Serrated pathway adenocarcinomas: molecular and immunohistochemical insights into their recognition

Bioinformatic Identification of TP53 Gene Mutation Hotspots in Colorectal Cancer

Mutations and inactivation of the TP53 gene are frequently observed in various types of malignancies. Precise knowledge of the genetic structure and detection of mutation hotspots are crucial, as these indicate a high probability of developing cancer. The aim of our study was to perform the bioinformatic detection of mutation hotspots in the TP53 gene in patients diagnosed with malignant colon neoplasms using self-developed software (version 1). We compared TP53 gene sequences from 50 healthy individuals with those from 50 patients diagnosed with colorectal carcinoma. Of the 50 samples from cancer patients, the most frequent mutations were observed in exons 5 and 8 (12 mutations per exon) and gene sequences of 12 samples, which differed from those of the 50 samples from healthy individuals. Based on our results, the distribution of mutations in the TP53 gene structure was not even across different exons. By comparing the gene sequences of healthy individuals with those of colon cancer samples, we conclude that structural changes occurring in similar gene regions are not associated with increases in susceptibility to malignancies in every case, namely, that the pathological mechanism is multifactorial.

Investigation of ENO2 as a promising novel marker for the progression of colorectal cancer with microsatellite instability-high

BACKGROUND

Microsatellite instability-high (MSI-H) has emerged as a significant biological characteristic of colorectal cancer (CRC). Studies reported that MSI-H CRC generally had a better prognosis than microsatellite stable (MSS)/microsatellite instability-low (MSI-L) CRC, but some MSI-H CRC patients exhibited distinctive molecular characteristics and experienced a less favorable prognosis. In this study, our objective was to explore the metabolic transcript-related subtypes of MSI-H CRC and identify a biomarker for predicting survival outcomes.

METHODS

Single-cell RNA sequencing (scRNA-seq) data of MSI-H CRC patients were obtained from the Gene Expression Omnibus (GEO) database. By utilizing the copy number variation (CNV) score, a malignant cell subpopulation was identified at the single-cell level. The metabolic landscape of various cell types was examined using metabolic pathway gene sets. Subsequently, functional experiments were conducted to investigate the biological significance of the hub gene in MSI-H CRC. Finally, the predictive potential of the hub gene was assessed using a nomogram.

RESULTS

This study revealed a malignant tumor cell subpopulation from the single-cell RNA sequencing (scRNA-seq) data. MSI-H CRC was clustered into two subtypes based on the expression profiles of metabolism-related genes, and ENO2 was identified as a hub gene. Functional experiments with ENO2 knockdown and overexpression demonstrated its role in promoting CRC cell migration, invasion, glycolysis, and epithelial-mesenchymal transition (EMT) in vitro. High expression of ENO2 in MSI-H CRC patients was associated with worse clinical outcomes, including increased tumor invasion depth (p = 0.007) and greater likelihood of perineural invasion (p = 0.015). Furthermore, the nomogram and calibration curves based on ENO2 showed potential prognosis predictive performance.

CONCLUSION

Our findings suggest that ENO2 serves as a novel prognostic biomarker and is associated with the progression of MSI-H CRC.

OLFM2 promotes epithelial-mesenchymal transition, migration, and invasion in colorectal cancer through the TGF-β/Smad signaling pathway

BACKGROUND

Colorectal cancer (CRC) is an aggressive tumor of the gastrointestinal tract, which is a major public health concern worldwide. Despite numerous studies, the precise mechanism of metastasis behind its progression remains elusive. As a member of the containing olfactomedin domains protein family, olfactomedin 2 (OLFM2) may play a role in tumor metastasis. It is highly expressed in colorectal cancer, and its role in the metastasis of CRC is still unclear. As such, this study seeks to explore the function of OLFM2 on CRC metastasis and its potential mechanisms.

