Exposure of preadipocytes to long-chain fatty acids induces the expression of several markers of adipocyte differentiation. In an attempt to identify novel genes and proteins that are regulated by fatty acids in preadipocytes, we performed a substractive hybridization screening and identified PTX3, a protein of the pentraxin family. PTX3 mRNA expression is transient during adipocyte differentiation of clonal cell lines and is absent in fully differentiated cells. Stable overexpression of PTX3 in preadipocytes has no effect on adipocyte differentiation. In line with this, PTX3 mRNA is expressed in the stromal-vascular fraction of adipose tissue, but not in the adipocyte fraction; however, in 3T3-F442A adipocytes, the PTX3 gene can be reinduced by tumor necrosis factor ␣ (TNF ␣ ) in a dose-dependent manner. This effect is accompanied by PTX3 protein secretion from both 3T3-F442A adipocytes and explants of mouse adipose tissue. PTX3 mRNA levels are found to be higher in adipose tissue of genetically obese mice versus control mice, consistent with their increased TNF ␣ levels. In conclusion, PTX3 appears as a TNF ␣ -induced protein that provides a new link between chronic low-level inflammatory state and obesity. -Abderrahim-Ferkoune, A., O.

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Background:To test the prognostic value of tumour protein and genetic markers in colorectal cancer (CRC) and examine whether deficient mismatch repair (dMMR) tumours had a distinct profile relative to proficient mismatch repair (pMMR) tumours.Methods:This prospective multicentric study involved 251 stage I–III CRC patients. Analysed biomarkers were EGFR (binding assay), VEGFA, thymidylate synthase (TS), thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) expressions, MMR status, mutations of KRAS (codons 12–13), BRAF (V600E), PIK3CA (exons 9 and 20), APC (exon 15) and P53 (exons 4–9), CpG island methylation phenotype status, ploidy, S-phase, LOH.Results:The only significant predictor of relapse-free survival (RFS) was tumour staging. Analyses restricted to stage III showed a trend towards a shorter RFS in KRAS-mutated (P=0.005), BRAF wt (P=0.009) and pMMR tumours (P=0.036). Deficient mismatch repair tumours significantly demonstrated higher TS (median 3.1 vs 1.4) and TP (median 5.8 vs 3.5) expression relative to pMMR (P<0.001) and show higher DPD expression (median 14.9 vs 7.9, P=0.027) and EGFR content (median 69 vs 38, P=0.037) relative to pMMR.Conclusions:Present data suggesting that both TS and DPD are overexpressed in dMMR tumours as compared with pMMR tumours provide a strong rationale that may explain the resistance of dMMR tumours to 5FU-based therapy.

Dihydropyrimidine dehydrogenase is a crucial enzyme for the degradation of 5-fluorouracil (5FU). DPYD, which encodes dihydropyrimidine dehydrogenase, is prone to acquire genomic rearrangements because of the presence of an intragenic fragile site FRA1E. We evaluated DPYD copy number variations (CNVs) in a prospective series of 242 stage I-III colorectal tumours (including 87 patients receiving 5FU-based treatment). CNVs in one or more exons of DPYD were detected in 27% of tumours (deletions or amplifications of one or more DPYD exons observed in 17% and 10% of cases, respectively). A significant relationship was observed between the DPYD intragenic rearrangement status and dihydropyrimidine dehydrogenase (DPD) mRNA levels (both at the tumour level). The presence of somatic DPYD aberrations was not associated with known prognostic or predictive biomarkers, except for LOH of chromosome 8p. No association was observed between DPYD aberrations and patient survival, suggesting that assessment of somatic DPYD intragenic rearrangement status is not a powerful biomarker to predict the outcome of 5FU-based chemotherapy in patients with colorectal cancer.

3596 Background: There is still a need to identify prognostic markers in stage II CRC for setting up adjuvant treatment. The prognostic value of tumor genetic and protein markers was analyzed in CRC patients, as well as relationships between markers. Given the strong prognostic and predictive value of deficient MMR (dMMR), we examined whether dMMR tumors had a distinct protein profile as compared to proficient (pMMR) tumors. Methods: This prospective multicentric study involved 251 stage I-II-III CRC patients with complete surgical resection. Primary end-point was disease free survival (DFS, 60 events, median follow-up 88 months). Biomarkers analyzed on frozen primary tumors were: MMR status (bat 25, bat 26), mutations of KRAS (codons 12-13), BRAF (V600E), PIK3CA (exons 9 and 20), APC (exon 15) and P53 (exons 4-9), CIMP status, ploidy, S-phase fraction, LOH (8p, 17p, 18q), EGFR (ligand-binding assay), VEGFA expression (Elisa), thymidylate synthase (TS) enzyme activity and expression (RT-PCR), thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) expressions (RT-PCR). Results: 30 stages I, 116 stages II and 105 stages III were included (FUFOL adjuvant treatment in 30 stages II and 61 stages III). 14% were dMMR. Multivariate Cox analyses showed that tumor staging was the only significant predictor of DFS. Log Rank analyses restricted to stage III showed tendencies for a shorter DFS in KRAS-mutated (p=0.005), BRAF wt (p=0.009) and pMMR tumors (p=0.036). dMMR tumors significantly expressed elevated TS (median 3.1 vs 1.4) and TP (median 5.8 vs 3.5) expression relative to pMMR (p<0.001) and tended to express higher DPD expression (median 14.9 vs 7.9, p=0.027) and EGFR content (median 69 vs 38, p=0.037) relative to pMMR. Conclusions: The present data, suggesting for the first time that both TS (5FU target) and DPD (FU catabolism enzyme) are overexpressed in dMMR tumors, bring strong arguments to explain the resistance of dMMR CRC tumors to FU-based therapy. The fact that dMMR tumors tend to express elevated EGFR levels and are prone to be KRAS wt suggests that anti-EGFR may be a relevant therapy in these patients. Clinical trial information: 1997.CHUNice-948.