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- Lewander, Andreas, 1973-
(author)
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Polymorphism and expression of NF-κB in relation to susceptibility and prognosis of colorectal cancer patients
- 2010
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Doctoral thesis (other academic/artistic)abstract
- Normal human cells are strictly controlled in their environment by extrinsic and intrinsic factors. Despite this, some cells begin to develop into cancer cells, and if this process is allowed to continue, it will develop into cancer disease. To become cancerous, a cell must break several biological barriers. Two important barriers are apoptosis and cellular growth control.Cancer is a multifactorial disease caused by environmental and hereditary factors. The incidence of colorectal cancer varies among different populations around the world. Sweden has a history of a relatively high incidence of colorectal cancer, whereas its incidence in China is relatively low.Nuclear factor kappa B (NF-κB) is a transcription factor protein family, regulating genes involved in several aspects of cancer development. In human cells five members have been identified: NFKB1 (p105/p50), NFKB2 (p100/p52), RelA (p65), RelB and c-Rel. They normally form homo- or heterodimers in the cytoplasm of the cells, where they are in an inactive state by binding to inhibitory proteins, I kappaB-α, -θ and -ε and Bcl-3. Stimulatory signals, both intrinsic and extrinsic, lead the inhibitory proteins to be phosphorylated, which marks them for degradation. On activation, NF-κB proteins are often posttranslationally modified.In the first project, we investigated the role of a polymorphism in the promoter region of NFKB1 gene. The polymorphism is a 4-basepair insertion/deletion located 94 basepairs upstream of the gene (-94ins/delATTG). It does not seem to alter the amino acid sequence of the protein and therefore does not alter the function of the protein itself. Instead, it alters the regulation of the protein transcription. The aim of the present study was to investigate whether the polymorphism was related to cancer risk or clinicopathological variables. We found that this polymorphism increased the risk of sporadic colorectal cancer in a Swedish population but not in Swedish populations with a family history of colorectal cancer or in Chinese population.In the second project we studied an 8-basepair insertion/deletion polymorphism in the promoter region of NFKBIA gene coding for the nuclear factor kappa B inhibitory protein, IκBα. This polymorphism is located 708 basepairs upstream of the gene (-708ins/del8). The aim of the study was to investigate whether the polymorphism was related to cancer risk or clinicopathological factors. We found that this polymorphism was very rare in a Swedish population of colorectal cancer patients and controls and was totally absent in a Chinese population of patients and controls. Our conclusion is that this polymorphism is too rare to have a major impact on colorectal cancer incidence in the two populations.In the third project we studied levels of p65 phosphorylated at Serine-536 in colorectal cancers in a Swedish population. After activation and IκB phosphorylation/degradation, p65 is phosphorylated at Serine-536. This phosphorylation is involved in regulating transcriptional activity, nuclear localisation and protein stability. The aim of the study was to investigate whether the expression of the phosphorylated protein correlated to any clinicopathological variables, including survival. The expression of p65 phosphorylated at Serine-536 increased from normal mucosa to primary tumour, but no further increase to lymph node metastases was found. We did find, however, that the strong expression in the cytoplasm was correlated to worse survival among the patients, independent of gender, age, tumour location, stage and differentiation.In the fourth project we continued to study p65 phosphorylated at Serine-536. In this project, however, we studied the expression in a population of rectal cancer patients who participated in a Swedish clinical trial of preoperative radiotherapy. The aim of the study was to investigate whether the expression correlated to response to radiotherapy or to clinicopathological and some biological factors. We found that the expression was increased from normal mucosa to primary tumour, but detected no further increase from primary tumour to lymph node metastases. We found that the expression of p65 protein phosphorylated at Serine-536 was positively related to expression of TEM1, FXYD-3, PRL, p73 and MAC30 in the group of patients who received radiotherapy. Although no such relationship was seen in the group of patients that had not received radiotherapy, we did not find that the expression of p65 protein phosphorylated at Serine-536 was directly related to the clinical response to radiotherapy.In summary, the -94ins/delATTG polymorphism in the promoter region of NFKB1 gene increases the risk of sporadic colorectal cancer in Swedish but not in Chinese populations. The -708ins/del8 polymorphism in the promoter region of the NFKBIA gene is too rare to have a major impact on colorectal cancer incidence in Swedish and Chinese populations. Strong expression of p65 protein phosphorylated at Serine-536 is independently related to worse survival in Swedish colorectal cancer patients, and the expression is positively correlated to biological factors associated with more malignant features of tumours in rectal cancer patients who received preoperative radiotherapy.
