P727Metabolic and functional differences between male and female endothelial cells from umbilical cords (HUVEC) of twin pairs

Background

Personalised Medicine is one of the hallmarks of future medicine. Sex and gender differences exist in the incidence, clinical manifestation and outcome of cardiovascular diseases. Gonadal hormones are thought to account for most of these sex differences. However, besides hormones, sexual dimorphisms at the cellular level may also contribute to physiological and pathophysiological cardiovascular differences between women and men.

Purpose

To analyse intrinsic sex differences at the cellular level, we aimed to elucidate sex-specific differences in endothelial cell migration and energy metabolism under pro-migratory conditions in male and female HUVECs. To reduce biological variability, we used HUVECS obtained from umbilical cords from twin pairs of the opposite sex. These cells are exposed in utero to the same maternal environment, and therefore represent a valuable tool to study intrinsic sex-specific differences at the cellular level.

Methods

Vascular endothelial growth factor (VEGF)-stimulated migration was determined with IBIDI migration chambers. Sex-specific levels of proteins were studied using proteome profiling. Cellular metabolism was measured by Seahorse and levels of intracellular metabolites were analysed using GC-MS based technology.

Results

Female cells showed significantly higher VEGF-induced cell migration than male HUVECs. Proteomic profiling revealed a sex-specific response to VEGF treatment. Mitochondrial respiration rate was higher in VEGF-stimulated male HUVECs compared to female cells. Whereas mean glycolytic rates did not significantly differ between sexes, the ratio of glycolysis/mitochondrial respiration after VEGF stimulation was higher in female than in male HUVECs. Female cells had higher intracellular ATP levels after serum starvation and treatment with VEGF. Under both conditions, female cells showed altered levels of metabolite pools compared to male HUVECs.

Conclusions

Higher intracellular ATP and metabolite levels in female cells after serum starvation and VEGF may contribute to the observed functional sexual dimorphisms, and may also point to an increased stress tolerance of female cells. The results of our study provide a strong argument to discriminate between male and female cells in in vitro experiments.

Acknowledgement/Funding

The work was supported by the DZHK (German Centre for Cardiovascular Research) and by the BMBF (German Ministry of Education and Research).

Efficacy and Tolerability of Temozolomide in an Alternating Weekly Regimen in Patients With Recurrent Glioma

Purpose

Evaluation of toxicity and efficacy of an alternating weekly regimen of temozolomide administered 1 week on and 1 week off in patients with recurrent glioma.

Patients and Methods

Ninety adult patients with recurrent gliomas accrued in one center received chemotherapy with temozolomide at 150 mg/m2/d (days 1 through 7 and 15 through 21 every 4 weeks) with individual dose adjustments according to hematologic toxicity.

Results

A total of 906 treatment weeks were delivered. Grade 4 hematotoxicity according to the Common Terminology Criteria for Adverse Events (CTCAE; version 3.0) was observed in 24 treatment weeks (2.6%). CTCAE grade 4 lymphopenia eventually developed in 11 patients (12%). There were neither cumulative lymphopenias nor opportunistic infections. The progression-free survival (PFS) rate at 6 months for glioblastoma patients was 43.8%. The median PFS in these patients was 24 weeks (95% CI, 17 to 26 weeks), the median survival time from diagnosis of progression was 38 weeks (95% CI, 30 to 46 weeks), and the 1-year survival rate from progression was 23%. O6-methylguanine DNA methyltransferase (MGMT) gene promoter methylation in the tumor tissue was not associated with longer PFS (log-rank P = .37).

Conclusion

These data imply that the alternating weekly schedule is feasible, safe, and effective and clearly warrants investigation in randomized studies. Compared with more protracted low-dose temozolomide schedules, the 1-week-on/1-week-off schedule may be less toxic. We provide preliminary evidence that this dose-dense schedule is also active in patients with tumors lacking MGMT gene promoter methylation.

