| 61. |
- Löfstedt, Tobias
(author)
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Transcriptional Regulation by Hypoxia-Inducible Factors in Tumor Cells
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- Cancer is a major cause of human morbidity and mortality, and the risk of developing cancer is about one in three life times. Neuroblastoma is the most common extra-cranial solid tumor among children and arises from early sympathetic nervous system (SNS) cells arrested in their development. Generally, a low tumor cell differentiation correlates to poor prognosis. Solid tumors, like neuroblastoma, frequently contain regions of oxygen deficiency ? hypoxia ? caused by a high rate of cellular proliferation and abnormal intratumoral blood supply. In this hypoxic microenvironment cancer cells undergo genetic and molecular changes, allowing continued survival and proliferation. Tumor hypoxia is also associated with increased aggressiveness, resistance to therapy and poor outcome. Cancer cells become less differentiated in response to hypoxia, which we previously demonstrated in neuroblastoma as well as breast cancer cells, indicating an evolvement of a more aggressive phenotype. In the present studies we find evidence of potential mechanisms behind the hypoxia-mediated de-differentiation of neuroblastoma cells. Hypoxia (1% O2) induced the expression of the negative transcription factor ID2 (Paper I), involved in blocking the function of tissue-specific basic helix-loop-helix (bHLH) proteins, such as the SNS-specifying transcription factors HASH-1 and dHAND. Hypoxic up-regulation of ID2 was dependent on direct in vivo DNA-binding and activity of hypoxia-inducible factors (HIF), the master transcriptional regulators of oxygen homeostasis. Induction of ID2 expression occurs as an early HIF-mediated hypoxic event, potentially leading to a more immature state. HIF-1alpha and HIF-2alpha, however differently, are both essential for normal development and are highly implicated in tumor progression. In Paper II we show that HIF-1alpha and HIF-2alpha share several target genes, but mediate regulation of these under different temporal and oxygen-dependent conditions. Interestingly, HIF-2alpha, but not HIF-1alpha, was present in neuroblastoma tumor cells near blood vessels, and thus in apparently better oxygenized tumor regions. In vitro, HIF-1alpha protein was transiently stabilized at hypoxia and primarily governed acute hypoxic responses, whereas HIF-2alpha became more important at prolonged hypoxia. In addition, high HIF-2alpha activity, including induction of classic hypoxic targets such as VEGF, was detected in cultured neuroblastoma cells already at 5% O2, a physiologically relevant oxygen level, similar to the findings in vivo. In a large clinical neuroblastoma material, significant correlations between high HIF-2alpha levels and high VEGF content, advanced tumor stage and poor outcome were found. These observations clearly suggest an oncogenic role of HIF-2alpha, and implicate HIF-2alpha as an independent prognostic marker in neuroblastoma. The MXI1 (MAX-interactor 1) gene, a reported MYC antagonist, has been detected by us and others as a commonly hypoxia-induced gene. In Paper III we further demonstrate that HIF proteins, via direct binding to hypoxia-response elements (HRE), up-regulate MXI1 mRNA and protein in both hypoxic neuroblastoma and breast cancer cells. Interestingly, reducing MXI1 levels had no overall effects on MYC/MYCN activity in hypoxic neuroblastoma cells. Instead, MXI1 appeared to be important in augmenting the hypoxic response, potentially by enhancing specific HIF-1 target gene induction. HIF proteins are primarily stabilized and activated in response to lowered oxygen concentrations. However, growth factor-induced signaling can promote HIF-1alpha protein synthesis as well as transactivation, even under normoxic conditions. In Paper IV we characterize a novel such a pathway, where stem cell factor (SCF)-evoked c-Kit-signaling leads to increased HIF-1alpha protein, HRE-activation and induction of several HIF-1alpha targets, such as VEGF and GLUT1, already at normoxia. In addition we find a reciprocal positive feedback loop between c-Kit and HIF-1alpha, where induced HIF-1alpha mediates reinforcement of c-Kit expression. Overall, this thesis shows the impact of HIF proteins on tumor cell behavior, principally as central hypoxic transcriptional regulators governing the expression of genes with potential importance in several biological processes, such as growth and differentiation, determining cancer cell aggressiveness as well as adaptation to low oxygen conditions.
