Tissue microarrays in drug discovery

Differential pattern and prognostic significance of CD4+, FOXP3+ and IL-17+ tumor infiltrating lymphocytes in ductal and lobular breast cancers

Background

Clinical relevance of tumor infiltrating lymphocytes (TILs) in breast cancer is controversial. Here, we used a tumor microarray including a large series of ductal and lobular breast cancers with long term follow up data, to analyze clinical impact of TIL expressing specific phenotypes and distribution of TILs within different tumor compartments and in different histological subtypes.

Methods

A tissue microarray (TMA) including 894 ductal and 164 lobular breast cancers was stained with antibodies recognizing CD4, FOXP3, and IL-17 by standard immunohistochemical techniques. Lymphocyte counts were correlated with clinico-pathological parameters and survival.

Results

CD4⁺ lymphocytes were more prevalent than FOXP3⁺ TILs whereas IL-17⁺ TILs were rare. Increased numbers of total CD4⁺ and FOXP3⁺ TIL were observed in ductal, as compared with lobular carcinomas. High grade (G3) and estrogen receptor (ER) negative ductal carcinomas displayed significantly (p < 0.001) higher CD4⁺ and FOXP3⁺ lymphocyte infiltration while her2/neu over-expression in ductal carcinomas was significantly (p < 0.001) associated with higher FOXP3⁺ TIL counts. In contrast, lymphocyte infiltration was not linked to any clinico-pathological parameters in lobular cancers. In univariate but not in multivariate analysis CD4⁺ infiltration was associated with significantly shorter survival in patients bearing ductal, but not lobular cancers. However, a FOXP3⁺/CD4⁺ ratio > 1 was associated with improved overall survival even in multivariate analysis (p = 0.033).

Conclusions

Ductal and lobular breast cancers appear to be infiltrated by different lymphocyte subpopulations. In ductal cancers increased CD4⁺ and FOXP3⁺ TIL numbers are associated with more aggressive tumor features. In survival analysis, absolute numbers of TILs do not represent major prognostic indicators in ductal and lobular breast cancer. Remarkably however, a ratio > 1 of total FOXP3⁺/CD4⁺ TILs in ductal carcinoma appears to represent an independent favorable prognostic factor.

Micro-immunohistochemistry using a microfluidic probe

A flexible method to extract more high-quality information from tissue sections is critically needed for both drug discovery and clinical pathology. Here, we present micro-immunohistochemistry (μIHC), a method for staining tissue sections at the micrometre scale. Nanolitres of antibody solutions are confined over micrometre-sized areas of tissue sections using a vertical microfluidic probe (vMFP) for their incubation with primary antibodies, the key step in conventional IHC. The vMFP operates several micrometres above the tissue section, can be interactively positioned on it, and even enables the staining of individual cores of tissue microarrays with multiple antigens. μIHC using such a microfluidic probe is preservative of tissue samples and reagents, alleviates antibody cross-reactivity issues, and allows a wide range of staining conditions to be applied on a single tissue section. This method may therefore find broad use in tissue-based diagnostics and in research.

Tissue microarrays as a tool in the discovery and validation of predictive biomarkers

The tissue microarray (TMA) is the embodiment of high-throughput pathology. The platform combines tens to hundreds of tissue samples on a single microscope slide for interrogation with routine molecular pathology tools. TMAs have enabled the rapid and cost-effective screening of biomarkers for diagnostic, prognostic, and predictive utility. Most commonly applied to the field of oncology, the TMA has accelerated the development of new biomarkers, and is emerging as an essential tool in the discovery and validation of tissue biomarkers for use in personalized medicine. This chapter provides an overview of TMA technology and highlights the advantages of using TMAs as tools toward rapid introduction of new biomarkers for clinical use.

Development of a Portable Tissue Micro Array Instrument

Tissue micro array (TMA) is based on the idea of applying miniaturization and a high throughput approach to hybridization-based analyses of tissues. It facilitates biomedical research on a large scale in a single experiment; thus representing one of the most commonly used technologies in translational research. A critical analysis of the existing TMA instruments indicates that there are potential constraints in terms of portability, apart from costs and complexity. This paper will present the development of an affordable, configurable, and portable TMA instrument to allow an efficient collection of tissues, especially in instrument-to-tissue scenarios. The purely mechanical instrument requires no energy sources other than the user, is light weight, portable, and simple to use.

The role of tissue microarray in the era of target-based agents

Tissue microarray (TMA) technologies have been developed over the last years, mainly to identify biomarkers useful for the correct identification and characterization of tumors. Moreover, TMA has been implemented in retrospective studies in order to identify predictive biomarkers of response to a given therapy and/or to find potential new targets for biological therapy. We analyzed the fields of application of TMA technology and the design of TMA varying according to the objectives to be studied. In this article, the reader will learn how to design TMAs in order to cover the objectives of clinical trials based upon the use of target-based agents. The main limits and advantages of TMA and the results achieved in cancer diagnosis will be also described. Tissue microarray technology should be systematically applied to define critical markers, in retrospective studies and in the screening of most human tumors in order to find new possible molecular targets and to molecularly define the diagnosis of the neoplastic diseases. TMAs have substantially improved the field of translational studies, even in the design and follow-up of studies based upon the use of target-based agents in cancer therapy.

Co-overexpression of p21 and Ki-67 in head and neck squamous cell carcinoma relative to a significantly poor prognosis

BACKGROUND

Head and neck squamous cell carcinomas (HNSCC) are treated by surgery or radiotherapy. Tumor cell death-related markers, such as p21 and Ki-67, may predict response to therapy and improve treatment choice. We evaluated and compared the effect of their coexpression between patients treated by surgery or radiotherapy.

METHODS

Immunohistochemistry for p21 and Ki-67 expression in 144 pharyngeal and laryngeal HNSCC samples was analyzed and correlated with follow-up parameters.

RESULTS

p21 expression correlated significantly with positive cN classification (p < .001), locoregional relapse (p = .031), and poor overall survival (p = .016), and Ki-67 positivity with poor survival only (p = .025). Coexpressing tumor phenotypes showed the worst survival (p = .009), observed primarily in patients treated by radiotherapy (p = .077).

CONCLUSIONS

Coexpression of p21/Ki-67 is a strong negative prognostic factor in HNSCC and could be of particular relevance in tumors treated by primary radiotherapy.

Can tissue microarray-based analysis of protein expression predict recurrence of stage Ta bladder cancer?

