| 1. |
- Dahlin, Anna, 1979-
(författare)
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The CpG island methylator phenotype in colorectal cancer : studies on risk and prognosis
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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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| 2. |
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| 3. |
- Gao, Jingfang, 1966-
(författare)
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Molecular and Biological Characteristics of Stroma and Tumor Cells in Colorectal Cancer
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Carcinogenesis is a progressive process involving multiple genetic alterations in tumor cells and complex interactions in the tumor-host microenvironment. To better understand the contribution of molecular alterations in tumor cells and stromal variables to the development of colorectal cancer (CRC) and identify prognostic factors, in this study we examined the clinicopathological and biological significance of stromal variables, including particularly interesting new cysteine-histidine rich protein (PINCH), inflammatory infiltration, angiogenesis and lymphangiogenesis, as well as hRAD50/hMRE11/hNBS1 proteins and hRAD50 mutation in tumor cell in CRC.PINCH protein expression in the stroma was increased from normal mucosa to primary tumors and further to lymph node metastases. In particular, PINCH expression was most intense at the tumor invasive margin, which was related to low inflammatory infiltration and independently related to an unfavorable prognosis. Low inflammatory infiltration at the tumor invasive margin was related to advanced tumor stage, worse differentiation and microsatellite instability (MSI). Further, it was independently related to an unfavorable prognosis. Increased blood and lymphatic vessel density was observed in the primary tumors compared with the corresponding normal mucosa. However, neither angiogenesis nor lymphangiogenesis was associated with tumor stage and patients’ survival. Moreover, PINCH was present in a proportion of endothelial cells of the tumor vasculature, and PINCH expression in tumor-associated stroma was positively related to blood vessel density.In primary tumor cells of CRC, strong expression of hRAD50, hMRE11 or hNBS1 was related to microsatellite stability (MSS). A high percentage of hMRE11 expression was associated with less local recurrence and high apoptotic activity. Further, we observed that the expression of hRAD50, hMRE11 or hNBS1 among normal mucosa, primary tumors and metastases in MSS CRC differed from that in MSI CRC. In MSS CRC, the expression intensity of hRAD50, hMRE11 and hNBS1 was consistently increased with respect to normal mucosa, but there was no difference between the primary tumors and metastases. In the primary MSS tumors, the expression of individual or combination of hRAD50/hMRE11/hNBS1 was associated with a favorable prognosis in the same series of the CRCs. Moreover, strong/high hRAD50 in MSS primary tumors was related to earlier tumor stage, better differentiation and high inflammatory infiltration, whereas strong hNBS1 expression tended to be independently related to a favorable prognosis in MSS CRC with earlier tumor stage. However, in MSI CRC, there were neither differences in the expression of hRAD50/hMRE11/hNBS1 among normal mucosa, primary tumors and metastases, nor any association of the protein expressions with clinicopathological variables. On the other hand, frameshift mutations of (A)9 at coding region of hRAD50 were only found in MSI CRC.Our study indicates that 1) PINCH is likely a regulator of angiogenesis, and PINCH expression at the tumor invasive margin is an independent prognostic indicator in CRC. 2) Inflammatory infiltration at the tumor invasive margin is also an independent prognostic indicator in CRC. The lack of association between high inflammatory infiltration and MSI may help to explain the non-association of MSI with survival in CRC patients. 3) Angiogenesis and lymphangiogenesis occur in the early stage of CRC development, but do not associate with CRC progression and patients’ prognosis. 4) hRAD50/hMRE11/hNBS1 may act dependently and independently, playing different roles in MSS and MSI CRC development. In MSS CRC, the strong expression of the three proteins, associated with a favorable prognosis, may present the cellular response against tumor progression. Expression of hNBS1 may be a prognostic indicator for MSS CRC patients in the earlier tumor stage. In MSI CRC, the frameshift mutations at the coding region of hRAD50 may contribute to tumor development.
