Optimal protocol for PTEN immunostaining; role of analytical and preanalytical variables in PTEN staining in normal and neoplastic endometrial, breast, and prostatic tissues

Molecular Evaluation of Endometrial Dedifferentiated Carcinoma, Endometrioid Carcinoma, Carcinosarcoma, and Serous Carcinoma Using a Custom-Made Small Cancer Panel

It is often difficult to histologically differentiate among endometrial dedifferentiated carcinoma (DC), endometrioid carcinoma (EC), serous carcinoma (SC), and carcinosarcoma (CS) due to the presence of solid components. In this study, we aimed to categorize these carcinomas according to The Cancer Genome Atlas (TCGA) classification using a small custom-made cancer genome panel (56 genes and 17 microsatellite regions) for integrated molecular diagnosis. A total of 36 endometrial cancer cases with solid components were assessed using IHC, next-generation sequencing (NGS), and the custom-made panel. Among 19 EC cases, six were categorized as MMR-deficient (MMR-d) and eight were classified as having a nonspecific molecular profile. Three EC cases were classified as POLE mutation (POLEmut)-type, which had a very high tumor mutation burden (TMB) and low microsatellite instability (MSI). Increased TMB and MSI were observed in all three DC cases, classified as MMR-d with mutations in MLH1 and POLD1. Except for one case classified as MMR-d, all SC cases exhibited TP53 mutations and were classified as p53 mutation-type. SC cases also exhibited amplification of CCND1, CCNE1, and MYC. CS cases were classified as three TCGA types other than the POLEmut-type. The IHC results for p53 and ARID1A were almost consistent with their mutation status. NGS analysis using a small panel enables categorization of endometrial cancers with solid proliferation according to TCGA classification. As TCGA molecular classification does not consider histological findings, an integrated analytical procedure including IHC and NGS may be a practical diagnostic tool for endometrial cancers.

The effect of pre-analytical variables on downstream application and data analysis of human endometrial biopsies

STUDY QUESTION

What are the effects of pre-analytical variables on the downstream analysis of patient-derived endometrial biopsies?

SUMMARY ANSWER

There are distinct differences in the protein levels of the master regulator of oxygen homeostasis, hypoxia-inducible factor-1-alpha (HIF1α), and the protein and mRNA levels of three related genes, carbonic anhydrase 9 (CA9), vascular endothelial growth factor A (VEGFA) and progesterone receptor (PR) in human endometrial biopsies, depending on the pre-analytical variables: disease status (cancer vs benign), timing of biopsy (pre- vs post-hysterectomy) and type of biopsy (pipelle vs full-thickness).

WHAT IS KNOWN ALREADY

Patient-derived biopsies are vital to endometrial research, but pre-analytical variables relating to their collection may affect downstream analysis, as is evident in other tissues.

STUDY DESIGN SIZE DURATION

A prospective observational study including patients undergoing hysterectomy for endometrial cancer (EC) or benign indications was conducted at a large tertiary gynaecological unit in the UK. Endometrial biopsies were obtained at different time points (pre- or post-hysterectomy) using either a pipelle endometrial sampler or as a full-thickness wedge biopsy.

PARTICIPANTS/MATERIALS SETTING METHODS

The changes in HIF1α, CA9, VEGFA and PR protein levels were measured by semi-quantitative analysis of immunostaining, and the expression levels of three genes (CA9, VEGFA and PR) were investigated by quantitative real-time PCR, in endometrial biopsies from 43 patients undergoing hysterectomy for EC (n = 22) or benign gynaecological indications (n = 21).

MAIN RESULTS AND THE ROLE OF CHANCE

An increase in HIF1α immunostaining was observed in EC versus benign endometrium (functionalis glands) obtained pre-hysterectomy (P < 0.001). An increase in CA9 immunostaining was observed in EC versus benign endometrial functionalis glands at both pre- and post-hysterectomy time points (P = 0.03 and P = 0.003, respectively). Compared with benign endometrial pipelle samples, EC samples demonstrated increased mRNA expression of CA9 (pre-hysterectomy P < 0.001, post-hysterectomy P = 0.008) and VEGFA (pre-hysterectomy P = 0.004, post-hysterectomy P = 0.002). In benign uteri, HIF1α immunoscores (functionalis glands, P = 0.03 and stroma, P = 0.009), VEGFA immunoscores (functionalis glands, P = 0.03 and stroma, P = 0.01) and VEGFA mRNA levels (P = 0.008) were increased in matched post-hysterectomy versus pre-hysterectomy samples. Similarly, in EC, an increase in VEGFA immunoscores (epithelial and stromal) and VEGFA mRNA expression was observed in the matched post-hysterectomy versus pre-hysterectomy biopsies (P = 0.008, P = 0.004 and P = 0.018, respectively). Full-thickness benign post-hysterectomy endometrial biopsies displayed increased VEGFA (P = 0.011) and PR (P = 0.006) mRNA expression compared with time-matched pipelle biopsies.

LARGE SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

This descriptive study explores the effect of pre-analytical variables on the expression of four proteins and three hypoxia-related genes in a limited number of endometrial biopsies from patients with EC and benign controls. Due to the small number, it was not possible to investigate other potential variables such as menstrual cycle phase, region-specific differences within the endometrium, grade and stage of cancer, and surgical technicalities.