OBJECTIVE

Being able to predict the recurrence or progression of non-muscle-invasive bladder cancer would facilitate effective planning of treatments and follow-up. Biomarkers are needed that can supply prognostic information beyond that provided by clinical and pathological parameters. Tissue microarray (TMA)-based analysis of Ta bladder tumours was used to investigate the prognostic value of expression of several proteins involved in bladder carcinogenesis.

MATERIAL AND METHODS

Tumour tissue from 52 patients with Ta bladder cancer was investigated. At least three 0.6 mm punch cores from each tumour were placed in a paraffin array block. Tumour expression of tumour protein 53 (TP53), CDH1 (E-cadherin), proliferating cell nuclear antigen (PCNA), cyclooxygenase-2 (COX2), fibroblast growth factor receptor-3 (FGFR3) and epidermal growth factor receptor (EGFR) was quantified by immunohistochemistry (IHC) and correlated with time to recurrence. Median follow-up time was 3.1 years. Whole-section IHC analysis was performed to validate significant findings.

RESULTS

Of all patients, 69% (36/52) experienced recurrence. In univariate analysis, recurrence was associated with multifocality, number of earlier recurrences and a low quantity score for EGFR. In a multivariate model, a low EGFR quantity score was correlated with early recurrence (hazard ratio = 5.5, p = 0.003). However, whole-section IHC results for EGFR differed markedly from the TMA findings (κ = 0.07) and no association with time to recurrence was found (p = 0.65).

CONCLUSIONS

Expression of EGFR measured by TMA-IHC, but not by whole-section IHC, was associated with early recurrence. The results suggest that the proteins assessed have no predictive value for recurrences. Concerns are raised regarding the methodology and generalization of results obtained with TMA-IHC.

Tissue microarrays: construction and uses

Tissue microarrays (TMAs) are produced by taking small punches from a series of paraffin-embedded (donor) tissue blocks and transferring these tissue cores into a positionally encoded array in a recipient paraffin block. Though TMAs are not used for clinical diagnosis, they have several advantages over using conventional whole histological sections for research. Tissue from multiple patients or blocks can be examined on the same slide, and only a very small amount of reagent is required to stain or label an entire array. Multiple sections (100-300) can be cut from a single array block, allowing for hundreds of analyses per microarray. These advantages allow the use of TMAs in high-throughput procedures, such as screening antibodies for diagnostics and validating prognostic markers that are impractical using conventional whole tissue sections. TMAs can be used for immunohistochemistry, immunofluorescence, in situ hybridization, and conventional histochemical staining. Finally, several tissue cores may be taken without -consuming the tissue block, allowing the donor block to be returned to its archive for any additional studies.

Usefulness of tissue microarrays for assessment of protein expression, gene copy number and mutational status of EGFR in lung adenocarcinoma

Specific inhibitors targeting the epidermal growth factor receptor (EGFR) can increase survival rates in certain lung adenocarcinoma patients with mutations in the EGFR gene. Although such EGFR-targeted therapies have been approved for use, there is no general consensus among surgical pathologists on how the EGFR status should be tested in lung adenocarcinoma tissues and whether the results of immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and mutational analysis by molecular methods correlate. We evaluated the EGFR status in 61 lung adenocarcinomas by IHC (using total and mutant-specific antibodies against EGFR), by FISH analysis on tissue microarrays (TMAs), and by direct sequencing. The results of each method were compared using χ² and κappa statistics. The sensitivity and negative predictive value estimating the presence of abnormal EGFR for each test was calculated. The results show that, with respect to expression patterns and clinicopathological parameters, the total and mutant-specific EGFR detected by immunohistochemistry and FISH analysis on TMAs are valid and are equivalent to conventional methods performed on whole-tissue sections. Abnormal EGFR was detected in 52.4% of patients by IHC, FISH, and sequencing. The best sensitivity (100%) and negative predictive value (100%) was determined by evaluating the EGFR status with all methods. Testing for molecular changes in EGFR using a single test is likely to underestimate the presence of EGFR abnormalities. Taken together, these results demonstrate the high potential of TMAs to test for the major mechanisms of EGFR activation in patients with lung adenocarcinoma.

Clinicopathological and protein characterization of BRAF- and K-RAS-mutated colorectal cancer and implications for prognosis

Recent evidence highlights the potential prognostic and predictive value of BRAF and K-RAS gene alterations in patients with colorectal cancer. However, a comprehensive evaluation of BRAF and K-RAS mutations and their specific clinicopathological features, histomorphological presentation and effect on protein expression have not been systematically analyzed. The aim of this study was to characterize the clinicopathological, histomorphological and protein expression profiles of BRAF- and K-RAS-mutated colorectal cancers and determine their impact on patient survival. Molecular analysis for microsatellite instability (MSI), K-RAS and BRAF was carried out on paraffin-embedded samples from 404 patients with primary colorectal cancer. Using tissue microarrays, 36 tumor-associated and 14 lymphocyte/inflammatory-associated markers were evaluated by immunohistochemistry. BRAF mutation was associated with right-sided tumor location (p < 0.001), higher tumor grade (p = 0.029), absence of peritumoral lymphocytic inflammation (p = 0.026) and MSI-H (p < 0.001). In right-sided tumors, loss of CDX2 expression was observed in 23 of 24 cases (95.8%). BRAF mutation was a poor prognostic indicator in patients with right-sided disease (p = 0.01). This result was maintained in multivariable analysis (p < 0.001; HR = 2.82; 95% CI: 1.5-5.5) with pT, pN and vascular invasion and independent of CDX2 expression. K-RAS mutation, in contrast, was not associated with any of the features analyzed. BRAF gene mutation is an adverse prognostic factor in right-sided colon cancer patients independent of MSI status and, moreover, in patients with lymph node-negative disease. These results indicate that molecular analysis for BRAF may be a useful biomarker for identifying patients with right-sided colon cancer with poor outcome who may benefit from a more individualized course of therapy.

Nrf2 and Keap1 abnormalities in non-small cell lung carcinoma and association with clinicopathologic features

PURPOSE

To understand the role of nuclear factor erythroid-2-related factor 2 (Nrf2) and Kelch-like ECH-associated protein 1 (Keap1) in non-small cell lung cancer (NSCLC), we studied their expression in a large series of tumors with annotated clinicopathologic data, including response to platinum-based adjuvant chemotherapy.

EXPERIMENTAL DESIGN

We determined the immunohistochemical expression of nuclear Nrf2 and cytoplasmic Keap1 in 304 NSCLCs and its association with patients' clinicopathologic characteristics, and in 89 tumors from patients who received neoadjuvant (n = 26) or adjuvant platinum-based chemotherapy (n = 63). We evaluated NFE2L2 and KEAP1 mutations in 31 tumor specimens.

