Upregulation of p16(INK4A) and Bax in p53 wild/p53-overexpressing crypts in ulcerative colitis-associated tumours

Proposal for an Organ-Specific Chronic Inflammation–Remodeling–Carcinoma Sequence

An organ-specific chronic inflammation–remodeling–carcinoma sequence has been proposed, mainly for the alimentary tract. As representative diseases, gastroesophageal reflux disease, chronic gastritis and inflammatory bowel disease (ulcerative colitis and Crohn’s disease of the colitis type) were adopted for this discussion. Tissue remodeling is such an important part of tumorigenesis in this sequence that an organ-specific chronic inflammation–remodeling–carcinoma sequence has been proposed in detail. Chronic inflammation accelerates the cycle of tissue injury and regeneration; in other words, cell necrosis (or apoptosis) and proliferation result in tissue remodeling in long-standing cases of inflammation. Remodeling encompasses epithelial cell metaplasia and stromal fibrosis, and modifies epithelial–stromal cell interactions. Further, the accumulation of genetic, epigenetic and molecular changes—as well as morphologic disorganization—also occurs during tissue remodeling. The expression of mucosal tissue adapted to chronic inflammatory injury is thought to occur at an early stage. Subsequently, dysplasia and carcinoma develop on a background of remodeling due to continuous, active inflammation. Accordingly, organ-specific chronic inflammation should be ameliorated or well controlled with appropriate monitoring if complete healing is unachievable.

p53 expression in patients with ulcerative colitis - associated with dysplasia and carcinoma: a systematic meta-analysis

Background

Tumor suppressor gene p53 expression has been reported in patients with ulcerative colitis (UC). However, the correlation between p53 expression and UC remains controversial. The aim of this meta-analysis was to investigate the association between p53 expression and different pathological types of UC.

Methods

Publications were searched in the PubMed, Embase, EBSCO, Wangfang, and CNKI databases. The overall odds ratios (ORs) and their corresponding 95% confidence intervals (95% CIs) were summarized in this study.

Results

Final 19 papers were identified in this meta-analysis, including 1068 patients with UC and 130 normal tissue samples. Immunohistochemical p53 expression was significantly higher in UC without dysplasia and carcinoma (UC group) compared to normal tissue samples (OR = 3.14, P = 0.001), higher in UC with dysplasia than in UC group (OR = 10.76, P < 0.001), and higher in UC with colorectal cancer (CRC) than in UC with dysplasia (OR = 1.69, P = 0.035). Subgroup analysis of ethnicity (UC group vs. normal tissues) showed that p53 expression was correlated with UC in Asians, but not in Caucasians. When UC with dysplasia was compared to UC group, p53 expression was linked to UC with dysplasia among both Asians and Caucasians. When UC-CRC was compared to UC with dysplasia, p53 expression was not associated with UC-CRC in both Caucasians and Asians.

Conclusions

p53 expression was closely associated with UC-CRC development. p53 expression showed different ethnic characteristics among different pathological types of UC.

Electronic supplementary material

The online version of this article (10.1186/s12876-017-0665-y) contains supplementary material, which is available to authorized users.

Small bowel adenocarcinomas complicating Crohn's disease are associated with dysplasia: a pathological and molecular study

BACKGROUND

Crohn's disease (CD) is associated with an increased risk of small bowel adenocarcinoma (SBA). However, there are no guidelines for the screening and early diagnosis of SBA. Colorectal cancer associated with chronic colitis arises from dysplasia. High-risk patients benefit from surveillance colonoscopies aimed to detect dysplasia. The dysplasia-carcinoma sequence remains poorly documented in CD-associated SBA. Moreover, molecular data about SBA complicating CD and associated dysplasia are very limited. We therefore assessed dysplasia and several key molecular markers of carcinogenesis in SBA and dysplasia developed in patients with CD.

METHODS

Forty-five SBA complicating CD and 4 specimens with dysplasia without SBA were screened. In SBA, we looked for dysplasia and determined their pathological characteristics (type, grade, distribution). We also stained for mismatch repair proteins (MLH1, MSH2, MSH6, PMS2), p53, β-catenin, and p16 and looked for KRAS, BRAF and PIK3CA mutations.

RESULTS

All neoplastic lesions, except 1 lesion, were found in inflamed mucosal areas. Dysplasia was found in 20 of 41 patients with SBA (49%). Dysplasia was flat or raised, low grade or high grade, and adjacent or distant to concomitant SBA. Molecular markers of SBA carcinogenesis complicating CD were similar to those observed in chronic colitis-related colorectal cancer (KRAS, BRAF, p53, MSI), although differences were observed for β-catenin and p16. No PIK3CA mutations were observed.