WIDER IMPLICATIONS OF THE FINDINGS

Careful consideration of the effects of these pre-analytical variables is essential when interpreting data relating to human endometrial biopsies. A standardized approach to endometrial tissue collection is essential to ensure accurate and clinically transferrable data.

STUDY FUNDING/COMPETING INTERESTS

The authors have no conflicts of interest to declare. The work included in this manuscript was funded by Wellbeing of Women project grants RG1073 and RG2137 (D.K.H.), Wellbeing of Women Entry-Level Scholarship ELS706 and Medical Research Council MR/V007238/1 (A.M./D.K.H.), Liverpool Women's Hospital Cancer Charity (M.A.) and University of Liverpool (L.B., L.R. and E.N.).

Differential Immunoexpression of BRAF/V600E, Senescence Markers, PTEN, and T-type Calcium Channels in Acquired Naevi According to their Histopathological and Dermoscopic Classification

BRAF/V600E mutation and other cell growth/growth-control mechanisms are involved in naevogenesis and melanomagenesis. Immunoexpression of BRAF/V600E and other molecules (p16, phosphatase and tensin homologue (PTEN), Ki67, hTERT and Cav3.1 and 3.2 calcium channels) were investigated in 80 histopathologically and dermoscopically classified acquired naevi. Regarding BRAF/V600E, dysplastic naevi showed lower immunostaining than common naevi, which was significant in comparison with intradermal naevi, which showed the highest BRAF/V600E histoscore. Junctional naevi showed the lowest BRAF/V600E levels. Globular/cobblestone and reticular dermoscopic patterns were consistently associated with high and low BRAF/V600E immunoexpression, respectively, but Zalaudek’s peripheral globule pattern (CR/PG) showed the highest BRAF/V600E immunoexpression. Among global patterns, the previously not investigated multicomponent pattern showed the lowest BRAF/V600E immunoexpression. Regarding the remaining biomarkers, new immunohistochemical features were found, in particular p16 and PTEN low expression in multicomponent pattern; and Ki67, hTERT and Cav.3.1 high expression in CR/PG. In conclusion, histopathology and dermoscopy provide complementary information regarding the biology of melanocytic naevi.

Diagnosis and management of an endometrial cancer patient with Cowden syndrome

Somatic PTEN alterations are common in endometrial carcinoma (EC), but in rare cases PTEN mutations are associated with inherited syndromes. Here, we present a case of Cowden syndrome-associated EC. We discuss clinical, pathologic and molecular features of her tumor and PTEN-mutated EC, inherited syndromes predisposing to EC and PTEN-targeted therapies.

Pulmonary sclerosing pneumocytoma masquerading adenocarcinoma with co-existing BRAF V600E and PTEN mutation

We report a case of a massive primary sclerosing pneumocytoma (PSP) involving the right lower lobe adhering esophagus with small synchronous PSP on the superior segment of the left lower lobe with concurrent mutation for B-RAF proto-oncogene, serine/threonine kinase (BRAF V600E), and phosphatase and tensin homolog (PTEN) gene in a young female. She underwent right lower lobectomy and mediastinal lymph node dissection under single lung ventilation with tumor-free margins on diagnosis-based findings of preoperative computed tomography-guided biopsy and positron emission tomography. Histopathology was suggestive of PSP-papillary variant with concurrent mutation of BRAF V600E and PTEN genes. Post-operative follow-up at four weeks was uneventful. She has to undergo wedge resection for the contralateral disease after six weeks following recovery from the first surgery.

Phase 2 study of copanlisib in combination with gemcitabine and cisplatin in advanced biliary tract cancers

BACKGROUND

Biliary tract cancer (BTC) has a poor prognosis despite treatment with first-line gemcitabine and cisplatin. In BTC, PI3K/AKT pathway activation has been shown to increase resistance to chemotherapy, which may be overcome with PI3K inhibition. This phase 2 study evaluated the safety and efficacy of copanlisib, a PI3K inhibitor, with gemcitabine and cisplatin in advanced BTCs. The role of PTEN expression in outcomes was also explored.

METHODS

Patients with advanced/unresectable BTC received gemcitabine, cisplatin, and copanlisib as their first-line treatment. The primary endpoint was progression-free survival (PFS) at 6 months. Secondary endpoints were the response rate (RR), median overall survival (OS)/PFS, and safety profile. An assessment of PTEN expression by immunohistochemistry was also performed along with molecular profiling.

RESULTS

Twenty-four patients received at least 1 dose of the study drug. The PFS rate at 6 months was 51%; the median OS was 13.7 months (95% CI, 6.8-18.0 months), and the median PFS was 6.2 months (95% CI, 2.9-10.1 months). Nineteen patients were evaluable for RR: 6 patients achieved a partial response (31.6%), and 11 (57.9%) had stable disease. The most common grade 3/4 adverse events were a decreased neutrophil count (45.83%), anemia (25%), increased lipase (25%), and hypertension (20.8%). Twenty patients had tissue evaluable for the PTEN status. The PFS for low (n = 9) and high PTEN expression (n = 11) was 8.5 and 4.6 months, respectively (P = .19). The median OS for low and high PTEN expression groups was 17.9 and 7.0 months, respectively (P = .19).

CONCLUSIONS

The addition of copanlisib to gemcitabine and cisplatin does not improve PFS at 6 months. However, future studies using PTEN as a potential biomarker should be considered.