RESULTS

We detected nuclear Nrf2 expression in 26% of NSCLCs; it was significantly more common in squamous cell carcinomas (38%) than in adenocarcinomas (18%; P < 0.0001). Low or absent Keap1 expression was detected in 56% of NSCLCs; it was significantly more common in adenocarcinomas (62%) than in squamous cell carcinomas (46%; P = 0.0057). In NSCLC, mutations of NFE2L2 and KEAP1 were very uncommon (2 of 29 and 1 of 31 cases, respectively). In multivariate analysis, Nrf2 expression was associated with worse overall survival [P = 0.0139; hazard ratio (HR), 1.75] in NSCLC patients, and low or absent Keap1 expression was associated with worse overall survival (P = 0.0181; HR, 2.09) in squamous cell carcinoma. In univariate analysis, nuclear Nrf2 expression was associated with worse recurrence-free survival in squamous cell carcinoma patients who received adjuvant treatment (P = 0.0410; HR, 3.37).

CONCLUSIONS

Increased expression of Nrf2 and decreased expression of Keap1 are common abnormalities in NSCLC and are associated with a poor outcome. Nuclear expression of Nrf2 in malignant lung cancer cells may play a role in resistance to platinum-based treatment in squamous cell carcinoma.

p16 expression in oropharyngeal cancer: its impact on staging and prognosis compared with the conventional clinical staging parameters

BACKGROUND

Currently, staging of head neck squamous cell carcinoma (HNSCC) is on the basis of primary tumor extension (cT), lymph node involvement (cN) and distant metastasis (cM). The aim of cancer staging was to improve diagnosis, prognosis and to compare outcome results. A new subgroup of oropharyngeal squamous cell carcinoma (OPSCC) induced by human papillomavirus (HPV) infection is reported to show an increasing incidence. These HPV-positive OPSCC show distinct molecular differences, specific p16 overexpression and a significantly better prognosis. Therefore, the aim of this study was to evaluate the prognostic influence of p16 expression in OPSCC and compare its relevance with the established prognostic markers cT and cN classification and the clinical stages I-IV.

PATIENTS AND METHODS

Immunohistochemistry for p16 was carried out on the basis of a tissue microarray including 102 OPSCC patients with corresponding retrospective clinicopathological and follow-up data.

RESULTS

p16 is the strongest independent prognostic marker in OPSCC, surpassing the significance of cT and cN classification as well as the clinical stages I-IV. Prognosis of p16-positive OPSCC of an advanced stage reached or even exceeded prognosis of the next clinically smaller conventionally staged group of tumors.

CONCLUSION

p16 is the most relevant prognostic marker in OPSCC and should be considered for inclusion into the official staging system of HNSCC.

High frequency of tumor-infiltrating FOXP3(+) regulatory T cells predicts improved survival in mismatch repair-proficient colorectal cancer patients

Regulatory T cells (T(reg)) inhibit the generation of host-versus-tumor immunity via suppression of tumor-specific effector T-cell responses and development of immune tolerance to neoplastic cells. The transcription factor forkhead box P3 (FOXP3) is an intracellular key molecule for T(reg) development and function and is considered to represent the most specific T(reg) cell marker. The aim of this study was to analyze the frequency and prognostic impact of tumor-infiltrating FOXP3(+) T(reg) in colorectal cancer (CRC) stratified by mismatch-repair (MMR) status. Using the tissue microarray technique, 1,420 tumor samples were immunohistochemically stained for FOXP3 and stratified into 1,197 MMR-proficient and 223 MMR-deficient CRCs. Additionally, the 1,197 MMR-proficient CRCs were randomized into 2 subgroups (Test Groups 1 and 2; n = 613 and 584, respectively). In both MMR-proficient CRC subgroups high frequency tumor-infiltrating FOXP3(+) T(reg) was associated with early T stage (p = 0.001 and <0.001), tumor location (p = 0.01 and 0.045) and increased 5-year survival rate (p = 0.004 and <0.001), whereas in MMR-deficient CRCs an association between FOXP3(+) T(reg) and absence of lymph node involvement (p = 0.023), absence of vascular invasion (p = 0.023) and improved 5-year survival rate (p = 0.029) could be detected. In a multivariable analysis including age, gender, T stage, N stage, tumor grade, vascular invasion, and tumor border configuration, a high FOXP3(+) T(reg) frequency was an independent prognostic factor in both MMR-proficient CRC subsets (p = 0.019 and p = 0.007), but not in the MMR-deficient CRCs (p = 0.13). Therefore, high frequency of tumor-infiltrating FOXP3(+) T(reg) is associated with early T stage and independently predicts improved disease-specific survival in MMR-proficient CRC patients.

Role of the VEGF ligand to receptor ratio in the progression of mismatch repair-proficient colorectal cancer

BACKGROUND

The VEGF family of ligands and receptors are intimately involved in tumor angiogenesis, lymphangiogenesis and metastasis. The evaluation of VEGF ligand/receptor ratios may provide a more profound understanding of the involvement of these proteins in colorectal tumour progression. The aim of this study was to elucidate the role of the VEGF ligand/receptor ratios on tumour progression and metastasis in patients with mismatch repair-proficient colorectal cancer.

METHODS

Immunohistochemistry for VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGFR1, VEGFR2 and VEGF3 was carried out on 387 mismatch repair-proficient colorectal cancers using a tissue microarray. Evaluation of immunoreactivity was performed semi-quantitatively and the ligand/receptor expression ratio was obtained.

RESULTS

An increased VEGF-A/VEGFR1 ratio, VEGF-A and VEGFR1 was linked to the presence of peritumoral lymphocytic inflammation at the invasive front (p = 0.032; p = 0.005; p = 0.032, respectively). VEGFR1 expression was related to poorer outcome in multivariable analysis with pT stage, pN stage, vascular invasion, and post-operative therapy. A higher ratio of VEGF-A/VEGFR2 was linked to advanced TNM stage (p = 0.005) while VEGF-A and VEGFR2 were elevated in tumours with an infiltrating tumour growth pattern (p = 0.006; p = 0.014; p = 0.006). No effect of VEGF-A/VEGFR2, VEGF-A or VEGFR2 on survival time was noted.