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| 62. |
- Olsson-Strömberg, Ulla, et al.
(author)
-
Successful mobilization of Ph-negative blood stem cells with intensive chemotherapy + G-CSF in patients with chronic myelogenous leukemia in first chronic phase
- 2006
-
In: Leukemia and Lymphoma. - : Informa UK Limited. - 1042-8194 .- 1029-2403. ; 47:9, s. 1768-73
-
Journal article (peer-reviewed)abstract
- The aim of the study was to investigate the feasibility of mobilizing Philadelphia chromosome negative (Ph-) blood stem cells (BSC) with intensive chemotherapy and lenograstim (G-CSF) in patients with CML in first chronic phase (CP1). During 1994-1999 12 centers included 37 patients <56 years. All patients received 6 months' IFN, stopping at median 36 (1-290) days prior to the mobilization chemotherapy. All received one cycle of daunorubicin 50 mg/m2 and 1 hour infusion on days 1-3, and cytarabine (ara-C) 200 mg/m2 24 hours' i.v. infusion on days 1-7 (DA) followed by G-CSF 526 microg s.c. once daily from day 8 after the start of chemotherapy. Leukaphereses were initiated when the number of CD 34+ cells was >5/microl blood. Patients mobilizing poorly could receive a 4-day cycle of chemotherapy with mitoxantrone 12 mg/m2/day and 1 hour i.v infusion, etoposide 100 mg/m2/day and 1 hour i.v. infusion and ara-C 1 g/m2/twice a day with 2 hours' i.v infusion (MEA) or a second DA, followed by G-CSF 526 microg s.c once daily from day 8 after the start of chemotherapy. Twenty-seven patients received one cycle of chemotherapy and G-CSF, whereas 10 were mobilized twice. Twenty-three patients (62%) were successfully (MNC >3.5 x 10(8)/kg, CFU-GM >1.0 x 10(4)/kg, CD34+ cells >2.0 x 10(6)/kg and no Ph+ cells in the apheresis product) [n = 16] or partially successfully (as defined above but 1-34% Ph+ cells in the apheresis product) [n = 7] mobilized. There was no mortality during the mobilization procedure. Twenty-one/23 patients subsequently underwent auto-SCT. The time with PMN <0.5 x 10(9)/l was 10 (range 7-49) and with platelets <20 x 10(9)/l was also 10 (2-173) days. There was no transplant related mortality. The estimated 5-year overall survival after auto-SCT was 68% (95% CI 47 - 90%), with a median follow-up time of 5.2 years.We conclude that in a significant proportion of patients with CML in CP 1, intensive chemotherapy combined with G-CSF mobilizes Ph- BSC sufficient for use in auto-SCT.
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| 63. |
- Schultz, Anna
(author)
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Localisation of Protein Kinase C in Apoptosis and Neurite Outgrowth
- 2005
-
Doctoral thesis (other academic/artistic)abstract
- Protein kinase C (PKC) is a family of serine/threonine kinases, which are subgrouped into classical (a, bI, bII, g), novel (d, e, h, q) and atypical (z, i/l) isoforms. One major aim of this thesis work was to investigate if altered levels of PKC isoforms influence the apoptotic responses of malignant cell-lines. We show that overexpression of PKCd or PKCq renders SK-N-BE(2) neuroblastoma cells sensitive to apoptosis induced by phorbol esters or C2-ceramide. Moreover, overexpression of PKCa, PKCd or PKCe sensitises both androgen-dependent and androgen-independent prostate cancer cells to phorbol ester-induced cell-death. The apoptotic effects of PKCd and PKCq in neuroblastoma cells are independent on the catalytic activity of the enzymes and the isolated regulatory domain (RD) of PKCq induces apoptosis in neuroblastoma cells. Induction of apoptosis depends on the localisation of PKCqRD to the Golgi complex, which is mediated by the C1b domain of the protein. Mutation of a single amino acid residue, Met-267 in PKCqC1b, blocks both the Golgi localisation and the apoptotic effect of the PKCqRD. Previous studies have shown that PKCe induces neurites in neuroblastoma cells. Here we report that treatment with cell-permeable C2-ceramide inhibits PKCe-induced neurite formation, conceivably by relocating the protein from the cytosol to the perinuclear region. Mutation of Asp-257 and Met-278 (the latter corresponding to Met-267 in PKCq) in PKCe blocks the C2-ceramide induced translocation of PKCe. Furthermore, the mutated variant of PKCe still induces neurites after C2-ceramide treatment. Thus, the specific subcellular localisation of PKCq and PKCe are important for their biological activities.