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| 2. |
- Dahlin, Anna, 1979-
(author)
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The CpG island methylator phenotype in colorectal cancer : studies on risk and prognosis
- 2011
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Doctoral thesis (other academic/artistic)abstract
- Background Colorectal cancer (CRC) is the second most common malignancy in developed countries. The mortality is high, with nearly half of patients dying from the disease. The primary treatment of CRC is surgery, and decisions about additional treatment with chemotherapy are based mainly on tumor stage. Novel prognostic markers that identify patients at high risk of recurrence and cancer-related death are needed. The development of CRC has been described in terms of two different pathways; the microsatellite instability (MSI) and chromosomal instability (microsatellite stable, MSS) pathway. More recently, the CpG island methylator phenotype (CIMP), characterized by frequent DNA hypermethylation, has been described as an alternative pathway of tumorigenesis. The event of DNA methylation is dependent on one-carbon metabolism, in which folate and vitamin B12 have essential functions. The purpose of this thesis was to study CIMP in CRC. The specific aims were to investigate the potential role of components of one-carbon metabolism as risk factors for this subgroup of tumors, and the prognostic importance of CIMP status, taking into consideration important confounding factors, such as MSI and tumor-infiltrating T cells. Methods CRC cases and referents included in the Northern Sweden Health and Disease Study (NSHDS, 226 cases and 437 referents) and CRC cases in the Colorectal Cancer in Umeå Study (CRUMS, n=490) were studied. Prediagnostic plasma concentrations of folate and vitamin B12 were analyzed in NSHDS. In both study groups, CIMP status was determined in archival tumor tissue by real-time quantitative PCR using an eight-gene panel (CDKN2A, MLH1, CACNA1G, NEUROG1, RUNX3, SOCS1, IGF2 and CRABP1). MSI screening status and the density of tumor-infiltrating T cells were determined by immunohistochemistry. Results An inverse association was found between plasma concentrations of vitamin B12 and rectal, but not colon, cancer risk. We also found a reduced risk of CIMP-high and CIMP-low CRC in study subjects with the lowest levels of plasma folate. We found that patients with CIMP-low tumors in both NSHDS and CRUMS had a poorer prognosis compared with CIMP-negative, regardless of MSI screening status. We also found that MSS CIMP-high patients had a poorer prognosis compared with MSS CIMP-negative. The density of tumor-infiltrating T cells and CIMP status were both found to be independent predictors of CRC patient prognosis. A particularly poor prognosis was found in patients with CIMP-low tumors poorly infiltrated by T cells. In addition, the density of T cells appeared to be more important than MSI screening status for predicting CRC patient prognosis. Conclusion Rather than being one disease, CRC is a heterogeneous set of diseases with respect to clinico-pathological and molecular characteristics. We found that the association between risk and plasma concentration of vitamin B12 and folate depends on tumor site and CIMP status, respectively. Patient prognosis was found to be different depending on CIMP and MSI screening status, and the density of tumor-infiltrating T cells.
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| 3. |
- Holmqvist, Annica, 1974-
(author)
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Biological and histological factors as predictors in rectal cancer patients : A study in a clinical trial of preoperative radiotherapy
- 2011
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Doctoral thesis (other academic/artistic)abstract
- With improved surgical techniques and preoperative radiotherapy (RT) the local recurrence rate in rectal cancer patients has been reduced, however the mortality rate is still high and there is a huge variation in the response to preoperative RT in patients with the same tumour stage. To improve patient’s survival, it is of great importance to identify good prognostic and predictive factors that help us to select the best suited patients for preoperative RT in the future.For many years, studies of neoplastic transformation have mainly focused on tumour cells. In recent years, researchers have realised that the stroma around tumour cells and their extracellular matrix components also play an important role in tumour carcinogensesis.The aim of this thesis was to investigate the biological factors, survivin and particularly interesting new cysteine-histidine rich protein (PINCH), histological factors, inflammatory infiltration, fibrosis, necrosis, mucinous content, angiogenesis and lymphangiogenesis as well as their relationships to preoperative RT and to clinical variables in rectal cancer patients who participated in a Swedish rectal cancer trial of preoperative RT.In paper I, the expression of survivin and its relationship to preoperative RT and clinical factors were investigated in 98 primary rectal tumours and adjacent normal mucosa. In all patients, positive survivin expression was independently related to worse survival compared to negative survivin expression in a multivariate analysis.In paper II, PINCH expression and its relationship to RT, clinical, histological and biological factors were investigated at the invasive margin and inner tumour area in 137 primary rectal tumours and in cell line of fibroblasts. In patients without RT, strong PINCH expression was independently related to worse survival in a multivariate analysis. No survival relationship was found in the patients with RT, and there was no difference in PINCH expression between the subgroups of non-RT and RT at the invasive margin/inner tumour area. In patients with RT, strong PINCH expression at the inner tumour area was related to a high level of lymphatic vessel density (LVD).In paper III, the frequency of LVD/blood vessel density (BVD) was analysed at the periphery, the inner tumour area and the invasive margin of 138/140 primary rectal tumours and correlated to RT, clinical, histological and biological factors. In all patients, LVD at the periphery of the tumour was independently related to better survival compared to LVD at the inner tumour area/invasive margin. In all patients, a higher LVD at the periphery was related to negative (wild type) p53 expression.In paper IV, the inflammatory infiltration, fibrosis, necrosis and mucinous content were studied in relation to RT, clinical and biological parameters in preoperative biopsies (n = 153) and in primary tumours (n = 148). In all patients and in the subgroups of non-RT and RT a higher grade of inflammatory infiltration was independently related to improved survival compared to weak inflammatory infiltration in a multivariate analysis.In this thesis, survivin, PINCH, LVD and inflammatory infiltration are independent prognostic factors in rectal cancer patients who participated in a clinical trial of preoperative RT. This information may help us to improve patient’s survival by selecting the best suited patients for preoperative RT in the future.
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