Hypermethylation and transcriptional downregulation of the CITED4 gene at 1p34.2 in oligodendroglial tumours with allelic losses on 1p and 19q

Deletions of chromosomal arms 1p and 19q are frequent in oligodendroglial tumours and have been associated with sensitivity to radio- and chemotherapy as well as favourable prognosis. By using microarray-based expression profiling, we found that oligodendroglial tumours with 1p and 19q losses showed significantly lower expression of the CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 4 gene (CITED4) at 1p34.2 as compared to tumours without 1p and 19q losses. Mutational analysis showed no CITED4 mutations in gliomas. However, 1p and 19q losses as well as low expression of CITED4 transcripts were significantly associated with hypermethylation of the CITED4-associated CpG island. In line with the latter finding, treatment of CITED4 hypermethylated glioma cell lines with 5-aza-2'-deoxycytidine and trichostatine A resulted in a marked increase of the CITED4 transcript levels. Furthermore, CITED4 hypermethylation was significantly associated with longer recurrence-free and overall survival of patients with oligodendroglial tumours. Taken together, our results indicate that CITED4 is epigenetically silenced in the vast majority of oligodendroglial tumours with 1p and 19q deletions and suggest CITED4 hypermethylation as a novel prognostic marker in oligodendroglioma patients.

Phase II trial of lomustine plus temozolomide chemotherapy in addition to radiotherapy in newly diagnosed glioblastoma: UKT-03

PURPOSE

To evaluate toxicity and efficacy of the combination of lomustine, temozolomide (TMZ) and involved-field radiotherapy in patients with newly diagnosed glioblastoma (GBM).

PATIENTS AND METHODS

Thirty-one adult patients (median Karnofsky performance score 90; median age, 51 years) accrued in two centers received involved-field radiotherapy (60 Gy in 2-Gy fractions) and chemotherapy with lomustine 100 mg/m2 (day 1) and TMZ 100 mg/m2/d (days 2 to 6) with individual dose adjustments according to hematologic toxicity.

RESULTS

A median of five courses (range, one to six courses) were delivered. WHO grade 4 hematotoxicity was observed in five patients (16%) and one of these patients died as a result of septicemia. Nonhematologic toxicity included one patient with WHO grade 4 drug-induced hepatitis (leading to discontinuation of lomustine and TMZ) and one patient with WHO grade 2 lung fibrosis (leading to discontinuation of lomustine). The progression-free survival (PFS) rate at 6 months was 61.3%. The median PFS was 9 months (95% CI, 5.3 to 11.7 months), the median overall survival time (MST) was 22.6 months (95% CI, 12.5 to not assessable), the 2-year survival rate was 44.7%. O6-methylguanine-DNA methyltransferase (MGMT) gene-promoter methylation in the tumor tissue was associated with longer PFS (P = .014, log-rank test) and MST (P = .037).

CONCLUSION

The combination of lomustine, TMZ, and radiotherapy had acceptable toxicity and yielded promising survival data in patients with newly diagnosed GBM. MGMT gene-promoter methylation was a strong predictor of survival.

Frequent loss of chromosome 9, homozygous CDKN2A/p14ARF/CDKN2B deletion and low TSC1 mRNA expression in pleomorphic xanthoastrocytomas

The molecular pathogenesis of pleomorphic xanthoastrocytoma (PXA), a rare astrocytic brain tumor with a relatively favorable prognosis, is still poorly understood. We characterized 50 PXAs by comparative genomic hybridization (CGH) and found the most common imbalance to be loss on chromosome 9 in 50% of tumors. Other recurrent losses affected chromosomes 17 (10%), 8, 18, 22 (4% each). Recurrent gains were identified on chromosomes X (16%), 7, 9q, 20 (8% each), 4, 5, 19 (4% each). Two tumors demonstrated amplifications mapping to 2p23-p25, 4p15, 12q13, 12q21, 21q21 and 21q22. Analysis of 10 PXAs with available high molecular weight DNA by high-resolution array-based CGH indicated homozygous 9p21.3 deletions involving the CDKN2A/p14(ARF)/CDKN2B loci in six tumors (60%). Interphase fluorescence in situ hybridization to tissue sections confirmed the presence of tumor cells with homozygous 9p21.3 deletions. Mutational analysis of candidate genes on 9q, PTCH and TSC1, revealed no mutations in PXAs with 9q loss and no evidence of TSC1 promoter methylation. However, PXAs consistently showed low TSC1 transcript levels. Taken together, our study identifies loss of chromosome 9 as the most common chromosomal imbalance in PXAs and suggests important roles for homozygous CDKN2A/p14(ARF)/CDKN2B deletion as well as low TSC1 mRNA expression in these tumors.

