Relationship between alpha-methylacyl-coenzyme A racemase expression and mucin phenotype in gastric cancer

Novel Histopathological Biomarkers in Prostate Cancer: Implications and Perspectives

Prostate cancer (PCa) is the second most frequently diagnosed cancer in men. Despite the significant progress in cancer diagnosis and treatment over the last few years, the approach to disease detection and therapy still does not include histopathological biomarkers. The dissemination of PCa is strictly related to the creation of a premetastatic niche, which can be detected by altered levels of specific biomarkers. To date, the risk factors for biochemical recurrence include lymph node status, prostate-specific antigen (PSA), PSA density (PSAD), body mass index (BMI), pathological Gleason score, seminal vesicle invasion, extraprostatic extension, and intraductal carcinoma. In the future, biomarkers might represent another prognostic factor, as discussed in many studies. In this review, we focus on histopathological biomarkers (particularly CD169 macrophages, neuropilin-1, cofilin-1, interleukin-17, signal transducer and activator of transcription protein 3 (STAT3), LIM domain kinase 1 (LIMK1), CD15, AMACR, prostate-specific membrane antigen (PSMA), Appl1, Sortilin, Syndecan-1, and p63) and their potential application in decision making regarding the prognosis and treatment of PCa patients. We refer to studies that found a correlation between the levels of biomarkers and tumor characteristics as well as clinical outcomes. We also hypothesize about the potential use of histopathological markers as a target for novel immunotherapeutic drugs or targeted radionuclide therapy, which may be used as adjuvant therapy in the future.

Current Knowledge on the Function of α-Methyl Acyl-CoA Racemase in Human Diseases

Branched chain fatty acids perform very important functions in human diet and drug metabolism. they cannot be metabolized in mitochondria and are instead processed and degraded in peroxisomes due to the presence of methyl groups on the carbon chains. Oxidative degradation pathways for lipids include α- and β-oxidation and several pathways. In all metabolic pathways, α-methyl acyl-CoA racemase (AMACR) plays an essential role by regulating the metabolism of lipids and drugs. AMACR regulates β-oxidation of branched chain lipids in peroxisomes and mitochondria and promotes chiral reversal of 2-methyl acids. AMACR defects cause sensory-motor neuronal and liver abnormalities in humans. These phenotypes are inherited and are caused by mutations in AMACR. In addition, AMACR has been found to be overexpressed in prostate cancer. In addition, the protein levels of AMACR have increased significantly in many types of cancer. Therefore, AMACR may be an important marker in tumors. In this review, a comprehensive overview of AMACR studies in human disease will be described.

Endoscopic and clinicopathological features of intramucosal, histologically mixed-type, low-grade, well-differentiated gastric tubular adenocarcinoma with the potential for late-onset lymph node metastasis

BACKGROUND

Intramucosal, histologically mixed-type, low-grade (LG), well-differentiated gastric tubular adenocarcinomas (tub1s; LG-tub1s) have larger mean diameters and exhibit a higher frequency of the gastric mucin phenotype (G-phenotype) than pure LG-tub1s. In proportion to their increases in diameter, G-phenotype differentiated-type early gastric cancer (EGC) tumours reportedly grow to eventually contain (an) undifferentiated-type component(s) and LG-tub1s, which are included in differentiated-type EGCs, reportedly exhibit changes in their glandular architectural and cytological atypia grades from LG to high-grade (HG) and can grow to contain a moderately differentiated tubular adenocarcinoma (tub2) component and undifferentiated components. Because they generally show a higher frequency of malignancy relative to tumours with a higher atypia grade and lower differentiation degree, it is suggested that, among mixed-type LG-tub1s, G-phenotype LG-tub1s containing an HG-tub2 component (LG-tub1s > HG-tub2) with undifferentiated components might lead to late-onset metastasis to lymph nodes even after a successful endoscopic submucosal dissection (ESD). We aimed to clarify the endoscopic and clinicopathological features of these G-phenotype LG-tub1s > HG-tub2.

