Pitfalls in immunohistochemical validation of tumor marker expression — Exemplified in invasive cancer of the uterine cervix

Infiltrating T-cell markers in cervical carcinogenesis: a systematic review and meta-analysis

BACKGROUND

The host adaptive immune response helps determine which cervical HPV infections persist and progress to precancer and cancer, and systematic characterisation of T-cell infiltration would help inform key steps in cervical carcinogenesis.

METHODS

A systematic review and meta-analysis were conducted of infiltrating T-cells in normal cervix, low-grade lesions, high-grade lesions, and invasive cancers including epithelial, stromal, and total tissue and the following markers: CD3, CD4, CD8, FoxP3, CD25, and the CD4:CD8 ratio. An additional qualitative review summarised longitudinal data on associations between infiltrating T-cells and cervical disease persistence, regression, progression, or prognosis.

RESULTS

There were fewer CD3+, CD4+, and CD8+ cells in cervical lesions and more cells in cancers compared to normal epithelium. FoxP3 and CD25+ regulatory T-cell infiltration is high in persistent and precancerous lesions, and longitudinal data show improved outcomes with lower regulatory T-cell levels.

CONCLUSIONS

Successful immune evasion may reduce T-cell infiltration in HPV infected and precancerous epithelium, while invasive cancers are highly immunogenic, and regulatory T-cell infiltration increases with cervical disease progression. Understanding these factors may have prognostic value and could aid in novel treatment development and clinical guidelines, but published data are highly heterogeneous and leave important gaps to be filled by future studies.

Adenocarcinoma of the uterine cervix: Pathologic features, treatment options, clinical outcome and prognostic variables

Adenocarcinoma accounts for 10-25% of all cervical cancers, and its relative and absolute rate has raised over the past decades. Most, but not all the authors, reported that adenocarcinoma has a greater propensity to lymph node, ovarian and distant metastases and a worse prognosis compared with squamous cell carcinoma. However, whether histologic type is an independent prognostic factor is still a debated issue. Moreover, adenocarcinoma is a very heterogenous disease, including different histological subtypes. Whereas radical hysterectomy and definitive radiotherapy achieve the same clinical outcome in early stage squamous cell carcinoma, surgery seems to obtain better survival compared with definitive radiotherapy in early stage adenocarcinoma. Chemoradiation is the standard treatment for locally advanced cervical cancer regardless of histologic type, although several retrospective studies showed that patients with adenocarcinoma were more likely to die than those with squamous cell carcinoma both before and after concurrent chemoradiation era. The prognostic relevance of biological variables, such as cyclin-dependent kinase inhibitors, p53, cyclooxygenase-2 [COX-2], cell surface tyrosine-kinases and programmed death-ligand [PD-L1], is still under investigation. Palliative chemotherapy is the only treatment option for persistent or recurrent cervical adenocarcinoma not amenable with surgery and radiotherapy. The use of immune checkpoint inhibitors as well as a therapeutic strategy targeting cell surface tyrosine kinases should be adequately explored in this clinical setting.

LRIG2 promotes the proliferation and cell cycle progression of glioblastoma cells in vitro and in vivo through enhancing PDGFRβ signaling

The leucine-rich repeats and immunoglobulin-like domains (LRIG) gene family, comprising LRIG1, 2 and 3, encodes integral membrane proteins. It has been well established that LRIG1 negatively regulates multiple growth factor signaling pathways and is considered to be a tumor suppressor; however, the biological functions of LRIG2 remain largely unexplored. It was previously demonstrated that LRIG2 positively regulates epidermal growth factor receptor (EGFR) signaling, the most common aberrant receptor tyrosine kinase (RTK) signaling in glioblastoma multiforme (GBM), which promotes GBM growth. In the present study, the effect of LRIG2 on the proliferation of GBM cells was further addressed, as well as the possible mechanisms underlying the regulatory effect of LRIG2 on platelet-derived growth factor receptor β (PDGFRβ) signaling, another common oncogenic RTK signaling pathway in GBM. First, the expression levels of endogenous LRIG2 and PDGFRβ were found to vary notably in human GBM, and the LRIG2 expression level was positively correlated with the expression level of PDGFRβ. Furthermore, to the best of our knowledge, this is the first study to demonstrate that LRIG2 promoted the PDGF-BB-induced proliferation of GBM cells in vitro and in vivo through regulating the PDGFRβ signaling-mediated cell cycle progression. Mechanistically, LRIG2 has the ability to physically interact with PDGFRβ, promoting the total expression and the activation of PDGFRβ, and enhancing its downstream signaling pathways of Akt and signal transducer and activator of transcription 3 and the effectors of key regulators of cell cycle progression, resulting in increased GBM cell proliferation. Collectively, these data indicated that LRIG2 may serve as a tumor promoter gene in gliomagenesis by positively regulating PDGFRβ signaling, another important oncogenic RTK signaling pathway, in addition to the previously reported EGFR signaling in GBM modulated by LRIG2, and validated LRIG2 as a promising therapeutic target for the treatment of GBM characterized by multiple aberrant RTK signaling.