METHODS

Real-time fluorescence quantitative PCR and western blotting were used to study the expression of OLFM2 in human CRC and adjacent normal tissues. Knockdown and overexpression OLFM2 cell lines were constructed using siRNA and overexpression plasmids to explore the role of OLFM2 in the migration and invasion of CRC through transwell, and wound healing experiments. Finally, the expression of epithelial-mesenchymal transition (EMT) -related proteins and TGF-β/Smad signaling pathway-related proteins was investigated using western blotting.

RESULTS

In this study, we observed an elevation of OLFM2 expression levels in CRC tissues. To investigate the function of OLFM2, we overexpressed and knocked down OLFM2. We discovered that OLFM2 knockdown inhibited migration and invasion of colon cancer cells. Furthermore, E-cadherin expression increased while N-cadherin and Vimentin expression were opposite. It is no surprise that overexpressing OLFM2 had the opposite effects. We also identified that OLFM2 knockdown resulted in reduced TGF-βR1 and downstream molecules p-Smad2 and p-Smad3, which are related to the TGF-β / Smad pathway. In contrast, overexpressing OLFM2 significantly boosted their expression levels.

CONCLUSION

The protein OLFM2 has been identified as a crucial determinant in the progression of CRC. Its mechanism of action involves the facilitation of EMT through the TGF-β/Smad signaling pathway. Given its pivotal role in CRC, OLFM2 has emerged as a promising diagnostic and therapeutic target for the disease. These results indicate the potential of OLFM2 as a valuable biomarker for CRC diagnosis and treatment and highlight the need for further research exploring its clinical significance.

Molecular Diagnostics, Pathology and Biomarkers of Gastrointestinal Neoplasms

This Special Issue aims to highlight the advances made regarding the molecular profile of digestive system tumors in experimental and clinical studies [...].

A PAX-8-Positive Female Urethral Adenocarcinoma, Intestinal-Type: A Case Report with Diagnostic Challenges and a Review of the Literature

Female urethral adenocarcinoma (FUA) is extremely rare. It is an aggressive malignancy, and clear cell and columnar/mucinous ("intestinal") represent the two primary histologic subtypes. Diagnosis is often delayed in patients because of their vague symptomatology; hence, they present with an advanced disease and a poor prognosis. The rarity of FUA brings challenges when determining treatment and management, and treatment guidelines for various stages are lacking. We report an intestinal-type FUA that developed from inflammation-related metaplasia in urethral diverticulum with positive paired box 8 (PAX-8) staining. In addition to intestinal-type FUA being extremely rare, this particular entity exhibiting PAX-8 positivity has not been previously described, to the author's best knowledge. The present report highlights the importance of clinical and radiological assessment as well as histomorphologic and immunophenotypic features for an accurate diagnosis of this rare and aggressive malignancy.

Genomic and transcriptomic analysis of MSI-H colorectal cancer patients with targetable alterations identifies clinical implications for immunotherapy

Introduction

Targetable alterations such as BRAFV600E mutation and NTRK fusion are enriched in microsatellite instability-high (MSI-H) colorectal cancer (CRC). MSI-H with targetable alterations (MSI-H altered) might present unique opportunities for both targeted therapy and immunotherapy. We systematically evaluated the molecular characteristics and immune-related features of MSI-H altered and MSI-H without targetable alterations (MSI-H wt) CRC patients in our study.

Methods

Among 1938 continuously enrolled CRC patients, 126 patients with MSI-H status (6.50%) were included in this retrospective study. Genomic and transcriptomic data were investigated by next-generation sequencing (NGS) and gene expression profiling (GEP), respectively.

Results

BRAFV600E, NTRK1, and FGFR2 mutations were the most frequent targetable alterations in MSI-H CRC patients. The MSI-H altered phenotype was significantly associated with older age (p< 0.001), right side (p=0.024) and females (p= 0.036). No lynch syndrome (LS) patients were identified in MSI-H altered group. The tumor mutational burden (TMB), and tumor neoantigen burden (TNB) of MSI-H altered and wt subgroups were comparable (p<0.05). Subsequently, transcriptomic study analysis further revealed MSI-H altered CRC patients were linked to an immune-active tumor microenvironment with higher levels of Teff IFN-gamma, CYT, and MERCK 18 signatures, and lower levels of the IPRES gene signature, EMT and TGF Beta signatures. In addition, case study supported MSI-H CRC patient harboring targetable alterations might also achieved a long-term disease-free survival benefit from immunotherapy.