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| 4. |
- Gnosa, Sebastian, 1984-
(författare)
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Astrocyte elevated gene-1 in relation to colorectal cancer development and radiotherapy response
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The incidence and death rate for colorectal cancer (CRC) decreased during the last decades as a result of improved diagnosis and treatment. However, CRC is still the third most common cancer in the world, and is responsible for about 700 000 deaths per year worldwide. Therefore, it is important to understand the mechanisms of the disease, and to find molecular markers in order to further improve prognosis, and to develop new treatment strategies. Astrocyte elevated gene-1 (AEG-1), encoded by the MTDH gene, is upregulated in a variety of cancers. AEG-1 is involved in cell survival, proliferation, migration, invasion, metastasis, angiogenesis, and apoptosis.The aim of this thesis was to investigate the role of AEG-1 in CRC development and the impact of AEG-1 on the response of radiation treatment. The AEG-1 expression, analysed in different CRC patient cohorts in paper I and III, was increased in the tumour tissue compared with the normal mucosa, and higher in the lymph node and liver metastases. Expression analyses in normal and cancer cell lines confirmed these results. In paper II, sequencing of the complete coding sequence of the MTDH gene in 356 patients revealed 50 single nucleotide variants of which 29 were novel. Eight exonic variants were detected, including three frameshift variants which were probably pathogenic, and two missense variants located in functional protein regions. There was no correlation of the MTDH variants or AEG-1 expression with the patient survival. In paper III, we also investigated the impact of AEG-1 on the response to radiation treatment. AEG-1 knockdown decreased the cellular survival upon radiation in several colon cancer cell lines. The AEG-1 expression was furthermore analysed in patients, which were randomised to either surgery alone or preoperative radiotherapy (RT), followed by surgery. The rectal cancer patients with high AEG-1 expression treated with RT had a significantly higher risk of developing distant recurrence and had a worse disease free survival, likely due to the metastasis promoting properties of AEG-1. In paper IV, the impact of AEG-1 knockdown and radiation on migration and invasion was analysed in colon cancer cell lines in vitro and in a novel zebrafish model in vivo. AEG-1 knockdown decreased migration and invasion, and radiation-enhanced migration and invasion in the cell lines tested.In conclusion, our data suggest that AEG-1 is involved in CRC development, while MTDH gene variants probably not have a high clinical importance in CRC. Furthermore, AEG-1 is a promising radiosensitising target and a valuable prognostic marker in CRC. We further showed that AEG-1 knockdown inhibits migration and invasion, as well as radiation-enhanced cell migration and invasion.
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| 5. |
- Holmqvist, Annica, 1974-
(författare)
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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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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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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| 6. |
- Kotti, Angeliki
(författare)
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Clinical and Biological Factors Related to Survival in Patients with Rectal Cancer
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rectal cancer is a common malignancy within the gastrointestinal tract. Despite the advances in diagnosis and treatment of rectal cancer patients during the last decades, there are still many patients who die from their disease. In order to personalise the therapy and optimise the clinical outcomes, it is important to identify factors that have an impact on survival of rectal cancer patients. Therefore, the overall aim of this thesis was to identify clinical and biological factors that were related to survival in patients with rectal cancer. Paper I aimed to evaluate the impact of statins on survival in older and younger patients with rectal cancer. The study included 238 older patients (≥70 years) and 227 younger patients (<70 years) from the southeast healthcare region of Sweden. The patients were classified as statin users if they used any type of statins at the time of the cancer diagnosis. In the older group, statin users had better cancer-specific survival, disease-free survival, and overall survival compared with non-users. No such association was present in the younger group. Paper II aimed to evaluate the impact of computed tomography (CT)-measured body composition on survival in rectal cancer patients. The study included 173 patients from the region Ostergotland of Sweden who underwent a CT colonography at the time of diagnosis. Skeletal muscle index (SMI) and visceral adipose tissue area (VAT) were quantified at the level of the third lumbar vertebral body, using the CT colonography acquired at the time of diagnosis. The patients were divided into a low or high SMI group, and a low or high VAT group. Low SMI was related to worse survival compared to high SMI in all the patients. High VAT was related to better survival in men with low or middle rectal cancer, while high VAT was related to worse survival in women with low or middle rectal cancer. Paper III aimed to evaluate the prognostic value of SPARCL1 expression in patients with rectal cancer with a focus on radiotherapy (RT). The study included 138 patients with rectal cancer who participated in the Swedish Rectal Cancer Trial. Of those, 63 patients underwent both preoperative RT and surgery, while 75 patients had surgery alone. SPARCL1 expression was determined by immunohistochemistry. Strong SPARCL1 expression was related to better overall survival compared to weak SPARCL1 expression in patients with stage III disease who received RT, but not in patients with stage III disease who did not receive RT. Moreover, SPARCL1 expression was increased in primary tumours with RT compared to tumours without RT. In summary, statin use was related to improved survival in older patients with rectal cancer. CT-measured body composition parameters provided useful information for determining the prognosis of rectal cancer patients. SPARCL1 was identified as a potential prognostic biomarker in rectal cancer patients who received preoperative RT. Conclusively, the results of this thesis indicate that statin drugs, CT-measured body composition and SPARCL1 are factors related to survival in patients with rectal cancer. The evidence may benefit patients by more accurate estimating of their prognosis, personalised treatment and improved clinical outcomes.
