Objective analysis of cancer stem cell marker expression using immunohistochemistry

Clinicopathologic and prognostic significance of LGR5, a cancer stem cell marker in patients with colorectal cancer

Aim:

To analyze the clinicopathologic and prognostic significance of Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5), a cancer stem cell marker expression in a cohort of colorectal cancer patients (CRC).

Patients & methods:

A total of 76 formalin-fixed paraffin-embedded tissue blocks of primary or metastatic tumors from 49 CRC patients were collected for duration 2009–2015. LGR5 expression was assessed through immunohistochemical staining of a tissue microarray.

Results:

LGR5 was significantly over expressed in CRC tissue samples and found to be a statistically significant independent prognostic marker for an improved overall survival.

Conclusion:

LGR5 expression was higher in colorectal cancer than in normal tissue. LGR5 was an independent prognostic marker for better clinical outcomes and might be used as a potential therapeutic target in CRCs.

LGR5 expression predicts peritoneal recurrence after curative resection of primary colon cancer

Background

The aim of this study was to clarify whether a cancer stem cell marker could be an indicator of post-operative peritoneal recurrence of colon cancer.

Methods

Expression of four putative markers (CD133, CD44 variant 6, aldehyde dehydrogenase-1 and leucine-rich repeating G-protein-coupled receptor-5 (LGR5)) was evaluated immunohistochemically in primary tumour samples from 292 patients who underwent curative resection for non-metastasised pT4 colon cancer at the University of Tokyo Hospital between 1997 and 2015.

Results

Peritoneal recurrence was significantly higher in LGR5-negative cases (5-year cumulative incidence: 27.5% vs. 14.4%, p = 0.037). Multivariable analysis confirmed that negative LGR5 expression was an independent risk factor for peritoneal recurrence (hazard ratio (HR) 2.79, p = 0.005) in addition to poor differentiation, positive lymph node metastasis, preoperative carcinoembryonic antigen > 5 ng/mL and anastomotic leakage. The addition of LGR5 significantly improved the predictive value of the multivariable model (net reclassification improvement: 0.186, p = 0.028: integrated discrimination improvement: 0.047, p = 0.008).

Conclusions

Negative LGR5 expression was a significant predictor of peritoneal recurrence in patients with pT4 colon cancer. Therefore, LGR5 might be a promising biomarker to identify patients at high risk of post-operative peritoneal metastasis.

Expression of PD-L1 and SOX2 during rectal tumourigenesis: Potential mechanisms for immune escape and tumour cell invasion

Immunoediting is defined as a process whereby tumour cells develop the capacity to escape immune cell recognition. Accumulating evidence suggests that cancer stem-like cells (CSCs) have an enhanced capacity to interact with the immune system. The expression of CSCs and immune cell-associated markers has been demonstrated to change with disease progression from premalignant lesions to invasive cancer. The present study investigated the expression of putative CSC and immune cell-associated markers in different stages of progression from dysplasia to invasive malignancy in rectal lesions. Immunohistochemistry was performed for the CSC markers Lgr5 and SOX2 and the immune-associated markers CD8, Foxp3 and PD-L1 in 79 cases of endoscopically-excised rectal lesions, ranging from low grade adenoma (LG) to invasive adenocarcinoma (AdCa). CD8 and Foxp3 expression significantly increased with advances in disease progression [AdCa vs. LG: Odds ratio (OR) 4.33; 95% confidence interval (CI), 1.16–16.3; P=0.03 and OR, 40.5; 95% CI, 6.57–249.6; P<0.0001, respectively]. An increase in programmed death-ligand 1 (PD-L1) expression was also observed with disease progression (OR, 24.0; 95% CI, 4.23–136.2; P=0.0003). The expression of sex determining region Y-box 2 (SOX2) did not correlate with disease progression, although an elevated expression was observed in areas with high grade dysplasia. Increased PD-L1 expression may be a mechanism by which tumour cells evade immune recognition, facilitating tumour cell invasion in rectal cancer. The expression of SOX2 in areas with high grade dysplasia may indicate the de-differentiation of tumour cells, or the activation of migration pathways for invasion.

Tumor heterogeneity of gastric cancer: From the perspective of tumor-initiating cell

Gastric cancer (GC) remains one of the most common and malignant types of cancer due to its rapid progression, distant metastasis, and resistance to conventional chemotherapy, although efforts have been made to understand the underlying mechanism of this resistance and to improve clinical outcome. It is well recognized that tumor heterogeneity, a fundamental feature of malignancy, plays an essential role in the cancer development and chemoresistance. The model of tumor-initiating cell (TIC) has been proposed to explain the genetic, histological, and phenotypical heterogeneity of GC. TIC accounts for a minor subpopulation of tumor cells with key characteristics including high tumorigenicity, maintenance of self-renewal potential, giving rise to both tumorigenic and non-tumorigenic cancer cells, and resistance to chemotherapy. Regarding tumor-initiating cell of GC (GATIC), substantial studies have been performed to (1) identify the putative specific cell markers for purification and functional validation of GATICs; (2) trace the origin of GATICs; and (3) decode the regulatory mechanism of GATICs. Furthermore, recent studies demonstrate the plasticity of GATIC and the interaction between GATIC and its surrounding factors (TIC niche or tumor microenvironment). All these investigations pave the way for the development of GATIC-targeted therapy, which is in the phase of preclinical studies and clinical trials. Here, we interpret the heterogeneity of GC from the perspectives of TIC by reviewing the above-mentioned fundamental and clinical studies of GATICs. Problems encountered during the GATIC investigations and the potential solutions are also discussed.