METHODS

Of the 13,217 oesophagogastroduodenoscopies performed at our institutions between September 2008 and March 2016, 185 EGC lesions were evaluated in this retrospective observational study. Among these EGC lesions, 60 intramucosal LG-tub1s were divided into 53 tub1 (44 pure LG-tub1s and nine LG-tub1s containing HG-tub1) lesions and seven LG-tub1 > tub2 (LG-tub1 containing LG- and HG-tub2) lesions.

RESULTS

The frequencies of the superficial depressed type (P = 0.026), reddish colour (P = 0.006), HG of contained tub2s (P = 0.006), and G-phenotype (P = 0.028) were significantly higher in the LG-tub1 > tub2 group than those in the tub1 group. However, the largest lesion of the LG-tub1 > tub2 group had a superficial flat appearance, an isochromatic colour, an HG-tub2 and an undifferentiated component, and a large diameter greater than 30 mm, and it exhibited a G-phenotype.

CONCLUSIONS

Intramucosal G-phenotype LG-tub1s > HG-tub2 are potential premalignant stomach neoplasms that may have specific endoscopic and clinicopathological features. However, G-phenotype LG-tub1s > HG-tub2 with undifferentiated component, which potentially show higher malignancy than those without undifferentiated components might change from a reddish to isochromatic colour. Accurately diagnosing, treating, and following-up G-phenotype LG-tub1s > HG-tub2 might decrease the number of patients who experience late-onset metastasis after ESD.

Effectiveness of Magnifying Narrow-Band Imaging Endoscopy for Differential Diagnosis between the High-Risk Mixed-Type and Low-Risk Simple-Type of Low-Grade, Well-Differentiated Gastric Tubular Adenocarcinoma

Backgrounds. Magnifying endoscopy with narrow-band imaging (NBI-ME) is useful for diagnosing differentiated early gastric cancer (D-EGC). D-EGC is classified as high- or low-grade based on its glandular architectural and cytological atypia. Low-grade, well-differentiated tubular adenocarcinoma (LG-tub1) mixed with high-grade tub1 (HG-tub1) and/or other histological types (M-LG-tub1) may indicate a primitive high-risk malignant lesion compared to histologically simple-type LG-tub1 (S-LG-tub1). Because LG-tub1 is occasionally difficult to diagnose due to its unclear demarcation under conventional white light endoscopy, early precise diagnoses are important. Methods. We compared NBI-ME and postendoscopic submucosal dissection histological findings for 30 S-LG-tub1 and 15 M-LG-tub1 lesions. We classified the NBI-ME findings of S-LG-tub1 (and not D-EGC) into four patterns. The differential diagnosis between M-LG-tub1 and S-LG-tub1 depended on the presence of more than one of these patterns without or with other patterns (referred to as “limited-to-four-pattern [LFP] sign-positive” and “sign-negative”, resp.). Result. The sensitivity, specificity, accuracy, positive and negative predictive values, and intraobserver and interobserver agreement, using the “LFP sign” for the differential diagnosis between M-LG-tub1 and S-LG-tub1, were 87.9%, 91.7%, 88.9%, 96.7%, 73.3%, and k = 0.842 and k = 0.737, respectively. Conclusion. NBI-ME may be useful in differentiating between high-risk M-LG-tub1 and low-risk S-LG-tub1.

Intestinal metaplasia in Barrett's oesophagus may be an epiphenomenon rather than a preneoplastic condition, and CDX2-positive cardiac-type epithelium is associated with minute Barrett's tumour

AIMS

Although intestinal-type epithelium in Barrett's oesophagus has been traditionally recognized as having a distinct malignant potential, whether this also holds true for cardiac-type epithelium remains controversial. The aim of this study was to identify a type of epithelium that is highly associated with Barrett's tumour.

METHODS AND RESULTS

We analysed tumours and the corresponding background mucosa with special regard to tumour size in 40 cases of superficial Barrett's tumour by using immunohistochemical staining for CDX2, CD10, MUC2, MUC5AC, and MUC6. Intestinal metaplasia in tumour-adjacent mucosa was not associated with tumour size, but was significantly correlated with the extent of Barrett's oesophagus (P < 0.001). The majority (69.2%, 9/13) of small tumours (≤10 mm) had no intestinal metaplasia in adjacent non-neoplastic mucosae. Minute (≤5 mm) tumours were significantly associated with a gastric immunophenotype (P < 0.001). Purely gastric-immunophenotype tumour cells expressed CDX2, and cardiac-type epithelium adjacent to small tumours also showed low-level CDX2 expression.

