| 1. |
- Andersson, Charlotta, 1976-
(author)
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Significance of Wilms’ tumor gene 1 as a biomarker in acute leukemia and solid tumors
- 2016
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Doctoral thesis (other academic/artistic)abstract
- Wilms’ tumor gene 1 (WT1) is a zinc finger transcriptional regulator with crucial functions in embryonic development. Originally WT1 was described as a tumor suppressor gene, but later studies have shown oncogenic properties of WT1 in a variety of tumors. Because of its dual functions in tumorigenesis, WT1 has been described as a chameleon gene. In this thesis, the significance of WT1 as a biomarker was investigated in acute myeloid leukemia (AML), clear cell renal cell carcinoma (ccRCC), ovarian carcinoma (OC) and childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL).Previous studies have suggested that expression of WT1 is a potential marker for detection of minimal residual disease (MRD) in AML. We aimed to define expression of WT1 as an MRD marker in AML. In adult AML patients, we found that a reduction of WT1 expression in bone marrow (≥ 1-log) detected less than 1 month after diagnosis was associated with an improved overall survival (OS) and freedom from relapse (FFR). In peripheral blood, a reduction of WT1 expression (≥ 2-log) detected between 1 and 6 months after treatment initiation was associated with an improved OS and FFR.WT1 harbor pathogenic genetic variants in a considerable proportion of AML and T-lymphoblastic leukemia (T-ALL), but mutations have not been reported in BCP-ALL. We aimed to evaluate the clinical impact of WT1 mutations and single nucleotide polymorphisms (SNPs) in BCP-ALL. Pathogenic mutations in the WT1 gene were rarely seen in childhood BCP-ALL. However, five WT1 SNPs were identified. In survival analyses, WT1 SNP rs1799925 was found to be associated with worse OS, indicating that WT1 SNP rs1799925 may be a useful marker for clinical outcome in childhood BCP-ALL. We also explored whether WT1 mutations and SNPs in ccRCC could be used as biomarkers for risk and treatment stratification. We therefore examined whether SNPs or mutations in WT1 were associated with WT1 expression and clinical outcome. Sequencing analysis revealed that none of the previously reported WT1 mutations were found in ccRCC; however, we identified six different WT1 SNPs. Our data suggest that pathogenic WT1 mutations are not involved in ccRCC, and the prognostic significance of WT1 SNPs in ccRCC is considerably weak. However, a favorable OS and disease-specific survival were found in the few cases harboring the homozygous minor allele.OC has a poor prognosis, and early effective screening markers are lacking. Serous OCs are known to express the WT1 protein. Overexpressed oncogenic proteins can be considered potential candidate antigens for cancer vaccines and T-cell therapy. It was therefore of great interest to investigate whether anti-WT1 IgG antibody (Ab) measurements in plasma could serve as biomarkers of anti-OC response. We found limited prognostic impact, but the results indicated that anti-WT1 IgG Ab measurements in plasma and WT1 staining in tissue specimens could be potential biomarkers for patient outcome in the high-risk subtypes of OCs.In conclusion, the results of this thesis indicate that WT1 gene expression can provide information about MRD of patients with AML, and WT1 SNP rs1799925 may be used as a biomarker for predicting clinical outcome in childhood BCP-ALL. In ccRCC, the prognostic significance of WT1 SNPs is weak and limited to the subgroup of patients that are homozygous for the minor allele. In OCs anti-WT1 IgG Ab measurement in plasma and WT1 staining in tissue specimens could possibly be used as biomarkers for predicting patient outcome in the high-risk subtypes of OCs.