CONCLUSIONS

Our findings highlight an involvement of VEGF-A, VEGR1 and VEGFR2 in events occurring at the invasive tumour front and a potential prognostic role of VEGFR1 expression in mismatch repair-proficient colorectal cancers. The VEGF-A ligand to VEGFR1 or VEGFR2 ratio may represent an alternative evaluation system for identifying patients with poorer clinical outcome.

Is the improved prognosis of p16 positive oropharyngeal squamous cell carcinoma dependent of the treatment modality?

The incidence of human papilloma virus (HPV) induced oropharyngeal squamous cell carcinoma (OPSCC) increases in the western countries. These OPSCC show distinct molecular characteristics and are characterized by an overexpression of p16, considered a surrogate marker for HPV infection. When compared to patients with p16 negative OPSCC, patients with HPV induced p16 positive OPSCC show a significantly better prognosis, which is reported to be caused by increased radiosensitivity. The objective of the present study was to analyze the impact of p16 expression status on the prognosis of OPSCC treated by either radiotherapy (RT) or primary surgery. Results are based upon a tissue microarray (TMA) of 365 head neck squamous cell carcinomas (HNSCC) including 85 OPSCC with clinico-pathological and follow-up data. p16 positivity correlated significantly with oropharyngeal tumor localization (p < 0.001). Patients with p16 positive OPSCC exhibited a significantly better overall survival than those with p16 negative tumors (p = 0.007). In a multivariate analysis, survival benefit of patients with p16 positive OPSCC was independent of clinico-pathological parameters such as cT and cN classification and treatment modality. The improved prognosis of p16 positive OPSCC is found after RT as well as after surgery.

Quantitative time-lapse fluorescence microscopy in single cells

The cloning of green fluorescent protein (GFP) 15 years ago revolutionized cell biology by permitting visualization of a wide range of molecular mechanisms within living cells. Though initially used to make largely qualitative assessments of protein levels and localizations, fluorescence microscopy has since evolved to become highly quantitative and high-throughput. Computational image analysis has catalyzed this evolution, enabling rapid and automated processing of large datasets. Here, we review studies that combine time-lapse fluorescence microscopy and automated image analysis to investigate dynamic events at the single-cell level. We highlight examples where single-cell analysis provides unique mechanistic insights into cellular processes that cannot be otherwise resolved in bulk assays. Additionally, we discuss studies where quantitative microscopy facilitates the assembly of detailed 4D lineages in developing organisms. Finally, we describe recent advances in imaging technology, focusing especially on platforms that allow the simultaneous perturbation and quantitative monitoring of biological systems.

Gene amplification in ductal carcinoma in situ of the breast

Multiple different biologically and clinically relevant genes are often amplified in invasive breast cancer, including HER2, ESR1, CCND1, and MYC. So far, little is known about their role in tumor progression. To investigate their significance for tumor invasion, we compared pure ductal carcinoma in situ (DCIS) and DCIS associated with invasive cancer with regard to the amplification of these genes. Fluorescence in situ hybridization (FISH) was performed on a tissue microarray containing samples from 130 pure DCIS and 159 DCIS associated with invasive breast cancer. Of the latter patients, we analyzed the intraductal and invasive components separately. In addition, lymph node metastases of 23 patients with invasive carcinoma were included. Amplification rates of pure DCIS and DCIS associated with invasive cancer did not differ significantly (pure DCIS vs. DCIS associated with invasive cancer: HER2 22.7 vs. 24.2%, ESR1 19.0 vs. 24.1%, CCND1 10.0 vs. 14.8%, MYC 11.8 vs. 6.5%; P > 0.05). Furthermore, we observed a high concordance of the amplification status for all genes if in situ and invasive carcinoma of individual patients were compared. This applied also to the corresponding lymph node metastases. Our results indicate no significant differences between the gene amplification status of DCIS and invasive breast cancer concerning HER2, ESR1, CCND1, and MYC. Therefore, our data suggest an early role of all analyzed gene amplifications in breast cancer development but not in the initiation of invasive tumor growth.

Prognostic and predictive value of TOPK stratified by KRAS and BRAF gene alterations in sporadic, hereditary and metastatic colorectal cancer patients

Background:

Our aim was to investigate the prognostic and predictive value of the oncogenic MAPKK-like protein T-cell-originated protein kinase (TOPK) stratified by KRAS and BRAF mutations in patients with sporadic, hereditary and metastatic colorectal cancer (CRC) treated with anti-EGFR therapy.

Methods:

Immunohistochemistry (IHC) for TOPK was performed on four study groups. Group 1 included two subgroups of 543 and 501 sporadic CRC patients used to test the reliability of TOPK expression by IHC. In Group 2, representing an additional 222 sporadic CRCs, the prognostic effect of TOPK stratified by KRAS and BRAF was assessed. The prognostic effect of TOPK was further analysed in Group 3, representing 71 hereditary Lynch syndrome-associated CRC patients. In Group 4, the predictive and prognostic value of TOPK was analysed on 45 metastatic patients treated with cetuximab or panitumumab stratified by KRAS and BRAF gene status.

Results:

In both sporadic CRC subgroups (Group 1), associations of diffuse TOPK expression with clinicopathological features were reproducible. Molecular analysis of sporadic CRCs in Group 2 showed that diffuse TOPK expression was associated with KRAS and BRAF mutations (p<0.001) and with poor outcome in patients with either mutation in univariate and multivariate analysis (P=0.017). In hereditary patients (Group 3), diffuse TOPK was linked to advanced pT stage. In metastatic patients treated with anti-EGFR therapy (Group 4), diffuse TOPK expression was linked to dismal outcome despite objective response to treatment (P=0.01).

Conclusions:

TOPK expression is an unfavourable prognostic indicator in sporadic patients with KRAS or BRAF mutations and also in patients with metastatic disease experiencing a response to anti-EGFR therapies. The inhibition of TOPK, which could benefit 30–40% of CRC patients, may represent a new avenue of investigation for targeted therapy.

Comparison of quantum dots immunofluorescence histochemistry and conventional immunohistochemistry for the detection of caveolin-1 and PCNA in the lung cancer tissue microarray

Luminescent semiconductor quantum dots (QDs) are a new class of fluorescent label with wide ranges of applications in cell imaging. In this study, we evaluated the capability of QDs immunofluorescence histochemistry (QDs-IHC) for detecting antigens of caveolin-1 and PCNA in the lung cancer tissue microarray (TMA) in comparison with the conventional immunohistochemistry (IHC) technique. Both methods revealed consistent antigen localization and statistically non-significant detection rates of caveolin-1 and PCNA expressions in our study. However, the sensitivity of QDs-IHC was higher than IHC. The positive detection rates of caveolin-1 and PCNA by QDs-IHC were 57% (40/70) and 86% (60/70), respectively, which were higher than the detection rates of 47% (33/70) and 77% (54/70), respectively, by IHC. Moreover, QDs exhibited a much better photostability, a broader excitation spectrum and a longer fluorescence lifetime. We showed here the advantages of QDs-IHC over IHC for the detection of caveolin-1 and PCNA in lung cancer TMA.

