A 'telomere-associated secretory phenotype' cooperates with BCR-ABL to drive malignant proliferation of leukemic cells

Telomere biology is frequently associated with disease evolution in human cancer and dysfunctional telomeres have been demonstrated to contribute to genetic instability. In BCR-ABL(+) chronic myeloid leukemia (CML), accelerated telomere shortening has been shown to correlate with leukemia progression, risk score and response to treatment. Here, we demonstrate that proliferation of murine CML-like bone marrow cells strongly depends on telomere maintenance. CML-like cells of telomerase knockout mice with critically short telomeres (CML-iG4) are growth retarded and proliferation is terminally stalled by a robust senescent cell cycle arrest. In sharp contrast, CML-like cells with pre-shortened, but not critically short telomere lengths (CML-G2) grew most rapidly and were found to express a specific 'telomere-associated secretory phenotype', comprising secretion of chemokines, interleukins and other growth factors, thereby potentiating oncogene-driven growth. Moreover, conditioned supernatant of CML-G2 cells markedly enhanced proliferation of CML-WT and pre-senescent CML-iG4 cells. Strikingly, a similar inflammatory mRNA expression pattern was found with disease progression from chronic phase to accelerated phase in CML patients. These findings demonstrate that telomere-induced senescence needs to be bypassed by leukemic cells in order to progress to blast crisis and provide a novel mechanism by which telomere shortening may contribute to disease evolution in CML.

Anti-tumour activity of two novel compounds in cisplatin-resistant testicular germ cell cancer

BACKGROUND

Resistance to cisplatin-based chemotherapy is associated with poor prognosis in testicular germ cell cancer, emphasising the need for new therapeutic approaches. In this respect, the therapeutic concept of anti-angiogenesis is of particular interest. In a previous study, we presented two novel anti-angiogenic compounds, HP-2 and HP-14, blocking the tyrosine kinase activity of angiogenic growth factor receptors, such as vascular endothelial growth factor receptor-2 (VEGFR-2), and related signalling pathways in testicular cancer. In this study, we investigated the efficacy of these new compounds in platinum-resistant testicular germ cell tumours (TGCTs), in vitro and in vivo.

METHODS AND RESULTS

Drug-induced changes in cell proliferation of the cisplatin-sensitive TGCT cell line 2102EP and its cisplatin-resistant counterpart 2102EP-R, both expressing the VEGFR-2, were evaluated by crystal violet staining. Both compounds inhibited the growth of cisplatin-resistant TGCT cells in a dose-dependent manner. In combination experiments with cisplatin, HP-14 revealed additive growth-inhibitory effects in TGCT cells, irrespective of the level of cisplatin resistance. Anti-angiogenic effects of HP compounds were confirmed by tube formation assays with freshly isolated human umbilical vein endothelial cells. Using TGCT cells inoculated onto the chorioallantoic membrane of fertilised chicken eggs (chicken chorioallantoic membrane assay), the anti-angiogenic and anti-proliferative potency of the novel compounds was also demonstrated in vivo. Gene expression profiling revealed changes in the expression pattern of genes related to DNA damage detection and repair, as well as in chaperone function after treatment with both cisplatin and HP-14, alone or in combination. This suggests that HP-14 can revert the lost effectiveness of cisplatin in the resistant cells by altering the expression of critical genes.

CONCLUSION

The novel compound HP-14 effectively inhibits the growth of cisplatin-resistant TGCT cells and suppresses tumour angiogenesis. Thus, HP-14 may be an interesting new agent that should be further explored for TGCT treatment, especially in TGCTs that are resistant to cisplatin.

Skeletal spread of an anaplastic astrocytoma (WHO grade III) and preservation of histopathological properties within metastases

BACKGROUND

The incidence of extraneural metastases of glioma is low. Metastases occur at different sites and, infrequently, as diffuse bone marrow infiltration. Direct contact of a glioma with extrameningeal tissues might be a reason for extraneural metastases. However, the role of haematogenous spread remains unclear.

METHODS

We report on a young patient who suffered from a left frontal anaplastic WHO grade III astrocytoma, which was treated with gross total resection and irradiation (60 Gy). No local relapse occurred during the following course, but a diffuse infiltration of the bone marrow was diagnosed 12 months after the initial diagnosis. The patient died 6 months later, as a result of hypercalcaemia and pancytopenia. The histopathological properties of the tumour and its bone metastases were analysed, as well as the mutations of the isocitrate dehydrogenase 1 gene (IDH1). To study the route of tumour dissemination, the peripheral blood of the patient was analysed for circulating tumour cells (CTCs).

RESULTS

This study describes a rare case of an extraneurally metastasised WHO grade III anaplastic astrocytoma. The occurrence of bone marrow infiltration coinciding with the finding of a stable intracranial tumour is a notably unusual situation. The properties of the primary tumour were maintained within the metastases in our patient. No CTCs were found in the peripheral blood at one random time point after the diagnosis of bone metastases.

