Expression of protein arginine methyltransferase‐5 in oral squamous cell carcinoma and its significance in epithelial‐to‐mesenchymal transition

Protein arginine methyltransferases (PRMT) 5, a member of type II arginine methyltransferases, catalyzes the symmetrical dimethylation of arginine residues on histone and non‐histone substrates. Although the overexpression of PRMT5 has been reported in various cancers, its role in oral squamous cell carcinoma (OSCC) has not been elucidated. In the present study, we immunohistochemically examined the expression of PRMT5 in surgically resected oral epithelial dysplasia (OED, n = 8), oral intraepithelial neoplasia (OIN)/carcinoma in situ (CIS) (n = 11) and OSCC (n = 52) with or without contiguous OED lesions. In the normal epithelium, PRMT5 was weakly expressed in the cytoplasm of basal layer cells. In OED, OIN/CIS, and OSCC, its expression consistently and uniformly increased in the cytoplasm of dysplastic and cancer cells. Moreover, nuclear and cytoplasmic localization was detected in the invasive front of cancer cells, particularly in cases showing poor differentiation or aggressive invasion patterns. The concomitant nuclear and cytoplasmic expression of PRMT5 correlated with the loss of E‐cadherin and cytokeratin 17, and the upregulation of vimentin, features that are both indicative of epithelial‐to‐mesenchymal transition. PRMT5 may play a role from early oncogenesis through to the progression of OSCC, particularly in the aggressive mode of stromal invasion.     

Expression of CD10 by stromal cells during colorectal tumor development

CD10 is a cell surface metalloprotease expressed by a variety of normal cell types, including lymphoid precursor cells, germinal center B lymphocytes, and some epithelial cells. We noticed that stromal cells of some cancers are positive for CD10. In this study, we investigated the role of CD10 produced by the stromal cells of colorectal neoplasms in the progression of colorectal neoplasms. Immunohistochemical examination of CD10 and p53 was performed in 169 colorectal epithelial neoplasms representing various stages of carcinogenesis. The results were correlated with the morphologic characteristics of the neoplasms. There was no expression of CD10 in the stromal cells of normal colorectal tissue. CD10-positive stromal cells were present adjacent to the tumor cells in 16 of 73 adenomas with mild or moderate dysplasia. More frequent expression of CD10 by the stromal cells was detected in adenomas with severe dysplasia (12 of 17), intramucosal carcinomas (10 of 16), and invasive carcinomas (50 of 63) than in adenomas with mild or moderate dysplasia (P < 0.0001). Expression of CD10 by > 10% of the stromal cells was detected only within the area of the invasive growth front of invasive carcinomas, not in adenomas and in only 1 of the intramucosal carcinomas. The difference between invasive and non invasive tumors was significant (P < 0.0001). The stromal expression of CD10 was significantly associated with the accumulation of p53 and a larger tumor size. These results indicate that CD10 expression is an integral part of colorectal carcinogenesis. CD10 expression seems to contribute to the invasion and thus probably facilitates metastasis.     

Early colorectal carcinomas: CD10 expression, mucin phenotype and submucosal invasion

We analyzed 170 tumors (polypoid, 98; non-polypoid, 72) of early colorectal carcinoma with or without submucosal invasions (Tis and T1 of TNM classification) from 161 patients to evaluate correlations between clinicopathological factors and immunohistochemical expressions of CD10, MUC2, and MUC5AC. The coexistence of adenomatous components was significantly less common in non-polypoid carcinomas (4.2%) than in polypoid carcinomas (66.3%) (P < 0.0001). Non-polypoid carcinomas were smaller in size and tended to infiltrate into the submucosa with higher incidence of lymphatic and venous permeations. CD10 was more frequently expressed in non-polypoid carcinomas (70.8%) than in polypoid carcinomas (51.0%) (P= 0.01). Total carcinomas with high grade atypia showed higher incidence of CD10 expression (60.6%) than those with low grade atypia (28.9%) (P < 0.0001). Carcinomas with low grade atypia exhibited a higher incidence of MUC2 and MUC5AC expression (91.1% and 57.8%, respectively), when compared with carcinomas with high grade atypia (41.6% and 20.0%, respectively) (both, P < 0.0001). In submucosal invasive carcinomas with residual intramucosal carcinoma component (IMCC), CD10 expression in IMCC and submucosal invasive carcinoma component (SMCC) simultaneously exhibited identical positive or negative results, regardless of the polypoid or non-polypoid growth pattern. The CD10 expression may occur in the early stage of carcinogenesis within the mucosa, and these neoplasms may retain CD10 in SMCC, possibly resulting in more advanced stages of stromal invasion and distant metastases. In conclusion, our data suggest that the CD10 expression and mucin phenotypes may be potentially useful markers for estimating biological properties of early colorectal carcinomas.     