Do we see what we think we see? The complexities of morphological assessment

Reliable pathological interpretation is vital to so many aspects of tissue-based research as well as being central to patient care. Understanding the complex processes involved in decision-making is the starting point to improve both diagnostic reproducibility and the definition of diagnostic groups that underpin our experiments. Unfortunately, there is a paucity of research in this field and it is encouraging to see The Journal of Pathology publishing work in this area. This review attempts to highlight the opportunities that exist in this field and the technologies that are now available to support this type of research. Key amongst these are the use of decision analysis tools such as inference networks, and virtual microscopy that allows us to simulate diagnostic decision-making. These tools have roles, not only in studying the subtleties of diagnostic decision-making, but also in delivering new methods of training and proficiency testing. Research which helps us to better understand what we see, why we see it, and standardizing interpretative reasoning in pathological classification is essential for improving the wide range of activities that pathologists support, including clinical diagnosis, teaching, training, and experimental research.

Combined histomorphologic and immunohistochemical phenotype to predict the presence of vascular invasion in colon cancer

PURPOSE

Vascular invasion is an adverse prognostic factor in colorectal cancer and often is considered an indication for systemic adjuvant therapy. The aim of this study was to develop a predictive model of vascular invasion in a large cohort of colon cancers with use of tumor-related features and immunohistochemical analysis of protein markers.

METHODS

A tissue microarray including 427 colon cancers was evaluated for 14 immunohistochemical protein markers. Complete data on pT, pN, tumor grade, tumor border configuration, vascular invasion, and tumor diameter were available. Classification and regression tree analysis was performed.

RESULTS

The presence of vascular invasion independently predicted adverse outcome (P < 0.001; hazard ratio = 1.52 (1.3 to 1.8)) and decreased survival from 49.0 to 19.0 months (P < 0.001) even in lymph node-positive patients. Tumor border configuration, Ki67, urokinase plasminogen activator receptor, and Raf-1 kinase inhibitor protein expression were predictive of vascular invasion. The cross-validated misclassification rate was 23.7 percent indicating a significant predictive accuracy of this model.

CONCLUSIONS

Tumor border configuration, Ki67, urokinase plasminogen activator receptor, and Raf-1 kinase inhibitor protein immunohistochemistry are highly predictive of vascular invasion and may play a decisive role in individualizing adjuvant treatment.

Two-marker protein profile predicts poor prognosis in patients with early rectal cancer

The aim of this study was to establish an immunohistochemical protein profile to complement preoperative staging and identify rectal cancer patients at high-risk of adverse outcome. Immunohistochemistry was performed on a tissue microarray including 482 rectal cancers for APAF-1, EphB2, MST1, Ki67, p53, RHAMM, RKIP and CD8⁺ tumour infiltrating lymphocytes (TILs). After resampling of the data and multivariable analysis, the most reproducible markers were combined and prognosis evaluated as stratified by pT and pN status. In multivariable analysis, only positive RHAMM (P<0.001; HR=1.94 (1.44–2.61)) and loss of CD8⁺ TILs (P=0.006; HR=0.63 (0.45–0.88)) were independent prognostic factors. The 5-year cancer-specific survival rate for RHAMM+/TIL− patients was 30% (95% CI 21–40%) compared to 76% (95% CI: 66–84%) for RHAMM−/TIL+ patients (P<0.001). The 5-year cancer-specific survival of T1/T2/RHAMM+/TIL− patients was 48% (20–72%) and significantly worse compared to T3/T4/RHAMM−/TIL+ patients (71% 95% CI 56–82%); P=0.039). Stratifying by nodal status, only N+/RHAMM+/TIL− patients demonstrated a significantly worse prognosis than N0/RHAMM+/TIL− patients (P=0.005). Loss of CD8⁺ TILs was predictive of local recurrence in RHAMM+ tumours (P=0.009) only. RHAMM and CD8⁺ TILs may assist in identifying early stage rectal cancer patients facing a particularly poor prognosis and who may derive a benefit from preoperative therapy.

Clinical significance of p53 alterations in surgically treated prostate cancers

Despite the high number of previous studies, the role of p53 alterations in prostate cancer is not clearly defined. To address the role of p53 alterations in prostate cancer biology, a total of 2514 cancers treated by radical prostatectomy were successfully analyzed by immunohistochemistry in a tissue microarray format. Overall a low rate of p53-positive tumors was found (2.5%). A significant underestimation of p53-positive cases was excluded by subsequent large section analyses and direct sequencing of the p53 gene in subsets of our patients. Large section analysis of 23 cases considered negative on the tissue microarray yielded only one weakly p53-positive tumor. Only 4 out of 64 (6.4%) high-grade tumors, that were considered negative for p53 by immunohistochemistry, presented exon 5-8 mutations. These data suggest a high sensitivity of our immunohistochemistry approach and confirm the overall low frequency of p53 alterations in clinically localized prostate cancer. A positive p53 immunostaining was strongly associated with presence of exon 5-8 mutations (P<0.0001), advanced pT-stage (P<0.0001), high Gleason grade (P<0.0001), positive surgical margins (P=0.03) and early biochemical tumor recurrence (P<0.0001). A higher rate of positive p53 immunostaining was detected in late-stage diseases including metastatic prostate cancer (P=0.0152) and hormone-refractory tumors (P=0.0003). Moreover, p53 expression was identified as an independent predictor of biochemical tumor recurrence in the subgroup of low- and intermediate-grade cancers. In summary, the results of this study show that p53 mutations characterize a small biologically aggressive subgroup of prostate cancers with a high risk of progression after prostatectomy. The rate of p53 alterations increases with prostate cancer progression.

