CDX2 as a marker for intestinal differentiation: Its utility and limitations

Ketogenesis contributes to intestinal cell differentiation

The intestinal epithelium undergoes a continual process of proliferation, differentiation and apoptosis. Previously, we have shown that the PI3K/Akt/mTOR pathway has a critical role in intestinal homeostasis. However, the downstream targets mediating the effects of mTOR in intestinal cells are not known. Here, we show that the ketone body β-hydroxybutyrate (βHB), an endogenous inhibitor of histone deacetylases (HDACs) induces intestinal cell differentiation as noted by the increased expression of differentiation markers (Mucin2 (MUC2), lysozyme, IAP, sucrase-isomaltase, KRT20, villin, Caudal-related homeobox transcription factor 2 (CDX2) and p21^Waf1). Conversely, knockdown of the ketogenic mitochondrial enzyme hydroxymethylglutaryl CoA synthase 2 (HMGCS2) attenuated spontaneous differentiation in the human colon cancer cell line Caco-2. Overexpression of HMGCS2, which we found is localized specifically in the more differentiated portions of the intestinal mucosa, increased the expression of CDX2, thus further suggesting the contributory role of HMGCS2 in intestinal differentiation. In addition, mice fed a ketogenic diet demonstrated increased differentiation of intestinal cells as noted by an increase in the enterocyte, goblet and Paneth cell lineages. Moreover, we showed that either knockdown of mTOR or inhibition of mTORC1 with rapamycin increases the expression of HMGCS2 in intestinal cells in vitro and in vivo, suggesting a possible cross-talk between mTOR and HMGCS2/βHB signaling in intestinal cells. In contrast, treatment of intestinal cells with βHB or feeding mice with a ketogenic diet inhibits mTOR signaling in intestinal cells. Together, we provide evidence showing that HMGCS2/βHB contributes to intestinal cell differentiation. Our results suggest that mTOR acts cooperatively with HMGCS2/βHB to maintain intestinal homeostasis.

Molecular profiles in foregut oncology

Oncology is and will continue to evolve resulting from a better understanding of the biology and intrinsic genetic profile of each cancer. Tumor biomarkers and targeted therapies are the new face of precision medicine, so it is essential for all physicians caring for cancer patients to understand and assist patients in understanding the role and importance of such markers and strategies to target them. This review was initiated in an attempt to identify, characterize, and discuss literature supporting clinically relevant molecular markers and interventions. The efficacy of targeting specific markers will be examined with data from clinical trials focusing on treatments for esophageal, gastric, liver, gallbladder, biliary tract, and pancreatic cancers.

Peutz-Jeghers Syndrome: Pathobiology, Pathologic Manifestations, and Suggestions for Recommending Genetic Testing in Pathology Reports

Peutz-Jeghers syndrome (PJS), in most cases, is attributed to mutation in STK11/LKB1 and is clinically characterized by gastrointestinal hamartomatous polyposis, mucocutaneous pigmentation, and predisposition to certain neoplasms. There are currently no recommended gynecologic screening or clinical surveillance guidelines beyond those recommended for the general population; however, cervical cytology samples must be examined with a high level of suspicion for cervical adenocarcinoma. It is considered prudent to note the established association with PJS and recommend referral for genetic counseling. Complete surgical excision after a diagnosis of atypical lobular endocervical glandular hyperplasia is recommended.

Immunohistochemical staining for p16 and BRAFV600E is useful to distinguish between sporadic and hereditary (Lynch syndrome-related) microsatellite instable colorectal carcinomas

