Mutational analysis of cancer candidate genes in different pancreatic cancer types

Alterations in the DNA sequence underline the development and progression of malignancy of any neoplasm as the result of the sequential accumulation of mutations in genes controlling cell homeostasis through different signaling pathways. Protein kinases are key regulators of these pathways and participate to the control of several cellular processes. If these enzymes display aberrant activity, cells may undergo unrestrained growth, thus giving rise to complex diseases such as cancer. Interestingly, these proteins could be therapeutically targeted. We conducted a gDNA sequence analysis of a subset of 35 genes belonging to the kinases gene family in a panel of 91 different pancreatic tumor types, for which no effective therapeutic strategy is currently available. Among other changes we found somatic mutations in ATM, EGFR, EPHA3, EPHB2, and KIT, none of which was previously described in cancers. Some of the mutated genes, including the tyrosine kinases EPHA3 and EPHB2, are clearly amenable to pharmacological intervention and could represent novel therapeutic targets for these incurable cancers. Furthermore, the mutational analysis of Pancreatic endocrine tumors (PETs) revealed a low rate of genetic abnormalities for kinase genes and highlighted mutations of ATM in cases that have been previously shown by our group to lack MEN1 mutations. Interestingly, both ATM and MEN1 map to the same chromosomal arm (11q), which is frequently lost in pancreatic endocrine tumors. Indeed, MEN1 alterations are the most common anomaly encountered in PET. To better define the role of this gene in the pathogenesis of PET we analyzed 100 apparently sporadic tumors with the aim to (i) assess the frequency and site of mutations in the MEN1 gene, (ii) compare MEN1 gene status with immunohistochemical stain for menin, and (iii) correlate this data with clinical pathological information. Finally, we found that less than one-third of sporadic NF-PETs are affected by MEN1 somatic mutations. These alterations are likely to alter protein function either by loss of its nuclear localization or by disrupting its multiple interaction. Furthermore, we observed that the lack of nuclear protein expression correlates with the presence of truncating mutations while positive cytoplasmic protein intensity is associated with the presence of mutation regardless of its predicted effect on the protein functionality and clinically was associated with a shorter time to progression.