Differential diagnostic and functional role of the multi-marker phenotype CDX2/CK20/CK7 in colorectal cancer stratified by mismatch repair status

The differentiation of colorectal cancer from primary tumors at other sites can be challenging. Often a panel of immunohistochemical protein markers is needed to distinguish between these entities. Protein expression differs significantly in colorectal cancer depending on mismatch repair status and is also heterogeneous among mismatch repair-proficient or -deficient tumors. The aim of this study was to systematically analyze the diagnostic and prognostic role of the commonly used multi-marker phenotype CK20/CK7/CDX2 on a large series of colorectal cancers stratified by mismatch repair status. The immunohistochemical analysis of CK20, CK7 and CDX2 was performed on 1197 mismatch repair-proficient and 223 mismatch repair-deficient colorectal cancers using a tissue microarray. Multi-marker combinations of CK20/CK7/CDX2 were explored. Univariate and multivariable analysis of the markers was evaluated for their association with several clinico-pathological end points namely T stage, N stage, tumor grade, vascular invasion, intratumoral lymphocytes and survival. Multi-marker phenotypes with CK20 and CDX2 negativity were more frequently found in mismatch repair-deficient than in mismatch repair-proficient colorectal cancer (19.3 vs 7.5% and 21.6 vs 6.7%, respectively; P<0.001). In both colorectal cancer subsets loss of CK20 was associated with higher tumor grade (P<0.001) and with presence of intratumoral lymphocytes (P<0.001 and P=0.02, respectively). In the proficient mismatch repair subset CK20 overexpression was an independent adverse prognostic factor (P=0.041) and CDX2 underexpression was linked to tumor progression. Loss of CDX2 and CK20 is more frequently encountered in mismatch repair-deficient colorectal cancer, which should be taken into consideration to differentiate between primary and metastatic colorectal cancer in daily practice. Although associated with lower tumor grade, CK20 overexpression is an independent adverse prognostic factor in mismatch repair-proficient colorectal cancer.

Local recurrence in mismatch repair-proficient colon cancer predicted by an infiltrative tumor border and lack of CD8+ tumor-infiltrating lymphocytes

PURPOSE

The identification of colon cancer patients at high risk of local recurrence is necessary to improve the selection of patients for more tailored treatment protocols. The aim of this study was to develop a predictive model of local recurrence by assessing the independent predictive effect of 7 clinicopathologic features, 24 protein markers of tumor progression, and their multifeature combinations in mismatch repair-proficient colon cancers.

EXPERIMENTAL DESIGN

Immunohistochemistry for 24 protein markers was done on 269 patients with complete clinicopathologic data. After univariate and multivariable analyses, independent predictors of local recurrence were identified and their multifeature combinations were analyzed. Kaplan-Meier and Cox proportional hazards regression were done for survival analysis.

RESULTS

Local recurrence was observed in 119 patients (55.8%). Independent predictors of tumor recurrence were lymph node involvement (P = 0.006), absence of CD8+ tumor-infiltrating lymphocytes (TIL; P < 0.001), and infiltrative tumor margin (P < 0.001). This independent effect persisted after adjusting for adjuvant therapy. Risk of recurrence was 0.75 and the 5-year survival rate was 8.8% in patients with these three adverse features. Node-negative patients with an infiltrative tumor margin and absence of CD8+ TILs were identified as high risk with a probability of 0.55 for recurrence and a 60% 5-year survival rate. The remaining node-negative cases fared significantly better with risks ranging from 8% to 26% and 5-year survival rates reaching 97.6%.

CONCLUSIONS

An infiltrative tumor margin and absence of CD8+ TILs are highly predictive of local recurrence in node-negative mismatch repair-proficient colon cancer and may help to identify high-risk patients who may benefit from adjuvant chemotherapy.

High-content analysis in neuroscience

High-content analysis (HCA) combines automated microscopy and automated image analysis to quantify complex cellular anatomy and biochemistry objectively, accurately and quickly. High-content assays that are applicable to neuroscience include those that can quantify various aspects of dendritic trees, protein aggregation, transcription factor translocation, neurotransmitter receptor internalization, neuron and synapse number, cell migration, proliferation and apoptosis. The data that are generated by HCA are rich and multiplexed. HCA thus provides a powerful high-throughput tool for neuroscientists.

The adult human brain in preclinical drug development

Neurodegenerative disorders are caused by the death and dysfunction of brain cells, but despite a huge worldwide effort, no neuroprotective treatments that slow cell death currently exist. The failure of translation from animal models to humans in the clinic is due to many factors including species differences, human brain complexity, age, patient variability and disease-specific phenotypes. Additional methods are therefore required to overcome these obstacles in neuroprotective drug development. Incorporating target validation using human brain-tissue microarray screening and direct human brain-cell testing at an early preclinical stage to isolate molecules that protect the human brain may be an effective strategy.

Multimarker phenotype predicts adverse survival in patients with lymph node-negative colorectal cancer

BACKGROUND

The heterogeneity of stage II colon cancer underlines the need for identifying high-risk, lymph node-negative patients. The objective of this study was to define a multimarker prognostic model of 5-year survival in patients with lymph node-negative, mismatch repair (MMR)-proficient colorectal cancer (CRC).

METHODS

Immunohistochemistry for 13 tumor markers was performed on 587 lymph node-negative, MMR-proficient CRC samples by using a tissue microarray. Immunoreactivity was evaluated semiquantitatively. A receiver-operating characteristic-based approach was used to detect clinically relevant tumor markers and to determine cutoff scores for tumor positivity. Univariate and multivariate analyses stratified by pathologic T3 (pT3) or pT4 tumor classification were performed.

RESULTS

In univariate analysis, the absence of CD8+ tumor infiltrating lymphocytes (TILs) (P < .001), loss of p27 (P = .006), positive urokinase-type plasminogen activator (uPA) expression (P = .002), and positive uPA receptor (uPAR) expression (P = .037) were associated with an adverse prognosis. In multivariate analysis, CD8 (P = .001), p27 (P = .031), and uPA (P = .014) were independent prognostic factors. The multimarker phenotype of negative CD8, loss of p27, and positive uPA expression led to significantly worse survival compared with all other combinations of these features. Stratified by pT3 or pT4 stage, CD8 (P = .006) and uPA (P = .011) had independent prognostic value. Combined CD8 negativity and uPA positivity led to a more adverse prognosis in both patients with pT3 tumors and patients with pT4 tumors (P < .001). No difference was observed in the length of survival between patients with pT3 tumors who had CD8 negativity and uPA positivity and patients with pT4 tumors (P = .267).

CONCLUSIONS

The multimarker phenotype of the absence of CD8+ TILs, loss of p27, and positive uPA expression was predictive of an adverse prognosis in patients with lymph node-negative, MMR-proficient CRC. The current findings suggested that a subgroup of patients with high-risk, lymph node-negative pT3 tumors should be considered for adjuvant therapy.

