Epithelial markers of colorectal carcinogenesis in ulcerative colitis and primary sclerosing cholangitis

Therapeutic potential of traditional Chinese medicine in the prevention and treatment of digestive inflammatory cancer transformation: Portulaca oleracea L. as a promising drug

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) has been used for centuries to treat various types of inflammation and tumors of the digestive system. Portulaca oleracea L. (POL), has been used in TCM for thousands of years. The chemical composition of POL is variable and includes flavonoids, alkaloids, terpenoids and organic acids and other classes of natural compounds. Many of these compounds exhibit powerful anti-inflammatory and anti-cancer-transforming effects in the digestive system.

AIM OF STUDY

In this review, we focus on the potential therapeutic role of POL in NASH, gastritis and colitis and their associated cancers, with a focus on the pharmacological properties and potential mechanisms of action of the main natural active compounds in POL.

METHODS

The information and data on Portulaca oleracea L. and its main active ingredients were collated from various resources like ethnobotanical textbooks and literature databases such as CNKI, VIP (Chinese literature), PubMed, Science Direct, Elsevier and Google Scholar (English literatures), Wiley, Springer, Tailor and Francis, Scopus, Inflibnet.

RESULTS

Kaempferol, luteolin, myricetin, quercetin, genistein, EPA, DHA, and melatonin were found to improve NASH and NASH-HCC, while kaempferol, apigenin, luteolin, and quercetin played a therapeutic role in gastritis and gastric cancer. Apigenin, luteolin, myricetin, quercetin, genistein, lupeol, vitamin C and melatonin were found to have therapeutic effects in the treatment of colitis and its associated cancers. The discovery of the beneficial effects of these natural active compounds in POL supports the idea that POL could be a promising novel candidate for the treatment and prevention of inflammation-related cancers of the digestive system.

CONCLUSION

The discovery of the beneficial effects of these natural active compounds in POL supports the idea that POL could be a promising novel candidate for the treatment and prevention of inflammation-related cancers of the digestive system. However, clinical data describing the mode of action of the naturally active compounds of POL are still lacking. In addition, pharmacokinetic data for POL compounds, such as changes in drug dose and absorption rates, cannot be extrapolated from animal models and need to be measured in patients in clinical trials. On the one hand, a systematic meta-analysis of the existing publications on TCM containing POL still needs to be carried out. On the other hand, studies on the hepatic and renal toxicity of POL are also needed. Additionally, well-designed preclinical and clinical studies to validate the therapeutic effects of TCM need to be performed, thus hopefully providing a basis for the validation of the clinical benefits of POL.

Molecular mechanisms in colitis-associated colorectal cancer

Sustained chronic inflammation of the large intestine leads to tissue damage and repair, which is associated with an increased incidence of colitis-associated colorectal cancer (CAC). The genetic makeup of CAC is somewhat similar to sporadic colorectal carcinoma (sCRC), but there are differences in the sequence and timing of alterations in the carcinogenesis process. Several models have been developed to explain the development of CAC, particularly the "field cancerization" model, which proposes that chronic inflammation accelerates mutagenesis and selects for the clonal expansion of phenotypically normal, pro-tumorigenic cells. In contrast, the "Big Bang" model posits that tumorigenic clones with multiple driver gene mutations emerge spontaneously. The details of CAC tumorigenesis-and how they differ from sCRC-are not yet fully understood. In this Review, we discuss recent genetic, epigenetic, and environmental findings related to CAC pathogenesis in the past five years, with a focus on unbiased, high-resolution genetic profiling of non-dysplastic field cancerization in the context of inflammatory bowel disease (IBD).

Genetic Profiling of Colorectal Carcinomas of Patients with Primary Sclerosing Cholangitis and Inflammatory Bowel Disease

BACKGROUND

Patients with primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD) run a 10-fold increased risk of developing colorectal cancer (CRC) compared to patients with IBD only. The aim of this study was to perform an extensive screen of known carcinogenic genomic alterations in patients with PSC-IBD, and to investigate whether such changes occur already in nondysplastic mucosa.

METHODS

Archival cancer tissue and nondysplastic mucosa from resection specimens of 19 patients with PSC-IBD-CRC were characterized, determining DNA copy-number variations, microsatellite instability (MSI), mutations on 48 cancer genes, and CpG island methylator phenotype (CIMP). Genetic profiles were compared with 2 published cohorts of IBD-associated CRC (IBD-CRC; n = 11) and sporadic CRC (s-CRC; n = 100).

RESULTS

Patterns of chromosomal aberrations in PSC-IBD-CRC were similar to those observed in IBD-CRC and s-CRC, MSI occurred only once. Mutation frequencies were comparable between the groups, except for mutations in KRAS, which were less frequent in PSC-IBD-CRC (5%) versus IBD-CRC (38%) and s-CRC (31%; P = .034), and in APC, which were less frequent in PSC-IBD-CRC (5%) and IBD-CRC (0%) versus s-CRC (50%; P < .001). Cases of PSC-IBD-CRC were frequently CIMP positive (44%), at similar levels to cases of s-CRC (34%; P = .574) but less frequent than in cases with IBD-CRC (90%; P = .037). Similar copy number aberrations and mutations were present in matched cancers and adjacent mucosa in 5/15 and 7/11 patients, respectively.

CONCLUSIONS

The excess risk of CRC in patients with PSC-IBD was not explained by copy number aberrations, mutations, MSI, nor CIMP status, in cancer tissue, nor in adjacent mucosa. These findings set the stage for further exome-wide and epigenetic studies.

