Gianluca Basso

PTX3 Is an Extrinsic Oncosuppressor Regulating Complement-Dependent Inflammation in Cancer

PTX3 is an essential component of the humoral arm of innate immunity, playing a nonredundant role in resistance against selected microbes and in the regulation of inflammation. PTX3 activates and regulates the Complement cascade by interacting with C1q and with Factor H. PTX3 deficiency was associated with increased susceptibility to mesenchymal and epithelial carcinogenesis. Increased susceptibility of Ptx3(-/-) mice was associated with enhanced macrophage infiltration, cytokine production, angiogenesis, and Trp53 mutations. Correlative evidence, gene-targeted mice, and pharmacological blocking experiments indicated that PTX3 deficiency resulted in amplification of Complement activation, CCL2 production, and tumor-promoting macrophage recruitment. PTX3 expression was epigenetically regulated in selected human tumors (e.g., leiomyosarcomas and colorectal cancer) by methylation of the promoter region and of a putative enhancer. Thus, PTX3, an effector molecule belonging to the humoral arm of innate immunity, acts as an extrinsic oncosuppressor gene in mouse and man by regulating Complement-dependent, macrophage-sustained, tumor-promoting inflammation.

Irrelevance of Microsatellite Instability in the Epidemiology of Sporadic Pancreatic Ductal Adenocarcinoma

Background and Aims Pancreatic cancer risk is increased in Lynch syndrome (LS) patients with mismatch repair gene defects predisposing to colonic and extracolonic cancers with microsatellite instability (MSI). However, the frequency of MSI pancreatic cancers has never been ascertained in consecutive, unselected clinical series, and their contribution to the sporadic and inherited burden of pancreatic cancer remains to be established. Aims of the study were to determine the prevalence of MSI in surgically resected pancreatic cancers in a multicentric, retrospective study, and to assess the occurrence of pancreatic cancer in LS. Methods MS-status was screened by a panel of 5 mononucleotide repeats (Bat26, Bat25, NR-21, NR-24 and NR-27) in 338 consecutive pancreatic ductal adenocarcinoma (PDAC), resected at two Italian and one German referral centres. The personal history of pancreatic cancer was assessed in an independent set of 58 probands with LS and in 138 first degree relatives who had cancers. Results Only one PDAC (0.3%) showed MSI. This was a medullary type cancer, with hMLH1-deficiency, and no identified germ-line mutation but methylation of hMLH1. Pancreatic cancer occurred in 5 (2.5%) LS patients. Histological sampling was available for 2 cases, revealing PDAC in one case and an ampullary cancer in the other one. Conclusions MSI prevalence is negligible in sporadic, resected PDAC. Differently, the prevalence of pancreatic cancer is 2.5% in LS patients, and cancers other than PDAC may be encountered in this setting. Surveillance for pancreatic cancer should be advised in LS mutation carriers at referral centers.

Occurrence and significance of tumor-associated neutrophils in patients with colorectal cancer.

Inflammatory cells are an essential component of the tumor microenvironment. Neutrophils have emerged as important players in the orchestration and effector phase of innate and adaptive immunity. The significance of tumor‐associated neutrophils (TAN) in colorectal cancer (CRC) has been the subject of conflicting reports and the present study was designed to set up a reliable methodology to assess TAN infiltration in CRC and to evaluate their clinical significance. CD66b and myeloperoxidase (MPO) were assessed as candidate neutrophil markers in CRC using immunohistochemistry. CD66b was found to be a reliable marker to identify TAN in CRC tissues, whereas MPO also identified a subset of CD68+ macrophages. CRC patients (n = 271) (Stages I–IV) were investigated retrospectively by computer‐assisted imaging on whole tumor sections. TAN density dramatically decreases in Stage IV patients as compared to Stage I–III. At Cox analysis, higher TAN density was associated with better prognosis. Importantly, multivariate analysis showed that prognostic significance of TAN can be influenced by clinical stage and 5‐fluorouracil(5‐FU)‐based chemotherapy. On separate analysis of Stage III patients (n = 178), TAN density had a dual clinical significance depending on the use of 5‐FU‐based chemotherapy. Unexpectedly, higher TAN density was associated with better response to 5‐FU‐based chemotherapy. Thus, TAN are an important component of the immune cell infiltrate in CRC and assessment of TAN infiltration may help identify patients likely to benefit from 5‐FU‐based chemotherapy. These results call for a reassessment of the role of neutrophils in cancer using rigorous quantitative methodology.