Implementation of alternating excitation schemes in a biochip-reader for quasi-simultaneous multi-color single-molecule detection

We report here the development of a device for single-molecule biochip readout using fast alternating excitation. The technology extends standard imaging cytometry by offering additional color channels in excitation. To enable the study of mobile objects, e.g. actively transported vesicles in living cells or freely diffusing lipids in a lipid bilayer, the frequency of the illumination pulses was chosen high enough to virtually freeze the motion of the biomolecules, as they are shifted through the illuminated area. The synchronization of sample illumination, scanning and line-camera readout yield two quasi-simultaneously recorded images covering the same sample region. Diffraction-limited resolution and high localization precision for point-light sources down to approximately 10 nm was shown by scanning immobilized 100 nm fluorescence latex beads. Ultra-sensitivity was demonstrated by imaging single fluorescent streptavidin molecules diffusing in a fluid lipid bilayer. Two-color streptavidin labeled with Cy3 and Cy5 could be easily identified in the two respective excitation channels; high accordance in the dye positions confirms the applicability for colocalization studies of moving objects. Finally, scans of antibody-receptor interactions in large populations of live cells illustrate the feasibility of this method for biochip application.

Node-Negative Colorectal Cancer at High Risk of Distant Metastasis Identified by Combined Analysis of Lymph Node Status, Vascular Invasion, and Raf-1 Kinase Inhibitor Protein Expression

Purpose: To identify independent clinicopathologic factors and protein markers leading to the identification of colorectal cancer (CRC) patients with mismatch repair proficiency at risk of developing metastasis and, consequently, more likely to benefit from combined modality therapy.

Experimental Design: Immunohistochemistry for 22 tumor markers was done using a tissue microarray. A subset of 387 CRC patients with complete clinicopathologic data and TNM stage was analyzed. Univariate and multivariate analyses were done to identify independent predictive markers of metastasis. The results were validated on 810 CRC patients.

Results: In univariate analysis, T stage (P &lt; 0.001), N stage (P &lt; 0.001), tumor grade (P = 0.005), vascular invasion (P &lt; 0.001), tumor budding (P &lt; 0.001), positive expression of β-catenin (P = 0.015), overexpression of RHAMM (P = 0.008), negative expression of Raf-1 kinase inhibitor protein (RKIP; P = 0.001), and absence of intraepithelial lymphocytes (P = 0.017) were significantly associated with the presence of distant metastasis. In multivariate analysis, higher N stage (P &lt; 0.001), presence of vascular invasion (P = 0.009), and RKIP loss (P = 0.003) independently predicted distant metastatic disease. A subgroup of node-negative patients was identified as high risk for distant metastasis and showed a similar probability of metastatic risk and nearly identical survival times as node-positive patients with absence of vascular invasion and positive RKIP expression (metastatic risk, 24% and 22%; median survival time, 45.0 and 47.0 months, respectively).

Conclusion: The combined analysis of N stage, vascular invasion, and RKIP expression is highly predictive of distant metastasis in patients with mismatch repair–proficient CRC. Additionally, a subgroup of more aggressive N0 tumors can be identified by evaluating vascular invasion and RKIP expression.

Role of APAF-1, E-cadherin and peritumoral lymphocytic infiltration in tumour budding in colorectal cancer

Tumour budding or dedifferentiation at the invasive margin of colorectal cancer (CRC) is an important prognostic marker and linked mechanistically to dysregulation of Wnt pathway signalling. Since budding is observed in only 40% of CRCs, we hypothesized that Wnt pathway dysregulation may be a necessary but insufficient explanation for budding and that buds may be destroyed selectively by tumour immune mechanisms. Twenty potential markers of tumour budding were evaluated in tissue microarrays (TMAs) obtained from the main tumour body of 1164 DNA mismatch repair-proficient CRCs and the findings were correlated with tumour budding, lymphocytic infiltration and survival. Loss of expression of E-cadherin and APAF-1 were independent predictors of budding (sensitivity 70.3% and specificity 48.2% when one or the other was lost). Peritumoral lymphocytes (PTLs) were observed more frequently in CRCs with loss of either E-cadherin or APAF-1 that were budding-negative. PTLs and tumour-infiltrating lymphocytes (TILs) were strongly correlated. The absence of TILs increased the adverse prognostic impact of E-cadherin and APAF-1 loss. Co-occurrence of E-cadherin loss, APAF-1 loss and low TIL counts in CRCs was an independent prognostic factor. The findings were verified in whole tissue sections from 88 CRCs with known KRAS mutation status (which was not associated with budding). Loss of E-cadherin and APAF-1 within the main body of CRCs are independent predictors of tumour budding. The prognostic benefit of lymphocytic infiltration may be explained by the immune destruction of budding cells.

Value of staining intensity in the interpretation of immunohistochemistry for tumor markers in colorectal cancer

The purpose of this study was to determine whether staining intensity in conjunction with the percentage of positive tumor cells should be used as an indicator of protein expression detected by immunohistochemistry. A tissue microarray of 1,197 colorectal cancers was immunostained for p53, Her2/neu, epidermal growth factor receptor (EGFR), adenomatosis polyposis coli (APC), and beta-catenin. Immunoreactivity was described by the percentage of positive tumor cells (percent positivity) and by the staining intensity (weak, moderate, strong). The interobserver reproducibility of both was evaluated by two pathologists. The association of T stage, N stage, tumor grade, vascular invasion, and survival with percent positivity, staining intensity, and the combination of both was assessed. In univariate analysis, protein expression assessed by percent positivity resulted in 11 significant associations between the proteins and clinico-pathological features. Eight of these 11 were also demonstrated using only the degree of staining intensity. However, more than half of the associations identified by percent positivity alone were lost when staining intensity was also analyzed in combination with the percentage of positive tumor cells. A scoring method based on percent positivity, rather than on staining intensity, for p53, Her2/neu, EGFR, APC, and beta-catenin is reproducible and appears to be sufficient for establishing associations of the selected tumor markers with most clinico-pathological features.

Molecular pathogenesis of early-stage non-small cell lung cancer and a proposal for tissue banking to facilitate identification of new biomarkers

Non-small cell lung carcinoma (NSCLC) is one of the leading causes of death from cancer in both Eastern and Western countries. For patients with stage I NSCLC, full lobar or more extensive surgical resection is the treatment of choice. However, even among patients with surgically resected, stage I NSCLC, up to 30% of patients die of the disease within 5 years. At present, apart from clinical stage, there are no established cancer-specific clinical variables or biomarkers that reliably identify individuals at increased risk of death after surgical resection-individuals who could be candidates for adjuvant therapy or alternative management strategies. At a recent international workshop, participants discussed a clinical trial to compare radiation therapy with surgery among patients with stage I NSCLC. This study offers the opportunity to prospectively obtain, bank, and analyze tissue and other clinical specimens, which should facilitate the identification of new biomarkers for early detection, prognosis, and therapy in lung cancer.