DNA mismatch repair (MMR) protein analysis by immunohistochemistry (IHC) can identify colorectal cancer (CRC) with microsatellite instability (MSI). As MLH1-deficient CRC can be hereditary or sporadic, markers to distinguish between them are needed. MLH1 promoter methylation assay is the reference method; however, sometimes, it is challenging on formalin-fixed paraffin-embedded tissue samples. We assessed by IHC the expression of BRAFV600E, p16, MGMT, and CDX2 in 55 MLH1-deficient MSI CRC samples (of which 8 had a germline MLH1 mutation) to determine whether this panel differentiates between sporadic and hereditary CRCs. We also analyzed MLH1 promoter methylation by methylation-specific PCR and pyrosequencing and BRAF status by genotyping. None of the hereditary CRCs showed MLH1 methylation, BRAF mutation, BRAFV600E-positive immunostaining, or loss of p16 expression. We detected MLH1 promoter methylation in 67 % and a BRAF mutation in 42 % of CRC, all showing MLH1 promoter methylation. BRAFV600E IHC and BRAF genotyping gave concordant results in all but two samples. Loss of expression of p16 was found in 30 % of CRC with methylation of the MLH1 promoter, but its expression was retained in all non-methylated and part of MLH1-methylated tumors (100 % specificity, 30 % sensitivity). CDX2 and MGMT expression was not associated with MLH1 status. Thus, BRAFV600E and p16 IHC may help in differentiating sporadic from hereditary MLH1-deficient CRC with MSI. Specifically, p16 IHC might be used as a surrogate marker for MLH1 promoter methylation, because all p16-negative CRCs displayed MLH1 methylation, whereas hereditary CRCs were all p16-positive.

Intestinal type gastric adenocarcinoma with unusual synchronous metastases to the colorectum and bladder

A 75-year-old male presented with difficult defecation and increasing urinary frequency over a few months. He had a significant history of previous partial gastrectomy for gastric carcinoma 20 years prior. Computed tomography of the abdomen and pelvis showed extensive lymphadenopathy, a gastric mass and rectal as well as bladder wall thickening with bilateral ureterohydronephrosis. Normal looking serosal surfaces of the bladder and bowel were seen on laparoscopy and a defunctioning ileostomy was created. Gastroscopy revealed a malignant mass while cystoscopy and sigmoidscopy found extensive tumour growth lining the mucosal surfaces. Biopsies from all sites were compatible with intestinal type adenocarcinoma of gastric origin with few signet ring cells. Metabolic response to palliative chemotherapy was good and the patient's symptoms have improved on follow-up four months post ileostomy. We discuss the immunohistochemical profile of the tumour and review the literature.

Adenocarcinoma of the thymus, enteric type: report of 2 cases, and proposal for a novel subtype of thymic carcinoma

We report 2 cases of primary thymic adenocarcinoma with enteric differentiation. One carcinoma occurred in a 41-year-old man as a 7-cm-diameter cystic tumor and the other one in a 39-year-old woman as a 6-cm-diameter solid mass. Both tumors were located in the anterior mediastinum. Clinical staging did not reveal any extrathymic tumor. Histologically, the tumors were classified as adenocarcinoma, not otherwise specified, and a mucinous (colloid) carcinoma, respectively. Immunohistochemically, both tumors were positive for cytokeratin 20 (CK20), CDX2, and carcinoembryonic antigen, reflecting enteric differentiation. A review of the literature on 43 other cases of primary thymic adenocarcinomas suggested 11 further cases with enteric differentiation, as assessed by CK20 and/or CDX2 expression. We propose that thymic adenocarcinoma with enteric differentiation represents a novel subtype of thymic carcinoma. It is mostly of mucinous morphology and frequently associated with thymic cysts. The clinical outcome is variable. Recognition of primary thymic adenocarcinoma with enteric differentiation is helpful for the differentiation from metastatic disease, mainly from the gastrointestinal tract.

The role of SATB2 as a diagnostic marker for tumors of colorectal origin: Results of a pathology-based clinical prospective study

OBJECTIVES

Immunohistochemistry is an important extension to clinical information and morphology, and prevails as an invaluable tool for establishing a correct cancer diagnosis in clinical diagnostic pathology. The applicability of immunohistochemistry is limited by the availability of validated cell- and cancer-type specific antibodies, rendering an unmet need to discover, test, and validate novel markers. The SATB2 protein is selectively expressed in glandular cells from the lower gastrointestinal tract and expression is retained in a large majority of primary and metastatic colorectal cancers.

METHODS

We analyzed the expression of SATB2 in all clinical cases (n = 840), in which immunohistochemistry for detection of CK20 was deemed necessary for a final diagnosis.