Discussion

Our study preliminary revealed MSI-H altered as a novel subtype of MSI-H CRC patients with unique molecular signatures and immune-active tumor microenvironment. Given the accessibility of immune checkpoint inhibitors (ICIs) treatment, our results might provide clinical evidence for immunotherapy in MSI-H CRC patients with targetable alterations.

Subcellular Expression of Maspin in Colorectal Cancer: Friend or Foe

In this review the authors aimed to emphasize the practical value of nuclear expression of the mammary serine protease inhibitor (maspin), also known as serpin B5 protein, in colorectal carcinoma (CRC), from pre-malignant disorders to carcinogenesis and metastasis. As the role of maspin is controversial and not yet understood, the present update highlights the latest data revealed by literature which were filtrated through the daily experience of the authors, which was gained at microscopic examination of maspin expression in CRCs and other tumors for daily diagnosis. Data regarding the subcellular localization of maspin, in correlation with the microsatellite status, grade of tumor dedifferentiation, and epithelial-mesenchymal transition (EMT) phenomenon of the tumor buds were presented with details. An original observation refers to the maspin capacity to mark the tumor cells which are "at the point of budding" that were previously considered as having "hybrid EMT phenotype". It refers to the transitional status of tumor cell that is between "epithelial status" and "mesenchymal status". The second original hypothesis highlights the possible role of maspin in dysregulating the intestinal microbiota, in patients with idiopathic inflammatory bowel diseases (IBD) and inducing IBD-related CRC. The dynamic process of budding and EMT of tumor buds, possible mediated by maspin, needs further investigation and validation in many human CRC samples. The histological and molecular data reveal that synthesis of maspin-based therapeutics might represent a novel individualized therapeutic strategy for patients with CRC.

Signal transduction pathway mutations in gastrointestinal (GI) cancers: a systematic review and meta-analysis

The present study was conducted to evaluate the prevalence of the signaling pathways mutation rate in the Gastrointestinal (GI) tract cancers in a systematic review and meta-analysis study. The study was performed based on the PRISMA criteria. Random models by confidence interval (CI: 95%) were used to calculate the pooled estimate of prevalence via Metaprop command. The pooled prevalence indices of signal transduction pathway mutations in gastric cancer, liver cancer, colorectal cancer, and pancreatic cancer were 5% (95% CI: 3–8%), 12% (95% CI: 8–18%), 17% (95% CI: 14–20%), and 20% (95% CI: 5–41%), respectively. Also, the mutation rates for Wnt pathway and MAPK pathway were calculated to be 23% (95% CI, 14–33%) and 20% (95% CI, 17–24%), respectively. Moreover, the most popular genes were APC (in Wnt pathway), KRAS (in MAPK pathway) and PIK3CA (in PI3K pathway) in the colorectal cancer, pancreatic cancer, and gastric cancer while they were beta-catenin and CTNNB1 in liver cancer. The most altered pathway was Wnt pathway followed by the MAPK pathway. In addition, pancreatic cancer was found to be higher under the pressure of mutation compared with others based on pooled prevalence analysis. Finally, APC mutations in colorectal cancer, KRAS in gastric cancer, and pancreatic cancer were mostly associated gene alterations.