CONCLUSIONS

These results suggest that there is an inflammation-dysplasia-adenocarcinoma sequence in at least half of CD-related SBA, similar to what is observed in chronic colitis-related colorectal cancer and may have implications for the prevention and treatment of this cancer.

Ulcerative colitis-associated colorectal cancer arises in a field of short telomeres, senescence, and inflammation

Inflammation plays a role in the progression to cancer and it is linked to the presence of senescent cells. Ulcerative colitis (UC) is a chronic inflammatory disease that predisposes to colorectal cancer. Tumorigenesis in this setting is associated with telomere shortening that can be observed in the nondysplastic epithelium of UC patients with high-grade dysplasia (HGD) or cancer (UC progressors). We hypothesized that a preneoplastic field of inflammation, telomere shortening, and senescence underlies tumor progression in UC progressors. Multiple biopsies of varying histologic grade were collected along the colon of nine UC progressors and analyzed for telomere length, DNA damage, senescence, p53, p16, and chronic and acute inflammation. Twenty biopsies from four UC nonprogressors and twenty-one biopsies from control individuals without UC were also analyzed. Short telomeres and increased DNA damage, senescence, and infiltrating leukocytes were observed in biopsies located less than 10 cm from HGD or cancer. Low-grade dysplasia (LGD) had the shortest telomeres along with the highest levels of senescence and infiltrating leukocytes, whereas HGD biopsies showed the opposite pattern. The expression of p16 and p53 was low in nondysplastic biopsies but progressively increased in LGD and HGD. In addition, high levels of infiltrating leukocytes were associated with telomere shortening, senescence, and reduced p53 expression. These results suggest that dysplasia arises in a preneoplastic field of chronic inflammation, which leads to telomere shortening, DNA damage, and senescence. Our findings argue that senescence acts as a tumor suppressor mechanism that is abrogated during the transition from LGD to HGD in UC.

CITED2 is activated in ulcerative colitis and induces p53-dependent apoptosis in response to butyric acid

BACKGROUND

In ulcerative colitis (UC), Fusobacterium varium is significantly detected in patients' mucosa, and butyric acid (BA), abundantly produced by the bacterium, activates the p53 system and induces epithelial apoptosis, as we previously reported. However, factors active in the link between BA and p53 have yet to be clarified. Here, we identified a gene activated by BA specifically in UC-associated cancer cell lines and ascertained the mechanism of its activation of p53.

METHODS

cDNA microarray analysis based on the Percellome (per cell normalization) method was performed on BA-stimulated UC-associated cancers and sporadic colorectal cancer cell lines under conditions mimicking colonic epithelium UC. For validation of microarray results, molecular, biochemical, and histopathological analyses were performed.

RESULTS

We found the CBP/p300-interacting transactivator with glutamic acid/asparagine-rich carboxy-terminal domain 2 (CITED2) to be specifically upregulated in UC-associated cancer cell lines by BA treatment, at both mRNA and protein expression levels. CITED2 could be shown to induce p53 acetylation and p53-dependent apoptosis, accompanied by binding of CBP/p300. BA-dependent apoptosis was suppressed by an inhibitor of monocarboxylate transporter-1 and an siRNA for p53. In inflammatory foci of UC, histologically evident inflammatory activity and CITED2 expression were significantly correlated.

CONCLUSIONS

CITED2 was identified as UC-associated protein by cDNA microarray based on the Percellome method under UC-mimicking conditions in vitro. CITED2 activation may induce mucosal apoptosis and erosion by activating p53 and thus play a critical role in linking enteric bacteria with mucosal inflammation in UC.

Oxidative stress in ulcerative colitis-associated carcinogenesis

Oxidative stress is defined as an imbalance between generation of reactive oxygen species (ROS) and decreased antioxidant defense systems. Oxidative stress develops particularly in inflammatory reactions because the inflammatory cells, neutrophils, and macrophages produce large amounts of ROS. It has been known for a long time that oxidative stress in inflamed tissue can pave the way for malignant tumors, and that it is a major pathogenetic factor for the well-established correlation between inflammatory diseases and cancer. Oxidative stress has long been associated with the pathogenesis of chronic inflammatory bowel disease (IBD)-related colorectal cancer. This article provides an overview of the pathology of ROS and presents recent advances concerning the role of ROS in IBD-related colorectal carcinogenesis (Fig. 1).