LRIG1, a 3p tumor suppressor, represses EGFR signaling and is a novel epigenetic silenced gene in colorectal cancer

Downregulation of LRIG1 was found in many types of cancer. However, data concerning the possible mechanism of LRIG1 reduction in cancers were not reported yet. To analyze the regulation and function of LRIG1 in colorectal cancer (CRC), 6 cell lines, 46 paired tissues from primary CRC cases were employed in this study. In CRC cell lines, under-expression of LRIG1 was correlated with promoter region hypermethylation, and restoration of LRIG1 was induced by 5-Aza-2'-deoxyazacytidine treatment. Subsequently, we ectopically expressed LRIG1 in LRIG1 low-expressing HCT-116 cells and suppressed LRIG1 in LRIG1 high-expressing LoVo cells. We found that over-expression of LRIG1 inhibits cell proliferation and colony formation and tumor growth, while knockdown of LRIG1 promotes cell proliferation and colony formation. Decreased and increased EGFR/AKT signaling pathway may partially explain the lower and higher rates of proliferation in CRC cells transfected with LRIG1 cDNA or shRNA. In clinical samples, we compared the methylation, mRNA and protein expression of LRIG1 in samples of CRC tissues. A significant increase in LRIG1 methylation was identified in CRC specimens compared to adjacent normal tissues and that it was negatively correlated with its mRNA and protein expression. In conclusion, LRIG1 is frequently methylated in human CRC and consequent mRNA and protein downregulation may contribute to tumor growth by activating EGFR/AKT signaling.

Promoter region methylation and loss of protein expression of PTEN and significance in cervical cancer

The genetic basis underlying cervical tumorigenesis and progression are largely unknown. Phosphatase and tensin homologue (PTEN) is a tumor suppressor gene, and genetic changes of PTEN occurs in various types of cancer suggesting that the inactivation of PTEN may play an important role in the pathogenesis of a variety of human malignancies. In the present study, 102 cervical cancer specimens were examined for the expression of the PTEN gene and promoter methylation using methylation-specific-polymerase chain reaction and immunohistochemistry. The PTEN gene mutation was also assessed using PCR single-strand conformational polymorphism. We examined the correlation between PTEN expression and its associated methylation status and the clinical characteristics of cervical cancer. The results showed that there was one case of an A to G point mutation on exon 9 of the PTEN gene in the cervical cancer tissues. This mutation caused the change of aspartic acid to glycine, and the rate of mutation was 1%. The PTEN gene methylation rate of cervical cancer was 62% (63/102) and the rate was associated with the International Federation of Gynecology and Obstetrics stage, cell differentiation, tumor size and lymph node metastasis (P<0.05). The positive rate of PTEN expression was 49% (50/102) in cervical carcinoma and the PTEN expression between stage I-II and III-IV [60 (27/45) vs. 40% (23/57)] was statistically significant (P<0.01). The PTEN gene expression between the metastasis and no lymph node metastasis groups [26 (10/38) vs. 63% (40/64)] was significantly different (P<0.01). The PTEN gene promoter methylation and its protein expression had a significant correlation (P=0.042). These results suggest that hypermethylation can inactivate the transcription of PTEN and reduce its protein expression. Downregulated PTEN expression is involved in the pathogenesis, invasion and metastasis of cervical cancer, possibly by regulating the balance between apoptosis and proliferation. Therefore, the PTEN expression may be a good marker for the prognosis of cervical cancer.

P27 as a prognostic factor of early cervical carcinoma

OBJECTIVE

The aim of this study was to clarify whether the evaluation of cell-cycle regulatory protein p27 can serve as a prognostic factor in patients with International Federation of Gynecology and Obstetrics (FIGO) stage IB cervical carcinoma.