Optimization of Immunophenotypic Panel to Differentiate Upper From Lower Gastrointestinal Adenocarcinomas: Analysis of New and Traditional Markers

Adenocarcinomas of the esophagus (EAC), stomach [gastric adenocarcinoma (GAC)], and colorectal carcinoma (CRC) frequently show similar morphology because upper gastrointestinal tumors (GITs) usually evolve from pathologies involving intestinal metaplasia. Upper and lower GIT may also show overlapping immunophenotypes when using the traditional CK7, CK20, and CDX2 panel, which in patients presenting with metastatic disease of unknown origin may lead to misdirected diagnostic workup and/or therapy. We compared the phenotype of upper and lower GIT using an expanded immunohistochemical panel that included the traditional and newer gastrointestinal markers: SATB2, DcR3, MUC5AC, and MUC6. The panel was applied to resection specimens from 40 CRC, 40 GAC, and 40 EAC. A panel using SATB2, CK7, and CDX2 provided the best discriminating power for separating upper from lower GIT and was applied to 101 biopsies including 17 EAC, 17 GAC, 19 CRC, 18 pancreatic adenocarcinomas, 15 cholangiocarcinomas, and 15 lung adenocarcinomas. The phenotype CK7/CDX2/SATB2 was moderately sensitive and highly specific of upper GIT, the phenotype CK7/CDX2/SATB2 was highly sensitive and specific for lower GIT, the phenotypes CK7/CDX2/SATB2 and CK7/CDX2/SATB2 favored pancreatobiliary or lung primaries. Less frequent phenotypes showed substantial overlap. Although strong diffuse expression of SATB2 was characteristic of CRC, weak and/or focal expression was present in one third or more of upper gastrointestinal, cholangiocarcinomas, and lung adenocarcinomas. DcR3, MUC5AC, and MUC6 improved specificity, but showed poor sensitivity, suggesting they should be used as second tier markers.

Loss of SATB2 Expression in Colorectal Carcinoma Is Associated With DNA Mismatch Repair Protein Deficiency and BRAF Mutation

The special AT-rich sequence binding protein (SATB2) has been reported to be a specific immunohistochemical marker for colorectal carcinoma; however, correlation of SATB2 expression with molecular alterations commonly assessed in colorectal carcinoma has not been performed. We examined the immunohistochemical expression of SATB2 in 586 adenocarcinomas of the gastrointestinal (GI) tract and pancreas to assess its utility in diagnosis and analyze the clinicopathologic and molecular characteristics of colorectal carcinoma stratified by SATB2 expression. SATB2 and CDX2 expression were evaluated in 266 adenocarcinomas of lower GI tract origin (246 colorectal and 20 appendiceal mucinous), 208 adenocarcinomas of upper GI tract and small intestinal origin (74 esophagus/esophagogastric junction, 103 stomach, 20 duodenal, and 11 jejunoileal), and 112 pancreatic ductal adenocarcinomas. SATB2 expression was more frequently identified in adenocarcinomas of lower GI tract origin (222/266, 83%) compared with upper GI tract, small intestinal, or pancreatic origin (26/320, 8%) (P<0.001). Compared with CDX2 alone, dual positive expression for SATB2 and CDX2 (SATB2/CDX2) has a significantly higher specificity for adenocarcinoma of lower GI tract origin (94% vs. 57%, P<0.001). In colorectal carcinoma, loss of SATB2 expression was more frequently observed in DNA mismatch repair (MMR) protein deficient tumors (31%) compared with MMR protein proficient tumors (13%) (P<0.01). A BRAF V600E mutation was more frequently identified in colorectal carcinomas with loss of SATB2 expression compared with those with positive SATB2 expression (29% vs. 3%) (P<0.001). In summary, SATB2 expression is a relatively specific marker of lower GI tract origin; however, loss of SATB2 expression is more commonly seen in colorectal carcinoma with MMR protein deficiency and BRAF mutation.