Changes in E-cadherin immunoreactivity in the adenoma-carcinoma sequence of the large bowel

We have used an avidin-biotin immunoperoxidase technique to localise epithelial cadherin (E-cadherin), a calcium-dependent cell-cell adhesion molecule, in 107 paraffin-embedded sections from 93 patients consisting of 24 with colorectal adenoma, 55 with rectal carcinoma and 14 with liver metastases. The corresponding primary colorectal tumours were also studied in these cases. E-cadherin was expressed by normal colorectal epithelial cells with typical membranous staining at the intercellular junctions. Loss of normal membranous E-cadherin expression and presence of cytoplasmic staining were found frequently in adenomas larger than 1 cm (P<0.01), with high grade dysplasia and villous histology (P<0.01). In primary rectal cancers, loss of membranous expression correlated with high tumour grade. No correlation was seen with Dukes and Jass stage, local extramural spread and 5-year recurrence rate. Complete loss of membranous E-cadherin immunoreactivity was seen in 7/14 (50%) liver metastases in which 6/7 (86%) showed intense membranous E-cadherin immunoreactivity in the corresponding primary tumour. Our data indicate that changes in E-cadherin immunoreactivity and cellular localisation correlate with size, severe dysplasia in adenomas and tumour grade in carcinomas. However, there seems to be no correlation between loss of membranous E-cadherin immunoreactivity and the invasive and metastatic potential of the carcinomas.     

The Incidence of Apoptosis During Colorectal Tumorigenesis

Epithelial homeostasis in colorectal tumorigenesis is dependent not only on the rate of cell production but also on the rate of apoptosis, a genetically programmed process of autonomous cell death. Ideally, an analysis of cell kinetics should be carried out for both cell proliferation and death. We investigated the incidence of apoptosis in 35 colorectal neoplasms (15 adenomas and 20 carcinomas) using the DNA nick end labeling method (TUNEL). The expression of Ki-67 as a marker of proliferating activity and some kinds of oncogene products were analyzed immunohistochemically. When the TUNEL labeling index (TI) and the Ki-67 labeling index (KI) were determined, TI was found to be significantly higher in adenomas with high-grade dysplasia (TI: 2.5%) than in adenomas with low-grade dysplasia (TI: 0.6%) or carcinomas (TI: 1.4%). In contrast, KI increased with the progression of colorectal tumorigenesis. Moreover, TI of the carcinomas was significantly higher in c-Myc-positive cases than in c-Myc-negative cases (p<0.05). The results indicate that apoptosis plays an important role in the early stage of the adenoma-carcinoma sequence, permitting us to speculate that the increased tumor cell proliferation is negated by increased apoptosis at the stage of adenoma with high-grade dysplasia (or intramucosal carcinoma), while cell proliferation overwhelms cell death at the stage of invasive carcinoma. Int J Surg Pathol 8(2):123-132, 2000     

Morphogenesis of nonpolypoid colorectal adenomas and early carcinomas assessed by cell proliferation and apoptosis