Epithelial and stromal genetic instability linked to tumor suppressor genes in ulcerative colitis-associated tumorigenesis

OBJECTIVE

We have previously documented not only epithelial but also stromal genetic instability in ulcerative colitis (UC)-associated lesions, including adenocarcinomas, using microsatellite markers close to the p53 gene on chromosome 17 (Chr.17). However, about half of the UC-associated tumors do not have p53 gene alterations. The purpose of this study was to detect early genetic instability (loss of heterozygosity (LOH) and microsatellite instability (MSI)) of both epithelial and stromal cells in UC-associated tumorigenesis, using different microsatellite markers from the p53 gene.

MATERIAL AND METHODS

The laser-captured microdissection-PCR-GeneScan method was applied to investigate genetic instability in both the epithelial and stromal elements of early UC-associated lesions (regenerative mucosa and dysplasia) and carcinomas using multiple microsatellite markers, chiefly close to tumor suppressor genes (TSGs: p16(INK4A), Rb, Smad4 and fragile histidine triad (FHIT)). Furthermore, expression of their gene products was analyzed by immunohistochemistry.

RESULTS

In epithelium, although LOH for Chr.17 markers increased along with histological progression, the frequencies of LOH or MSI for TSG markers were found to be almost constantly increased in both stromal and epithelial components of all lesion types. In contrast, genetic instability of National Cancer Institute (NCI)-recommended standard markers was not found to be significantly correlated with UC-associated tumorigenesis. Immunohistochemically, epithelial p16(INK4A) expression tended to be decreased in LOH-positive lesions (p = 0.0780) and Smad4 expression was significantly decreased (p < 0.05).

CONCLUSIONS

These results suggest that genetic instability in the stroma, especially regarding TSG markers, may play an important role in early-phase, UC-associated tumorigenesis. In addition, decreased expression of TSG due to genetic alteration might contribute to tumorigenesis.

Midkine expression in colorectal tumors: correlation with Ki-67 labeling in sporadic, but not ulcerative colitis-associated ones

Midkine (MK) is a heparin-binding growth factor encoded by a retinoic acid responsive gene. To investigate the possible contribution of MK to genesis of colorectal carcinomas, an immunohistochemical examination of protein expression was conducted in sporadic and ulcerative colitis (UC)-associated tumors. MK expression significantly differed among normal mucosa, adenomas with low-grade dysplasia (LGD), adenomas with high-grade dysplasia (HGD) and invasive adenocarcinomas: MK expression was increased along with tumor progression. UC-associated lesions (regenerative mucosa of UC, UC-associated dysplasia and UC-associated adenocarcinoma) had similar variations. MK expression in UC-associated lesions was significantly higher than in normal mucosa, although there was no significant difference among UC-associated lesions. However, in UC-associated dysplasia, MK expression did not differ between the upper and lower halves, in contrast to adenoma with LGD and HGD, in which MK expression was significantly higher in the upper than lower halves, corresponding to cell proliferative zone. Furthermore, correlations with Ki-67 and single-strand DNA labeling, respectively, reflecting cellular proliferative activity and apoptosis, were noted in sporadic but not UC-associated lesions. These results suggest that MK is involved in genesis/development of sporadic colorectal tumors as well as of UC-associated tumors, but might contribute differently to genesis/development in these two types of tumors.

Induction of the tumor-suppressor p16(INK4a) within regenerative epithelial crypts in ulcerative colitis

p16(INK4a) is a major tumor-suppressor protein, but its regulation and settings of fuction remain poorly understood. To explore the notion that p16 is induced in vivo in response to replicative stress, we examined p16 expression in tissues from human ulcerative colitis (UC; n = 25) and normal controls (n = 20). p16 was expressed strongly in UC-associated neoplasms (n = 17), as seen previously in sporadic colonic neoplasms. In non-neoplastic UC epithelium, p16 was expressed in 33% of crypts (the proliferative compartment) compared to < 1% of normal controls. p16 expression did not correlate with degree of inflammation but did correlate with the degree of crypt architecture distortion (P = .002)-a reflection of epithelial regeneration. In coimmunofluorescence studies with Ki67, p16 expression was associated with cell cycle arrest (P < .001). Both UC and normal crypts displayed evidence for the activation of the DNA damage checkpoint pathway, and p16 was induced in primary cultures of normal epithelial cells by ionizing irradiation (IR). However, induction by IR displayed delayed kinetics, implying that p16 is not an immediate target of the checkpoint pathway. These findings support a model in which p16 is induced as an "emergency brake" in cells experiencing sustained replicative stress.