Immunophenotypic Comparison of Neoplasms of the Appendix, Right Colon, and Left Colon in Search of a Site-Specific Phenotypic Signature

Aims. The proximal colon derives from the midgut endoderm, the distal one third derives from the hindgut endoderm, and the distal anal canal is of ectodermal origin. At least 5 molecular subtypes of colorectal carcinomas (CRC) have been identified, and some have a marked preferential right-sided location. Histologically, some CRC are much more common in the appendix. We hypothesized that these findings suggest the existence of diverse molecular genetic colonic subregions and compared the expression of classic and recently discovered colorectal markers in tumors at various locations to determine if a site-specific immunophenotypic signature could be identified. Methods and Results. Immunostains for CK7, CK20, MUC2, MUC5AC, MUC6, SATB2, DCR3/TNF6B, CDX2, Ki-67, and MMR proteins were performed on 17 appendiceal low-grade mucinous neoplasms and 6 crypt cell adenocarcinomas of the appendix, 15 right-sided and 15 left-sided mucinous adenocarcinomas, 17 right-sided and 15 left-sided conventional adenocarcinomas, and 5 signet ring cell adenocarcinomas (SRCCA). Statistically significant differences in the expression of MUC2, MUC5AC, MUC6, CK7, and SATB2 by site and/or histologic type were documented. MMR deficiency showed a significant correlation with MUC5AC and MUC6 expression. DCR3, CDX2, and CK20 expression was consistent throughout the colon. A CK7+/CK20+ phenotype was most common in appendiceal tumors and SRCCA. Conclusions. Statistically significant differences in the expression of some markers by histologic type and site were documented, supporting the existence of regional molecular genetic heterogeneity in the colon that result in site-specific epigenetic susceptibilities, tumor phenotypes, and immunophenotypes.

Gastrointestinal Carcinoma with Plasmacytoid Morphology: Positivity for c-MET, Arylsulfatase, and Markers of Epithelial-Mesenchymal Transition, as Indicators of Aggressivity

BACKGROUND

Plasmacytoid urothelial carcinoma is a rare and aggressive histologic variant of high-grade carcinoma of the urinary bladder. Few than 250 cases have been reported in the urinary bladder till January 2019. In this paper, a case series of unusual gastrointestinal carcinomas with plasmacytoid morphology was included. Only one similar case of the stomach was previously published and no such cases were found in colon.

METHODS

We present the complex immunoprofile, using a panel of 39 biomarkers, of the largest group of primary gastrointestinal carcinomas with plasmacytoid morphology reported in literature (one from upper rectum and six from stomach).

RESULTS

All of the seven cases showed lymph node metastases and only one survived over 25 weeks after surgical excision. The indicators of aggressivity were age (over 60), advanced stage (from IIIA to IV), E-cadherin negativity, and vimentin positivity. The immunoprofile indicated unfavorable prognosis for mesenchymal-type carcinomas (negativity for E-cadherin and positivity for vimentin, with membrane to nuclear translocation or negativity of β-catenin). The survivor showed an "epithelial-type adenocarcinoma with plasmacytoid dedifferentiation", with membrane positivity for E-cadherin and β-catenin and vimentin negativity. All of the cases expressed c-MET and were negative for HER-2.

CONCLUSIONS

Primary carcinoma with plasmacytoid morphology is a dedifferentiated variant of adenocarcinoma or poorly cohesive carcinomas. Vimentin positive dedifferentiated-poorly cohesive carcinomas should be considered as mesenchymal-type highly malignant carcinomas. This rare histologic variant of gastrointestinal cancer might respond to anti-c-MET tyrosine kinases.

Distribution of somatic mutations of cancer-related genes according to microsatellite instability status in Korean gastric cancer

