Immunohistochemical localization of coagulation, fibrinolytic and antifibrinolytic markers in adenocarcinoma of the lung

Experimental and Clinical Evidence Supports the Use of Urokinase Plasminogen Activation System Components as Clinically Relevant Biomarkers in Gastroesophageal Adenocarcinoma

Simple Summary

Patients with gastric and oesophageal adenocarcinomas (GOCs) have short life expectancies as their tumours spread to other sites early. This is facilitated by the increased expression of the urokinase plasminogen activation system (uPAS); a feature of the majority of GOCs. There is increasing appreciation of the importance of uPAS expression in a range of cell types within the tumour microenvironment. Abundant clinical evidence indicates that altered expression of uPAS proteins is associated with worse outcomes, including time to tumour recurrence and patient survival. Emerging technologies, including liquid biopsy, suggest a role of uPAS for the detection of circulating tumour cells, which are responsible for the dissemination of cancers. We review and summarise pre-clinical and clinical data that supports the use of uPAS as a biomarker in GOC.

Abstract

Gastric and oesophageal cancers (GOCs) are lethal cancers which metastasise early and recur frequently, even after definitive surgery. The urokinase plasminogen activator system (uPAS) is strongly implicated in the invasion and metastasis of many aggressive tumours including GOCs. Urokinase plasminogen activator (uPA) interaction with its receptor, urokinase plasminogen activator receptor (uPAR), leads to proteolytic activation of plasminogen to plasmin, a broad-spectrum protease which enables tumour cell invasion and dissemination to distant sites. uPA, uPAR and the plasminogen activator inhibitor type 1 (PAI-1) are overexpressed in some GOCs. Accumulating evidence points to a causal role of activated receptor tyrosine kinase pathways enhancing uPAS expression in GOCs. Expression of these components are associated with poorer clinicopathological features and patient survival. Stromal cells, including tumour-associated macrophages and myofibroblasts, also express the key uPAS proteins, supporting the argument of stromal involvement in GOC progression and adverse effect on patient survival. uPAS proteins can be detected on circulating leucocytes, circulating tumour cells and within the serum; all have the potential to be developed into circulating biomarkers of GOC. Herein, we review the experimental and clinical evidence supporting uPAS expression as clinical biomarker in GOC, with the goal of developing targeted therapeutics against the uPAS.

Progression and metastasis of lung cancer

Metastasis in lung cancer is a multifaceted process. In this review, we will dissect the process in several isolated steps such as angiogenesis, hypoxia, circulation, and establishment of a metastatic focus. In reality, several of these processes overlap and occur even simultaneously, but such a presentation would be unreadable. Metastasis requires cell migration toward higher oxygen tension, which is based on changing the structure of the cell (epithelial-mesenchymal transition), orientation within the stroma and stroma interaction, and communication with the immune system to avoid attack. Once in the blood stream, cells have to survive trapping by the coagulation system, to survive shear stress in small blood vessels, and to find the right location for extravasation. Once outside in the metastatic locus, tumor cells have to learn the communication with the “foreign” stroma cells to establish vascular supply and again express molecules, which induce immune tolerance.

Increased PADI4 expression in blood and tissues of patients with malignant tumors

Background

Peptidylarginine deiminase type 4 (PAD4/PADI4) post-translationally converts peptidylarginine to citrulline. Recent studies suggest that PADI4 represses expression of p53-regulated genes via citrullination of histones at gene promoters.

Methods

Expression of PADI4 was investigated in various tumors and non-tumor tissues (n = 1673) as well as in A549, SKOV3 and U937 tumor cell lines by immunohistochemistry, real-time PCR, and western blot. Levels of PADI4 and citrullinated antithrombin (cAT) were investigated in the blood of patients with various tumors by ELISA (n = 1121).

Results

Immunohistochemistry detected significant PADI4 expression in various malignancies including breast carcinomas, lung adenocarcinomas, hepatocellular carcinomas, esophageal squamous cancer cells, colorectal adenocarcinomas, renal cancer cells, ovarian adenocarcinomas, endometrial carcinomas, uterine adenocarcinomas, bladder carcinomas, chondromas, as well as other metastatic carcinomas. However, PADI4 expression was not observed in benign leiomyomas of stomach, uterine myomas, endometrial hyperplasias, cervical polyps, teratomas, hydatidiform moles, trophoblastic cell hyperplasias, hyroid adenomas, hemangiomas, lymph hyperplasias, schwannomas, neurofibromas, lipomas, and cavernous hemangiomas of the liver. Additionally, PADI4 expression was not detected in non-tumor tissues including cholecystitis, cervicitis and synovitis of osteoarthritis, except in certain acutely inflamed tissues such as in gastritis and appendicitis. Quantitative PCR and western blot analysis showed higher PADI4 expression in gastric adenocarcinomas, lung adenocarcinomas, hepatocellular carcinomas, esophageal squamous cell cancers and breast cancers (n = 5 for each disease) than in the surrounding healthy tissues. Furthermore, western blot analysis detected PADI4 expression in cultured tumor cell lines. ELISA detected increased PADI4 and cAT levels in the blood of patients with various malignant tumors compared to those in patients with chronic inflammation and benign tumors. This was consistent with immunohistochemical results. Additionally, PADI4 and cAT levels were significantly associated with higher levels of known tumor markers.