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| 2. |
- Li, Xingru, 1987-
(author)
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Wilms' tumor gene 1 in different types of cancer
- 2015
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Doctoral thesis (other academic/artistic)abstract
- The Wilms’ tumor gene 1 (WT1) was first reported as a tumor suppressor gene in Wilms’ tumor. However, later studies have shown the oncogenic properties of WT1 in a variety of tumors. It was recently proposed that WT1 was a chameleon gene, due to its dual functions in tumorigenesis. We aimed to investigate the clinical significance of WT1 as biomarker in acute myeloid leukemia (AML) and clear cell renal cell carcinoma (ccRCC) and to elucidate the function of WT1 as an oncogene in squamous cell carcinoma of head and neck (SCCHN).In AML, it was suggested that WT1 expression was an applicable marker of minimal residual disease (MRD). In adult patients with AML, we found a good correlation between WT1 expression levels normalized to two control genes, β-actin and ABL. Outcome could be predicted by a reduction in WT1 expression in bone marrow (≥ 1-log) detected less than 1 month after diagnosis, when β-actin was used as control. Also, irrespective of the control gene used, outcome could be predicted by a reduction in WT1 expression in peripheral blood (≥ 2-log) detected between 1 and 6 months after treatment initiation.Previous studies in RCC demonstrated that WT1 acted as a tumor suppressor. Thus, we tested whether single nucleotide polymorphisms (SNPs) or mutations in WT1 might be associated with WT1 expression and clinical outcome in patients with ccRCC. We performed sequencing analysis on 10 exons of the WT1 gene in a total of 182 patient samples, and we identified six different SNPs in the WT1 gene. We found that at least one or two copies of the minor allele were present in 61% of ccRCC tumor samples. However, no correlation was observed between WT1 SNP genotypes and RNA expression levels. Moreover, none of the previously reported WT1 mutations were found in ccRCC. Nevertheless, we found that a favorable outcome was associated the homozygous minor allele for WT1 SNP. We then further investigated whether WT1 methylation was related to WT1 expression and its clinical significance. Methylation array and pyrosequencing analyses showed that the WT1 promoter region CpG site, cg22975913, was the most frequently hypermethylated CpG site. We found a trend that showed nearly significant correlation between WT1 mRNA levels and hypermethylation in the 5’-untranslated region. Hypermethylation in the WT1 CpG site, cg22975913, was found to be associated with patient age and a worse prognosis.One previous study reported that WT1 was overexpressed in SCCHN. That finding suggested that WT1 might play a role in oncogenesis. We found that both WT1 and p63 could promote cell proliferation. A positive correlation between WT1 and p63 expression was observed, and we identified p63 as a WT1 target gene. Furthermore, several known WT1 and p63 target genes were affected by knocking down WT1. Also, co-immunoprecipitation analyses demonstrated a protein interaction between WT1 and p53.In summary, WT1 gene expression can provide useful information for MRD detection during treatment of patients with AML. In RCC, our results suggested that the prognostic impact of WT1 SNPs was limited to the subgroup of patients that were homozygous for the minor allele, and that WT1 promoter hypermethylation could be used as a prognostic biomarker. In SCCHN, WT1 and p63 acted as oncogenes by affecting multiple genes involved in cancer cell growth.
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| 3. |
- Li, Xingru, et al.
(author)
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Wilms' tumor gene 1 regulates p63 and promotes cell proliferation in squamous cell carcinoma of the head and neck
- 2015
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In: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 15
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Journal article (peer-reviewed)abstract
- Background: Wilms' tumor gene 1 (WT1) can act as a suppressor or activator of tumourigenesis in different types of human malignancies. The role of WT1 in squamous cell carcinoma of the head and neck (SCCHN) is not clear. Overexpression of WT1 has been reported in SCCHN, suggesting a possible oncogenic role for WT1. In the present study we aimed at investigating the function of WT1 and its previously identified protein partners p63 and p53 in the SCCHN cell line FaDu. Methods: Silencing RNA (siRNA) technology was applied to knockdown of WT1, p63 and p53 in FaDu cells. Cell proliferation was detected using MTT assay. Chromatin immunoprecipitation (ChIP)/PCR analysis was performed to confirm the effect of WT1 on the p63 promoter. Protein co-immunoprecipitation (co-IP) was used to find protein interaction between WT1 and p53/p63. Microarray analysis was used to identify changes of gene expression in response to knockdown of either WT1 or p63. WT1 RNA level was detected using real-time quantitative PCR (RT-qPCR) in patients with SCCHN. Results: We found that WT1 and p63 promoted cell proliferation, while mutant p53 (R248L) possessed the ability to suppress cell proliferation. We reported a novel positive correlation between WT1 and p63 expression. Subsequently, p63 was identified as a WT1 target gene. Furthermore, expression of 18 genes involved in cell proliferation, cell cycle regulation and DNA replication was significantly altered by downregulation of WT1 and p63 expression. Several known WT1 and p63 target genes were affected by WT1 knockdown. Protein interaction was demonstrated between WT1 and p53 but not between WT1 and p63. Additionally, high WT1 mRNA levels were detected in SCCHN patient samples. Conclusions: Our findings suggest that WT1 and p63 act as oncogenes in SCCHN, affecting multiple genes involved in cancer cell growth.
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| 4. |
- Wu, Chen, et al.