Identification of novel genes associated with astrocytoma progression using suppression subtractive hybridization and real-time reverse transcription-polymerase chain reaction

To identify novel genes involved in glioma progression we performed suppression subtractive hybridization combined with cDNA array analysis on 4 patients with primary low-grade gliomas of World Health Organization (WHO) grade II that recurred as secondary glioblastomas (WHO grade IV). Eight genes showing differential expression between primary and recurrent tumors in 3 of the 4 patients were selected for further analysis using real-time reverse transcription-PCR on a series of 10 pairs of primary low-grade and recurrent high-grade gliomas as well as 42 astrocytic gliomas of different WHO grades. These analyses revealed that 5 genes, i.e., AMOG (ATP1B2, 17p13.1), APOD (3q26.2-qter), DMXL1 (5q23.1) DRR1 (TU3A, 3p14.2) and PSD3 (KIAA09428/HCA67/EFA6R, 8p22), were expressed at significantly lower levels in secondary glioblastomas as compared to diffuse astrocytomas of WHO grade II. In addition, AMOG, DRR1 and PSD3 transcript levels were significantly lower in primary glioblastomas than in diffuse astrocytomas. Treatment of glioma cell lines with 5-aza-2'-deoxycytidine and trichostatin A resulted in increased expression of AMOG and APOD transcripts. Sequencing of sodium bisulfite-modified DNA demonstrated AMOG promoter hypermethylation in the glioma cell lines and 1 primary anaplastic astrocytoma with low AMOG expression. Taken together, we identified interesting novel candidate genes that likely contribute to glioma progression and provide first evidence for a role of epigenetic silencing of AMOG in malignant glioma cells.

Somatic mutations in the PTCH, SMOH, SUFUH and TP53 genes in sporadic basal cell carcinomas

BACKGROUND

Basal cell carcinoma (BCC) of the skin is the most common human cancer. The genetic alterations underlying BCC development are only partly understood.

OBJECTIVES

To investigate further the molecular genetics of sporadic BCCs, we performed mutation analyses of 10 skin cancer-associated genes in 42 tumours.

METHODS

Single-strand conformational polymorphism analysis followed by DNA sequencing was used to screen for mutations in the sonic hedgehog pathway genes PTCH, SMOH, SUFUH and GLI1, in the TP53 tumour suppressor gene, and in the proto-oncogenes NRAS, KRAS, HRAS, BRAF and CTNNB1. Microsatellite markers flanking the PTCH, SUFUH and TP53 loci at 9q22, 10q24 and 17p13, respectively, were studied for loss of heterozygosity (LOH).

RESULTS

PTCH mutations were found in 28 of 42 tumours (67%). Microsatellite analysis revealed LOH on 9q22 in 20 of 38 tumours investigated (53%), including 14 tumours with and six tumours without PTCH mutations. SMOH mutations were identified in four of the 42 BCCs (10%) while two tumours demonstrated mutations in SUFUH, including one missense mutation and one silent mutation. None of the BCCs showed LOH at markers flanking the SUFUH locus. Seventeen BCCs (40%) carried TP53 mutations, with only three tumours showing evidence of biallelic TP53 inactivation. TP53 mutations were present in BCCs with and without mutations in PTCH, SMOH or SUFUH. Interestingly, 72% of the TP53 alterations were presumably ultraviolet (UV)-induced transition mutations. In contrast, only 40% of the PTCH and SMOH alterations corresponded to UV signature mutations. No mutations were identified in GLI1, NRAS, KRAS, HRAS, BRAF or CTNNB1.

CONCLUSIONS

Our data confirm the importance of PTCH, SMOH and TP53 mutations in the pathogenesis of sporadic BCCs. SUFUH alterations are restricted to individual cases while the other investigated genes do not appear to be important targets for mutations in BCCs.