LAY SUMMARY

The addition of copanlisib, a PI3K inhibitor, to standard chemotherapy for advanced biliary tract cancers was assessed for efficacy and safety. Twenty-four patients with advanced biliary tract cancer received treatment in this study. There was no difference in survival with the addition of copanlisib in comparison with standard chemotherapy. Copanlisib may be more effective and increase survival in patients with low PTEN expression levels. Further studies are needed to confirm this. No unexpected adverse events occurred.

PTEN/PI3K/VEGF signaling pathway involved in the protective effect of xanthine oxidase inhibitor febuxostat against endometrial hyperplasia in rats

Endometrial hyperplasia (EH) is a medical condition that affects many females as it increases their uterine carcinogenic potential. EH results from entangling hormonal imbalance and inflammatory response. The study examined the role of a xanthine oxidase inhibitor, febuxostat, in a rat model of EH. Adult female Wistar albino rats were subjected to estradiol valerate (EV) 2 mg/kg for 10 days to induce EH. Another group was treated concomitantly with febuxostat 10 mg/kg for the same period. The uterine malondialdehyde, reduced glutathione (GSH), and superoxide dismutase (SOD) were assessed by chemical methods. Gene expressions of phosphatidylinositol-3-kinase (PI3K), Akt, and hypoxia-inducible factor 1 alpha were assessed by the quantitative real-time polymerase chain reaction. Moreover, the vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) were measured by enzyme-linked immunosorbent assay. Histopathology and immunohistochemical techniques were used for the detection of phosphatase and tensin homolog (PTEN). The results revealed that EV administration induced complex EH with focal atypia and loss of PTEN expression by the histological examination. Uteri of the EV group showed a significant drop in GSH content and SOD activity and rise in the expressions of PI3K, Akt, VEGF, and IL-6. Febuxostat administration significantly improved the uterine GSH and SOD levels. It decreased the expressions of PI3K, Akt, VEGF, and IL-6. The endometrium showed a regression of the proliferative epithelium with the restoration of PTEN expression and the absence of the atypical features. In conclusion, febuxostat protected the endometrium against estrogen-induced EH and may be beneficial in the management along with the hormonal therapy.

Precise Immunodetection of PTEN Protein in Human Neoplasia

PTEN is a major tumor-suppressor protein whose expression and biological activity are frequently diminished in sporadic or inherited cancers. PTEN gene deletion or loss-of-function mutations favor tumor cell growth and are commonly found in clinical practice. In addition, diminished PTEN protein expression is also frequently observed in tumor samples from cancer patients in the absence of PTEN gene alterations. This makes PTEN protein levels a potential biomarker parameter in clinical oncology, which can guide therapeutic decisions. The specific detection of PTEN protein can be achieved by using highly defined anti-PTEN monoclonal antibodies (mAbs), characterized with precision in terms of sensitivity for the detection technique, specificity for PTEN binding, and constraints of epitope recognition. This is especially relevant taking into consideration that PTEN is highly targeted by mutations and posttranslational modifications, and different PTEN protein isoforms exist. The precise characterization of anti-PTEN mAb reactivity is an important step in the validation of these reagents as diagnostic and prognostic tools in clinical oncology, including their routine use in analytical immunohistochemistry (IHC). Here, we review the current status on the use of well-defined anti-PTEN mAbs for PTEN immunodetection in the clinical context and discuss their potential usefulness and limitations for a more precise cancer diagnosis and patient benefit.

Serum Prolactin Contributes to Enhancing Prolactin Receptor and pJAK2 in Type I Endometrial Cancer Cells in Young Women Without Insulin Resistance

Elevated levels of serum prolactin and a high expression of prolactin receptor (PRLR) in cancer cells was recently identified in patients with endometrial cancer (EC). However, the impact of prolactin on EC remains unknown. The aim of this study was to elucidate the clinical and immunohistochemical characteristics of hyperprolactinemic patients with EC according to the pathogenetic types, type I and type II. EC patients were retrospectively divided into a high prolactin (HP) group and a low prolactin (LP) group by a serum prolactin level of 20 ng/mL and were compared between 2 groups. The expression of PRLR, phosphorylated Janus-kinase 2 (pJAK2), estrogen receptor-α, progesterone receptor, and PTEN in cancer tissue were evaluated by immunohistochemistry. Ninety-nine patients were identified. In the type I group, HP group was significantly younger (45.2 vs. 52.2, P=0.028) and their insulin resistance was significantly lower (1.6 vs. 2.5, P=0.033) than those in LP group, and the expression of PRLR and pJAK2 in the HP group was significantly higher than that in the LP group (immunoreactive score: 6.8 vs. 3.9, P=0.003; 5.7 vs. 2.6, P<0.001, respectively). In the type 2 group, there were no differences between all the term. In the type I group, the rate of loss of PTEN in the HP group was significantly lower than the LP group (25.0% vs. 60.7%, P=0.024). Prolactin-PRLR signaling may play a crucial role for the progression of type I EC without involving the PTEN mutation in young hyperprolactinemic women without insulin resistance.