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| 7. |
- Lewander, Andreas, 1973-
(författare)
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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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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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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| 8. |
- Loftås, Per, 1964-
(författare)
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Response to neoadjuvant treatment in rectal cancer surgery
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rectal cancer is one of the three most common malignancies in Sweden with an annual incidence of about 2000 cases. Current treatment consists of surgical resection of the rectum including the loco-regional lymph nodes in the mesorectum. In advanced cases, neoadjuvant chemo-radiotherapy (CRT) prior to the operative treatment reduces local recurrences and enables surgery. The neoadjuvant treatment can also eradicate the tumour completely, i.e. complete response. This research project was designed to investigate the effects of preoperative radiotherapy/ CRT and analyze methods to predict response to CRT.Study I investigated the expression of the FXYD-3 protein with immunohistochemistry in rectal cancer, with or without preoperative radiotherapy. The results from the total cohort showed that, strong FXYD-3 expression was correlated to infiltrative tumour growth (p = 0.02). In the radiotherapy group, strong FXYD-3 expression was related to an unfavourable prognosis (p = 0.02). Tumours with strong FXYD-3 expression had less tumour necrosis (p = 0.02) after radiotherapy. FXYD-3 expression in the primary tumour was increased compared to normal mucosa (p=0.008). We concluded that FXYD-3 expression was a prognostic factor in patients receiving preoperative radiotherapy for rectal cancer.Study II investigated FXYD-3 expression in tumours that developed local recurrences following surgery and compared this with expression in tumours that did not develop local recurrences. There was no difference in the expression of FXYD-3 between the group that developed local recurrences and the group that did not develop local recurrences. There was no difference in survival between those with strong or weak FXYD-3 expression. We concluded that this study could not confirm the findings from study 1 i.e. that FXYD-3 expression has prognostic significance in rectal cancer.Study III was a register-based study on the incidence and effects of complete response to neoadjuvant treatment. Eight per cent of the patients with adequate CRT to achieve complete response also had a complete histological response of the luminal tumor in the resected bowel. Sixteen per cent of that group had remaining lymph node metastases in the operative specimen. Chemotherapy together with radiotherapy doubled the chance of complete response in the luminal tumour. Patients with remaining lymph node metastases had a lower survival rate compared to those without. We concluded that residual nodal involvement after neoadjuvant treatment was an important factor for reduced survival after complete response in the luminal tumour.Study IV followed up the results from the previous study by re-evaluating magnetic resonance imaging (MRI)- images in patients with complete tumour response. Two experienced MRI radiologists performed blinded re-staging of post CRT MR- images from patients with complete response in the luminal tumour. One group with lymph node metastases and another one without were studied and the results compared with the pathology reports. The sensitivity, specificity, and positive and negative predicted values for correct staging of positive lymph nodes was 37%, 84%, 70% and 57%. The size of the largest lymph node (4.5 mm, p=0.04) seemed to indicate presence of a tumour positive lymph node. We concluded that MRI couldn’t correctly stage patients for lymph node metastases in patients with complete response to CRT in the luminal tumour.