In studies of the molecular basis of gastric cancer (GC), microsatellite instability (MSI) is one of the key factors. Somatic mutations found in GC are expected to contribute to MSI-high (H) tumorigenesis. We estimated somatic mutation distribution according to MSI status in 52 matched pair GC samples using the Ion Torrent Ion S5 XL with the AmpliSeq Cancer Hotspot panel.Seventy-five (9.8%) somatic variants consisting of 34 hotspot mutations and 41 other likely pathogenic variants were identified in 34 GC samples. The TP53 mutations was most common (35%, 26/75), followed by EGFR (8%, 6/75), HNF1A (8%, 6/75), PIK3CA (8%, 6/75), and ERBB2 (5%, 4/75). To determine MSI status, 52 matched pair samples were estimated using 15 MSI markers. Thirty-nine MS stable (S), 5 MSI-low (L), and 8 MSI-H were classified. GCs with MSI-H tended to have more variants significantly compared with GCs with MS stable (MSS) and MSI-L (standardized J-T statistic  =  3.161 for number of variants; P  =  .002). The mean number of all variants and hotspot mutations per tumor samples only in GCs with MSI-H were 3.9 (range, 1-6) and 1.1 (range, 0-3), respectively. Whereas, the mean number of all variants and hotspot mutations per tumor samples only in GCs with MSS/MSI-L were 1 (0-5)/0.8 (0-1) and 0.5 (0-3)/0.8 (0-1), respectively.In conclusion, GC with MSI-H harbored more mutations in genes that act as a tumor suppressor or oncogene compared to GC with MSS/MSI-L. This finding suggests that the accumulation of MSIs contributes to the genetic diversity and complexities of GC. In addition, targeted NGS approach allows for detection of common and also rare clinically actionable mutations and profiles of comutations in multiple patients simultaneously. Because GC shows distinctive patterns related to ethnics, further studies pertaining to different racial/ethnic groups or cancer types may reinforce our investigations.

Systematic review of the old and new concepts in the epithelial-mesenchymal transition of colorectal cancer

Epithelial-to-mesenchymal transition (EMT) is defined as the transformation of an epithelial cell into a spindle cell with the loss of membrane E-cadherin expression and the gain of mesenchymal markers positivity. In the field of colorectal cancer (CRC), first data about EMT was published in 1995 and more than 400 papers had been written up to March 2016. Most of them are focused on the molecular pathways and experimentally-proved chemoresistance. In the present article, an update in the field of EMT in CRC based on the review of the literature and personal experience of the authors is presented. The information about the molecular and immunohistochemical (IHC) particularities of these processes and their possible role in the prognosis of CRC were also up-dated. This article focuses on the IHC quantification of the EMT, the immunoprofile of tumor buds and on the relation between EMT, angiogenesis, and stem cells activation. The EMT-induced chemoresistance vs chemotherapy- or radiotherapy-induced EMT and cellular senescence was also synthesized for both conventional and targeted therapy. As a future perspective, the EMT-angiogenesis-stemness link could be used as a possible valuable parameter for clinical follow-up and targeted therapeutic oncologic management of patients with CRC. Association of dexamethasone and angiotensin converting enzyme inhibitors combined with conventional chemotherapies could have clinical benefits in patients with CRC. The main conclusion is that, although many studies have been published, the EMT features are still incompletely elucidated and newly discovered EMT markers provide confusing data in understanding this complicated process, which might have significant clinical impact.

Reappraisal of hMLH1 promoter methylation and protein expression status in the serrated neoplasia pathway

AIMS

The aim of this study was to determine whether human mutL homologue 1 (hMLH1) inactivation precedes the progression of sessile serrated lesion (SSL) into SSL with cytological dysplasia (SSL/D) and to define the histological stage at which promoter methylation and inactivation of hMLH1 occur.

METHODS AND RESULTS

Using the MassARRAY EpiTYPER assay and immunohistochemistry, we examined methylation levels and the protein expression status of hMLH1 in 33 SSL/Ds with conventional epithelial dysplasia and compared the results with those of control hyperplastic polyps (HPs) and SSLs. The methylation level of hMLH1 was higher in the dysplastic component than in the non-dysplastic component of SSL/Ds (P = 0.005), and differed significantly with regard to the degree of dysplasia (P = 0.002). The methylation levels of hMLH1 in the dysplastic component of SSL/Ds tended to be higher than those of control SSLs and HPs (P = 0.063 and P = 0.017, respectively). The loss of hMLH1 protein expression was identified in only 13 of 33 (39.39%) dysplastic components of SSL/Ds.