(author)
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WT1 Enhances Proliferation and Impedes Apoptosis in KRAS Mutant NSCLC via Targeting cMyc
- 2015
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In: Cellular Physiology and Biochemistry. - : S. Karger AG. - 1015-8987 .- 1421-9778. ; 35:2, s. 647-662
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Journal article (peer-reviewed)abstract
- Background: A novel link between oncogenic KRAS signalling and WT1 was recently identified. We sought to investigate the role of WT1 and KRAS in proliferation and apoptosis. Methods: KRAS mutations and WT1 (cMyc) expression were detected using Sanger sequencing and real-time PCR in 77 patients with non-small cell lung cancer (NSCLC). Overexpression and knockdown of WT1 were generated with plasmid and siRNA via transient transfection technology in H1299 and H1568 cells. MTT assay for detection of cell proliferation, and TUNEL assay amd proteomic profiler assay for apoptosis evaluation were carried out. Dual luciferase reporter assay and ChIP-PCR were performed to validate the effect of WT1 on the cMyc promoter. Results: KRAS mutations showed a negative impact on overall survival ( OS). High expressions of WT1 and cMyc were associated with poor OS in KRAS mutant subgroup. The potential mechanisms that WT1 promotes proliferation and impedes apoptosis through affecting multiple apoptosis-related regulators in KRAS mutant NSCLC cells were identified. WT1 could activate cMyc promoter directly in KRAS mutant cells. Conclusion: The results suggest that WT1 and c-MYC expression is important for survival in KRAS mutant tumors as opposed to KRAS wild-type tumors. For treatment of KRAS mutant NSCLC, targeting WT1 and cMyc may provide alternative therapeutic strategies.
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| 5. |
- Ling, Agnes, 1976-
(author)
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Immune cell infiltration and prognosis in colorectal cancer
- 2018
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Doctoral thesis (other academic/artistic)abstract
- Background: Colorectal cancer (CRC) is globally the second most common form of cancer among women, and third in men. It is also one of the most common causes of cancer-related death in high-income countries. Surgical resection is the basis for curative therapy but still almost half of the patients die from metastatic disease. It is therefore imperative to strive on in the search for more efficient strategies to improve patient survival. The success scores for accurate prediction of patient prognosis remain discouraging and novel markers to identify high-risk patients are called for.The tumour immune response has proven critical to prognosis in CRC. A high amount of tumour infiltrating lymphocytes have in studies been found to significantly improve patient outcome. The opposite has been seen in patients with sparsely infiltrated tumours. Findings in this area have driven forth the design of the Immunoscore® system, which may be implemented in clinic as a complement to the TNM staging system. Ongoing research is also focusing on which immune evading mechanisms CRC might deploy in order to progress and metastasize.Aim: To study immune cell infiltration in relation to prognosis in CRC. More specifically the aim has been to investigate the prognostic importance of different subsets of immune cells infiltrating the tumour, not only according to quantity but also to intratumoural subsite (tumour invasive front, tumour centre and within the tumour epithelium). The tumour immune response was also evaluated in different molecular subgroups of CRC. Another part of this thesis concerns possible molecular mechanisms involved in tumour immune escape in CRC.Methods: CRC cases in the Colorectal Cancer in Umeå Study (CRUMS) were evaluated using immunohistochemistry, gene expression analyses as well as methylation analyses. Cytokine and chemokine expression was evaluated in CRC tumour tissues and one CRC cell line (Caco2) and derivatives using semi-quantitative real-time PCR. Methylation was analysed using methylation-specific pyrosequencing.Results: We found high quantities of both cytotoxic T cells (CTLs) as well as of regulatory T cells (Tregs) to associate with a better patient outcome. The infiltration of CTLs within the tumour epithelium provided the strongest prognostic information, whilst Tregs withheld the strongest association to prognosis at the tumour invasive front and tumour centre. We could further show that a high Th1 lymphocyte infiltration was strongly associated with a better prognosis in patients with CRC, independently of intratumoural subsite. Another finding was that the extent of Th1 infiltration and patient outcome differed in different molecular subgroups of CRC. We also found down-regulation of TAP1, a protein involved in antigen presentation by MHC class I, to be significantly associated with low infiltration of various subtypes of immune cells. Down-regulation of TAP1 was also correlated to poor prognosis in patients with early stages of CRC. Furthermore, we found TAP1 expression to be inversely correlated with methylation at sites close to the TAP1 promoter region.Conclusion: Tumour infiltrating T lymphocytes have a significant positive impact on prognosis in CRC patients. Different subsets of T lymphocytes vary in their dependency on intratumoural subsite, in to what extent they exert their prognostic influence. We moreover found varying Th1 lymphocyte infiltration rates as well as prognostic impact thereof, in different molecular subgroups of CRC. Our results also show down-regulation of TAP1 to be a mechanism of tumour immune escape in CRC. Further findings suggest methylation of the TAP1 gene to be a putative mechanism for TAP1 down-regulation.
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| 6. |
- Ling, Agnes, 1976-, et al.