Presence of Twist1-Positive Neoplastic Cells in the Stroma of Chromosome-Unstable Colorectal Tumors

BACKGROUND & AIMS Cancer cells undergo an epithelial-to-mesenchymal transition (EMT) to become invasive, allowing tumors to progress. However, there is no direct evidence that human cancer cells undergo an EMT. In mouse cancer cells, up-regulation of transcription factor Twist1 was shown to promote an EMT. We searched the stroma of human colorectal tumor samples for TWIST1-positive cells with a mesenchymal phenotype and neoplastic genotype. METHODS We measured the expression of TWIST1 in human colorectal cancer (CRC) cell lines and examined the effects of overexpression or knockdown in vitro and in mice. We used immunohistochemistry to measure levels of TWIST1 in 201 colorectal tumor samples. In 20 samples, immunostaining was combined with fluorescence in situ hybridization analyses. Levels of TWIST1 messenger RNA (mRNA) were measured in blood samples from 15 patients. RESULTS TWIST1 was required to maintain the mesenchymal phenotype and invasiveness of the microsatellite-stable CoLo741 cells (which express endogenous TWIST1) and SW480 (expressing transgenic TWIST1). TWIST1 mRNA was not translated in CRC cells with microsatellite instability (HCT116). Syngenic TWIST1-positive colon carcinoma cells (CT26) that invaded tissues surrounding tumors acquired a mesenchymal phenotype. The presence of TWIST1-positive cells in the stroma of human colorectal tumors correlated with microsatellite stability (P = .05), stage IV cancer (P = .02), and disease-free survival time (P < .01). Trisomies of chromosome 7 and/or chromosome 20 were detected in 17 of 20 colorectal tumor samples, each of which contained TWIST1-positive cells with matching chromosomal gains in the tumor stroma (86 of 776 counted cells; 11.1%). No trisomy was observed in TWIST1-negative stromal cells (0 of 1249 cells; P < .001). Levels of TWIST1 mRNA were significantly higher in blood samples from patients with CRC than controls. CONCLUSIONS The stroma of human colorectal tumors contains TWIST1-positive cancer cells with mesenchymal phenotypes. Patients with CRC have higher levels of TWIST1 mRNA than healthy individuals.

ERK-Dependent Downregulation of the Atypical Chemokine Receptor D6 Drives Tumor Aggressiveness in Kaposi Sarcoma

Savino, Caronni, and colleagues report that D6 expression was inversely correlated with increased tumor-associated M2-macrophages and aggressiveness in ERK pathway–activated Kaposi sarcoma (KS), and suggest targeting of CCR2 and the ERK pathway as a therapeutic option for patients with KS. D6 is an atypical chemokine receptor acting as a decoy and scavenger for inflammatory CC chemokines expressed in lymphatic endothelial cells. Here, we report that D6 is expressed in Kaposi sarcoma (KS), a tumor ontogenetically related to the lymphatic endothelium. Both in human tumors and in an experimental model, D6 expression levels were inversely correlated with tumor aggressiveness and increased infiltration of proangiogenic macrophages. Inhibition of monocyte recruitment reduced the growth of tumors, while adoptive transfer of wild-type, but not CCR2−/− macrophages, increased the growth rate of D6-competent neoplasms. In the KS model with the B-Raf V600E–activating mutation, inhibition of B-Raf or the downstream ERK pathway induced D6 expression; in progressing human KS tumors, the activation of ERK correlates with reduced levels of D6 expression. These results indicate that activation of the K-Ras–B-Raf–ERK pathway during KS progression downregulates D6 expression, which unleashes chemokine-mediated macrophage recruitment and their acquisition of an M2-like phenotype supporting angiogenesis and tumor growth. Combined targeting of CCR2 and the ERK pathway should be considered as a therapeutic option for patients with KS. Cancer Immunol Res; 2(7); 679–89. ©2014 AACR.