AGPAT1 as a Novel Colonic Biomarker for Discriminating Between Ulcerative Colitis With and Without Primary Sclerosing Cholangitis

INTRODUCTION

Ulcerative colitis (UC) associated with primary sclerosing cholangitis (PSC-UC) is considered a unique inflammatory bowel disease (IBD) entity. PSC diagnosis in an IBD individual entails a significantly higher risk of gastrointestinal cancer; however, biomarkers for identifying patients with UC at risk for PSC are lacking. We, therefore, performed a thorough PSC-UC biomarker study, starting from archived colonic tissue.

METHODS

Proteins were extracted out of formalin-fixed paraffin-embedded proximal colon samples from PSC-UC (n = 9), UC (n = 7), and healthy controls (n = 7). Patients with IBD were in clinical and histological remission, and all patients with UC had a history of pancolitis. Samples were processed by the multienzyme digestion FASP and subsequently analyzed by liquid chromatography-tandem mass spectrometry. Candidate proteins were replicated in an independent cohort (n: PSC-UC = 16 and UC = 21) and further validated by immunohistochemistry.

RESULTS

In the discovery step, 7,279 unique proteins were detected. The top 5 most differentiating proteins (PSC-UC vs UC) based on linear regression analysis were selected for replication. Of these, 1-acetylglycerol-3-phosphate O-acyltransferase 1 (AGPAT1) was verified as higher in PSC-UC than UC (P = 0.009) in the replication cohort. A difference on the group level was also confirmed by immunohistochemistry, showing more intense AGPAT1 staining in patients with PSC-UC compared with UC.

DISCUSSION

We present AGPAT1 as a potential colonic biomarker for differentiating PSC-UC from UC. Our findings have possible implication for future PSC-IBD diagnostics and surveillance.

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.

Malignancies in Primary Sclerosing Cholangitis--A Continuing Threat

Primary sclerosing cholangitis (PSC) is a chronic inflammatory liver disease of unknown etiology, primarily targeting cholangiocytes at any portion of the biliary tree. No effective medical treatments are currently available. A unique feature of PSC is its close association (about 80%) with inflammatory bowel disease (IBD), mainly ulcerative colitis (UC). As in many chronic inflammatory conditions, cancer development can complicate PSC, accounting for >40% of deaths. Cholangiocarcinoma (CCA), gallbladder carcinoma (GBC) and colorectal carcinoma (CRC) have been variably associated to PSC, with a prevalence up to 13-14%. The risk of cancer is one of the most challenging issues in the management of PSC; it raises several questions about cancer surveillance, early diagnosis, prevention and treatment.

KEY MESSAGES

Among the different cancers complicating PSC, CCA is the most relevant, because it is more frequent (incidence of 0.5-1.5%) and because the prognosis is poor (5-year survival <10%). Early diagnosis of CCA in PSC can be difficult because lesions may not be evident in radiological studies. Surgical resection provides disappointing results; liver transplantation combined with neoadjuvant chemoradiotherapy is being proposed, but this approach is limited to a highly selected group of patients and is available only in a few specialized centers. Similar to CCA, GBC carries a dismal prognosis. Since it is difficult to discriminate GBC from other gallbladder abnormalities, cholecystectomy has been proposed in all gallbladder lesions detected in PSC, regardless of their size. CRC is a frequent complication of PSC associated to UC; its incidence steadily increases with time of colitis, reaching up to 20-30% of the patients after 20 years. Colonoscopy with extensive histologic sampling at an annual/biannual interval is an effective surveillance strategy. However, when dysplastic lesions are detected, preemptive proctocolectomy should be considered.

CONCLUSIONS

PSC may be regarded as paradigmatic of the sequence leading from chronic inflammatory epithelial damage to neoplastic transformation. Understanding the molecular mechanisms regulating this pathogenetic sequence, may improve strategies of disease surveillance and cancer prevention and treatment. PSC is a chronic inflammatory cholangiopathy of unknown etiology but likely immune-mediated, characterized by peribiliary inflammation and fibrosis leading to strictures in any portion (intra- and/or extrahepatic) of the bile duct system. No effective medical treatments are currently available. A unique feature of PSC is the close association (about 80%) with IBD, mainly UC, often diagnosed before PSC (PSC/UC). As in other chronic inflammatory diseases, development of malignancies is a feared complication of PSC.

Chronic ulcerative colitis and colorectal cancer

One of the most important consequences of chronically active ulcerative colitis (UC) or Crohn's disease (CD) - the two major forms of inflammatory bowel disease (IBD) - is the development of colorectal cancer (CRC). An increased risk for the occurrence of CRC in up to 30% of affected patients after 35years of UC has been reported. Recent evidence from population based studies indicates a lower risk. Nevertheless the incidence is still significantly increased as compared to individuals without chronic colitis. Colitis-associated CRC (CAC) does not display the adenoma-carcinoma sequence which is typical for sporadic CRC and the pathophysiology appears to be different. Chronic inflammation and the increased turnover of epithelial cells contribute to the development of low- and high-grade dysplasia which may further transform into CAC. Reactive oxygen species (ROS) generated by the inflammatory infiltrate are thought to contribute to the generation of dysplastic lesions. In sporadic CRC the sequence of mutations that finally lead to malignancy involves early activation of Wnt/β-catenin pathway (in 90% of cases) including mutations in adenomatous polyposis coli (APC) tumor suppressor gene, its regulating kinase GSK3β and β-catenin itself. β-catenin mutations are rarer in CAC and mutations in APC occur rather late during the disease progression, whereas there are earlier mutations in p53 and K-ras. Recent data indicate that the intestinal microbiome and its interaction with a functionally impaired mucosal barrier may also play a role in CAC development. CACs frequently show aggressive growth and early metastases. The treatment of CAC in patients with colitis always includes proctocolectomy with ileoanal anastomosis as meta- or synchronic lesions are frequent.