CONCLUSIONS

Despite young patient age, a stable intracranial course with a single location and mutations in the IDH1 gene, the patient's overall survival was short at 18 months after diagnosis. This finding illustrates the therapeutic dilemma in patients with bone marrow involvement complicating the use of alkylating agents, such as temozolomide. Repeated and systematic blood sampling in a large cohort of patients is needed for the detection of CTCs in glioma patients with systemic tumour spread. Future studies investigating how intrinsic factors in glioma cell biology cause rare metastases in these tumours are needed.

Telomere length analysis in monocytes and lymphocytes from patients with systemic lupus erythematosus using multi-color flow-FISH

In order to analyse telomere length in subsets of human peripheral blood lymphocytes and monocytes, we modified a recently developed multicolor flow- fluorescent in situ hybridization (FISH) methodology that combines flow-FISH and antibody staining for cell surface antigens. We analysed telomere length of peripheral blood mononuclear cells in a group of 22 patients with systemic lupus erythematosus (SLE) and 20 age-matched healthy donors. We found that neither CD4+, CD8+, CD19+ cells nor CD14+ monocytes have significantly shorter telomeres compared with their healthy counterparts. On the basis of these findings, we then used monocyte telomere length as internal reference in order to control for intra-individual variability in telomere length. By using this approach, we could demonstrate significant telomere shortening in all three lymphocyte subsets (in all cases P < 0.05) compared with monocytes. However, these differences did not vary significantly between SLE patients and controls. In summary, telomere lengths in subpopulations of hematopoietic cells can be monitored in patients with SLE using multicolor flow-FISH. While confirming data by other groups on telomere length in lymphocyte subpopulations, our data argue against an increased proliferation rate of peripheral blood monocytes reflected by accelerated telomere shortening in patients with SLE.

Global proteome analysis of germ cell tumor (GCT) cell lines under treatment with cisplatin (CDDP)

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Background: GCTs are the most common malignancy in young Caucasian males aged 20–40. With CDDP-based chemotherapy, highly effective treatment has been developed for the majority of patients with GCT. However, the molecular mechanisms underlying treatment response remain elusive. Therefore, we used a global proteomics approach to screen for changes induced in GCT cell lines by CDDP. Material and Methods: Global protein expression analysis of three GCT cell lines, NTERA2, 2102EP, and NCCIT, both untreated and treated with CDDP for 48 hours at the IC50, was performed using 2-dimensional gel electrophoresis. Differentially expressed proteins were analyzed using matrix-assisted laser desorption/ionization - time of flight (MALDI TOF) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Identification of proteins was performed using peptide mass-fingerprinting and NCBI/SwissProt and The Global Proteome Machine database search. Results: In total, 66 proteins were found to be differentially expressed comparing untreated and treated cells. Numbers of proteins showing upregulation under CDDP were 18 in NTERA2, 10 in NCCIT, and 9 in 2102EP, whereas 17 proteins were downregulated in NTERA2, 5 in NCCIT, and 7 in 2102EP. Identification of corresponding proteins was successful in 44 out of 66 spots (67%). Differential expression of 5 proteins was found in more than one cell line. One protein (Enolase 1) was consistently up-regulated in all three cell lines under CDDP. The identified proteins can be grouped into different categories: 15 are involved in DNA-binding/transcription, 8 in metabolism, 8 in protein folding/binding/chaperone, 6 in cell signaling/differentiation, 4 in apoptosis, and 3 in cytoskeleton/cell movement. Conclusion: The results of this screening approach identify factors differentially regulated during response to CDDP in GCTs, and reveal a specific response pattern for each cell line. This knowledge can help to identify therapeutic targets and factors potentially involved in treatment sensitivity and resistance.

No significant financial relationships to disclose.

Telomere length dynamics in normal hematopoiesis and in disease states characterized by increased stem cell turnover

Telomeres both reflect and limit the replicative lifespan of normal somatic cells. Immature sub-populations of human CD34+38- hematopoietic stem cell (HSC) can be identified in vitro based on their growth kinetics and telomere length. Fluorescence in situ hybridization and flow cytometry (flow-FISH) has been used to characterize telomere length dynamics as a surrogate marker for HSC turnover in vivo. Investigations in normal steady-state hematopoiesis provided the basis for follow-up studies in model scenarios characterized by increased HSC turnover. Disorders with underlying malignant transformation of HSC (e.g., chronic myeloid leukemia (CML)) can be discriminated from disease states with increased HSC turnover rates secondary to depletion of the stem cell compartment, for example, as in defined bone marrow failure syndromes. In some of these model scenarios, the degree of telomere shortening can be correlated with disease duration, disease stage and severity as well as with response to disease-modifying treatment strategies. Whether increased telomere shortening represents a causal link between HSC turnover, replicative senescence and/or the induction of genetic instability in acquired HSC disorders remains to be shown. However, data from congenital disorders, like dyskeratosis congenita (DKC), suggest that disturbed telomere maintenance may play a role for replicative exhaustion of the HSC pool in vivo.