PATIENTS AND METHODS

A retrospective study was performed on 130 surgically treated patients with FIGO stage IB cervical carcinoma with at least a 5-year follow-up. The expression of p27 was investigated independently by 2 experienced pathologists using immunohistochemistry. The prognostic significance of established prognostic factors and p27 expression were analyzed using univariate and multivariate analyses.

RESULTS

In a univariate analysis, lymph node status, tumor diameter, Gynecologic Oncology Group (GOG) score, lymph vascular space invasion, and p27 expression were significant prognostic factors for overall survival (OS). We found a correlation between p27 expression and lymph node status, tumor diameter, invasion, and GOG score. The p27 expression was a statistically significant prognostic factor for OS in a univariate analysis (log-rank test, P = 0.03). In a multivariate analysis, only lymph node status and tumor diameter were statistically significant prognostic factors for OS.

CONCLUSIONS

This study demonstrated that a low p27 expression is associated with lymph node metastasis, deep stromal invasion, tumor diameter more than 20 mm, and high GOG score and had a prognostic influence on OS in a univariate analysis in a series of 130 women with FIGO stage IB cervical carcinoma. Lymph node status and the diameter of the tumor were the only statistically significant prognostic factors in multivariate analysis.

LRIG1 is a triple threat: ERBB negative regulator, intestinal stem cell marker and tumour suppressor

In baseball parlance, a triple threat is a person who can run, hit and throw with aplomb. Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) is a cell surface protein that antagonises ERBB receptor signalling by downregulating receptor levels. Over 10 years ago, Hedman et al postulated that LRIG1 might be a tumour suppressor. Recently, Powell et al provided in vivo evidence substantiating that claim by demonstrating that Lrig1 loss in mice leads to spontaneously arising, highly penetrant intestinal adenomas. Interestingly, Lrig1 also marks stem cells in the gut, suggesting a potential role for Lrig1 in maintaining intestinal epithelial homeostasis. In this review, we will discuss the ability of LRIG1 to act as a triple threat: pan-ERBB negative regulator, intestinal stem cell marker and tumour suppressor. We will summarise studies of LRIG1 expression in human cancers and discuss possible related roles for LRIG2 and LRIG3.

Tissue biomarkers as prognostic variables of cervical cancer

The most important prognostic variables of cervical carcinoma are FIGO stage, lymph node status and clinical-pathological features of primary tumor. Recently, there has been increasing interest in the identification of biomarkers able to predict both response to treatment and survival. The aim of this review is to critically evaluate current published evidence on the ability of various tissue biomarkers to predict the clinical outcome of patients with cervical carcinoma. In particular, the paper takes into account DNA content, cell-cycle and apoptosis-regulatory proteins, epidermal growth factor receptor [EGFR], vascular endothelial growth factor [VEGF], cyclooxygenase [COX]-2, signal transducer and activator of transcription [Stat]3, human papilloma virus [HPV] status, tumor hypoxia, tumor infiltrating lymphocytes [TIL], microarray technology and microRNA (miRNA). The presence of HPV-18 genotype and an elevated VEGF expression appear to be poor prognostic factors in women with early disease treated with primary surgery, whereas the expression of EGFR, VEGF, COX-2 and tumor hypoxia may have a major impact on the survival of patients treated with definitive radiotherapy or chemoradiation. The data supporting the reliability of ΔNp73 and TAp73α as novel biomarkers of response to radiotherapy are interesting but still limited. DNA microarray technology could offer new laboratory tools for a rationale planning of treatment strategy, and miRNAs might represent new candidate targets to be investigated for both prognostic and therapeutic purposes. Moreover, the assessment of different types of TIL and their ligands in tumor biopsies could enable the identification of a subset of high-risk patients, paving the way to novel immune therapies aimed at blocking T-reg cell activity.