Cancer surveillance in inflammatory bowel disease: new molecular approaches

PURPOSE OF REVIEW

Patients with chronic inflammatory bowel disease, such as ulcerative colitis and Crohn's disease, have an increased risk of colorectal cancer. Life-long colonoscopy surveillance is performed to detect the presence of dysplasia, but this approach is expensive and time-consuming. Thus, there is intensive research to identify molecular factors with prognostic value. This review summarizes recent research, with a special emphasis on the mechanisms underlying these molecular alterations.

RECENT FINDINGS

The role of chromosomal instability in the progression to inflammatory bowel disease-associated colorectal cancer is clear and likely relates to chronic cycles of injury, inflammation, repair and telomere shortening. The role of microsatellite instability has been a subject of discussion, and data suggest that microsatellite instability in inflammatory bowel disease might be different from microsatellite instability in sporadic colorectal cancer. Methylation, as a mechanism of gene silencing, also plays a role in ulcerative colitis tumorigenesis. Chronic inflammation has been linked to p53 activation and oxidative stress, contributing to the extensive genomic DNA damage observed in ulcerative colitis.

SUMMARY

Improved understanding of the molecular biology of cancer progression in inflammatory bowel disease will hopefully lead to the identification of useful prognostic biomarkers. Efforts are needed to prove the clinical utility of the most promising markers now identified.

p53, Ki-67, and serum alpha feto-protein as predictors of hepatocellular carcinoma recurrence in liver transplant patients

Patients with hepatocellular carcinoma who undergo orthotopic liver transplantation (OLT) are at risk for post-transplant tumor recurrence. The aim of this study was to evaluate whether expression of p53 and Ki-67 in hepatocellular carcinoma lesions present in explanted liver tissue was associated with time to tumor recurrence after OLT. Subjects consisted of 20 consecutive patients who underwent OLT and were found to have hepatocellular carcinoma in the liver explant. Immunostaining for p53 and Ki-67 was performed by standard methods. The presence of nuclear immunostaining in >10% of the tumor tissue was considered positive. Time to recurrence of hepatocellular carcinoma after OLT was compared between patients with positive and negative immunostaining by the log rank test. Multivariate analysis was performed using a Cox regression model to control for potentially confounding clinical factors. Time to post-transplant hepatocellular carcinoma recurrence was significantly more rapid in p53+ (P=0.0007) and Ki-67+ cases (P=0.001). These associations remained significant in multivariate analysis. Furthermore, time to recurrent hepatocellular carcinoma was significantly shorter in patients with a serum alpha feto-protein (AFP) level >or=100 ng/ml at time of diagnosis, compared to those with an AFP level <100 ng/ml (P=0.003). In conclusion, expression of p53 and Ki-67 in hepatocellular carcinoma lesions, and a serum AFP level >or=100 ng/ml were associated with more rapid recurrence of hepatocellular carcinoma after OLT. Identification of patients at risk for early post-transplant recurrence could be used to guide surveillance and adjuvant treatment strategies.

Disruption of the p53-p53r2 DNA repair system in ulcerative colitis contributes to colon tumorigenesis

With ulcerative colitis (UC)-associated tumorigenesis, p53 gene alteration is considered to be a key event. To clarify whether the p53-checkpoint is operating in foci of inflammation and that its disruption is a feature of UC-associated neoplasms, the present immunohistochemical study was conducted. Since accumulation of butyric acid with active UC is associated with apoptosis, effects of in vitro exposure of newly established UC-cancer derived cell lines to organic acids were also assessed. The regulatory subunit of ribonucleotide reductase, p53R2, was found to be localized with p53 in situ, and levels of p53, phospho-p53, p53R2 and inducible nitric oxide synthase were significantly intercorrelated. However, p53R2 expression was clearly reduced with progression through UC-associated dysplasia to carcinoma, demonstrating an inverse relation with p53 overexpression. In vitro treatment with butyrate or propionic acid, but not succinic acid, elicited a positive response in the p53-p53R2 system. Moreover, p53-dependent DNA repair, investigated by radioactive nucleotide incorporation, was induced by butyric acid and inhibited by short-interfering p53 and p53R2 RNAs. Therefore, it was concluded that the p53-p53R2-dependent DNA repair system is constitutively stimulated by butyric acid, which accumulates in UC inflammatory lesions. Since failure of the p53-G(1) checkpoint may cause dysfunction of repair under the influence of butyrate, gene alterations may increase and spread through the genome, leading to tumorigenesis.