CONCLUSION

Promoter methylation and loss of protein expression of hMLH1 are not parallel processes that occur concurrently. hMLH1 methylation is an early molecular event which occurs even in HP. However, the loss of hMLH1 expression is a much later step, found in approximately 40% of SSL/Ds at various histological stages. Notably, the loss of hMLH1 protein expression does not necessarily precede the development of cytological dysplasia in SSL.

LEF-1 is frequently expressed in colorectal carcinoma and not in other gastrointestinal tract adenocarcinomas: an immunohistochemical survey of 602 gastrointestinal tract neoplasms

LEF-1 is a DNA-binding protein that interacts with β-catenin and activates Wnt-responsive target genes. We analyzed the immunohistochemical expression of LEF-1 in 602 gastrointestinal and pancreatobiliary neoplasms in an attempt to (1) investigate the utility of LEF-1 immunohistochemistry as an ancillary marker in gastrointestinal/pancreatobiliary neoplasia, and (2) to perform a clinicopathologic and survival analysis of colorectal carcinoma stratified by LEF-1 expression. LEF-1 nuclear positivity was frequently identified in colorectal carcinoma (89/241, 37%) and only infrequently identified in other neoplasms: 11% esophagus/esophagogastric adenocarcinomas, 7% gastric adenocarcinomas, 1% pancreatic ductal adenocarcinomas, 4% pancreatic intraductal papillary mucinous neoplasms, and in no cases of appendiceal mucinous neoplasms or pancreatic mucinous cystic neoplasms. LEF-1 expression was identified in 35% of colorectal carcinomas that lacked CK20 and CDX2 expression. In colorectal carcinomas, LEF-1-positive tumors more frequently harbored KRAS mutations compared with LEF-1-negative tumors (39% vs. 16%, P=0.005). Patients with moderate/strong LEF-1-positive colorectal carcinoma had a trend of worse overall survival compared with patients with colorectal carcinomas with weak/negative LEF-1 expression (5 y overall survival, 31% vs. 47%, P=0.15). In conclusion, LEF-1 is most commonly expressed in colorectal carcinoma and infrequently observed in the upper gastrointestinal tract and pancreatic adenocarcinoma. LEF-1 Immunohistochemistry may be especially useful as an ancillary diagnostic marker in colorectal carcinomas, which lack the expression of both CK20 and CDX2. LEF-1 expression is associated with the presence of KRAS mutations and may have prognostic value as a trend of worse overall survival is seen in patients with LEF-1-positive colorectal carcinoma.

Copy number alterations of chromosomal regions enclosing protein tyrosine phosphatase receptor-like genes in colorectal cancer

Protein tyrosine phosphatases that act in different cellular pathways are described most commonly as tumor suppressors, but also as oncogenes. Their role has previously been described in colorectal cancer, as well as in gastric, breast, thyroid, prostate, ovarian, pancreatic, glioma, liver, leukemia and many other cancers. In a previous study, we have described protein tyrosine phosphatase receptor type T, M, Z1 and Q genes (PTPRT, PTPRM, PTPRZ1 and PTPRQ) hypermethylated in sporadic colorectal cancer. Thus, in this study, we examined the relation of unbalanced chromosomal alterations within regions covering these four protein tyrosine phosphatase genes with this cancer. One hundred and two cancer tissues were molecularly characterized, including analysis of the BRAF and K-ras mutations and methylator phenotype. The analysis of chromosomal aberrations was performed using Comparative Genomic Hybridization. We observed amplification of three regions containing genes coding for PTPs, such as PTPRZ1 (7q31.3, amplified in 23.5% of cases), PTPRQ (12q21.2, amplified in 5.9% of cases), PTPRT (20q12, amplified in 29.4% of cases), along with deletions in the region of PTPRM (18p11.2, deleted in 21.6% of cases). These data may suggest that in sporadic colorectal cancer PTPRZ1, PTPRT, PTPRQ probably act as oncogenes, while PTPRM acts as a tumor suppressor gene. Our study also revealed that gains on chromosome 20q12 and losses on chromosome 18p11.2 are connected with the absence of the BRAF mutation and the conventional adenocarcinoma pathway.