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| 64. |
- Sorbe, Bengt, et al.
(author)
-
Intravaginal brachytherapy in FIGO stage I low-risk endometrial cancer : a controlled randomized study
- 2009
-
In: International Journal of Gynecological Cancer. - 1048-891X .- 1525-1438. ; 19:5, s. 873-878
-
Journal article (peer-reviewed)abstract
- The purpose of the study was to compare postoperative vaginal irradiation with surgery alone in low-risk International Federation of Gynecology and Obstetrics (FIGO) stage IA-IB endometrial carcinoma. The study was a prospective, randomized trial of 645 evaluable low-risk endometrial carcinoma patients from 6 European gynecologic cancer centers. All tumors were in FIGO stage IA-IB, of endometrioid histological type, and FIGO grade 1-2. High-dose-rate afterloading equipments (iridium [Ir] 192 or cobalt [co] 60) were used at 5 centers, and low-dose-rate (LDR) afterloading equipment (cesium [Cs] 137) at 1 center. Perspex vaginal applicators or ovoids were normally used, and the dose was specified at 5 mm from the surface of the applicator. Three to 6 fractions (3.0-8.0 Gy) were given, and the overall treatment time was 4 to 15 days. A total of 319 patients were treated with surgery plus vaginal irradiation (treatment group), and 326 patients with surgery alone (control group).Twenty-six recurrences (4.0%) were recorded in the complete series. The locoregional recurrence rate was 2.6%, whereas distant metastases occurred in 1.4%. The rate of vaginal recurrences was 1.2% in the treatment group versus 3.1% in the control group. The difference was not statistically significant (P = 0.114). Side effects were few and mild (grade 1-2). Dysuria, frequency, and incontinence were slightly more common after vaginal irradiation (2.8% vs 0.6%, respectively). Late intestinal problems were few and similar in the 2 groups. The conclusions were that the impact of postoperative brachytherapy on even the locoregional recurrence rate seems to be limited in patients with low-risk endometrial carcinoma. The overall recurrence rate and survival were similar in the 2 groups.
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| 65. |
- Steffen, Ann-Charlott, et al.
(author)
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Differences in radiosensitivity between three HER2 overexpressing cell lines.
- 2008
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In: European journal of nuclear medicine and molecular imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 35:6, s. 1179-91
-
Journal article (peer-reviewed)abstract
- PURPOSE: HER2 is a potential target for radionuclide therapy, especially when HER2 overexpressing breast cancer cells are resistant to Herceptin(R) treatment. Therefore, it is of interest to analyse whether HER2 overexpressing tumour cells have different inherent radiosensitivity. METHODS: The radiosensitivity of three often used HER2 overexpressing cell lines, SKOV-3, SKBR-3 and BT-474, was analysed. The cells were exposed to conventional photon irradiation, low linear energy transfer (LET), to characterise their inherent radiosensitivity. The analysis was made with clonogenic survival and growth extrapolation assays. The cells were also exposed to alpha particles, high LET, from (211)At decays using the HER2-binding affibody molecule (211)At-(Z(HER2:4))(2) as targeting agent. Assays for studies of internalisation of the affibody molecule were applied. RESULTS: SKOV-3 cells were most radioresistant, SKBR-3 cells were intermediate and BT-474 cells were most sensitive as measured with the clonogenic and growth extrapolation assays after photon irradiation. The HER2 dependent cellular uptake of (211)At was qualitatively similar for all three cell lines. However, the sensitivity to the alpha particles from (211)At differed; SKOV-3 was most resistant, SKBR-3 intermediate and BT-474 most sensitive. These differences were unexpected because it is assumed that all types of cells should have similar sensitivity to high-LET radiation. The sensitivity to alpha particle exposure correlated with internalisation of the affibody molecule and with size of the cell nucleus. CONCLUSION: There can be differences in radiosensitivity, which, if they also exist between patient breast cancer cells, are important to consider for both conventional radiotherapy and for HER2-targeted radionuclide therapy.