Oligodendroglial tumors: refinement of candidate regions on chromosome arm 1p and correlation of 1p/19q status with survival

Loss of heterozygosity (LOH) on the chromosome arms 1p and 19q is frequent in oligodendroglial tumors and has been correlated with chemosensitivity and good prognosis in anaplastic oligodendrogliomas. The oligodendroglioma-associated tumor suppressor genes on 1p and 19q are as yet unknown. To narrow down candidate regions on 1p, we investigated oligodendroglial tumors from 89 patients for LOH at up to 30 polymorphic loci on 1p. In addition, all tumors were studied for LOH at 7 loci on 19q. Combined LOH on 1p and 19q was detected in 20 (83%) of 24 oligodendrogliomas, 15(63%) of 24 anaplastic oligodendrogliomas, 10 (56%) of 18 oligoastrocytomas, and 12 (52%) of 23 anaplastic oligoastrocytomas. Five tumors demonstrated partial deletions on 1p, which allowed to define 3 distinct candidate regions at 1p36.31-pter distal to D1S2633, 1p36.22-p36.31 between D1S489 and D1S2642, and 1p34.2-p36.1 between D1S2743 and D1S482, respectively. No partial deletions were detected on 19q. Combined LOH on 1p and 19q was associated with prolonged time to progression (TTP), longer overall survival (OS), and a higher 5-year survival rate. Depending on the presence or absence of combined LOH on 1p and 19q, patients with anaplastic oligodendroglial tumors treated with adjuvant radio- and/or chemotherapy showed a median TTP of 86 months versus 39 months, a median OS of 91 months versus 46 months, and a 5-year survival rate of 80% versus 36%, respectively. Similarly, LOH on 1p and 19q was associated with longer survival in patients with low-grade oligodendroglial tumors (TTP: 57 months versus 47 months; OS: 172 months versus 105 months; 5-year survival rate: 92% versus 70%). Thus, our results refine the location of putative oligodendroglioma suppressor genes on 1p and support the significance of LOH on 1p and 19q as a favorable prognostic marker.

Hypermethylation and transcriptional downregulation of the carboxyl-terminal modulator protein gene in glioblastomas

The carboxyl-terminal modulator protein (CTMP) has been identified as a negative regulator of protein kinase B/Akt. Aberrant Akt signaling is frequently observed in glioblastomas, the most common and most malignant glial brain tumors. Because loss of CTMP function and/or expression may remove the inhibitory effects on Akt and promote tumorigenesis, we studied 93 primary glioblastomas and nine glioblastoma cell lines for CTMP deletion, mutation, promoter hypermethylation, and mRNA expression. None of the tumors or cell lines had CTMP-homozygous deletions or coding sequence mutations. However, CTMP mRNA expression was lower by at least 50% relative to non-neoplastic brain tissue in 37 (40%) glioblastomas and six (67%) glioma cell lines. Reduced CTMP mRNA levels were closely associated with hypermethylation of the CTMP promoter. Furthermore, treatment of CTMP-hypermethylated A172 glioma cells with the demethylating agent 5-aza-2'-deoxycytidine and the histone deacetylase inhibitor trichostatin A resulted in partial demethylation of the CTMP promoter and increased CTMP mRNA expression. Thus, epigenetic downregulation of CTMP transcription is a common aberration in glioblastomas.

Frequent alterations of Ras signaling pathway genes in sporadic malignant melanomas