Prognostic significance of the wnt signalling pathway molecules APC, beta-catenin and E-cadherin in colorectal cancer: a tissue microarray-based analysis

AIMS

To investigate dysregulation of the wnt signalling pathway by assessing beta-catenin expression/increasing expression and loss of cytoplasmic adenomatous polyposis coli (APC) and membranous E-cadherin in colorectal cancer (CRC) and determining the prognostic significance of these variables.

METHODS AND RESULTS

Unselected, non-consecutive CRC resections (n = 1420) were subdivided into three groups: mismatch repair (MMR)-proficient, MLH1- and presumed hereditary non-polyposis colonic cancer (HNPCC). Immunohistochemical analysis of beta-catenin expression (0% versus > 0%) and increasing expression (increasing percentage-positivity) and loss of APC and E-cadherin was performed using the tissue microarray technique. In MMR-proficient CRC, increased nuclear beta-catenin expression and loss of membranous E-cadherin were independently associated with higher N stage (P = 0.03 and < 0.0001), vascular invasion (P < 0.01 and < 0.001) and worse survival (P < 0.01 and < 0.001). Additionally, there was an association between loss of membranous E-cadherin and higher T stage (P = 0.03). In MLH1- CRC, loss of membranous E-cadherin was associated with higher N stage (P = 0.05) and worse survival (P = 0.03). In presumed HNPCC CRC nuclear beta-catenin and membranous E-cadherin were not associated with tumour progression or worse survival. In all CRC subsets loss of cytoplasmic APC was not associated with clinicopathological features.

CONCLUSIONS

Increasing nuclear beta-catenin expression and loss of membranous E-cadherin are independent, adverse prognostic factors in MMR-proficient and MLH1- CRC.

Prognostic significance of mucins in colorectal cancer with different DNA mismatch-repair status

BACKGROUND

Expression of mucin antigen MUC1 and down regulation of MUC2 are associated with adverse prognosis in colorectal cancer (CRC), but their prognostic significance with respect to differing DNA mis- match repair (MMR) status is poorly understood.

OBJECTIVE

To determine the prognostic significance of MUC1 and MUC2 in CRC with different MMR statuses.

METHODS

Using the tissue microarray (TMA) technique, a series of 1420 unselected, non-consecutive CRC resections was subdivided into three groups: (1) MMR-proficient; (2) MLH1-negative; and (3) presumed hereditary non-polyposis colon cancer (HNPCC). Immunohistochemical analysis of MUC1 and MUC2 expression (>0%) and loss (0%) was performed, and the results were correlated with clinicopathological parameters.

RESULTS

In MMR-proficient CRC, MUC1 expression was more frequently found in tumours with higher tumour stage (p=0.004) and higher tumour grade (p=0.041) and loss of MUC2 was associated with higher tumour stage (p=0.028), node stage (p=0.001), presence of vascular invasion (p=0.028) and worse survival (p=0.034). In MLH1-negative CRC, MUC2 loss was associated with the presence of lymph node metastasis (p=0.028) and worse survival (p=0.015), but there was no association between MUC1 expression and clinicopathological features. In presumed HNPCC, MUC1 expression and MUC2 loss were not associated with clinicopathological parameters.

CONCLUSIONS

Mucins have a prognostic significance in sporadic CRC, but not in hereditary CRC. Loss of MUC2 is an adverse prognostic factor in MMR-proficient and MLH1-negative CRC, whereas MUC1 expression is associated with tumour progression in MMR-proficient CRC only.

Two distinct types of blood vessels in clear cell renal cell carcinoma have contrasting prognostic implications

PURPOSE

Intratumoral microvascular density (MVD) has been controversial as an indicator of prognosis in clear cell renal cell carcinoma (CCRCC). Classification of the intratumoral blood vessels based on differential expressions of blood vessel markers has not been correlated with patient prognosis in CCRCC. In this study, we aimed to evaluate the association of different categories of blood vessels with the patients' outcomes.

EXPERIMENTAL DESIGN

Seventy-eight CCRCC patients who underwent nephrectomy alone were enrolled. Paraffin-embedded CCRCC tissues, together with 16 nonmalignant kidney cortex tissues, were used in tissue microarray analyses and conventional section analyses. The characteristics of intratumoral blood vessels were identified by multiple blood vessel markers and pericyte markers. A computerized image analysis program was used to quantitatively calculate the vascular density.

RESULTS

Two distinct types of microvessels were identified in CCRCC: undifferentiated (CD31(+)/CD34(-)) and differentiated (CD34(+)) vessels. A higher undifferentiated MVD significantly correlated with higher tumor grades and shorter patient survival. In contrast, a higher differentiated MVD significantly correlated with lower tumor grade and longer survival. Multivariate analyses showed that undifferentiated MVD was an independent prognostic factor for patient survival. An inverse correlation between undifferentiated MVD and differentiated MVD was also identified in CCRCC.

CONCLUSIONS

This is the first report showing distinct types of vasculature in CCRCC correlated with contrasting prognoses. A refined classification of CCRCC based on vasculature is therefore important for evaluating prognosis, and it may also have therapeutic implications.

Loss of APAF-1 expression is associated with tumour progression and adverse prognosis in colorectal cancer

The aim of this study was to determine the prognostic value of APAF-1 in colorectal cancer (CRC). Immunohistochemistry for APAF-1 was performed on a tissue microarray of 1015 mismatch-repair (MMR) proficient and 130 sporadic MLH1-negative CRCs. The association of APAF-1 with clinico-pathological features including 10-year survival time was analysed. Methylation specific PCR was performed on a subset of MMR-proficient and MLH1-negative CRC. Loss of APAF-1 was associated with advanced T stage (p-value=0.022), N stage (p-value=0.009), vascular invasion (p-value=0.001) and worse survival (p-value=0.017) in MMR-proficient CRC. In MLH1-negative CRC, loss of APAF-1 was associated with metastasis (p-value=0.041), worse prognosis (p-value<0.001) and independently predicted shorter survival time (p-value<0.001). No methylation was found in the selected region of APAF-1. APAF-1 is a marker of tumour progression in MMR-proficient CRC and an independent adverse prognostic factor in MLH1-negative CRC.