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Background/aim Chronic inflammation generates large quantities of reactive oxygen and nitrogen species that damage DNA. DNA repair is important for cellular viability and genome integrity. Materials and methods Expression levels of the DNA repair proteins OGG1, XPA, MLH1, PARP1, and XRCC6, which function in base excision repair, nucleotide excision repair, mismatch repair, single-strand break repair and double-strand break repair, respectively, were assessed using immunohistochemistry in ulcerative colitis and sporadic colorectal cancer biopsies. Levels of oxidative/ nitrosative stress biomarkers were also assessed. Results Ulcerative colitis and colorectal cancer lesions expressed significantly higher levels of all DNA repair proteins and oxidative/ nitrosative stress biomarkers compared to normal colonic mucosa. Ulcerative colitis had the highest XPA and XRCC6 expression. Conclusion Oxidative/nitrosative stress is prevalent in the colon of both diseases. Nucleotide excision repair and non-homologous end-joining double-strand break repair may be compromised in colorectal cancer, but not in ulcerative colitis.

Background Keratoacanthoma (KA) has a unique life cycle of rapid growth and spontaneous regression that shows similarities to the hair follicle cycle, which involves an active Wnt signaling during physiological regeneration. We analyzed the expression of the Wnt signaling proteins β-catenin, Lef1, Sox9, and Cyclin D1 in young and old human KAs to investigate a possible role for Wnt signaling in KAs. Aim To investigate the role of the Wnt/β-catenin signaling pathway in human KAs. Methods and results Formalin-fixed, paraffin-embedded tissue samples of 67 KAs were analyzed for protein expression using immunohistochemistry. The majority of KAs were positive for Sox9 and Cyclin D1 but not for nuclear-localized β-catenin or Lef-1. No significant differences in protein expressions were seen between young and old KAs. However, we found a significant association between Ki67 and Cyclin D1 proteins (P= .008). Conclusions The Wnt signaling pathway does not appear to play a significant role in the biogenesis of human KA. Sox9 overexpression may be indicative of inhibition of Wnt signaling. Sox-9 and Cyclin D1 are proliferation markers that are most likely transactivated by alternate signaling pathways.

Background Keratoacanthoma (KA) is a common keratinocytic skin neoplasm that typically develops rapidly and undergoes complete spontaneous regression. As the pro-apoptotic p53 protein may be involved in the lifecycle of KA, we studied the p53 status throughout the main stages of KA that include proliferation, maturation and regression in a large series of lesions. Methods One-hundred and twenty-four KAs were characterized with respect to age of the lesions both clinically and histopathologically, in addition to phenotypic characteristics such as cellular atypia, infiltration, inflammation and fibrosis. Tp53 mutations were detected by capillary electrophoresis, and p53 protein levels were assessed by immunohistochemistry. Results Tp53 mutations were detected in 49 cases (39.5%) and were associated with high p53 protein levels (p = 0.007) and histopathologic age of the lesions (p = 0.044). Significant association was also seen between high p53 protein levels and atypia (p = 0.036), whereas the association with infiltration showed borderline significance (p = 0.057). High p53 protein levels were significantly associated with gene mutations in transplanted, but not in non-transplanted patients. Conclusion We show a high frequency of Tp53 mutations in KAs that is associated with increased p53 levels. The results indicate a role for the p53 protein in KA development.

Background The colon and rectum are continuously exposed to oxidative stress that generates reactive oxygen species, which are a major cause of DNA double-strand breaks (DSB). Furthermore, chronic inflammatory diseases such as ulcerative colitis (UC) are characterized by an excess of reactive nitrogen species that can also lead to DNA double-strand breakage and genomic instability. We investigated the expression of the nuclear casein kinase and cyclin-dependent kinase substrate 1 (NUCKS1) protein in UC and sporadic colorectal cancer (CRC) due to its involvement in both DNA double-strand break repair and inflammatory signaling. Methods NUCKS1 expression and expression of the DNA double-strand break marker gamma-H2AX (γH2AX) were assessed in formalin-fixed, paraffin-embedded UC and CRC patient biopsies using peroxidase immunohistochemistry. Expression levels for both proteins were evaluated together with previously published expression-level data for hTERT and TP53 proteins in the same material. Results Nondysplastic UC lesions had 10-fold lower γH2AX expression and approximately 4-fold higher NUCKS1 expression compared with sporadic CRC, indicating minimal DNA DSB damage and heightened DNA DSB repair in these lesions, respectively. NUCKS1 expression in UC tended to decrease with increasing grades of dysplasia, whereas γH2AX, hTERT, and TP53 expression tended to increase with increasing grades of dysplasia. The highest γH2AX expression was seen in sporadic CRC, indicating considerable DNA DSB damage, whereas the highest NUCKS1 expression and hTERT expression were seen in nondysplastic UC. Conclusions Overall, our data suggest that NUCKS1 may be involved in DNA DSB repair and/or inflammatory signaling in UC, but a more thorough investigation of both pathways in UC is warranted.