Nonpolypoid neoplasms, as well as ordinary polypoid tumours, are occasionally found in the colorectum. To clarify whether cell kinetic status affects the macroscopic morphology of colorectal neoplasms, we investigated proliferative indices (PI), apoptotic indices (AI), and the expression of apoptosis-related gene products. We examined 110 colorectal neoplasms comprised of 36 polypoid, 38 flat elevated and 36 depressed tumours. According to WHO’s criteria these tumours consisted of 61 adenomas with low grade dysplasia (LGD), 30 adenomas with high grade dysplasia (HGD) and 19 carcinomas with submucosal invasion. Apoptotic cells were detected by TUNEL staining. Proliferating cells and apoptosis-related gene products were assessed by immunohistochemistry for Ki-67, p53, Bcl-2, and Bax antigens. AI were closely associated with macroscopic morphology in adenomas but not in carcinomas. PI were relatively constant among the three macroscopic types in adenomas and carcinomas. Median AI values of polypoid, flat elevated and depressed tumours were 1.8%, 2.1% and 4.6% for adenomas with LGD, 0.8%, 2.4% and 6.2% for adenomas with HGD and 2.9%, 4.0% and 3.6% for carcinomas, respectively. Overall PI were significantly higher in carcinomas than in adenomas with LGD, whereas AI were not different. Although the incidence of expression was significantly higher in carcinomas for p53 and in adenomas for Bcl-2 than the others, the expression of apoptosis-related gene products (p53, Bcl-2 and Bax) was similar among polypoid, flat elevated and depressed tumours. Macroscopic morphology of colorectal adenomas is determined by the apoptosis not by proliferation, and high apoptosis found in depressed adenomas implies their low net growth. Received: 1 July 1999 / Accepted: 17 January 2000     

Elevated early gastric carcinoma. Differential diagnosis as regards adenomatous polyps.

Differential diagnostic problems between gastric carcinomas and precancerous lesions with severe dysplasia have become more perceptible with the increasing number of resected early carcinomas. Although such problems come up for all macroscopic and histologic types of gastric cancer they are particularly marked between early carcinomas of the elevated type and adenomatous polyps. Elevated early carcinomas are usually highly differentiated adenocarcinomas with a morphology which often reminds of of adenomas. But sometimes the carcinomas also demonstrate convincing signs of being developed from adenomas. The criterion of distinction between intramucosal carcinomas and adenomas is invasion through the basal membrane, often difficult to evaluate. The morphological relation between elevated early gastric carcinomas and adenomas and the criterion of distinction between them were studied in 20 early gastric carcinomas of the Japanese types I and IIa, 6 intramucosal and 14 submucosal all highly differentiated adenocarcinomas, and in 42 polyps, of which 5 were of the adenomatous type. All lesions were taken from resection specimens. Among the carcinomas 5 demonstrated convincing signs of being malignant transformed adenomas. In addition, 6 carcinomas had a morphology which more or less reminded of adenomas, but their genetic origin was more uncertain. Nine carcinomas revealed no sign of an adenomatous origin. Among the 5 polyps diagnosed as adenomas 2 revealed an extraordinary degree of severe dysplasia which caused uncertainty on the benign diagnosis. The rest of the polyps were without dysplasia. The significance of invasion through the basal membrane as an indispensable factor of distinction between adenoma and carcinoma in the stomach is discussed. It is concluded that the degree of dysplasia can be so severe and the invasion so difficult to evaluate that the classification of some few tumours depends on the subjectivity of the single pathologist. Four of the tumours, 2 adenomas and 2 intramucosal carcinomas, having a remarkable macroscopic appearance like a large mucosal fold are especially mentioned. Their relation to gastric mucosal prolaps is discussed. Furthermore, a tumour apparently demonstrating only a moderate degree of dysplasia, but even so setting up metastases is mentioned in detail.     

Clinical significance of Fhit expression in development of colorectal carcinoma of various macroscopic types

It is unclear how expression of the FHIT (fragile histidine triad) gene by the colorectal neoplasm correlates with histogenesis and progression of the disease. We studied the association between expression of Fhit protein and development of colorectal carcinoma (CRC). We also examined relations between Fhit protein expression, macroscopic type, Ki-67 labeling index (LI), and p53 overexpression in carcinoma in situ. We examined 27 colorectal adenomas, 82 carcinomas in situ and 21 invasive CRCs resected endoscopically or surgically. The carcinomas in situ comprised three macroscopic types: polypoid (n=27), superficial (flat elevated, n=27; depressed, n=10) and granulonodular laterally spreading tumor (G-LST, n=23). Fhit, Ki-67, and p53 overexpression were examined immunohistochemically. Levels of Fhit protein were lower in invasive CRC than in adenoma and carcinoma in situ (p<0.01). In carcinoma in situ, reduced Fhit expression was observed in 7 of 22 (31.8%) polypoid types, 13 of 27 (48.1%) superficial flat elevated types, 8 of 10 (80%) superficial depressed types and 7 of 23 (30.4%) G-LST. Frequencies of reduced Fhit expression were significantly higher in the polypoid type and G-LST lesions than in the depressed type (p<0.05). Reduced expression of Fhit protein was related significantly to Ki-67 LI and p53 overexpression in carcinoma in situ (p<0.01). The present findings suggest that reduced expression of Fhit protein is related to development of colorectal neoplasm. Polypoid CRC and G-LST appear to differ from superficial depressed CRC in terms of Fhit expression.     