Emerging relationships between papillary proliferation of the endometrium and endometrial carcinoma: evidence from an immunohistochemical and molecular analysis

Papillary proliferation of the endometrium (PPE) is an uncommon lesion that frequently shows mucinous metaplasia. PPE occasionally has concurrent or preceding endometrial hyperplasia and carcinomas, but there is little molecular evidence to support the relationships between PPEs and endometrial neoplasia. In this study, we analyzed the clinicopathological and immunohistochemical features in 30 PPEs (22 simple PPEs and 8 complex papillary hyperplasia (CPH)). Hotspot mutations of KRAS, PI3KCA, AKT1, PTEN (exons 3, 5, and 7), and ARID1A (exons 1 and 14) were detected by pyrosequencing or bidirectional Sanger sequencing. We found that endometrial hyperplasia and carcinoma were more common in CPHs (4/6, 66.7%) than in simple PPEs (4/21, 19.0%) (p < 0.05). Compared with the adjacent normal endometrium, PPEs frequently showed loss of PAX2 (56.7%) and PTEN (10%) expression, diffuse p16 expression (36.7%), decreased PR expression (84.3%), and lower Ki67 labeling index (median 1%, range 1-15%). Simple PPEs and CPHs had similar immunohistochemical features (p > 0.05). KRAS mutations were identified in 14 PPEs and 1 concurrent endometrial carcinoma. The prevalence of KRAS mutations was not statistically different between simple PPEs (10/21, 45.5%) and CPHs (4/8, 50%) (p > 0.05), but was higher in PPEs displaying mucinous metaplasia (12/24, 50%) than in those without (2/6, 33.3%) (p < 0.05). One simple PPE with a KRAS mutation had an AKT1 mutation. No PPEs demonstrated mutations in PI3KCA, PTEN, and ARID1A. In conclusion, both simple PPE and CPH share some common molecular alterations with endometrial neoplasia, in which, KRAS mutations might be a driver.

Precise definition of PTEN C-terminal epitopes and its implications in clinical oncology

Anti-PTEN monoclonal antibodies (mAb) are arising as important tools for immunohistochemistry (IHC) and protein quantification routine analysis in clinical oncology. Although an effort has been made to document the reliability of tumor tissue section immunostaining by anti-PTEN mAb, and to standardize their IHC use in research and in the clinical practice, the precise topological and biochemical definition of the epitope recognized by each mAb has been conventionally overlooked. In this study, six commercial anti-PTEN mAb have been validated and characterized for sensitivity and specificity by IHC and FISH, using a set of prostate and urothelial bladder tumor specimens, and by immunoblot, using PTEN positive and PTEN negative human cell lines. Immunoblot precise epitope mapping, performed using recombinant PTEN variants and mutations, revealed that all mAb recognized linear epitopes of 6–11 amino acid length at the PTEN C-terminus. Tumor-associated or disease-associated mutations at the PTEN C-terminus did not affect subcellular localization or PIP3 phosphatase activity of PTEN in cells, although resulted in specific loss of reactivity for some mAb. Furthermore, specific mimicking-phosphorylation mutations at the PTEN C-terminal region also abolished binding of specific mAb. Our study adds new evidence on the relevance of a precise epitope mapping in the validation of anti-PTEN mAb for their use in the clinics. This will be substantial to provide a more accurate diagnosis in clinical oncology based on PTEN protein expression in tumors and biological fluids.

Identification of genetic alterations associated with primary resistance to EGFR-TKIs in advanced non-small-cell lung cancer patients with EGFR sensitive mutations

Background

Identification of activated epidermal growth factor receptor (EGFR) mutations and application of EGFR-tyrosine kinase inhibitors (EGFR-TKIs) have greatly changed the therapeutic strategies of non-small-cell lung cancer (NSCLC). However, the long-term efficacy of EGFR-TKI therapy is limited due to the development of drug resistance. The aim of this study was to investigate the correlation between the aberrant alterations of 8 driver genes and the primary resistance to EGFR-TKIs in advanced NSCLC patients with activated EGFR mutations.

Methods

We retrospectively reviewed the clinical data from 416 patients with stage III/IV or recurrent NSCLC who received an initial EGFR-TKI treatment, from April 2004 and March 2011, at the Sun Yat-sen University Cancer Center. Several genetic alterations associated with the efficacy of EGFR-TKIs, including the alterations in BIM, ALK, KRAS, PIK3CA, PTEN, MET, IGF1R, and ROS1, were detected by the routine clinical technologies. The progression-free survival (PFS) and overall survival (OS) were compared between different groups using Kaplan–Meier survival analysis with the log-rank test. A Cox regression model was used to estimate multivariable-adjusted hazard ratios (HRs) and their 95% confidence intervals (95% CIs) associated with the PFS and OS.

Results

Among the investigated patients, 169 NSCLC patients harbored EGFR-sensitive mutations. EGFR-mutant patients having PTEN deletion had a shorter PFS and OS than those with intact PTEN (P = 0.003 for PFS, and P = 0.034 for OS). In the combined molecular analysis of EGFR signaling pathway and resistance genes, we found that EGFR-mutant patients coexisted with aberrant alterations in EGFR signaling pathway and those having resistant genes had a statistically poorer PFS than those without such alterations (P < 0.001). A Cox proportional regression model determined that PTEN deletion (HR = 4.29,95% CI = 1.72–10.70) and low PTEN expression (HR = 1.96, 95% CI = 1.22–3.13), MET FISH + (HR = 2.83,95% CI = 1.37–5.86) were independent predictors for PFS in patients with EGFR-TKI treatment after adjustment for multiple factor.

Conclusions

We determined that the coexistence of genetic alterations in cancer genes may explain primary resistance to EGFR-TKIs.

Electronic supplementary material

The online version of this article (10.1186/s40880-019-0354-z) contains supplementary material, which is available to authorized users.