RESULTS

SATB2 showed a high sensitivity (93%) and specificity (77%) to determine a cancer of colorectal origin and in combination with CK7 and CK20, the specificity increased to 100%.

CONCLUSIONS

We conclude that SATB2 provides a new and advantageous supplement for clinical differential diagnostics.

Effect of up-regulation of CDX2 expression on miRNA expression profiles and biological behavior in gastric cancer SGC-7901 cells

AIM: To screen differentially expressed miRNAs in human gastric carcinoma cells with up-regulated caudal type homeobox gene 2 (CDX2) expression and to analyze their effect on biological behavior of cells.

METHODS: A recombinant eukaryotic expression plasmid carrying the CDX2 gene was constructed. SGC-7901 cells were divided into three groups: non-transfected cells, cells transfected with PEGFP-N1 or PEGFP-N1-CDX2. The expression of GFP was observed by fluorescent microscopy. Expression of CDX2 mRNA and EGFP-CDX2 fusion protein was detected by qRT-PCR and Western blot, respectively. Cell proliferation was measured using CCK8 assay. In vitro cell migration and adhesion were measured by cell scratch assay, Transwell assay and cell adhesion assay. Differentially expressed miRNAs were detected using a miRNA chip, and their target genes were forecasted using Miranda, TargetScan and Mirtarget2 software.

RESULTS: The eukaryotic expression vector PEGFP-N1-CDX2 was successfully constructed. The expression levels of CDX2 mRNA and protein were higher in SGC-7901 transfected with PEGFP-N1-CDX2 than in control cells. In SGC-7901 cells transfected with PEGFP-N1-CDX2, cell proliferation, invasion and adhesion were significantly inhibited (all P < 0.05) compared with non-transfected cell or cells transfected with PEGFP-N1. Of 59 identified differentially expressed miRNAs between cells transfected PEGFP-N1-CDX2 and those transfected with PEGFP-N1, 25 had > 2-fold up-regulation and 34 had > 2-fold down-regulation in cells transfected with PEGFP-N1-CDX2. Many target genes of these differentially expressed miRNAs were predicted using miRNA target predication tools.

CONCLUSION: Up-regulation of CDX2 expression inhibits the growth, migration and adhesion of SGC-7901 cells. The antitumor effect of CDX2 may be associated with miRNA expression.

Metastatic colorectal adenocarcinoma in cervicovaginal cytology specimens confirmed by immunocytochemical stains on liquid base specimens: Two study cases with review of the literature

Only a few cases of adenocarcinoma (ACA) metastatic to the female lower genital tract diagnosed on cervicovaginal Pap smear have been reported during the past several decades. Both conventional and liquid based cytology (LBC) have limited sensitivity and specificity in diagnosing metastatic disease and immunocytochemical (ICC) staining may be needed for confirming the diagnosis. We present two cases of metastatic colorectal ACA diagnosed on cervicovaginal ThinPrep (TP) Pap smears, with one confirmed by ICC staining method. Recognition of extra-uterine malignancy in the cervicovaginal cytology specimen is critical for the disease diagnosis, prognosis, and the treatment. ICC staining performed on the residual LBC specimen is an important methodology to confirm the diagnosis.

Sox9 induction, ectopic Paneth cells, and mitotic spindle axis defects in mouse colon adenomatous epithelium arising from conditional biallelic Apc inactivation