Telomerase activity and hTERT mRNA in development and progression of adenoma to colorectal cancer

Telomerase activity and hTERT mRNA expression are upregulated in colorectal cancer. Whether they are inherent in colorectal adenomas, premalignant lesions to cancer, however, remains to be elucidated. We examined telomerase activity by the fluorescence-based telomeric repeat amplification protocol method and analyzed the level of hTERT mRNA by real-time polymerase chain reaction in 74 surgically obtained neoplasms from 29 patients. The specimens were divided into 6 categories according to the criteria of the Vienna Classification. The control comprising 29 non-pathological mucosa were classified into category 1, 6 adenomas indefinite for neoplasia into category 2, 21 non-invasive low grade adenomas into category 3, 23 high grade adenomas or non-invasive carcinomas into category 4, and 15 intramucosal or submucosal carcinomas into category 5. Carcinoma invading beyond the submucosa (9 samples) was referentially subdivided into category 6. Telomerase activity (mean +/- standard error) in 1 categories to 6 were 5.0+/-1.2, 1.8+/-1.7, 4.3+/-1.6, 20.2+/-2.1, 36.4+/-5.5, and 55.5+/-8.2 units/microg protein, respectively. There were no statistical differences between categories 1 and 2, 1 and 3, and 2 and 3. A significant statistical difference in the other two was observed by the multiple comparison test. The mean levels of hTERT mRNA was 103.1+/-102.4, 103.6+/-103.0, 103.6+/-102.9, 103.7+/-102.9, 104.0+/-103.4, and 104.4+/-104.0 copies/microg total RNA, respectively. There was a significant statistical difference only between category 6 and each of the other categories. These results suggest that telomerase activation occurs during the progression from low-grade to high-grade dysplasia in adenomas and increases steadily with the progression of the degree of dysplasia and invasion during colorectal carcinogenesis, and that hTERT mRNA expression is a feature of the late stage development of colorectal cancer.     

Intraductal papillary-mucinous tumours represent a distinct group of pancreatic neoplasms: an investigation of tumour cell differentiation and K-ras,p53 and c-erbB-2 abnormalities in 26 patients

Intraductal papillary growth of mucin producting hypersecreting, columnar cells characterizes a group of rare pancreatic exocrine neoplasms which we propose to call intraductal papillary-mucinous tumors (IPMT). We analysed the histopathology of 26 IPMT in relation to gastro-enteropancreatic marker expression, genetic changes and biology. Four IPMT showing only mild dysplasia were considered to be adenomas. Nine tumours displayed moderate dysplasia and were regarded as borderline. Severe dysplasia-carcinoma in situ changes were found in 13 IPMT which were therefore classified as intraductal carcinomas. Six of these carcinomas were frankly invasive and two of these had lymph node metastases. The invasive component resembled mucinous noncystic carcinoma in all but one tumour which showed a ductal invasion pattern. Immunohistochemically, an intestinal marker type was found in most carcinomas, while gastric type differentiation prevailed among adenomas or borderline tumours. K-ras mutations (seven at codon 12 and one at codon 13) were found in 31% of IPMT (2 adenomas, 1 borderline, 5 carcinomas). Nuclear p53 overexpression was detected in 31% of IPMT (6 carcinomas and 2 borderline IPMT) and correlated with p53 mutations (one at exon 8 and the other at exon 5) in two carcinomas. p53 abnormalities were unrelated to K-ras mutation. c-erbB-2 overexpression was observed in 65% of IPMT, with various grades of dysplasia. Twenty-two of 24 patients are alive and well after a mean post-operative follow-up of 41 months. Only two patients, both with invasive cancer at the time of surgery, died of tumour disease. It is concluded that pancreatic IPMT encompass neoplasms which, in general, have a favorable prognosis, but are heterogeneous in regard to grade of dysplasia and marker expression. Adenoma, borderline tumour, intraductal carcinoma and invasive carcinoma can be differentiated. p53 changes but not K-ras mutation or c-erbB-2 overexpression are related to the grade of malignancy. Most IPMT differ in histological structure, marker expression and behaviour from ductal adenocarcinoma.     