Tumor Pre-Analytics in Molecular Pathology: Impact on Protein Expression and Analysis

Purpose of Review

Precision medicine promises patient tailored, individualized diagnosis and treatment of diseases and relies on clinical specimen integrity and accuracy of companion diagnostic testing. Therefore, pre-analytics, which are defined as the collection, processing, and storage of clinical specimens, are critically important to enable optimal diagnostics, molecular profiling, and clinical decision-making around harvested specimens. This review article discusses the impact of tumor pre-analytics on molecular pathology focusing on biospecimen protein expression and analysis.

Recent Findings

Due to busy clinical schedules and workflows that have been established for many years and to lack of standardization and limited assessment tools to quantify variability in pre-analytical processing, the effects of pre-analytics on biospecimen integrity are often overlooked. Several studies have recently emphasized an emerging crisis in science and reproducibility of results.

Summary

Biomarker instability due to pre-analytical variables affects comprehensive analysis and molecular phenotyping of patients’ tissue. This problematic emphasizes the critical need for standardized protocols and technologies to be applied in the clinical and research setting.

Luteinizing Hormone/Human Chorionic Gonadotropin Receptor Immunohistochemical Score Associated with Poor Prognosis in Endometrial Cancer Patients

The aim of this study was to develop a scoring system of the immunohistochemical (IHC) expression of luteinizing hormone/human chorionic gonadotropin receptor (LHCG-R) in endometrial cancer (EC) patients. Nonconsecutive hysterectomy specimens containing EC collected from April 2013 to October 2015 were selected. Hematoxylin-eosin stained sections from each case were reviewed and representative sections from each tumor were selected. IHC staining was performed for the detection of LHCG-R. The percentage of stained cells and the staining intensity were assessed in order to develop an immunohistochemical score. Moreover, we examined the correlation of the score with grading and lymphovascular space invasion (LVSI). There was a statistically significant positive correlation between grading and IHC scoring (p = 0.01) and a statistically significant positive correlation between LVSI and IHC score (p < 0.01). In conclusion, we suggest that the immunohistochemical score presented here could be used as a marker of bad prognosis of EC patients. Nevertheless, further studies are needed in order to validate it. The study was registered in the Careggi Hospital public trials registry with the following number: 2013/0011391.

In depth evaluation of the prognostic and predictive utility of PTEN immunohistochemistry in colorectal carcinomas: performance of three antibodies with emphasis on intracellular and intratumoral heterogeneity

Background

Phosphatase and tensin homolog deleted in chromosome 10 (PTEN) loss of function is frequently detected in advanced colorectal cancer. Its detection is thought to have prognostic significance and it is being considered to predict responsiveness to anti-EGFR therapy. Unfortunately, while immunohistochemical assessment of PTEN expression is widespread, it lacks standardization and the results are hardly comparable across the available publications.

Methods

Retrospectively collected, formalin-fixed and paraffin-embedded colorectal tumor tissue samples from 55 patients were combined into tissue microarray (TMA) blocks. We used three different PTEN antibodies to determine the frequency, intensity and intracellular pattern of PTEN immunohistochemical labeling: Neomarkers, Dako and CellSignaling. We evaluated the aforementioned parameters in selected regions of colorectal cancers and in their lymph node metastases by using three scoring methods that take into consideration both staining frequency and intensity (H1-H3-score). We also evaluated intracellular localization.

Results

The Dako and CellSignaling antibodies stained predominantly cytoplasms, while the Neomarkers antibody specifically stained cell nuclei. PTEN H-scores were significantly lower in all tumor areas as compared to the normal colonic mucosa based on staining with the DAKO and CellSignaling antibodies. Intratumoral regional differences or differences between matching tumors and metastases were not detected with any of the antibodies. Neither Dako, neither CellSignaling, nor the Neomarkers antibodies revealed a significant correlation between PTEN expression and pT, Dukes/MAC and clinical stage. KRAS status, histological grade correlated with PTEN H-scores based on staining with the Neomarkers antibody. PTEN H-scores did not correlate with MMR status. PTEN H-scores did not show any correlation with relapse-free survival based on staining with either antibody.

Conclusions

While PTEN expression decreased in colorectal cancer according to two antibodies, neither of the three applied PTEN antibodies could justify significant correlation with clinicopathological data, nor had prognostic value. Thus, we might conclude that immunohistochemical PTEN investigation remains a challenge requiring more standardized evaluation on larger number of cases to clarify its utility as a prognostic and predictive tool in CRC. The standardization of immunohistochemical method is key in the evaluation process, which is further discussed.

Electronic supplementary material

The online version of this article (doi:10.1186/s13000-016-0508-0) contains supplementary material, which is available to authorized users.

Expression of PTEN and Its Correlation with Proliferation Marker Ki-67 in Head and Neck Cancer

Introduction

PTEN is part of large family of tyrosine phosphatases and has been found inactivated in a wide variety of human cancers.

Aims

In the present study we have tried to determine the association of the expression patterns of this gene with carcinogenesis.

Methods

First, a systematic review was carried out to ascertain the importance of the PTEN gene and its role in carcinogenesis. In the second phase, a case-control study was designed using different expression analysis techniques. Expression of PTEN mRNA was analyzed using reverse transcriptase polymerase chain reaction (RT-PCR).