Mutant cohesin drives chromosomal instability in early colorectal adenomas

Chromosome missegregation leads to chromosomal instability (CIN), thought to play a role in cancer development. As cohesin functions in guaranteeing correct chromosome segregation, increasing data suggest its involvement in tumorigenesis. In a screen of a large series of early colorectal adenomas, a precocious step during colorectal tumorigenesis, we identified 11 mutations in SMC1A core cohesin subunit. In addition, we sequenced the SMC1A gene in colorectal carcinomas and we found only one mutation. Finally, the transfection of the SMC1A mutations identified in early adenomas and wild-type SMC1A gene silencing in normal human fibroblasts led to CIN. Our findings that SMC1A mutations decrease from early adenomas to colorectal cancers and that mutations lead to CIN suggest that mutant cohesin could play a pivotal role during colorectal cancer development.

Patients with genetically heterogeneous synchronous colorectal cancer carry rare damaging germline mutations in immune-related genes

Synchronous colorectal cancers (syCRCs) are physically separated tumours that develop simultaneously. To understand how the genetic and environmental background influences the development of multiple tumours, here we conduct a comparative analysis of 20 syCRCs from 10 patients. We show that syCRCs have independent genetic origins, acquire dissimilar somatic alterations, and have different clone composition. This inter- and intratumour heterogeneity must be considered in the selection of therapy and in the monitoring of resistance. SyCRC patients show a higher occurrence of inherited damaging mutations in immune-related genes compared to patients with solitary colorectal cancer and to healthy individuals from the 1,000 Genomes Project. Moreover, they have a different composition of immune cell populations in tumour and normal mucosa, and transcriptional differences in immune-related biological processes. This suggests an environmental field effect that promotes multiple tumours likely in the background of inflammation.

Molecular heterogeneity and prognostic implications of synchronous advanced colorectal neoplasia

Background:It is uncertain whether synchronous colorectal cancers (S-CRCs) preferentially develop through widespread DNA methylation and whether they have a prognosis worse than solitary CRC. As tumours with microsatellite instability (MSI) may confound the effect of S-CRC methylation on outcome, we addressed this issue in a series of CRC characterised by BRAF and MS status.Methods:Demographics, clinicopathological records and disease-specific survival (DSS) were assessed in 881 consecutively resected CRC undergoing complete colonoscopy. All tumours were typed for BRAFc.1799T>A mutation and MS status, followed by search of germ-line mutation in patients with MSI CRC.Results:Synchronous colorectal cancers (50/881, 5.7%) were associated with stage IV microsatellite-stable (MSS) CRC (19/205, 9.3%, P=0.001) and with HNPCC (9/32, 28%, P<0.001). BRAF mutation (60/881, 6.8%) was associated with sporadic MSI CRC (37/62, 60%, P<0.001) but not with S-CRC (3/50, 6.0%, P=0.96). Synchronous colorectal cancer (HR 1.82; 95% CI 1.15–2.87; P=0.01), synchronous advanced adenoma (HR 1.81; 95% CI 1.27–2.58; P=0.001), and BRAFc.1799T>A mutation (HR 2.16; 95% CI 1.25–3.73; P=0.01) were stage-independent predictors of death from MSS CRC. Disease-specific survival of MSI CRC patients was not affected by S-CRC (HR 0.74; 95% CI 0.09–5.75; P=0.77).Conclusion:Microsatellite-stable CRCs have a worse prognosis if S-CRC or synchronous advanced adenoma are diagnosed. The occurrence and the enhanced aggressiveness of synchronous MSS advanced neoplasia are not associated with BRAF mutation.