Expression of MUC1 and MUC2 mucins and relationship with cell proliferative activity in human colorectal neoplasia

Our previous studies on MUC1 and MUC2 mucin expression in various human neoplasms have found that MUC1 expression is related with a poor outcome whereas MUC2 expression is related with a favorable outcome. In the present study, we examined the alteration of MUC1 and MUC2 antigens on malignant transformation of colorectal mucosa, and also its relationship with cell proliferative activity (Ki-67 labeling index) of neoplastic epithelial cells in 200 adenomas and 58 carcinomas. In the 200 adenomas, we analyzed a total of 400 adenomatous lesions (mild dysplasia, 200 lesions; moderate dysplasia, 153 lesions; severe dysplasia, 47 lesions). MUC1 was expressed in carcinomas (24%) and adenomas with severe dysplasia (4%), but was not expressed in adenomas with mild or moderate dysplasia. MUC2 was expressed in a significantly greater number of adenomas with mild dysplasia (72%) than in adenomas with moderate dysplasia (45%) or severe dysplasia (47%), as well as in the carcinomas (38%; P < 0.0001). The Ki-67 labeling index was significantly lower in the MUC2-positive cases than in the MUC2-negative cases in the adenomas with mild dysplasia (13.6 vs 24.2%; P < 0.0001) or moderate dysplasia (25.7 vs 44.4%; P < 0.0001), and in the carcinomas (32.5 vs 48.4%; P < 0.05). In conclusion, the data from our study indicate that increased MUC1 expression and reduced MUC2 expression may be related to malignant transformation of colorectal neoplasia. We also demonstrated that decreased MUC2 expression, which is correlated with increased Ki-67 labeling, may play an important role in the progression of colorectal adenomatous change.     

Clusterin expression is associated with decreased disease‐free survival of patients with colorectal carcinomas

Redondo M, Rodrigo I, Alcaide J, Tellez T, Roldan M J, Funez R, Diaz‐Martin A, Rueda A & Jiménez E
(2010) Histopathology 56, 932–936
Clusterin expression is associated with decreased disease‐free survival of patients with colorectal carcinomas Aims: It has been demonstrated that increased clusterin expression is involved in malignant progression and that anticlusterin treatment leads to selective apoptosis. The aim of this study was to determine the clinicopathological significance of clusterin expression in human colorectal carcinomas. Methods and results: The expression of clusterin was examined in 31 adenomas and 103 colorectal carcinomas. Normal epithelial cells were always negative for clusterin expression, but clusterin expression was present in 16% (5/31) of adenomas and this percentage increased in colorectal carcinomas (30%, 31/103). Immunopositivity always presented an apical cytoplasmic pattern. The expression level of clusterin did not correlate with age, gender, grade or stage. However, its expression was significantly associated with a decrease in disease‐free survival (P < 0.05). In a multivariate Cox proportional hazards model, clusterin expression remained a significant independent predictor. Conclusions: Clusterin expression may have a role in colonic carcinogenesis and may help identify patients with more aggressive tumours who may benefit from targeted therapy.     