Results

Significantly downregulated expression of PTEN was observed in patients with head and neck cancer (HNC) compared to adjacent normal-tissue controls. These results were confirmed with quantitative polymerase chain reaction (qPCR). Significant downregulation of the gene was observed in HNC patients compared to adjacent normal-tissue controls. PTEN expression was correlated with different histopathological parameters of the study cohort by Spearman's correlation coefficient and a significant negative correlation was observed with pT stage (r = −0.271*; p<0.02) and grade (r = −0.228*; p<0.02) of HNC tissues. Furthermore, the expression variations of PTEN were correlated with the expression pattern of the proliferation marker Ki-67. Significantly (p<0.008) upregulated expression of Ki-67 was observed in HNC patients compared with adjacent normal-tissue controls This upregulation of Ki-67 was confirmed at the protein level by immunohistochemistry in HNC patients. When Spearman's correlation was carried out a significant negative correlation was observed between PTEN and Ki-67 (r = −0.230*; p<0.03).

Conclusions

Our data suggest that downregulation of PTEN and overexpression of Ki-67 may contribute to the initiation and progression of HNC.

Assessing PTEN Subcellular Localization

PTEN subcellular localization is fundamental in the execution of the distinct PTEN biological activities, including not only its PI(3,4,5)P3 phosphatase activity when associated to membranes but also its subcellular compartment-specific interactions with regulatory and effector proteins, including those exerted in the nucleus. As a consequence, PTEN subcellular localization is tightly regulated in vivo by both intrinsic and extrinsic mechanisms. The plasma membrane/nucleus/cytoplasm partitioning of PTEN has been the focus of several studies, both from a mechanistic and from a disease-association point of view. Here, we summarize the current knowledge on PTEN plasma membrane/nucleus/cytoplasm distribution, and present subcellular fractionation, immunofluorescence, and immunohistochemical methods to study the distribution and shuttling of PTEN between these subcellular compartments.

PTEN mRNA detection by chromogenic, RNA in situ technologies: a reliable alternative to PTEN immunohistochemistry

Immunohistochemical staining for phosphatase and tensin homolog (PTEN) does not have either an acceptable standard protocol or concordance of scoring between pathologists. Evaluation of PTEN mRNA with a unique and verified sequence probe may offer a realistic alternative providing a robust and reproducible protocol. In this study, we have evaluated an in situ hybridization (ISH) protocol for PTEN mRNA using RNAScope technology and compared it with a standard protocol for PTEN immunohistochemistry (IHC). PTEN mRNA expression by ISH was consistently more sensitive than PTEN IHC, with 56% of samples on a mixed-tumor tissue microarray (TMA) showing high expression by ISH compared with 42% by IHC. On a prostate TMA, 49% of cases showed high expression by ISH compared with 43% by IHC. Variations in PTEN mRNA expression within malignant epithelium were quantifiable using image analysis on the prostate TMAs. Within tumors, clear overexpression of PTEN mRNA on malignant epithelium compared with benign epithelium was frequently observed and quantified. The use of SpotStudio software in the mixed-tumor TMA allowed for clear demonstration of varying levels of PTEN mRNA between tumor samples by the mRNA methodology. This was evident by the quantifiable differences between distinct oropharyngeal tumors (up to 3-fold increase in average number of spots per cell between 2 cases). mRNA detection of PTEN or other biomarkers, for which optimal or standardized immunohistochemical techniques are not available, represents a means by which heterogeneity of expression within focal regions of tumor can be explored with more confidence.

FISH analysis of PTEN in endometrial carcinoma. Comparison with SNP arrays and MLPA

AIMS

To check the usefulness of a standardized protocol of PTEN FISH in 31 endometrial carcinomas (ECs) in comparison with SNP array (SNPA), multiplex ligation-dependent probe amplification (MLPA), and immunohistochemistry.

METHODS AND RESULTS

Fluorescence in-situ hybridization analysis showed two PTEN copies in 17 cases, three copies in nine cases, hemizygous deletion in two cases, and diverse cell populations with different PTEN copy number in three cases. A good correlation was seen between FISH and SNPA, particularly in cases with three copies. FISH identified two cases with entire deletion of chromosome 10, but did not identify a focal deletion of PTEN. Five cases with PTEN deletion and duplication of the second allele by SNPA were interpreted as normal by FISH. Concordance between FISH and MLPA was seen in 15 cases with two copies, and in two cases with PTEN deletion. Six cases were interpreted as amplified by MLPA, but showed polyploidy by FISH. FISH was superior to SNPA and MLPA in assessing the tumours with diverse cell populations with different PTEN copies.

CONCLUSIONS

The results show good concordance between FISH, SNPA and MLPA. SNPA was superior in tumours with deletion of one copy and duplication of the second allele. FISH was superior in assessing tumour heterogeneity.

Hereditary Syndromes Manifesting as Endometrial Carcinoma: How Can Pathological Features Aid Risk Assessment?

Endometrial carcinoma is the most common gynecological tumor worldwide. It can be the presenting malignancy, acting as the harbinger, of an undiagnosed hereditary syndrome. Up to 50% of females with Lynch syndrome present in this manner. Differentiation between Lynch, Muir-Torre, and Cowden syndromes can at times be challenging due to the overlapping features. Our review emphasizes on the strengths, pitfalls, and limitations of microscopic features as well as immunohistochemical and polymerase chain reaction- (PCR-) based tests used by laboratories to screen for DNA mismatch repair (MMR) and PTEN gene mutations in patients to enable a more targeted and cost effective approach in the use of confirmatory gene mutational analysis tests. This is crucial towards initiating timely and appropriate surveillance measures for the patient and affected family members. We also review the evidence postulating on the possible inclusion of uterine serous carcinoma as part of the spectrum of malignancies seen in hereditary breast and ovarian carcinoma syndrome, driven by mutations in BRCA1/2.