Conclusion

Our results suggest that PADI4 expression is increased in the blood and tissues of many malignant tumors, a finding useful for further understanding of tumorigenesis.

Expression of peptidylarginine deiminase type 4 (PAD4) in various tumors

Peptidylarginine deiminase type 4 (PAD4/PADI4) posttranslationally converts peptidylarginine to citrulline, in a process known as citrullination. Evidence suggests that PAD4 plays an essential role in pathogenesis of rheumatoid arthritis (RA). RA synovium has many features in common with tumor tissues, including abnormal cell proliferation, extensive fibrin deposition, high coagulation activity, and extreme angiogenesis. The purpose of the present study was to investigate expression of PAD4 in various tumor tissues. Immunohistochemistry indicated that PAD4 had significant expression in many tumor tissues, especially various adenocarcinoma. Western blotting with anti PAD4 antibody and immunostaining with anti citrulline antibody confirmed the expression of the enzyme in these tumors. Furthermore, our immunohistochemistry also detected co-location of PAD4 with cytokeratin (CK), a well-known tumor marker for oncological study in many tumors. Western blot analysis also detected citrulline signals in CK extracted from the tumors. In addition, CK 8, 18, and 19 following in vitro citrullination resisted to the digestion of caspase. The results further confirm the expression of PAD4 in the tumors and support that PAD4 may contribute to the disrupted apoptosis of tumors by caspase-mediated cleavage of CK. Double immunofluorescent labeling detected co-location of PAD4 with CD34, a cell marker of heamatopoietic progenitor cells (HPC) in bone marrow and other normal tissues, as well as in some fibroblast-like cells at stroma region of tumors, but not in the tumor cells. The findings imply that PAD4 is initially expressed in CD34(+) cells of bone marrow and then distributed in derives of the multi-potent progenitor cells in diverse tissues. The development of tumor cells expressing PAD4 is possibly associated with abnormal proliferation of CD34(+) stem cells.

[Usefulness of cytosolic tissue-type plasminogen activator levels in lung adenocarcinomas]

BACKGROUND

We aimed at studying the behavior of cytosol tissue-type plasminogen activator (t-PA) levels in lung adenocarcinomas and their correlation with other clinical and biological parameters.

MATERIAL AND METHOD

t-PA cytosol levels were determined using EIA (Boehringer Mannheim. Germany) in 59 samples of lung adenocarcinoma and in 16 samples of normal lung tissue from the same patients. Cathepsin D, CA125, pS2, hyaluronic acid (HA), free beta subunit of chorionic gonadotropin hormone and neuron specific enolase (NSE) cytosol concentrations were determined. We also determined the concentrations of HA, erbB2 oncoprotein, epidermal growth factor receptor (EGFR), CD44s, CD44v5 and CD44v6 in cell surfaces. The following parameters were considered: clinical stage, ploidy, cellular S-phase fraction and histological grade.

RESULTS

In adenocarcinomas, t-PA cytosol levels ranged from 0.1 to 14.6 ng/mg prot. (median, 1.4). These levels were lower than those in normal lung tissue (r, 0.1-18.6; median, 2.95 ng/mg prot.) but did not reach statistical significance. On the other hand, t-PA concentrations decreased as the clinical stage increased and were higher in stage I than stage II-III (p = 0.080) and stage III (p = 0.0622). No significant differences of t-PA levels were observed when the histological grade, ploidy and S-phase were considered. Adenocarcinomas with high t-PA values (> 3.7 ng/mg prot., representing the 75th percentile of the whole group), had lower CA125 (p = 0.015) and erbB2 oncoprotein (p = 0.087) concentrations.

CONCLUSIONS

These results suggest that cytosol t-PA levels are negatively correlated with tumor size in lung adenocarcinomas. However, the usefulness of t-PA as a prognostic factor needs to be clarified in further studies.