Reciprocity between membranous and nuclear expression of β-catenin in colorectal tumours

 β-Catenin has a central role not only in linking the cadherin-mediated cell adhesion system but also in the intercellular signalling pathway. To investigate alterations of β-catenin in the development of colorectal carcinoma, the pattern of β-catenin expression was studied using immunohistochemistry in 74 sporadic colorectal adenomas, in histologically normal mucosa adjacent to 65 of these adenomas, and in 52 carcinomas arising in adenomas. All normal epithelia displayed cell boundary staining for β-catenin. Adenomas and carcinomas showed varying degrees of membranous staining. However, some tumours also showed nuclear staining of β-catenin protein. Decreased membranous and increased nuclear β-catenin staining were associated with increasing degrees of dysplasia in adenomas (P < 0.005, P < 0.05, respectively). Carcinomas manifested significantly reduced membranous, but enhanced nuclear β-catenin expression compared with their associated adenomas (P < 0.001, P < 0.005, respectively). An inverse correlation was found between decreased membranous and increased nuclear staining of β-catenin in both adenomas and carcinomas (P < 0.025, P < 0.05, respectively). The data confirm that reduced membranous and increased nuclear expression of β-catenin is associated with the progression of colorectal adenomas to carcinomas. Our results also suggest that decreased membranous expression of β-catenin may result from aberrant localisation of the protein in the cell nucleus. Received: 1 January 1997 / Accepted: 26 February 1997     

结直肠肿瘤P53蛋白表达与肿瘤临床病理学特征及预后的关系

应用免疫组织化学方法观察７２例结直肠、１１例腺瘤、３０例癌旁粘主１５例正常粘膜Ｐ５３蛋白表达及其与肿瘤临床病理学特征和预后的关系。结果显示：结直肠癌Ｐ５３蛋白阳性率为５０％，腺瘤的阳性率为１８．１８％（Ｐ＜０．０５），阳性细胞主要分布在腺瘤的增生区或不典型增生区；正常粘膜、癌粘膜Ｐ５３蛋白均阴性。Ｐ５３蛋白阳性的结直肠癌多呈浸润性生长方式，且以浸润至浆膜外者居多，患者片存率较Ｐ５３蛋白阴性者（Ｐ＜     

High nuclear expression of phosphorylated extracellular signal–regulated kinase in tumor cells in colorectal glands is associated with poor outcome in colorectal cancer

Extracellular signal–regulated kinase (ERK) is a major downstream transducer of Ras and plays an important role in transducing extracellular signals to the nuclei of cells. It is located in both the cytoplasm and the nucleus of cells. The nuclear localization of phosphorylated or activated ERK is involved in the invasive behavior of tumor cells. We studied the association between Ras mutation/ERK activation and the prognosis of patients with colorectal cancer. We analyzed 126 surgically resected colorectal cancer specimens for K-Ras mutation using direct sequencing. Activation/phosphorylation of ERK was assayed by immunohistochemistry with tissue microarray, and the staining intensity was analyzed using a semiquantitative scoring system. K-Ras mutations were detected in 32.5% (41/126) of the colorectal tumors. Colorectal glands are important functional organs in colorectal tissue and form the origin of colorectal carcinomas. Tissue microarray immunohistochemistry tests showed that tumors in colorectal cancer specimens were significantly stained for phospho-ERK (100%; 126/126), whereas nonneoplastic colorectal glands mainly showed faint phosphorylated ERK staining. High nuclear phospho-ERK expression in tumors was associated with highly invasive cancer stage and T status of the disease. Kaplan-Meier analysis showed that nuclear but not cytoplasmic phosphorylated ERK expression correlated with the patients' overall survival rate (P = .039). Colorectal adenomas including tubular adenomas and tubulovillous adenomas mainly showed weak cytoplasmic phospho-ERK expression. Our results suggest that immunohistologic analysis of phosphorylated ERK expression in colorectal glands may aid the diagnosis of colorectal cancer and that nuclear phosphorylated ERK might be a valuable prognostic marker for colorectal cancer.     

Annexin A10 expression correlates with serrated pathway features in colorectal carcinoma with microsatellite instability