Loss of PTEN expression is associated with aggressive behavior and poor prognosis in Middle Eastern triple-negative breast cancer

PTEN is a tumor suppressor that negatively regulates the PI3 K-AKT signaling pathway which is involved in the pathogenesis of many different tumor types and serves as a prognostic marker in breast cancer. However, the significance of the role of PTEN in Middle Eastern ethnic breast cancer has not been explored especially with the fact that breast cancer originating from this ethnic population tend to behave more aggressively than breast cancer in the west. In this study, we analyzed PTEN alteration in a tissue microarray format containing more than 1000 primary breast cancers with clinical follow-up data. Tissue Microarray sections were analyzed for protein expression and copy number change using immunohistochemistry and fluorescence in situ hybridization. Loss of PTEN immunostaining was observed in 77 % of the cases. PTEN loss was significantly associated with large tumor size (p = 0.0030), high grade (p = 0.0281), tumor recurrence (p = 0.0333), and triple-negative breast cancers (p = 0.0086). PTEN loss in triple-negative breast cancers was significantly associated with rapid tumor cell proliferation (p = 0.0396) and poor prognosis (p = 0.0408). PTEN deletion was found only in 60 cases (6.4 %). Loss of PTEN protein expression occurs at high frequency in Middle Eastern breast cancer. PTEN inactivation may potentially lead to an aggressive behavior of tumor cells through stimulation of tumor cell proliferation. Furthermore, PTEN signaling pathway might be used as potential therapeutic target in triple-negative breast cancers since loss of its expression is shown to be significantly associated with this aggressive subtype of breast cancer.

Immunohistochemical and genetic profiles of endometrioid endometrial carcinoma arising from atrophic endometrium

OBJECTIVE

Endometrial carcinomas are divided into type I endometrioid endometrial carcinomas (EECs), thought to arise from hyperplastic endometrium, and type II nonendometrioid endometrial carcinomas, thought to arise from atrophic endometrium. However, a minority (20%) of EECs have atrophic background endometrium, which was shown to be a marker of a worse prognosis. This study compares the immunohistochemical and genetic profiles of this possible third type to that of the known two types.

METHODS

43 patients with grade 1 EEC and hyperplastic background endometrium (type I), 43 patients with grade 1 EEC and atrophic background endometrium (type III) and 21 patients with serous carcinoma (type II) were included (n=107). Tissue microarrays of tumor samples were immunohistochemically stained for PTEN, L1CAM, ER, PR, p53, MLH1, PMS2, β-catenin, E-cadherin and MIB1. The BRAF, KRAS, and PIK3CA genes were analyzed for mutations.

RESULTS

A significantly higher expression of ER and PR, and a lower expression of L1CAM, p53 and MLH1 were found in type I and III compared to type II carcinomas. Expression of E-cadherin was significantly reduced in type III compared to type I carcinomas. Mutation analysis showed significantly less mutations of KRAS in type III compared to type I and II carcinomas (p<0.01).

CONCLUSION

There appear to be slight immunohistochemical and genetic differences between EECs with hyperplastic and atrophic background endometrium. Carcinogenesis of EEC in atrophic endometrium seems to be characterized by loss of E-cadherin and a lack of KRAS mutations. As expected, endometrioid and serous carcinomas were immunohistochemically different.

Lung neuroendocrine tumors: correlation of ubiquitinylation and sumoylation with nucleo-cytosolic partitioning of PTEN

Background

The tumor suppressor phosphatase and tensin homolog (PTEN) is a pleiotropic enzyme, inhibiting phosphatidyl-inositol-3 kinase (PI3K) signaling in the cytosol and stabilizing the genome in the nucleus. Nucleo-cytosolic partitioning is dependent on the post-translational modifications ubiquitinylation and sumoylation. This cellular compartmentalization of PTEN was investigated in lung neuroendocrine tumors (lung NET).

Methods

Tumor tissues from 192 lung NET patients (surgical specimens = 183, autopsies = 9) were investigated on tissue microarrays. PTEN was H-scored by two investigators in nucleus and cytosol using the monoclonal antibody 6H2.1. Results were correlated with immunoreactivity for USP7 (herpes virus-associated ubiquitin-specific protease 7) and SUMO2/3 (small ubiquitin-related modifier protein 2/3) as well as PTEN and p53 FISH gene status. Clinico-pathologic data including overall survival, proliferation rate and diagnostic markers (synaptophysin, chromogranin A, Mib-1, TTF-1) were recorded.

Results

The multicentre cohort included 58 typical carcinoids (TC), 42 atypical carcinoids (AC), 32 large cell neuroendocrine carcinomas (LCNEC) and 60 small cell lung carcinomas (SCLC). Carcinoids were smaller in size and had higher synaptophysin and chromogranin A, but lower TTF-1 expressions. Patients with carcinoids were predominantly female and 10 years younger than patients with LCNEC/SCLC. In comparison to the carcinoids, LCNEC/SCLC tumors presented a stronger loss of nuclear and cytosolic PTEN associated with a loss of PTEN and p53. Concomitantly, a loss of nuclear USP7 but increase of nuclear and cytosolic SUMO2/3 was found. Loss of nuclear and cytosolic PTEN, loss of nuclear USP7 and increase of cytosolic SUMO2/3 thus correlated with poor survival. Among carcinoids, loss of cytosolic PTEN was predominantly found in TTF1-negative larger tumors of male patients. Among SCLC, loss of both cytosolic and nuclear PTEN but not proliferation rate or tumor size delineated a subgroup with poorer survival (all p-values <0.05).