KRAS mutation in lung metastases from colorectal cancer: prognostic implications

KRAS mutant colorectal cancer (CRC) patients develop lung and brain metastases more frequently than KRAS wild‐type (WT) counterpart. We retrospectively investigated the prognostic role of KRAS, BRAF, and PIK3CA (exon 20) mutations and loss of phosphatase and tensin homolog (PTEN) in surgically resected lung metastases. Lung specimens from 75 metastatic CRC (mCRC) patients treated with one or more metastasectomies with curative intent were analyzed. Sixty‐four percent of patients had KRAS WT lung metastases. PTEN loss‐of‐function was found in 75%. BRAF and PIK3CA exon 20 mutations were not found. Seven patients subsequently developed brain metastases and 43% of them had KRAS mutation. In univariate analysis, median overall survival (OS) for KRAS WT patients was longer, compared to KRAS mutant patients (median 60.9 vs. 36.6 months, P = 0.035). In addition, both progression‐free survival (PFS) and lung disease‐free survival (LDFS) between lung surgery and relapse were not associated with KRAS and PTEN status. In multivariate analysis, the risk of death was significantly increased by KRAS mutational status (OS Hazard ratio (HR) 2.17, 95% IC 1.19–3.96, P = 0.012) and lack of adjuvant chemotherapy (OS HR 0.10, 95% IC 0.01–0.74, P = 0.024). The proportion of KRAS mutations in lung metastases was similar to the expected proportion in primary tumors. Patients harboring KRAS mutation had a poorer survival rate compared to WT group both in univariate and multivariate analysis. Moreover, administration of adjuvant chemotherapy after lung metastasectomy (LM) significantly improved both PFS and OS. KRAS mutation is a negative prognostic factor in mCRC patients undergoing LM. Further larger and prospective studies are necessary to confirm these findings.

Early expression of the fractalkine receptor CX3CR1 in pancreatic carcinogenesis.

Background:In pancreatic ductal adenocarcinoma (PDAC), fractalkine receptor CX3CR1 contributes to perineural invasion (PNI). We investigated whether CX3CR1 expression occurs early in PDAC and correlates with tumour features other than PNI.Methods:We studied CX3CR1 and CX3CL1 expression by immunohistochemistry in 104 human PDAC and coexisting Pancreatic Intraepithelial Neoplasia (PanIN), and in PdxCre/LSL-KrasG12D mouse model of PDAC. CX3CR1 expression in vitro was studied by a spheroid model, and in vivo by syngenic mouse graft of tumour cells.Results:In total, 56 (53.9%) PDAC expressed CX3CR1, 70 (67.3%) CX3CL1, and 45 (43.3%) both. CX3CR1 expression was independently associated with tumour glandular differentiation (P=0.005) and PNI (P=0.01). Pancreatic Intraepithelial Neoplasias were more frequently CX3CR1+ (80.3%, P<0.001) and CX3CL1+ (86.8%, P=0.002) than matched cancers. The survival of PDAC patients was better in those with CX3CR1+ tumour (P=0.05). Mouse PanINs were also CX3CR1+ and -CL1+. In vitro, cytokines significantly increased CX3CL1 but not CX3CR1 expression. Differently, CX3CR1 was upregulated in tumour spheroids, and in vivo only in well-differentiated tumours.Conclusion:Tumour differentiation, rather than inflammatory signalling, modulates CX3CR1 expression in PanINs and PDAC. CX3CR1 expression pattern suggests its early involvement in PDAC progression, outlining a potential target for interfering with the PanIN transition to invasive cancer.