Ras signaling is important for the intracellular transduction of mitogenic stimuli from activated growth factor receptors. We have investigated 37 sporadic malignant melanomas (15 primary cutaneous melanomas and 22 melanoma metastases) and 6 melanoma cell lines for mutations in the 3 Ras genes NRAS, KRAS and HRAS. All tumors and cell lines were additionally analyzed for mutation and expression of BRAF, which encodes a Ras-regulated serine/threonine kinase with oncogenic properties, as well as for expression of RASSF1A, which encodes a Ras-binding protein with tumor suppressor properties. Mutational analyses identified somatic NRAS mutations in 2 primary melanomas, 4 melanoma metastases and 2 cell lines. One melanoma metastasis showed a somatic KRAS mutation whereas HRAS mutations were not detected. Eight primary melanomas, 6 melanoma metastases and 4 melanoma cell lines carried BRAF mutations affecting the known hot-spot codon 599. None of the tumors or cell lines with BRAF mutation demonstrated NRAS or KRAS mutations. Real-time reverse transcription-PCR showed that 8 melanomas (3 primary tumors, 5 melanoma metastases) had reduced RASSF1A transcript levels of < or =50% relative to benign melanocytic nevi and normal skin. Three melanoma cell lines lacked detectable RASSF1A transcripts. The RASSF1A gene promoter was hypermethylated in these 3 cell lines as well as in 6 of 8 melanomas with reduced RASSF1A mRNA levels. Treatment of the cell lines with 5-aza-2'-deoxycytidine and trichostatin A resulted in demethylation of the RASSF1A promoter and re-expression of RASSF1A transcripts. Most tumors and all cell lines with RASSF1A promoter methylation additionally carried BRAF or NRAS mutations, suggesting a synergistic effect of these aberrations on melanoma growth. Taken together, 57% of the investigated melanomas and 100% of the melanoma cell lines carried mutations in either NRAS, KRAS or BRAF. In addition, 22% of the melanomas and 50% of the cell lines showed reduced RASSF1A transcript levels. Thus, alterations of Ras pathway genes are of paramount importance in the pathogenesis of sporadic melanomas.

Genetic alterations commonly found in diffusely infiltrating cerebral gliomas are rare or absent in pleomorphic xanthoastrocytomas

Pleomorphic xanthoastrocytoma (PXA) is a rare, usually well-circumscribed and superficially located neoplasm that preferentially arises in the cerebral cortex of children and young adults. The molecular aberrations that are associated with these tumors have not been studied systematically so far. We here report on a molecular genetic analysis of 62 PXAs (46 PXAs of World Health Organization [WHO] grade II and 16 PXAs with anaplastic features) for alterations of 5 candidate genes known to be frequently aberrant in diffusely infiltrating astrocytic gliomas, i.e. TP53, CDKN2A (p16(INK4a)), CDK4, MDM2, and EGFR. Only 3 PXAs (5%) carried a TP53 mutation. None of the 62 PXAs had lost both copies of the CDKN2A gene. The CDK4, MDM2, or EGFR genes were not amplified in any of the tumors. Fourteen PXAs were additionally analyzed for loss of heterozygosity (LOH) at microsatellite markers located on the chromosomes/chromosomal arms 1, gp, 9p, 10, 17, 19q, and 22q. Two PXAs (14%) had LOH at all informative markers on 9p, while 1 PXA demonstrated an interstitial area of allelic imbalance between D22S533 and D22S417 at 22q11.2-q13.3. Further analysis of 10 PXAs for inactivation of the CDKN2A. p14(ARF), and CDKN2B (p15(INK4b)) genes on 9p21 did not reveal any homozygous deletion, mutation, promoter hypermethylation, or complete loss of mRNA expression. Taken together, our results indicate that the chromosomal and genetic aberrations in PXAs are different from those typically associated with the diffusely infiltrating astrocytic and oligodendroglial gliomas. These genetic differences likely contribute to the more favorable behavior of PXAs and may be helpful for the molecular differential diagnosis of cerebral gliomas.

Molecular genetic analysis of malignant melanomas for aberrations of the WNT signaling pathway genes CTNNB1, APC, ICAT and BTRC