Conclusions

Cellular ubiquitinylation and sumoylation likely influence the functional PTEN loss in high grade lung NET. Both nuclear and cytosolic PTEN immunoreactivity should be considered for correlation with clinico-pathologic parameters.

Immunohistochemical assessment of PTEN in vulvar cancer: best practices for tissue staining, evaluation, and clinical association

BACKGROUND

Pten encodes a well-characterized protein that is important in several cancers due to its tumor suppressor function. Yet, the detection and evaluation of PTEN by immunohistochemistry (IHC) for clinical practice have not been standardized. Thus, in this study, we performed a literature review of protocols for PTEN assessment by IHC and the possible differences in evaluation, based on our experience with vulvar carcinomas. Also, we report some of our most recent findings regarding the clinical impact of PTEN in this type of tumor.

METHODS

In total, 150 FFPE vulvar carcinoma samples in a tissue microarray were examined by IHC with regard to PTEN, PI3K, AKT, and mTOR. All evaluations were performed by slide digitalization and quantification using APERIO ImageScope software. All measurements were converted into HScore values for the statistical analysis.

RESULTS

Sharp and specific PTEN expression was observed in the nuclei and cytoplasmic compartments. Its HScore values ranged from 3.5 to 226, with a median of 92.5. mTOR expression was robust in all cases (mean HScore=248.1). AKT and PI3K had median HScore values of 200.5 and 156.5, respectively. In addition, PTEN expression was associated with higher rates of patient survival.

CONCLUSION

The preanalytical step is the first issue in the immunohistochemical evaluation of PTEN. With regard to the analytical procedure, the antigen retrieval step yielded better stains for protocols with high-pH buffers, and antibody clone 6H2.1 effected the most reliable results. PTEN is a good prognostic marker for vulvar cancer, correlating with higher rates of patient survival. Our data underscore the importance of technical standardization to ensure more reliable and reproducible evaluation of PTEN in clinical practice.

Modeling glands with PTEN deficient cells and microscopic methods for assessing PTEN loss: endometrial cancer as a model

PTEN is an important tumor suppressor gene. Interpreting PTEN deficiency in the appropriate microscopic context of cancer may be important to understand its role in tumor development and progression. This may be particularly relevant in heterogeneous tumors. Here, we discuss the usefulness of 3D cultures in understanding the consequences of PTEN inactivation in tissue architecture. Afterwards, we discuss the role of immunohistochemistry and fluorescent in situ hybridization in assessing PTEN loss in tumors. In this review, endometrial carcinoma is used as a model.

Identification of cellular and genetic drivers of breast cancer heterogeneity in genetically engineered mouse tumour models

The heterogeneous nature of mammary tumours may arise from different initiating genetic lesions occurring in distinct cells of origin. Here, we generated mice in which Brca2, Pten and p53 were depleted in either basal mammary epithelial cells or luminal oestrogen receptor (ER)-negative cells. Basal cell-origin tumours displayed similar histological phenotypes, regardless of the depleted gene. In contrast, luminal ER-negative cells gave rise to diverse phenotypes, depending on the initiating lesions, including both ER-negative and, strikingly, ER-positive invasive ductal carcinomas. Molecular profiling demonstrated that luminal ER-negative cell-origin tumours resembled a range of the molecular subtypes of human breast cancer, including basal-like, luminal B and 'normal-like'. Furthermore, a subset of these tumours resembled the 'claudin-low' tumour subtype. These findings demonstrate that not only do mammary tumour phenotypes depend on the interactions between cell of origin and driver genetic aberrations, but also multiple mammary tumour subtypes, including both ER-positive and -negative disease, can originate from a single epithelial cell type. This is a fundamental advance in our understanding of tumour aetiology.

MicroRNA-103 promotes colorectal cancer by targeting tumor suppressor DICER and PTEN

MicroRNAs (miRNAs) are a class of small, noncoding RNAs that act as key regulators in various physiological and pathological processes. However, the regulatory mechanisms for miRNAs in colorectal cancer remain largely unknown. Here, we found that miR-103 is up-regulated in colorectal cancer and its overexpression is closely associated with tumor proliferation and migration. In addition, repressing the expression of miR-103 apparently inhibits colorectal cancer cell proliferation and migration in vitro and HCT-116 xenograft tumor growth in vivo. Subsequent software analysis and dual-luciferase reporter assay identified two tumor suppressor genes DICER and PTEN as direct targets of miR-103, and up-regulation of DICER and PTEN obtained similar results to that occurred in the silencing of miR-103. In addition, restoration of DICER and PTEN can inhibit miR-103-induced colorectal cancer cell proliferation and migration. Our data collectively demonstrate that miR-103 is an oncogene miRNA that promotes colorectal cancer proliferation and migration through down-regulation of the tumor suppressor genes DICER and PTEN. Thus, miR-103 may represent a new potential diagnostic and therapeutic target for colorectal cancer treatment.