Gene expression differences in primary colorectal tumors and matched liver metastases: chemotherapy related or tumoral heterogeneity?

BACKGROUND: Treatment of metastatic colorectal cancer (mCRC) is generally based on genetic testing performed in primary tumor biopsies, but whether the genomic status of primary tumors is identical to that of metastases is not well known. We compared the gene expression profiles of formalin-fixed paraffin-embedded (FFPE) biopsies of colorectal primary tumors and matched liver metastases. PATIENTS AND METHODS: We compared the expression of 18 genes in FFPE CRC tumors and their matched liver metastases from 32 patients. The expression of each gene in CRC primary tumors and their matched liver metastases was tested using Student's t test for paired samples. Pairwise correlations of each gene in the primary tumors and matched liver metastases were evaluated by Pearson's correlation coefficient. RESULTS: The expression of six genes was significantly different in primary tumors compared with their matched liver metastases [CXCR4 (p < 0.001), THBS1 (p = 0.007), MMP 9 (p = 0.048), GST Pi (p = 0.050), TYMP (p = 0.042) and DPYD (p < 0.001)]. For the remaining genes, where no significant differences were observed, only SMAD4 (r s = 0.447, p = 0.010), ERCC1 (r s = 0.423, p = 0.016) and VEGF A (r s = 0.453, p = 0.009) showed significant correlation in expression between the two tissues. Therefore, we only detected similar gene expression levels between the tumor and the metastases in these three markers. CONCLUSIONS: We only found similar gene expression levels between the tumor and the metastases in three genes (SMAD4, ERCC1, and VEGF A). However, our study could not assess whether the differences in gene expression were secondary to tumoral heterogeneity or to molecular changes induced by previous chemotherapy.

Biological traits and growth patterns of pejerrey Odontesthes argentinensis.

This study assesses for the first time the relationship between annual cycles of different biological indices with growth patterns of a marine pejerrey Odontesthes argentinensis population near its southern-distribution boundary in North Patagonia. The reproductive period is between September and November evidenced by an increase in the gonado-somatic index with a peak in October corresponding to spawning. The reproductive cycle was also coupled with metabolic processes related to energy allocation as shown by changes in the hepato-somatic index and body condition. Total length (L(T) ) at maturity was 270 for females and 282 mm for males, whereas fecundity was estimated at mean ±s.d. = 9380 ± 1797 mature oocytes. Based on the marginal increment analysis, most of the scales showed a maximum value during summer, with a sharp decline thereafter during autumn and winter, indicating that scale rings are formed during the latter period and only once a year. Growth fitted by the von Bertalanffy model for both males and females did not show significant differences and showed a rapid growth during the first 2 years. The shorter reproductive period compared with that of the northern O. argentinensis populations inhabiting tropical and subtropical areas was interpreted as an adjustment to temperate environmental conditions. The larger maximum L(T) and L(T) at first maturity are in agreement with the counter-gradient hypothesis and could be related to the selective effects of low temperature and a shorter growing season. This latitude dependency argues strongly against the application of the same fishing regulations for different O. argentinensis populations as a whole and reinforces the need to assess basic biological features at a population scale to promote local sustainable fisheries management.