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| 66. |
- Stendahl, Maria
(author)
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Predictive markers for tamoxifen response in primary breast cancer
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- It is well-known that a majority of breast cancers are hormone-dependent, making endocrine therapy an important adjuvant treatment after surgery. Susceptibility to endocrine treatment is determined by the presence of estrogen receptors (ER) and progesterone receptors (PR) in the tumors. Tamoxifen is the most well-established endocrine treatment available, inhibiting tumor growth and improving survival. Resistance to tamoxifen despite ER/PR positivity is a well-known clinical problem. Cyclin D1, initially described as a cell cycle regulator, also functions as a co-factor to the ER, activating the receptor in the absence of ligand. We investigated the predictive impact of cyclin D1 on tamoxifen treatment response in tumors from patients previously enrolled in randomized trials and found that high levels of cyclin D1 in tumors of tamoxifen treated patients predicted for poor response and reduced recurrence-free survival despite ER positivity. Furthermore, amplification of the cyclin D1 gene (CCND1) was associated with an adverse outcome upon tamoxifen treatment. P27 is a cell cycle regulator, acting as a cdk-inhibitor but also as an assembly factor to the cyclin D1-cdk4/6 complex. We found that low levels of p27 correlated to a poor tamoxifen response but had no prognostic value in untreated patients. ER and PR are the only clinical tools available for predicting treatment response, with a cut-off at 10% positive tumor cell nuclei. We investigated if a more detailed mapping of hormone receptor levels could provide additional information and found that it was predominantly tumors with high levels of PR (>75%) that responded well to tamoxifen treatment. Further studies, confirming cyclin D1, p27 and other factors possibly inducing tamoxifen treatment resistance, are needed. In the meantime, a more precise assessment of hormone receptor status could be informative.
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| 67. |
- Svensson Månsson, Sofie
(author)
-
Invasion and Proliferation in Malignant Cells
- 2006
-
Doctoral thesis (other academic/artistic)abstract
- Two key events in the oncogenic process of tumor cells are to acquire uncontrolled proliferation and invasive properties. This allows the tumor to grow and invade beyond the tissue from which the tumor cells originate. We here specifically studied p16 and ERK1/2 with special focus on and the relation to proliferation and invasion in non-melanoma skin cancer and in breast cancer. In a model system of basal cell carcinoma, we observed that tumor cells changed phenotype from a highly proliferative type in the centre of the tumor to an invasive type with low proliferation and a marked upregulation of p16 at the invasive front. The expression of p16 was transcriptionally regulated and possible p16 activators such as ERK1/2 or Ets were not the sole contributors. Similar findings were observed in squamous cell carcinoma of the skin, despite a non functional Rb pathway, which might indicate a proliferation independent role for p16 in invasive behaviors. In primary breast cancer, a signaling cascade from VEGFR2 via ERK1/2 phosphorylation to Ets2 phosphorylation and cyclin D1, could be outlined and ERK1/2 phosphorylation was linked to small tumors with good prognosis. We also observed a Notch1 independent activation of Hes1 in breast cancer. Further, postmenopausal patients with ERK1/2 phosphorylated tumors had an impaired tamoxifen response, but ERK1/2 phosphorylation was not linked to tamoxifen resistance in premenopausal women. Taken together, our results implicate that there is a general inverse association between invasion and proliferation in some malignancies and this novel finding could be important when designing new treatment strategies for cancer patients.
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| 68. |
- Tina, Elisabet, et al.