Cellular localization of urokinase-type plasminogen activator, its inhibitors, and their mRNAs in breast cancer tissues

The plasminogen activation (PA) system may participate in cancer invasion and metastasis. A series of breast cancer tissue specimens was analysed using in situ hybridization and immunohistochemistry. Urokinase-type plasminogen activator (u-PA) mRNA was detected in cancer cells and fibroblasts adjacent to them and its expression was found to be more intense in invasive than in intraductal regions. In invasive but not in intraductal regions, especially those with abundant stroma, plasminogen activator inhibitor-1 (PAI-1) mRNA was observed in cancer cells, fibroblasts, macrophages, and endothelial cells, and PAI-2 mRNA was present in cancer cells, and fibroblasts, macrophages, and lymphocytes around them. These PAI-1- and PAI-2-positive cancer cells were localized at the periphery of the invasive front. Immunohistochemistry yielded basically similar results. A retrospective study of surgically resected breast cancers from 73 patients revealed significant clinical differences associated with u-PA and PAI-2 expression in cancer cells, associated with a poor and a good prognosis, respectively. These findings indicate that breast cancer cells and fibroblasts express u-PA initially and then its inhibitors, and that this process is related to invasion. Expression of u-PA and PAI-2 in cancer cells themselves may serve to up-regulate and limit PA-mediated invasion and metastasis, respectively.

Levels of plasminogen activator inhibitor type 1 and urokinase plasminogen activator receptor in non-small cell lung cancer as measured by quantitative ELISA and semiquantitative immunohistochemistry

The components of the plasminogen activation system have been reported to have prognostic impact in several cancer types, e.g. breast-, colon-, gastric- and lung cancer. Most of these studies have used quantification by enzyme-linked immunosorbent assay (ELISA) on tumour tissue extracts. However, results in non-small cell lung cancer (NSCLC) studies obtained by quantitative ELISA and semiquantitative immunohistochemistry differ. If the prognostic value of the components of the plasminogen activation system is to be exploited clinically in the future, it is important to choose an easy and valid methodology. In the present study we investigated levels of plasminogen activator inhibitor type 1 (PAI-1) and urokinase plasminogen activator receptor (uPAR), as quantitated by ELISA in tumour extracts from 64 NSCLC patients (38 squamous cell carcinomas, 26 adenocarcinomas), and compared them to staining intensity as semiquantitated by immunohistochemistry for PAI-1 and uPAR on corresponding cryostat sections. A significant association (r = 0.49, P < 0.0001) was found between the PAI-1 levels measured by ELISA and semiquantitated by immunohistochemistry. No association was found for uPAR. When correlating levels of PAI-1 and uPAR determined by ELISA and immunohistochemistry, respectively, to survival status, no significant correlation was found for any of the subgroups. At present neither of the methods examined in the present study can be recommended as superior for quantitating PAI-1 and uPAR with the aim of predicting prognosis. In conclusion, a larger comparative study is needed to clarify the relationship between ELISA and immunohistochemical results, before a methodology for clinical use can be chosen in non-small cell lung cancer.

The plasminogen activation system and its role in lung cancer. A review

The urokinase pathway of the plasminogen activation is involved in proteolytic degradation of various tissues, including dissolution of the extracellular matrix and basement membranes during the process of cancer cell invasion. Recent studies have demonstrated that components of the plasminogen activation system have a prognostic impact in breast-, lung-, colorectal, bladder and gastric cancer. A number of studies, reviewed here, have focused on the role of the plasminogen activation system in different lung cancer types. There seems to be an obvious difference between the expression, localization and prognostic impact of the components of the plasminogen activation system in different lung cancer types. The differences seen could be helpful in understanding the biology of different lung cancer types, and components of the plasminogen activation system may have prognostic relevance and clinical implications in some lung cancer types, even though confirmatory studies are needed.

Plasminogen activators and their inhibitors in non-small cell lung cancer. Low content of type 2 plasminogen activator inhibitor associated with tumor dissemination

BACKGROUND

Evidence suggests that plasminogen activators and their inhibitors play an important role in tumor spread.

METHODS

In this study, we measured the antigen levels of urokinase (u-PA), tissue plasminogen activator (t-PA), type 1 plasminogen activator inhibitor (PAI-1), and type 2 plasminogen activator inhibitor (PAI-2), and cancer tissue (19 adenocarcinomas and 19 squamous cell carcinomas) and normal lung tissue.

RESULTS

u-PA, PAI-1, and PAI-2 antigen levels in cancer tissue were significantly higher than those in normal tissue (P < 0.001 in u-PA and PAI-1; P < 0.005 in PAI-2), whereas t-PA antigen levels in cancer tissue were significantly lower than those in normal tissue (P < 0.005). In case with lymph node involvement (LN+ cases), PAI-2 antigen levels were significantly lower than those in cases without lymph node involvement (LN- cases) (P < 0.02), whereas there was no difference in either u-PA or PAI-1 antigen levels between these two groups. Furthermore, u-PA antigen levels showed a significant positive correlation with PAI-2 antigen levels in LN- cases (r = 0.696; P < 0.005), although there was no correlation between these two parameters in LN+ cases.

CONCLUSIONS

The antigen levels of u-PA, PAI-1, and PAI-2 in cancer tissue were significantly higher than those in normal tissue, and lower content of PAI-2 was associated with lymph node metastasis.