MAIN RESULTS

1. Molecular basis of tumour perineural invasion: a forgotten pathway of invasion and metastasis. 
2. Targeting cancer-related inflammation in  human colorectal tumours.
3. Added value of  the novel anti-tumour Trabectedin (Yondelis): anti-inflammatory properties.
4. Mechanism(s) of M2 polarization of tumour-associated macrophages.

MAIN OBJECTIVES AND RESEARCH LINES

This group is mainly focused on cancer biology and on the role of inflammatory molecules and inflammatory cells on tumour progression and dissemination.

1. The chemokine/receptor system in malignancy: studies in human pancreatic ductal adenocarcinoma and colorectal cancer.

- We have reported the upregulation of certain chemokine/receptor pairs in human pancreatic ductal carcinoma and have studied the role of their expression in tumour biology. The CXCR4/CXCL12 axis was found to regulate migration and invasion of tumour cells as well as to enhance cell survival under pro-apoptotic conditions (Cancer Res. 2004). More recently, we have demonstrated that pancreatic cancer cells strongly upregulate the chemokine receptor CX3CR1, which is involved in the perineural dissemination, frequently occurring in this tumour (Cancer Res. 2008). Its specific ligand CX3CL1, also known as Fractalkine or Neurotactin, is expressed by neurons, nerve fibers and activated endothelial cells and - unlike other chemokines - possesses intrinsic cell-adhesive properties.     CX3CR1-positive tumour cells   migrate toward and adhere   to CX3CL1-expressing cells of neural origin, via mechanisms that involve activation of Gi proteins, and 1-integrins and focal adhesion kinase. The actual relevance of CX3CR1 expression in pancreatic in relation to tumour perineural invasion was assessed in cancer patients.    High CX3CR1 receptor expression by tumour cells was significantly associated with more prominent perineural invasion detected pathologically and earlier local tumour recurrence. Future lines of work for this project include: molecular mechanisms of CX3CR1 expression by cancer cells; analysis of two know polymorphisms in the receptor gene; set up of a murine model of pancreatic cancer to study the feasibility of a therapeutic approach targeted to the CX3CR1/ CX3CL1 axis.

- The chemokine CX3CL1 is up-regulated in samples of human colorectal cancer, compared to normal mucosa, with higher expression in the advanced stages. By immunohistochemistry    CX3CL1 is produced by tumour cells, while the receptor CX3CR1 is mainly expressed by infiltrating leukocytes and selected tumour areas. The role of CX3CL1 in regulating the recruitment of infiltrating leukocytes is under investigation. A collaborative project within the Department is analyzing the density of infiltrating CD3 T cells and CD68 macrophages in these tumours and their association with clinical parameters.   These results may clarify the ambiguous role of tumour-associated macrophages (TAM) in colorectal cancer, that have been related to favourable prognosis in this tumour type, unlike most other carcinomas.

2. Identification of inflammation-related genes in the micro-environment of colorectal tissues.

A transcriptional profile of colorectal tumour samples revealed the up-regulation of several interesting genes compared the autologous normal colonic mucosa: chemokines and their receptors (CCL3, CCL4 and CCR1,CCR5; CXCL8 and CXCR2); cytokines (IL-23, IL-24) and matrix-related proteins (Osteopontin and SPARC). While tumour cells predominantly produced CXCL8 and IL-24, the cellular source of IL-23 and of matrix proteins was tracked in TAM. The project will address the presence and significance IL-23-producing TAM and IL-17-positive T cells in colorectal cancer.
This study will also take into consideration the genetic origin of colorectal tumours. Samples    with micro-satellite instability (MSI) and with micro-satellite stability (MSS) will be analyzed. Tumours with MSI are usually associated with more favourable prognosis.

3.  Anti-inflammatory properties of the anti-tumour agent Trabectedin: the myxoid liposarcoma experience.

The novel drug Trabectedin has been recently registered in Europe for ovarian, breast and sarcoma tumours. We have reported that Trabectedin is selectively cytotoxic to monocytes/ macrophages and inhibits in vitro the production of selected inflammatory mediators, e.g.: CCL2 and IL-6. The effects of Trabectedin in vivo on the recruitment of monocytes at the tumour site has been also confirmed in tumour-bearing models. Human soft tissue sarcomas, especially myxoid liposarcoma, are particularly responsive to Trabectedin therapy. We are investigating whether the anti-inflammatory effects of the drug contributes to its anti-tumour activity. Myxoid liposarcoma produce CCL2 and CXCL8, inhibited by the drug, and secrete high levels of the acute phase protein PTX3.    Notably, PTX3 is also a matricellular binding protein involved in the organization of the extra-cellular matrix and its production is strongly inhibited by Trabectedin. The role of PTX3 in the biology of these liposarcomas is studied in vitro and in vivo.

4.  Conditioning by cancer cells of the polarized functions of macrophages

In an effort to identify tumour-derived molecules affecting the differentiation and function of monocytes/macrophages we found that tumour cells secrete a soluble isoform of proteoglycan-M-CSF    with very high MW   that is   responsible for the in vitro differentiation of macrophages. Phenotypic, functional and transcriptional profiling experiments indicates that the tumour-conditioned macrophages are M2-polarized. We are currently investigating whether the proteoglycan isoform is engaging, in addition to the M-CSF-R, other surface receptors on monocytes.