Aberrant activation of the Wnt signaling pathway has been reported in different human tumor types, including malignant melanomas. We investigated 37 malignant melanomas (15 primary tumors and 22 metastases) for alterations of 4 genes encoding members of this pathway, i.e., CTNNB1 (beta-catenin gene, 3p22.1), APC (adenomatous polyposis coli gene, 5q22.2), BTRC (beta-transducin repeat-containing protein gene, 10q24.3) and ICAT (inhibitor of beta-catenin and Tcf-4, 1p36.2). Mutational analysis of CTNNB1 identified somatic mutations in 1 primary melanoma and 1 melanoma metastasis from 2 different patients (5%). Both mutations affected the N-terminal degradation box of beta-catenin, which is important for the regulation of beta-catenin homeostasis. Another primary melanoma carried a somatic APC missense mutation within the known mutation cluster region in exon 15. Fourteen tumors (40%) showed LOH at microsatellite markers on 1p36. None of the tumors had lost both copies of the ICAT gene, but 1 melanoma metastasis carried a somatic point mutation altering the translation start codon of ICAT. Real-time RT-PCR showed markedly reduced ICAT transcript levels (<or=20% relative to normal skin and benign melanocytic nevi) in 28/36 malignant melanomas (78%), including 13/14 tumors with LOH on 1p36. Allelic loss on 10q was detected in 15 tumors (44%). We found neither mutations nor complete loss of expression of the BTRC gene in our melanoma series. Taken together, our results indicate that the Wnt pathway may be altered in malignant melanomas by different mechanisms, including rare somatic mutations in CTNNB1, APC or ICAT, as well as low or absent expression of ICAT transcripts.

Oligodendroglial tumors frequently demonstrate hypermethylation of the CDKN2A (MTS1, p16INK4a), p14ARF, and CDKN2B (MTS2, p15INK4b) tumor suppressor genes

We investigated 34 oligodendroglial tumors (7 oligodendrogliomas, 11 anaplastic oligodendrogliomas, 8 oligoastrocytomas, and 8 anaplastic oligoastrocytomas) for deletion, mutation, hypermethylation, and expression of the CDKN2A (MTS1, p16INK4a), p14ARF, and CDKN2B (MTS2, p15INK4b) tumor suppressor genes at 9p21. One anaplastic oligoastrocytoma carried a homozygous deletion including all 3 genes. None of the tumors demonstrated point mutations in any of the genes. Methylation-specific polymerase chain reaction (MSP) analysis and sequencing of bisulfite-modified DNA, however, revealed frequent hypermethylation of the 5'-CpG islands in CDKN2A, p14ARF, and CDKN2B. Partial or complete methylation of the majority of CpG sites analyzed from each gene was detected in 32% of the tumors at the CDKN2A gene and at a similar percentage (41%) of the tumors at the p14ARF gene and the CDKN2B gene. Most tumors with CDKN2A, p14ARF, and/or CDKN2B hypermethylation either lacked detectable transcripts from these genes or had lower mRNA levels than those determined for non-neoplastic brain tissue. There was a significant correlation between hypermethylation of these genes and the presence of allelic losses on chromosomal arms 1p and 19q. In addition, p14ARF hypermethylation was predominantly found in tumors without a demonstrated TP53 mutation. Taken together, our results indicate that hypermethylation of CDKN2A, p14ARF, and CDKN2B is an important epigenetic mechanism by which oligodendroglial tumors may escape from p53- and pRb-dependent growth control.

Analysis of human meningiomas for aberrations of the MADH2, MADH4, APM-1 and DCC tumor suppressor genes on the long arm of chromosome 18

We have previously reported that losses of genomic material from the long arm of chromosome 18 are frequent in atypical and anaplastic meningiomas but rare in benign meningiomas. In the present study, we have investigated a series of 37 meningiomas for mutation and expression of 4 tumor suppressor genes (MADH2, MADH4, APM-1 and DCC) located at 18q21. Comparative genomic hybridization or loss of heterozygosity analysis showed losses on chromosome 18 that included sequences from 18q21 in 15 of 37 tumors. Mutation analysis of APM-1 revealed a missense mutation (c. 1819G>A: G607S) in 1 atypical meningioma. None of the tumors showed mutations of MADH2 and MADH4 or loss of detectable transcripts from MADH2, MADH4, APM-1 and DCC. In contrast to human brain tissue, normal leptomeninges and meningiomas showed preferential expression of a DCC splice variant lacking 60 base pairs from exon 17. Taken together, our data do not support a significant role for MADH2, MADH4, APM-1 and DCC alterations in the pathogenesis of meningiomas. The targeted gene that is inactivated in most meningiomas with 18q losses remains to be identified.