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| 9. |
- Pfeifer, Daniella
(författare)
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p73 in colorectal cancer
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Colorectal cancer (CRC) is the third most common cancer in the world, with about 5000 new cases in Sweden every year. CRC is caused by mutation (inherited or acquired) in genes, by gene variants and changed expression of proteins. The primary way to achieve a curative result for CRC is to remove the tumor by surgery. To reduce risk of recurrence chemo- or radiotherapy are given as a complement to surgery. p73 is a structural and functional homologue of tumor suppressor p53. However, p73 is rarely mutated in tumors, but rather overexpressed as compared to normal tissue. There are two main isoforms of p73, the transactivation capable TAp73 and the truncated ΔNp73, which are involved in an autoregulatory loop with TAp73 and p53.The aim of this study was to investigate the role of p73 and related proteins in the development and treatment of CRC. A G4C14-to-A4T14 polymorphism of p73 was studied in CRC patients and healthy controls (Paper I), and rectal cancer patients who were randomized to treatment with either surgery alone or preoperative radiotherapy and surgery (Paper II). The AT/AT genotype of the p73 polymorphism may increase risk of CRC development and CRC patients with the AT allele had a better prognosis. When dividing the cases into colon and rectal cancer it was seen that in colon cancer the AT allele tended to be more favorable for overall survival, while in rectal cancer the GC allele seemed to be more favorable. Rectal cancer patients, with a combination of GC/GC genotype, wild type p53 and weak survivin expression survived longer after preoperative radiotherapy. This was not observed in the patients only receiving surgery. The protein expression of p73 was further studied in the rectal cancer patients randomized to treatment with either surgery alone or preoperative radiotherapy and surgery (Paper III). p73 was expressed higher in tumor tissue than in normal mucosa. Patients with p73 negative tumors had a lower risk of local recurrence after radiotherapy, as opposed to patients that had p73 positive tumors or patients with p73 negative tumors that did not receive radiotherapy. Effects of γ-radiation was further studied in colon cancer cell lines KM12C, KM12SM and KM12L4a regarding cell cycle, survival fraction (clonogenicity), apoptosis and protein expression patterns of mutated p53, TAp73, ΔNp73, survivin and PRL-3 (Paper IV). KM12C displayed low survival fraction, low apoptosis, no cell cycle arrest and an upregulation of the antiapoptotic ΔNp73 after irradiation. KM12L4a showed a high survival fraction, but high apoptosis, arresting of the cell cycle and upregulation of the radio-resistance factor survivin. The effects of overexpression and knockdown of survivin on TAp73, ΔNp73 and p53 expression in colon cancer cell lines HCT-116p53+/+ and HCT-116p53-/- with and without γ-radiation were studied (Paper V). Overexpression of survivin decreased wild type p53, whilst downregulation of survivin lead to a simultaneous downregulation of TAp73 and ΔNp73, mRNA and protein, both with and without γ- radiation. Knockdown of survivin also demonstrated an increase in apoptosis.In conclusion, we showed that the G4C14-to-A4T14 polymorphism of p73 and p73 protein expression may be involved in CRC development, radiotherapy response and survival. We further showed that TAp73, ΔNp73 and p53 were regulated by survivin in colon cancer cells.
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| 10. |
- Sun, Xiao-Feng, 1959-
(författare)
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Expression of ras and p53, DNA ploidy and 5-phase fraction in human colorectal adenocarcinoma
- 1993
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The accumulation of oncogene and anti-oncogene alterations play an important role in the development of colorectal adenocarcinomas. These specific gene alterations cause changes of DNA ploidy and cell proliferation and, in turn, DNA instability might lead to more genetic changes. In the present work, the expression of ras p21 (79 cases) and p53 protein (293 cases) was investigated by immunohistochemistry, and DNA ploidy and S-phase fraction (279 cases) were measured by flow cytometry on colorectal adenocarcinomas.Overexpression of ras p21, nuclear and cytoplasmic p53 were found in 58%, 39% and 25% of the tumours, respectively, while in normal colorectal cases, only 35% were ras positive and no case showed p53 staining. Overexpression of ras was significantly associated with a high S-phase fraction. The frequencies of ras and nuclear p53 staining tended to be increased in DNA non-diploid tumours compared with diploid tumours. Cytoplasmic p53 positive tumours were more common in the proximal colon, while DNA non-diploid tumours were more frequent in the distal colon and rectum. The intensity of ras staining was significantly related to grade of differentiation and increased from Dukes' stage A to C tumours. Cytoplasmic p53 staining increased from Dukes' stage A to D tumours. In multivtiriate survival analyses of patients with Dukes' stage A-C tumours, the prognosticsignificance of ras expression remained even after adjustment for both stage and DNA ploidy. Nuclear p53 and cytoplasmic p53 staining prognosticated clinical Outcome independent of stage, DNA ploidy and each other. DNA non-diploidy predicted an unfavourable survival irrespective of stage, nuclear and cytoplasmic p53 expression. A highS-phase fraction was significantly associated with poor survival in univariate analysis but not after adjustment for other prognostic factors. Analyses in subgroups of tumours showed that the prognostic importance of cytoplasmic p53 expressionwas greater in patients with DNA diploid tumours than in those with non·diploid tumours, and that DNA ploidy exhibited prognostic effect in patients with Dukes' stage B tumours as well as in those with stage C tumours. We conclude that immunohistochemistry and flow cytometry may be used to detect overexpression ofras p21, nuclear p53 and cytoplasmic p53 as wellas abnormal DNA content, and that these alterations may be implicated in different biological mechanisms of colorectal adenocarcinomas and provide important prognostic information.
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