(author)
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TAP1 down-regulation elicits immune escape and poor prognosis in colorectal cancer
- 2017
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In: Oncoimmunology. - 2162-4011 .- 2162-402X. ; 6:11
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Journal article (peer-reviewed)abstract
- The anti-tumor immune response has been shown to be of great prognostic importance in colorectal cancer (CRC) and so has the tumors ability for immune evasion. Our aim of this study was to investigate tumor factors that influence immunity. We used a gene expression array to search for potential mechanisms of tumor immune escape. One candidate gene identified was TAP1, involved in antigen presentation by MHC class I. TAP1 protein expression was evaluated by immunohistochemistry in 436 CRC patients of the Colorectal Cancer in Umeå Study cohort. We found a significant association between a downregulated expression of TAP1 and low infiltration of various subtypes of lymphocytes as well as macrophages. A downregulated expression of TAP1 was further found to be independent of molecular characteristics, suggesting TAP1 down-regulation to reach beyond the well described highly immunogenic MSI CRCs. A low expression of TAP1 was also significantly associated with poor prognosis in patients with CRC, a result that stayed significant in tumor front of early stage tumors (stage I-II) through multivariable analyses. Furthermore, we found that TAP1 expression was inversely correlated with methylation at sites in close proximity to the promoter region. In summary, our results show down-regulation of TAP1 to be a general mechanism of tumor immune escape in CRC and a poor prognostic factor in stage I-II CRC patients. We also suggest that methylation of the TAP1 gene may be a putative mechanism for TAP1 downregulation.
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| 7. |
- Lundberg, Ida, et al.
(author)
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MicroRNA expression in KRAS- and BRAF-mutated colorectal cancers
- 2018
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In: Anticancer Research. - : International Institute of Anticancer Research. - 0250-7005 .- 1791-7530. ; 38:2, s. 677-683
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Journal article (peer-reviewed)abstract
- Background/Aim: KRAS and BRAF are two genes commonly mutated in colorectal cancer (CRC). Even though BRAF is a downstream target of KRAS in the MAPK signalling pathway, KRAS- and BRAF-mutated CRCs are found to display several different clinical and histopathological features. We investigated whether a differential expression of microRNAs (miRNAs) could explain the clinicopathological differences seen between KRAS-and BRAF-mutated CRCs.Materials and Methods: Using a PCR array, we analyzed the expression of 84 different miRNAs in CRC cell lines wild-type in KRAS and BRAF, or mutated in KRAS or BRAF.Results: Ten miRNAs were selected for further analyses in tumor tissue specimens (let-7a, let-7i, miR-10a, miR-10b, miR-31, miR-100, miR-181a, miR-181b, miR-372, and miR-373). BRAF-mutated tumors were found to express significantly higher levels of miR-31 as well as significantly lower levels of miR-373, compared to wild-type tumors.Conclusion: Our results suggest that KRAS and BRAF-mutated CRCs may have different miRNA signatures compared to CRC tumors wild-type in KRAS and BRAF. However, no difference in expression levels between KRAS-and BRAF-mutated tumors was evident for the miRNAs analyzed in this study.
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| 8. |
- Wikberg, Maria L., et al.
(author)
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Neutrophil infiltration is a favorable prognostic factor in early stages of colon cancer
- 2017
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In: Human Pathology. - : Elsevier BV. - 0046-8177 .- 1532-8392. ; 68, s. 193-202
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Journal article (peer-reviewed)abstract
- The tumor immune response has been proven critical to prognosis in colorectal cancer (CRC), but studies on the prognostic role of neutrophil infiltration have shown contradictory results. The aim of this study was to elucidate the prognostic role of infiltrating neutrophils at different intratumoral subsites and in different molecular subgroups of CRC. The relations between neutrophil infiltration and infiltration of other immune cells (T-cell and macrophage subsets) were also addressed. Expression of the neutrophil marker CD66b was assessed by immunohistochemistry in 448 archival human tumor tissue samples from patients surgically resected for CRC. The infiltration of CD66b-positive cells was semi-quantitatively evaluated along the tumor invasive front, in the tumor center, and within the tumor epithelium (intraepithelial expression). We found that poor infiltration of CD66b-positive cells in the tumor front indicated a worse patient prognosis. The prognostic significance of CD66b infiltration was found to be mainly independent of tumor molecular characteristics and maintained significance in multivariable analysis of stage I-II colon cancers. We further analyzed the prognostic impact of CD66b-positive cells in relation to other immune markers (NOS2, CD163, Tbet, FOXP3, and CD8) and found that neutrophil infiltration, even though strongly correlated to infiltration of other immune cell subsets, had additional prognostic value. In conclusion, we find that low infiltration of neutrophils in the tumor front is an independent prognostic factor for a poorer patient prognosis in early stages of colon cancers. Further studies are needed to elucidate the biological role of neutrophils in colorectal carcinogenesis.
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