Inflammation and uPAR-Expression in Colorectal Liver Metastases in Relation to Growth Pattern and Neo-adjuvant Therapy

Abstract

Proteolytic activity and inflammation in the tumour microenvironment affects cancer progression. In colorectal cancer (CRC) liver metastases it has been observed that three different immune profiles are present, as well as proteolytic activity, determined by the expression of urokinase-type plasminogen activator (uPAR).The main objectives of this study were to investigate uPAR expression and the density of macrophages (CD68) and T cells (CD3) as markers of inflammation in resected CRC liver metastases, where patients were neo-adjuvantly treated with chemotherapy with or without the angiogenesis inhibitor bevacizumab. Chemonaive patients served as a control group. The markers were correlated to growth patterns (GP) of liver metastases, i.e. desmoplastic, pushing and replacement GP. It was hypothesised that differences in proteolysis and inflammation could reflect tumour specific growth and therapy related changes in the tumour microenvironment. In chemonaive patients, a significantly higher level of uPAR was observed in desmoplastic liver metastases in comparison to pushing GP (p=0.01) or replacement GP (p=0.03). A significantly higher density of CD68 was observed in liver metastases with replacement GP in comparison to those with pushing GP (p=0.01). In liver metastases from chemo treated patients, CD68 density was significantly higher in desmoplastic GP in comparison to pushing GP (p=0.03). In chemo and bevacizumab treated patients only a significant lower CD3 expression was observed in liver metastases with a mixed GP than in those with desmoplastic (p= 0.01) or pushing GP (p=0.05). Expression of uPAR and the density of macrophages at the tumour margin of liver metastasis differ between GP in the untreated patients. A higher density of T cells was observed in the bevacizumab treated patients, when desmoplastic and pushing metastases were compared to liver metastases with a mix of the GP respectively, however no specific correlations between the immune markers of macrophages and T cells or GP of liver metastases could be demonstrated.

International consensus guidelines for scoring the histopathological growth patterns of liver metastasis

“…In the current study, the HGPs scored according to the proposed guidelines predict outcome: patients with a predominant desmoplastic HGP have a significant overall survival advantage as compared with patients with a predominant replacement HGP or predominant pushing HGP. This is clearly in accordance with the studies in Table 1 that have addressed the prognostic value of the HGPs ( Okano et al , 2000 ; Lunevicius et al , 2001 ; Nystrom et al , 2012 ; Van den Eynden et al , 2012 ; Nielsen et al , 2014 ; Pinheiro et al , 2014 ; Eefsen et al , 2015 ; Frentzas et al , 2016 ). However, there are some discrepancies in the reported impact of the replacement HGP and the pushing HGP on outcome (for details, see Table 1 ).…”

“…Indeed, as an example, the pushing HGP was reported as the predominant HGP in ∼7% of all samples in the study by Frentzas et al (2016 ) and in ∼3% of all samples in the survival study in this manuscript. However, in other studies, this fraction was as high as 16% ( Van den Eynden et al , 2012 ), 33% ( Nielsen et al , 2014 ), 34% ( Eefsen et al , 2015 ) and even 50% ( Nystrom et al , 2012 ). These issues highlight the need for standardised and uniform criteria for HGP classification – a major aim of the present guidelines.…”

“…The team of experts responsible for the proposed guidelines consists of members of the Liver Metastasis Research Network ( www.lmrn.org ) all of whom have had experience in the assessment of the HGPs of liver metastases. Based on many observations in previous studies on HGPs ( Vermeulen et al , 2001 , 2002 ; Eefsen et al , 2012 , 2015 ; Van den Eynden et al , 2012 , 2013 ; Frentzas et al , 2016 ), and consequently multiple discussions at annual meetings of the LMRN, consensus was reached on a systematic approach to assessing the HGPs. A draft manuscript was produced by a writing committee and was circulated to all the co-authors.…”

“…This co-option of sinusoidal blood vessels and peri-sinusoidal space (space of Disse) in the replacement HGP is in contrast to the desmoplastic HGP where extensive stromal remodelling and angiogenesis are observed ( Vermeulen et al , 2001 ; Frentzas et al , 2016 ). Desmoplastic liver metastases have an upregulated uPA–uPAR–PAI-1 proteolytic system and an elevated content of type I and type IV collagens ( Illemann et al , 2009 ; Nystrom et al , 2012 ; Eefsen et al , 2015 ).…”

Stromal Targets for Fluorescent-Guided Oncologic Surgery

“…As component of the proteolytic plasminogen activation cascade, uPAR is involved in degradation/remodeling of the extracellular matrix, important for migrating cells. Therefore, uPAR is not only upregulated on invading cancer cells but also on tumor stromal cells like tumor-associated macrophages and neo-angiogenic cells ( 62 – 65 ). The simultaneous targeting of (invading) tumor cells as well as tumor stromal cells by a uPAR-specific probe increases the percentage of tumor mass that will be targeted and would make uPAR a pluripotent tumor target, applicable for a broad range of tumor types ( 66 – 68 ).…”