abutting the N-terminal negative regulatory helix (helix A), which also undergo gain-of-function germline mutations in cardio-facio-cutaneous (CFC) syndrome. One such mutation, MEK1(P124L), was identified in a resistant metastatic focus that emerged in a melanoma patient treated with AZD6244. Both MEK1(P124L) and MEK1(Q56P), which disrupts helix A, conferred cross-resistance to PLX4720, a selective B-RAF inhibitor. However, exposing BRAF-mutant melanoma cells to AZD6244 and PLX4720 in combination prevented emergence of resistant clones. These results affirm the importance of MEK dependency in BRAF-mutant melanoma and suggest novel mechanisms of resistance to MEK and B-RAF inhibitors that may have important clinical implications.

Proteomic analysis of serum in patients with non-alcoholic steatohepatitis using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

OBJECTIVE: We sought to investigate whether serum proteomic pattern analysis obtained using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF-MS) may help to diagnose non-alcoholic steatohepatitis (NASH) in the setting of non-alcoholic fatty liver disease (NAFLD). MATERIAL AND METHODS: We enrolled 80 patients with biopsy-proven NAFLD and 19 healthy comparison subjects. Patients with NAFLD were classified according to their liver histology as having definite NASH (n = 48), borderline NASH (n = 22) or simple steatosis (n = 10). Liver ultrasound scanning was performed to assess the degree of steatosis. Mass spectra of serum samples were obtained using a Ultraflex II mass spectrometer. RESULTS: The highest accuracy for NASH diagnostics was reached using 15 peaks. Corresponding sensitivity and specificity values were 73.95% +/- 3.38% and 88.71% +/- 1.39%, respectively. However, mass spectra did not allow us to distinguish NASH from simple steatosis. CONCLUSIONS: We conclude that proteomic analyses of serum samples from NAFLD patients by MALDI TOF-MS do not seem to have a major clinical value for diagnosing NASH. However, the identification of 15 peaks in our study may help to further elucidate the pathophysiology of NASH and merits further investigation.

Combined spectral karyotyping, comparative genomic hybridization, and in vitro apoptyping of a panel of Burkitt's lymphoma-derived B cell lines reveals an unexpected complexity of chromosomal aberrations and a recurrence of specific abnormalities in chemoresistant cell lines.

The comprehensive cytogenetic profiles of a panel of 10 Burkitt's lymphoma (BL)-derived B cell lines, designated Akata, BL-28, BL-41, Daudi, DG-75, Mutu I, Mutu III, Namalwa, Rael, and Ramos, respectively, are reported herein. The unique origin of each cell line was established using multiplex quantitative fluorescence polymerase chain reaction (QF-PCR). Spectral karyotyping (SKY) revealed a large number of structural and numerical chromosomal aberrations, many of which had not been previously identified or resolved by conventional G-banding techniques. Notably, whereas all 10 cell lines harbored the hallmark translocation t(8;14)(q24;q32), no other common structural aberrations were identified, although translocations involving chromosomes 3, 13, and 17 were frequently seen. Moreover, analysis of chromosomal breakpoints by comparative genomic hybridization (CGH) revealed a number of recurring aberrations, such as gain of chromosomes 7 and 20, gains of regions at 2p, 3q, 13q and 16q, and losses at 3p, 4q and 17p. In addition, apoptyping (i.e. determination of in vitro responses to apoptosis stimulation) of the cell lines suggested specific association patterns between karyotypic changes (e.g. translocations involving 17p, and gains of portions of chromosomes 7 and 20) and resistance to the chemotherapeutic agent, etoposide. The current molecular cytogenetic characterization of 10 BL cell lines has thus identified several novel sites of rearrangements; moreover, the combined karyotyping and functional assessment (apoptyping) of these cell lines serves to enhance their utility in future studies aimed at gene discovery and gene function.