Keratoacanthoma (KA) is a common keratinocytic skin neoplasm that typically develops rapidly and undergoes complete spontaneous regression. As the pro-apoptotic p53 protein may be involved in the lifecycle of KA, we studied the p53 status throughout the main stages of KA that include proliferation, maturation and regression in a large series of lesions.One-hundred and twenty-four KAs were characterized with respect to age of the lesions both clinically and histopathologically, in addition to phenotypic characteristics such as cellular atypia, infiltration, inflammation and fibrosis. Tp53 mutations were detected by capillary electrophoresis, and p53 protein levels were assessed by immunohistochemistry.Tp53 mutations were detected in 49 cases (39.5%) and were associated with high p53 protein levels (p = 0.007) and histopathologic age of the lesions (p = 0.044). Significant association was also seen between high p53 protein levels and atypia (p = 0.036), whereas the association with infiltration showed borderline significance (p = 0.057). High p53 protein levels were significantly associated with gene mutations in transplanted, but not in non-transplanted patients.We show a high frequency of Tp53 mutations in KAs that is associated with increased p53 levels. The results indicate a role for the p53 protein in KA development.

Background The glycerophospholipid lysophosphatidic acid (LPA), which is present in most tissues and in high concentrations in saliva, may exert profound effects on oral cancer cells. We have investigated mitogenic signalling induced by LPA in the two oral carcinoma cell lines, D2 and E10, focusing on the role of EGFR transactivation and downstream pathways. Methods Two oral squamous carcinoma cell lines, D2 and E10, were analysed for effects of LPA on signalling pathways and induction of DNA synthesis. Pathway activation was investigated by examining phosphorylation of signalling proteins and by the use of specific pathway inhibitors. Results The D2 cells had higher levels of activated signalling proteins and higher DNA synthesis activity in the basal condition than E10 cells. EGF did not induce proliferation in D2 cells, whereas LPA induced proliferation in both cell lines, by mechanisms depending on EGFR transactivation. Release of EGFR ligands was involved in basal and LPA-induced proliferation in both D2 and E10 cells. The proliferation in D2 cells was dependent on the PI3K/Akt pathway, but not the MEK/ERK pathway. In E10 cells, the PI3K/Akt, MEK/ERK and p38 pathways were all involved in the proliferation. Conclusion Transactivation of EGFR is required for LPA-induced DNA synthesis in D2 and E10 cells. Our results also show that although proliferation of oral carcinoma cells is regulated by several pathways, and differentially in E10 and D2 cells, the PI3K pathway has a crucial role in both cell lines.

Data are limited on oncogene mutation frequencies in polyps from principally asymptomatic participants of population-based colorectal cancer screening studies. In this study, DNA from 204 polyps, 5 mm or larger, were collected from 176 participants of the NORCCAP screening study and analyzed for mutations in KRAS, BRAF, and PIK3CA including the rarely studied KRAS exons 3 and 4 mutations. KRAS mutations were identified in 23.0% of the lesions and were significantly associated with tubulovillous adenomas and large size. A significantly higher frequency of KRAS mutations in females was associated with mutations in codon 12. The KRAS exon 3 and 4 mutations constituted 23.4% of the KRAS positive lesions, which is a larger proportion compared to previous observations in colorectal cancer. BRAF mutations were identified in 11.3% and were associated with serrated polyps. None of the individuals were diagnosed with de novo or recurrent colorectal cancer during the follow-up time (median 11.2 years). Revealing differences in mutation-spectra according to gender and stages in tumorigenesis might be important for optimal use of oncogenes as therapeutic targets and biomarkers.