We generated transgenic mice in which human CDX2 gene elements control expression of a tamoxifen-regulated Cre protein (CDX2P-CreER(T2)) to allow for inducible gene targeting in intestinal epithelium. After tamoxifen dosing of CDX2P-CreER(T2) mice, Cre activity was detected in the distal ileal, cecal, colonic, and rectal epithelium, with selected crypt base, transit amplifying, and surface cells all capable of activating Cre function. Four weeks after tamoxifen dosing of CDX2P-CreER(T2) mice carrying a Cre-activated fluorescent reporter, single crypts were uniformly fluorescence positive or negative, reflecting Cre activation in crypt stem cells. Biallelic inactivation of the Apc tumor suppressor gene via the CDX2P-CreER(T2) transgene in colon epithelium led to acute alterations in cell proliferation, apoptosis, and morphology, along with mitotic spindle misorientation, β-catenin nuclear localization, and induction of the intestinal stem cell markers Lgr5 and Musashi-1 and the Sox9 transcription factor. Normal mouse colon epithelium lacks Paneth cells, a key small intestine niche cell type, and Paneth cell differentiation is dependent on Sox9 function. In Apc-deficient colon epithelium, ectopic Paneth-like cells were seen outside the crypt base, such as new crypt budding sites. Our data indicate Apc inactivation via CDX2P-CreER(T2) targeting in mouse colon epithelium is sufficient to induce adenomatous changes and the generation of Paneth-like cells from neoplastic progenitors, with potentially significant roles in colon adenoma development and progression.

Reactivation of the homeotic tumor suppressor gene CDX2 by 5-aza-2'-deoxycytidine-induced demethylation inhibits cell proliferation and induces caspase-independent apoptosis in gastric cancer cells

The DNA methylation inhibitor 5-aza-2′-deoxycytidine (5-aza-CdR) is widely used as an anticancer drug for the treatment of leukemia and solid tumors. Gastric cancer (GC) patients who were positive for caudal type homeobox transcription factor 2 (CDX2) expression showed a higher survival rate compared with those who were CDX2 negative, which suggests that CDX2 performs a tumor suppressor role. However, the molecular mechanisms leading to the inactivation of CDX2 remain unclear. In the present study we demonstrated that the expression levels of CDX2 and DNA methyltransferase enzyme 1 (DNMT1) mRNA were significantly higher in GC compared with distal non-cancerous tissue. The expression of CDX2 mRNA was significantly correlated with Lauren classification, TNM stage and lymph node metastasis. DNMT1 mRNA expression was significantly correlated with TNM stage, pathological differentiation and lymph node metastasis. The expression of CDX2 mRNA was inversely correlated with that of DNMT1 mRNA in GC. Hypermethylation of the CDX2 gene promoter region, extremely low expression levels of CDX2 mRNA and no expression of CDX2 protein were the characteristics observed in MKN-45 and SGC-7901 GC cell lines. Following the treatment of MKN-45 cells with 5-aza-CdR, the hypermethylated CDX2 gene promoter region was demethylated and expression of CDX2 was upregulated, while DNMT1 expression was downregulated. Furthermore, a concentration- and time-dependent growth inhibition as well as increased apoptosis were observed. Caspase-3, −8 and −9 activities increased in a concentration-dependent manner following exposure to different concentrations of 5-aza-CdR. Therefore, our data show that the overexpression of DNMT1 and methylation of the CDX2 gene promoter region is likely to be responsible for CDX2 silencing in GC. 5-Aza-CdR may effectively induce re-expression of the CDX2 gene, inhibit cell proliferation and enhance the caspase-independent apoptosis of MKN-45 cells in vitro.

Primary lung cancer presenting with metastasis to the colon: a case report

Although about 50% of lung cancers have distant metastasis at the time of initial diagnosis, colonic metastases are extremely rare. This report presents a rare clinical case of colonic metastasis from primary squamous cell carcinoma of the lung. A 60-year-old female with anorexia and fatigue was referred to the department of pulmonary surgery in our hospital. The patient was diagnosed with primary squamous cell carcinoma of the lung, T2b N3 M1b Stage IV, and chemoradiotherapy was initiated. This treatment led to a good partial response in the primary lung lesion without any new metastatic lesions. The patient developed left abdominal pain due to a bulky sigmoid colon tumor 6  months later, and was preoperatively diagnosed with primary colon cancer. She underwent colonic resection, and the pathology specimen demonstrated poorly differentiated squamous cell carcinoma that was suspected to be colonic metastasis from the primary lung cancer. The postoperative course was uneventful, and she was discharged. Chemotherapy for the lung cancer was scheduled in the department of pulmonary surgery. This report presented a rare case of colonic metastasis from lung cancer. When patients with advanced primary lung cancer complain of abdominal symptoms, we should consider gastrointestinal tract metastasis from lung cancer.