BRAF-mutated microsatellite stable colorectal carcinoma: an aggressive adenocarcinoma with reduced CDX2 and increased cytokeratin 7 immunohistochemical expression

Reduced CDX2 and cytokeratin 20 (CK20) expression in colorectal carcinoma with BRAF mutation and high-level microsatellite instability (MSI-H) has been well documented. The immunophenotype of BRAF-mutated microsatellite stable (MSS) colorectal carcinoma has not been reported. We analyzed 205 colorectal carcinomas including 28 BRAF-mutated MSS, 53 BRAF-mutated MSI-H, and 124 BRAF wild-type MSS tumors for CDX2, cytokeratin 7 (CK7), and CK20 immunohistochemical expression. CDX2 was scored semiquantitatively for both staining intensity and percent of tumor cells staining and a modified CDX2 H-score was calculated. Patients with BRAF-mutated MSS colorectal carcinomas were more frequently stage IV at presentation compared to patients with BRAF-mutated MSI-H colorectal carcinomas and BRAF wild-type MSS colorectal carcinomas (32% versus 8% versus 15%, P < .001). BRAF-mutated MSS colorectal carcinoma displayed reduced CDX2 expression compared to BRAF wild-type MSS colorectal carcinoma (75% versus 94%; mean CDX2 H-score 98 versus 150, P < .001). CK7 expression was more often identified in BRAF-mutated MSS colorectal carcinoma compared to both BRAF-mutated MSI-H colorectal carcinoma and BRAF wild-type MSS colorectal carcinoma (39% versus 6% versus 6%, P = .0001). BRAF-mutated MSI-H colorectal carcinomas were less often CK20 positive compared to BRAF-mutated MSS and BRAF wild-type MSS tumors (70% versus 93% versus 90%, P = 0.001). In summary, BRAF-mutated MSS colorectal carcinoma often displays reduced CDX2 and increased CK7 expression. Knowledge of this altered immunophenotype is important as patients with BRAF-mutated MSS colorectal carcinoma often present with metastatic disease and the altered tumor immunophenotype may lead to the erroneous assumption that origin from the colon/rectum is unlikely.

Activation of pro-oncogenic pathways in colorectal hyperplastic polyps

Background

In contrast to sessile serrated adenomas and traditional serrated adenomas which are associated with a significant cancer risk, the role of hyperplastic polyps (HP) in colorectal carcinogenesis as well as the molecular mechanisms underlying their development remain controversial and still need to be clarified. Several reports suggest that a subset of HP may represent precursor lesions of some colorectal cancers. However, biomarkers are needed to identify the subset of HP that may have a malignant potential. The hormone precursor, progastrin (PG) has been involved in colon carcinogenesis and is known to activate pro-oncogenic pathways such as the ERK or the STAT3 pathway. We therefore analyzed PG expression and the activation of these signaling factors in HP.

Methods

We retrospectively analyzed PG expression as well as the phosphorylation of ERK and STAT3 by immunohistochemistry in HP from 48 patients.

Results

Mean percentages of epithelial cells positive for PG or phospho-ERK were respectively, 31% and 33% in HP and were significantly higher in these lesions compared to normal colon (3%, p = 0.0021 and 7%, p = 0.0008, respectively). We found a significant correlation between PG and phospho-ERK expression in HP with ERK activation significantly stronger in lesions with high progastrin expression (p = 0.015). In contrast, STAT3 was not significantly activated in HP compared to normal colon and we did not observe a significant correlation with PG expression.

Conclusions

HP overexpressing PG that have the highest activation of the ERK pathway might reflect less latent lesions that might have a malignant potential.