CONCLUSIONS

Our data suggest that intestinal metaplasia in Barrett's oesophagus is an epiphenomenon rather than a preneoplastic condition, and that CDX2-positive cardiac-type epithelium is highly associated with minute Barrett's tumour. Further prospective studies are needed to evaluate the risk of malignancy of cardiac-type epithelium with regard to sub-morphological intestinalization.

Magnifying narrow-band imaging of surface maturation in early differentiated-type gastric cancers after Helicobacter pylori eradication

BACKGROUND

Even after successful Helicobacter pylori eradication, primary or metachronous gastric cancers are sometimes discovered. The endoscopic features of these cancers may be modified by controlling inflammation. Characteristic findings for such lesions in terms of narrow-band imaging with magnifying endoscopy (NBI-ME) and histopathology need to be clarified to allow accurate diagnosis.

METHODS

Distinctive NBI-ME characteristics were examined retrospectively in intramucosal or minimally submucosal and differentiated-type adenocarcinomas from a successful eradication group (42 patients, 50 lesions) and a non-eradicated control group (44 patients, 50 lesions) matched in age and sex. A "gastritis-like" appearance under NBI-ME was characterized by uniform papillae and/or tubular pits with a whitish border, regular or faint microvessels and unclear demarcation, resembling the adjacent noncancerous mucosa. Histological differentiation at the luminal surface of the cancer was evaluated according to Ki-67 immunoreactivity restricted at the middle or lower portion of the tubules. NBI-ME alteration was prospectively confirmed in 29 patients (30 lesions) after eradication therapy.

RESULTS

The frequency of a "gastritis-like" appearance was 44% (22/50) for the eradication group, which was significantly higher than the 4% (2/50) for the control group (p < 0.001). In the eradication group, the "gastritis-like" appearance was significantly correlated with histological surface differentiation (p < 0.001). In the prospective study, NBI-ME showed changes to heterogeneous papillary microstructures in 43% (10/23) of the lesions after successful eradication at short-term follow-up.

CONCLUSIONS

Identification of surface maturation under NBI-ME offers a promising approach for accurate diagnosis of early gastric cancers after successful eradication.

Alpha-methylacyl-coenzyme A racemase expression in neuroendocrine neoplasms of the stomach

The enzyme alpha-methylacyl-coenzyme A racemase plays an important role in the beta-oxidation of branched-chain fatty acid and its derivatives. It has been used to detect prostatic adenocarcinoma and high-grade intraepithelial neoplasia, and recently also as a marker for other neoplasms, including those of the genitourinary system, breast, upper and lower gastrointestinal tract and their precursor lesions. We assessed expression of alpha-methylacyl-coenzyme A racemase by immunohistochemistry in neuroendocrine tumours of the stomach to determine differences in the incidence and pattern of expression among different types of gastric neuroendocrine tumours. While none of the grade 1 neuroendocrine tumours were immunoreactive, 67 % of grade 2 neuroendocrine tumours and 90 % of neuroendocrine carcinomas were positive for alpha-methylacyl-coenzyme A racemase. Furthermore, an adenocarcinoma component was found in 72.5 % (37 of 51) of neuroendocrine carcinomas, whereas none of the grade 1 and 2 neuroendocrine tumours contained an adenocarcinoma component. In 83 % of neuroendocrine carcinomas, the adenocarcinoma component was positive for alpha-methylacyl-coenzyme A racemase, and both adenocarcinoma and neuroendocrine carcinoma components stained positively in 78 % of these cases. Our results indicate that alpha-methylacyl-coenzyme A racemase is a useful marker for distinguishing between grade 1 (negative) and grade 2 neuroendocrine tumours, and neuroendocrine carcinoma of the stomach (frequently positive). Different patterns of alpha-methylacyl-coenzyme A racemase expression between gastric neuroendocrine tumours and neuroendocrine carcinoma suggest that these might develop via different tumourigenic pathways.