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- Fredlund, Erik
(författare)
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Hypoxic gene regulation and oncogenic pathways in neuroblastoma
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neuroblastoma patients show remarkable clinical heterogeneity, with courses ranging from spontaneous regression to fatal tumor progression despite intense multi-modal treatment. Previous studies have shown that hypoxia pushes neuroblastoma cells towards a more immature phenotype, which correlates to aggressive disease. Here we define a role for the hypoxia inducible factor-2α in neuroblastoma tumor progression. While HIF-1α was transiently stabilized at hypoxia (1% oxygen), HIF-2α was induced and regulated HIF-specific target genes, such as VEGF, at later time points. Furthermore, HIF-2α was stabilized and transcriptionally active in cells grown at physiological oxygen levels (5% O2). Subsequent microarray analysis showed that HIF-2α induced genes, previously identified as hypoxia regulated, at this physiological oxygen level. Several of these genes have been implicated in tumorigenic processes and correlated to adverse patient outcome in various tumor forms. Indeed, siRNA mediated knock-down of HIF-2α in neuroblastoma cells significantly reduced xenograft tumor growth, as compared to siHIF1-α treated or wild-type cells. Moreover, immunohistochemical analyses of a large neuroblastoma tumor material arranged in a tissue microarray showed that HIF-2α expression correlated to VEGF, and that high HIF-2α levels was predictive of poor patient prognosis. Prognostic markers of neuroblastoma patient adverse prognosis include amplification of the MYCN oncogene and an undifferentiated morphology. While these features discriminate high- from low-risk patients with precision, identification of poor outcome low- and intermediate-risk patients is more challenging. We analyze two large neuroblastoma microarray data sets by using a priori-defined gene expression signatures. The results show that differential overexpression of Myc transcriptional targets and low expression of genes involved in sympathetic neuronal differentiation predict relapse and death from disease. This was evident not only for high-risk patients, but also was robust in identifying groups of poor prognosis patients otherwise judged to be at low- or intermediate-risk for adverse outcome. These data suggest that pathway-specific gene expression profiling might be useful in the clinic to adjust treatment strategies for children with neuroblastoma.
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| 2. |
- Jurstrand, Margaretha, 1947-
(författare)
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Detection of Chlamydia trachomatis and Mycoplasma genitalium by genetic and serological methods
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Chlamydia trachomatis infections are associated with a spectrum of clinical diseases including urethritis, prostatitis and epididymitis among men and cervicitis and pelvic inflammatory disease (PID), with an increased risk of infertility and ectopic pregnancy (EP), among women. In the search for other pathogens causing urethritis, Mycoplasma genitalium was isolated from urethral specimens from two men with acute urethritis (1980). Mycoplasma bacteria are extremely difficult to isolate by culture, and clinical studies have been possible only after the advent of the first PCR-based detection method. M. genitalium has been found to be associated with lower genital tract infections in both men and women. Finding evidence for a connection between M. genitalium and upper genital tract infections in women is still of major importance. The aim in papers I and II was to develop a PCR method for genetic characterization of clinical C. trachomatis isolates by sequence analysis of the omp1 gene, and to study the distribution of genotypes within sexual networks and determine if genotyping would improve partner notification. The method was used to determine the genotypes of C. trachomatis in 237 positive urogenital and/or urine specimens from men and women attending the STDClinic in Örebro during one year. Sequence analysis of the omp1 gene revealed that the most prevalent genotypes corresponded to C. trachomatis serovar E (47%), followed by F (17%), and K (9%). There were 161 networks found and specimens were sequenced from at least two patients in 47 networks. In seven of these 47 networks there were discrepant genotypes. In the largest network comprising 26 individuals two different C. trachomatis genotypes were found, and one partner had urethritis due to a Mycoplasma genitalium infection but was C. trachomatis negative. The need for a new method for M. genitalium DNA detection was one reason for study III. An existing conventional PCR protocol for detection of M. genitalium DNA was further developed into a real-time PCR (RT-PCR) with hybridisation probes. In order to evaluate the RT-PCR assay with clinical material, specimens from 398 men and 301 women attending the STD Clinic in Örebro were analysed, using the RT-PCR assay, and also by the well established conventional PCR in Copenhagen. Using the conventional PCR method as “gold standard”, the sensitivity for the RT-PCR assay was 72.2% and 68.2% and the specificity was 99.7% and 98.6%, respectively, in urogenital specimens from men and women. The aim in paper IV was to adapt a Triton X-114 extracted Lipid-Associated Membrane Protein (LAMP) Enzyme Immuno Assays (EIA) method to detect antibodies against M. genitalium and to evaluate the association between M. genitalium and PID and EP, using sera sampled in Örebro during the 1980s, and also to compare the number of sera having M. genitalium antibodies against those having C. trachomatis antibodies, using a commercial anti- Chlamydia trachomatis EIA assay. No statistical significant association could be demonstrated between M. genitalium antibodies and PID or EP in our serum material. However, a slight trend toward association was found when focusing on younger individuals. Antibodies against C. trachomatis were found to be significantly associated with PID and EP.
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