Colorectal cancer: genetic abnormalities, tumor progression, tumor heterogeneity, clonal evolution and tumor-initiating cells

Colon cancer is the third most common cancer worldwide. Most colorectal cancer occurrences are sporadic, not related to genetic predisposition or family history; however, 20-30% of patients with colorectal cancer have a family history of colorectal cancer and 5% of these tumors arise in the setting of a Mendelian inheritance syndrome. In many patients, the development of a colorectal cancer is preceded by a benign neoplastic lesion: either an adenomatous polyp or a serrated polyp. Studies carried out in the last years have characterized the main molecular alterations occurring in colorectal cancers, showing that the tumor of each patient displays from two to eight driver mutations. The ensemble of molecular studies, including gene expression studies, has led to two proposed classifications of colorectal cancers, with the identification of four/five non-overlapping groups. The homeostasis of the rapidly renewing intestinal epithelium is ensured by few stem cells present at the level of the base of intestinal crypts. Various experimental evidence suggests that colorectal cancers may derive from the malignant transformation of intestinal stem cells or of intestinal cells that acquire stem cell properties following malignant transformation. Colon cancer stem cells seem to be involved in tumor chemoresistance, radioresistance and relapse.

Single-cell heterogeneity in ductal carcinoma in situ of breast

Heterogeneous patterns of mutations and RNA expression have been well documented in invasive cancers. However, technological challenges have limited the ability to study heterogeneity of protein expression. This is particularly true for pre-invasive lesions such as ductal carcinoma in situ of the breast. Cell-level heterogeneity in ductal carcinoma in situ was analyzed in a single 5 μm tissue section using a multiplexed immunofluorescence analysis of 11 disease-related markers (EGFR, HER2, HER4, S6, pmTOR, CD44v6, SLC7A5 and CD10, CD4, CD8 and CD20, plus pan-cytokeratin, pan-cadherin, DAPI, and Na+K+ATPase for cell segmentation). Expression was quantified at cell level using a single-cell segmentation algorithm. K-means clustering was used to determine co-expression patterns of epithelial cell markers and immune markers. We document for the first time the presence of epithelial cell heterogeneity within ducts, between ducts and between patients with ductal carcinoma in situ. There was moderate heterogeneity in a distribution of eight clusters within each duct (average Shannon index 0.76; range 0-1.61). Furthermore, within each patient, the average Shannon index across all ducts ranged from 0.33 to 1.02 (s.d. 0.09-0.38). As the distribution of clusters within ducts was uneven, the analysis of eight ducts might be sufficient to represent all the clusters ie within- and between-duct heterogeneity. The pattern of epithelial cell clustering was associated with the presence and type of immune infiltrates, indicating a complex interaction between the epithelial tumor and immune system for each patient. This analysis also provides the first evidence that simultaneous analysis of both the epithelial and immune/stromal components might be necessary to understand the complex milieu in ductal carcinoma in situ lesions.

Current Pathologic Scoring Systems for Metal-on-metal THA Revisions are not Reproducible

BACKGROUND

The aseptic lymphocyte vasculitis-associated lesion (ALVAL) score and the modified Oxford ALVAL score are frequently used scoring methods to evaluate the morphologic features of periprosthetic tissues around metal-on-metal (MoM) hip implants. Except for the initial studies of these two morphology scoring methods, to our knowledge, no other studies have reported on intraclass correlation coefficient (ICC) values for interobserver reliability of these scoring methods.

QUESTIONS/PURPOSES

Are the ALVAL and Oxford ALVAL scores reproducible?

METHODS

The periprosthetic tissue of 37 revisions of 36 patients with failed MoM THAs were independently scored by three experienced pathologists using ALVAL and Oxford ALVAL scoring methods. All patients were included who underwent revision surgery in our hospital until January 2013, with a large-head MoM prosthesis and also met the criteria: blood serum cobalt levels, available MRI scan, and intraarticular cobalt levels. The population included 26 patients with pseudotumors diagnosed by two radiologists using the method described by Matthies et al. The ALVAL describes morphologic features of the synovial lining, tissue organization, and inflammatory cell infiltrate in periprosthetic tissues. The Oxford-ALVAL score uses a semiquantitative measure of the immune response which should be easier to score.

RESULTS

The ALVAL score showed an ICC of 0.38 (95% CI, 0.18-0.58) (fair) for the sum score and this improved up to 0.50 (95% CI, 0.31-0.68) (moderate) using the modified Oxford ALVAL score. The individual parameters of the ALVAL score showed an ICC for the scoring of inflammatory infiltrate of 0.37 (95% CI, 0.17-0.57), an ICC of 0.32 (95% CI, 0.12-0.53) for the scoring of tissue organization, and an ICC of 0.14 (95% CI, -0.04 to 0.34) for synovial lining.

CONCLUSIONS

Scoring morphologic features of MoM tissue is not reproducible using the ALVAL score or the Oxford ALVAL score. This may reflect heterogeneous morphologic features in tumor tissue and between different tumor tissue samples that cannot be reliably quantified by pathologists using the parameters of these two scoring methods. An alternative, simplified scoring system should be developed to improve the interrater agreement.

LEVEL OF EVIDENCE

Level III, diagnostic study.