Comparative proteome analysis of gonadal and extragonadal germ cell tumors

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Background: Germ cell tumors (GCTs) are the most common malignancy in young Caucasian males aged 20–40. Even though highly effective treatment strategies have been developed for the majority of patients (pts) with GCT, long term survival rate in pts with primary mediastinal non-seminomas nowadays remains below 50%. The molecular mechanism underlying the increased resistance to treatment remains elusive. Therefore, a systematic approach of global proteome analysis was used as a screening tool to compare GCT cell lines of gonadal and extragonadal origin. Methods: Comparative protein expression analysis of two GCT cell lines, NTERA2 (of gonadal origin) and NCCIT (of mediastinal origin) was performed using 2-dimensional gelelectrophoresis. Differentially expressed proteins were analyzed using matrix-assisted laser desorption/ionization - time of flight mass spectrometry (MALDI-TOF). Identification of proteins was performed using peptide mass-fingerprinting and NCBI/SwissProt database search. Results: On average, 761 spots on each gel were detected. Of these, 66 proteins were found to be differentially expressed in an at least in 2-fold manner. Expression of 47 proteins was found to be higher in NCCIT than in NTERA2, 19 proteins showed lower expression in NCCIT than in NTERA2. All 66 spots were analyzed, and 35 (51%) proteins were positively identified by peptid mass fingerprinting and database search. These proteins could be grouped into different categories: 9 are involved in metabolism, 5 each in protein folding and DNA-binding/transcription, 4 in cytoskeleton/cell movement, 3 in cell signaling/differentiation, and 1 each in ion transport and membrane/vesicle trafficking. Of 7 proteins, the function is currently unknown. Conclusions: This analysis demonstrates that proteomic tools are valuable in studying similarities and differences between gonadal and primary extragonadal GCTs. Further characterization and functional analysis of selected proteins is ongoing, with special emphasis on factors potentially involved in treatment resistance and sensitivity. Furthermore, the acquired proteome map of untreated cells will help to identify cellular changes occuring under different experimental conditions in vitro like induction of differentiation and response to cytotoxic treatment.

No significant financial relationships to disclose.

Tumour-related enzyme alterations in the clear cell type of human renal cell carcinoma identified by two-dimensional gel electrophoresis

To identify tumour-related enzyme alterations we have used 2D-gels to analyse the proteome from dissected malignant and benign kidney areas from patients with clear-cell-type renal carcinoma. The expression of 12 proteins was diminished in tumour. Four proteins were characterized by mass spectrometry and were identified as enoyl-CoA hydratase, alpha-glycerol-3-phosphate dehydrogenase, aldehyde dehydrogenase 1 and aminoacylase-I.

Differential expression of the subunits of the glucose-6-phosphatase system in the clear cell type of human renal cell carcinoma - no evidence for an overexpression of protein kinase B

The expression of two components of the glucose-6-phosphatase system, the catalytic subunit (G6PaseC) and the glucose-6-phosphate transporter, was analyzed in the clear cell type of human renal cell carcinoma. The expression of G6PaseC was decreased in tumours compared with non-tumourous tissue of the same patient. The expression of G6PaseT varied with no general trend between tumours and control tissue. The expression of protein kinase B (PKB) was unchanged in the tumours, suggesting that the down-regulation of G6PaseC in clear cells and the maintenance of the transformed phenotype are not predominantly caused by an overexpression of PKB.

Immunoreactive parathyroid hormone, calcium, and magnesium in human cerebrospinal fluid

Parathyroid hormone (PTH) was measured radioimmunologically in simultaneous plasma and cerebrospinal fluid (CSF) samples obtained from 72 patients aged 20 to 80 years without endocrine or psychiatric diseases and from 2 patients aged 40 and 70 years with secondary hyperparathyroidism due to renal insufficiency. They underwent routine diagnostic lumbar puncture because of suspected prolapse of a disc. Total calcium (Ca) and magnesium (Mg) were also determined in these samples by complexometry . The following findings were obtained (ng/ml, median, range in brackets): Plasma PTH 1.7 (0.7-6.6); CSF PTH 0.8 (0.5-2.3), respectively. No correlation was found between PTH concentrations in plasma and CSF in all 74 samples. The Ca concentrations in plasma, with a median of 2.3 mmol/l (2.1-2.6) were significantly higher than the Ca concentrations in CSF (median 1.1 mmol/l, range 0.4-1.3). The correlation between PTH and calcium levels in CSF was only weak (r = 0.284 P less than 0.05). The Mg levels in CSF (median 1.1 mmol/l, range 0.7-1.6) were higher than Mg concentrations in plasma (median 0.9 mmol/l, range 0.6-1.1). No correlation was found between PTH and Mg in CSF. Our study demonstrated that in man PTH is a normal constituent of CSF.