Annexin A10 (ANXA10) has recently been identified as a marker of sessile serrated adenomas/polyps of the colorectum. Although the serrated neoplasia pathway is thought to be involved in the majority of microsatellite instability‐high (MSI‐H) sporadic colorectal carcinomas (CRCs), the clinicopathological implications of ANXA10 expression in CRC are unknown. Here, we evaluated ANXA10 expression status in 168 MSI‐H CRCs by immunohistochemistry. Among 168 MSI‐H CRCs, nuclear staining for ANXA10 in tumor cells revealed 28 cases (17%) with ANXA10‐positive (ANXA10+) tumors. Most of the ANXA10+ tumors were located in the proximal colon (96%, p < 0.001). The ANXA10+ phenotype in MSI‐H CRC was significantly associated with female gender (68%, p = 0.016), CpG island methylator phenotype‐high (CIMP‐H) (68%, p < 0.001), MLH1 promoter hypermethylation (61%, p < 0.001), loss of MLH1 expression (82%, p = 0.019), and wild‐type KRAS status (96%, p = 0.023). Survival analysis revealed no prognostic significance of ANXA10 expression in MSI‐H CRC. In conclusion, ANXA10+ MSI‐H colon carcinomas are characterized by serrated pathway features, including proximal location, female predominance, and high frequencies of CIMP‐H status and MLH1 methylation.     

Identification of an intermediate signature that marks the initial phases of the colorectal adenoma-carcinoma transition

The colorectal adenoma-carcinoma sequence describes the stepwise progression from normal to dysplastic epithelium and then to carcinoma. Only a small proportion of colorectal adenomas (CRAs) progress to colorectal carcinomas (CRCs). Endoscopic intervention is currently being used on patients with high grade dysplasia CRAs, with diameters of >1 cm, or villous components of >25% who are at higher risk than other CRA sufferers. During the process, biopsy samples are taken for conventional histological diagnosis, but poor pathomorphological sensitivity and specificity greatly limit the diagnostic accuracy. Unfortunately, there are no reliable molecular criteria available that can predict the potential development of CRA to CRC. Gene expression profiles of normal colorectal mucosa (NOR), CRA and different Dukes' stages of CRC biopsy specimens, which represent the gradual progress of the CRA to CRC sequence, were determined by Affymetrix technology. Representative regulated genes were further analyzed by quantitative real-time PCR (qRT-PCR) and immunohistochemistry (IHC). Intersectional analyses of discriminative expression signatures of CRC vs. CRA and CRA vs. NOR allowed the identification of an intermediate signature of 463 probe sets (psets) that mark the NOR--> CRA-->CRC progression. This signature represents a reservoir of candidate markers for the early diagnosis of higher-risk CRA, thus allowing for timely therapeutic intervention and more selective treatment. A further 279 CRC-specific psets pointing to the malignant transition from CRA to CRC were identified and these could represent potential therapeutic targets for CRC. The reliability of the results was further confirmed by qRT-PCR and IHC analyses of the 4-gene sets randomly selected from the 463 psets.     

PDCD4 nuclear loss inversely correlates with miR-21 levels in colon carcinogenesis

Programmed cell death 4 (PDCD4) has recently been demonstrated to be a new tumor suppressor gene involved in colon carcinogenesis. PDCD4 immunohistochemical expression was assessed in 300 polypoid lesions of the colon mucosa (50 hyperplastic polyps [HP], 50 serrated adenomas [SA], 50 tubular adenomas with low-grade-intraepithelial neoplasia [LG-IEN], 50 tubular adenomas with high-grade-IEN [HG-IEN]), and in 50 colon adenocarcinomas (CRC). As normal controls, we considered 50 biopsy samples obtained from patients with irritable bowel syndrome (N). We further investigated PDCD4 messenger RNA (mRNA) levels by quantitative real-time polymerase chain reaction (PCR) in a different series of N, LG-IEN, HG-IEN, and CRC biopsy samples. miR-21 expression (an important PDCD4-expression regulator) was also determined by quantitative real-time PCR and in situ hybridization. Normal colocytes and HP featured strong PDCD4 nuclear immunostaining whereas a significantly lower PDCD4 nuclear expression was observed in dysplasia (low- and high-grade adenomas and SA) and invasive CRC. PDCD4 immunostaining and mRNA levels decreased significantly as the phenotypic changes occurring during colon carcinogenesis progressively increased (p < 0.001). As expected, miR-21 expression was significantly upregulated in preneoplastic/neoplastic samples, consistent with PDCD4 downregulation. These results consistently support the use of nuclear PDCD4 immunohistochemical downregulation as a novel biomarker for the diagnosis of dysplastic/neoplastic lesions in colon biopsy samples.