(author)
-
Topoisomerase IIalpha expression in acute myeloid leukaemia cells that survive after exposure to daunorubicin or ara-C
- 2009
-
In: Oncology Reports. - Athen : Spandidos Publications. - 1021-335X .- 1791-2431. ; 22:6, s. 1527-1531
-
Journal article (peer-reviewed)abstract
- Patients diagnosed with acute myeloid leukaemia are often treated with a combination of daunorubicin and 1-β-D-arabinofuranosylcytosine (ara-C). Both daunorubicin and ara-C exert their effects in the cell nucleus but by different mechanisms, i.e. daunorubicin causes double stranded DNA breaks by inhibition of the nuclear enzyme, topoisomerase (topo) IIα, whereas ara-C is an anti-metabolite that integrates with DNA during DNA synthesis and causes cell cycle arrest. Despite the initial efficacy of these drugs, resistance often develops in the clinical setting. The mechanisms underlying clinical resistance to these drugs are poorly understood, but may be associated with an increase in the proportion of topo IIα negative cells. Therefore, the aim of this study was to determine whether daunorubicin treatment results in increased numbers of topo IIα negative subpopulations in vitro. Acute myeloid leukaemia cells isolated from 12 consenting patients were treated for 24 h with increasing concentrations of daunorubicin or ara-C and the proportion of topo IIα-negative cells in surviving cell populations determined by flow cytometry. Treatment with daunorubicin, but not ara-C, resulted in a significant increase in the proportion of topo IIα negative cells (p=0.0023). These results suggest that daunorubicin may act by cell cycle arrest and/or by selection of pre-existing topo IIα negative subpopulations. Both of these mechanisms can theoretically contribute to a reduced efficacy of a second dose of daunorubicin. The clinical relevance of these interactions should be further elucidated in experimental and clinical studies.
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| 69. |
- Vallon-Christersson, Johan
(author)
-
Functional and Molecular Characterization of BRCA1 and BRCA2 Associated Breast Cancer
- 2005
-
Doctoral thesis (other academic/artistic)abstract
- This doctoral dissertation is based on five appended papers primarily concerned with three main topics, namely: the functional characterization of specific and clinically relevant perturbations found in BRCA1 ? one of the major breast cancer susceptibility genes; the use of microarray technologies for molecular characterization of hereditary breast tumor samples from a genomic perspective; and finally, the development of software to address some of the logistical problems of data analysis and management that arise when utilizing microarrays. Results obtained from the work presented herein demonstrate the following: that transcription az says can aid in the characterization of C-terminal missense mutations but that it may not be possible to unambiguously characterize variants with a yeast-based assay alone; that a naturally occurring C-terminal germline mutation in BRCA1 encodes a protein with apparent temperature-dependant functional properties; that open-source software can provide comprehensive solutions to meet data management needs of microarray experimenters; that BRCA1 and BRCA2 associated breast tumors exhibit markedly different copy number aberrations when compared to each other as well as to sporadic tumors; and that gene expression profiling in BRCA1 and BRCA2 associated breast tumors reveals specific gene expression patterns.
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| 70. |
- Zendehrokh, Nooreldin
(author)
-
Integration of Molecular Biology and Morphology in Effusions with Focus on in situ Detection of Telomerase and its Components
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- Clinical cytology is a rapid method to detect malignancy in effusions of the serous cavities, but the morphological characteristics of the cells do not always allow diagnosis and a specific marker for malignant cells would improve the diagnostic performance. Telomerase adds telomere repeats to the chromosome ends. It is the most promising universal indicator of malignancy and the project focuses on TRAP in situ, a unique PCR-based method to detect telomerase activity. With TRAP in situ we demonstrated telomerase activity in 95% of all malignant cell populations. Some mesothelial cells and lymphocytes showed weak reactivity. When compared with the results of TRAP using whole cell lysates we found that discrepant results could be due to cell composition and activity intensity in positive cells and we concluded that whole cell lysate TRAP is not a suitable method to detect telomerase in effusions. We further studied the relation between telomerase activity in malignant cells in effusions and prognosis and found that weak telomerase activity in tumor cells was associated with shorter survival times. A possible explanation is that cells with highly aggressive potential may find a way to preserve their telomeres in the absence of telomerase. Telomerase activity correlates to its catalytic subunit, hTERT and immunocytochemical detection of the hTERT protein is an attractive way to detect up regulation of telomerase. As telomerase activity was stronger in malignant than in mesothelial cells absolute quantification of the immunoreactivity would allow the identification of a cut-off level for malignancy. In a pilot study we showed that this could be achieved with time resolved fluorescence (TRF) imaging, a method that has never before been applied to cytological specimens.
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