Prognostic significance of cyclooxygenase-2 in cervical cancer: a meta-analysis

Published data on the prognostic value of cyclooxygenase-2 (COX-2) overexpression in cervical cancer are conflicting and heterogeneous. We performed a meta-analysis to more precisely estimate its prognostic significance. The pooled hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the effects. Twenty-three studies with 1,477 cervical cancer patients were selected to evaluate the association between COX-2 and overall survival (OS), disease-free survival (DFS), response to chemoradiation (RC) and clinicopathological parameters. High COX-2 expression predicted poor OS (HR: 2.53, 95% CI: 1.54-4.18), DFS (HR: 2.41, 95% CI: 1.58-3.69) and RC (OR: 3.03, 95% CI: 1.97-4.64). Subgroup analyses showed that COX-2 overexpression was related significantly with poor OS in patients treated by chemoradiation or surgery, and in patients with squamous cell carcinoma, respectively. Besides, COX-2 overexpression was related significantly with poor DFS in chemoradiation subgroup. Furthermore, COX-2 overexpression was associated with poor RC in patients who received "FP" regimen or "P" regimen. Additionally, there were significant associations between COX-2 expression and all clinicopathological parameters except tumor grade. The pooled ORs (95% CI) were as follows: 1.49 (1.09-2.04) for age, 1.77 (1.22-2.56) for lymph node metastasis, 1.04 (0.74-1.47) for tumor grade, 1.71 (1.12-2.64) for tumor size, 2.38 (1.28-4.45) for FIGO stage, 3.96 (2.32-6.77) for histological type, 2.45(1.10-5.42) for parametrical involvement. This meta-analysis indicated that COX-2 overexpression might be an unfavorable prognostic and a chemoradiation resistance predictive factor for cervical cancer; it could potentially help to stratify patients further in clinical treatment.

Membranous expression of ectodomain isoforms of the epidermal growth factor receptor predicts outcome after chemoradiotherapy of lymph node-negative cervical cancer

PURPOSE

We compared the prognostic significance of ectodomain isoforms of the epidermal growth factor receptor (EGFR), which lack the tyrosine kinase (TK) domain, with that of the full-length receptor and its autophosphorylation status in cervical cancers treated with conventional chemoradiotherapy.

EXPERIMENTAL DESIGN

Expression of EGFR isoforms was assessed by immunohistochemistry in a prospectively collected cohort of 178 patients with squamous cell cervical carcinoma, and their detection was confirmed with Western blotting and reverse transcriptase PCR. A proximity ligation immunohistochemistry assay was used to assess EGFR-specific autophosphorylation. Pathways associated with the expression of ectodomain isoforms were studied by gene expression analysis with Illumina beadarrays in 110 patients and validated in an independent cohort of 41 patients.

RESULTS

Membranous expression of ectodomain isoforms alone, without the coexpression of the full-length receptor, showed correlations to poor clinical outcome that were highly significant for lymph node-negative patients (locoregional control, P = 0.0002; progression-free survival, P < 0.0001; disease-specific survival, P = 0.005 in the log-rank test) and independent of clinical variables. The ectodomain isoforms were primarily 60-kD products of alternative EGFR transcripts. Their membranous expression correlated with transcriptional regulation of oncogenic pathways including activation of MYC and MAX, which was significantly associated with poor outcome. This aggressive phenotype of ectodomain EGFR expressing tumors was confirmed in the independent cohort. Neither total nor full-length EGFR protein level, or autophosphorylation status, showed prognostic significance.

CONCLUSION

Membranous expression of ectodomain EGFR isoforms, and not TK activation, predicts poor outcome after chemoradiotherapy for patients with lymph node-negative cervical cancer.

Exon-array profiling unlocks clinically and biologically relevant gene signatures from formalin-fixed paraffin-embedded tumour samples

Background:

Degradation and chemical modification of RNA in formalin-fixed paraffin-embedded (FFPE) samples hamper their use in expression profiling studies. This study aimed to show that useful information can be obtained by Exon-array profiling archival FFPE tumour samples.

Methods:

Nineteen cervical squamous cell carcinoma (SCC) and 9 adenocarcinoma (AC) FFPE samples (10–16-year-old) were profiled using Affymetrix Exon arrays. The gene signature derived was tested on a fresh-frozen non-small cell lung cancer (NSCLC) series. Exploration of biological networks involved gene set enrichment analysis (GSEA). Differential gene expression was confirmed using Quantigene, a multiplex bead-based alternative to qRT–PCR.

Results:

In all, 1062 genes were higher in SCC vs AC, and 155 genes higher in AC. The 1217-gene signature correctly separated 58 NSCLC into SCC and AC. A gene network centered on hepatic nuclear factor and GATA6 was identified in AC, suggesting a role in glandular cell differentiation of the cervix. Quantigene analysis of the top 26 differentially expressed genes correctly partitioned cervix samples as SCC or AC.

Conclusion:

FFPE samples can be profiled using Exon arrays to derive gene expression signatures that are sufficiently robust to be applied to independent data sets, identify novel biology and design assays for independent platform validation.