Andrea Cavazzana

KLF4 is a Novel Candidate Tumor Suppressor Gene in Pancreatic Ductal Carcinoma

Ductal pancreatic carcinoma (DPC) is a deadly disease with an incidence of 9 cases in 100,000 people per year and a mortality rate close to 100%. Allelic losses in the long arm of chromosome 9 are commonly encountered in many human malignancies but no data are yet available about DPC. We screened 40 laser-microdissected DPC samples and 6 pre-invasive lesions for 9 microsatellite mapping markers of region 9q21.3 through 9q34.2. A small overlapping region of deletion, spanning 8 million base pairs, was identified between D9S127 and D9S105. Two genes, RSG3 and KLF4, mapped to 9q31.1 through 9q32, were further investigated. A highly significant association was found between KLF4 gene expression levels and genomic status. Similarly, absence of immunohistochemical expression of KLF4 protein was found in 86.8% cases of DPC (33/38). Overexpression of KLF4 in a human pancreatic carcinoma cell line induced a significant decrease in the proliferation associated with up-regulation of p21 and the down-regulation of cyclin D1. In conclusion, we identified a novel oncosuppressor region located at the 9q 31.1-3 locus that is lost in DPC at high frequency. Loss of KLF4 expression is closely related to the genomic loss, and its restoration inhibits cancer cell proliferation, suggesting a key suppressor role in pancreatic tumorigenesis.

Identification of low intratumoral gene expression heterogeneity in neuroblastic tumors by genome-wide expression analysis and game theory

Neuroblastic tumors (NTs) are largely comprised of neuroblastic (Nb) cells with various quantities of Schwannian stromal (SS) cells. NTs show a variable genetic heterogeneity. NT gene expression profiles reported so far have not taken into account the cellular components. The authors reported the genome‐wide expression analysis of whole tumors and microdissected Nb and SS cells.

Papillary lesions of the breast: a molecular progression?

SummaryIntroduction. Breast papillary lesions represent a heterogeneous group of tumors ranging from benign to malignant, including several intermediate forms. Malignant papillary tumors are rare and their molecular characterization is still limited. A few studies pointed to the presence of specific genetic alterations that could be relevant both for diagnostic purposes and to elucidate tumour development and progression. In order to look into the issue, we compared LOH relative frequencies of four microsatellite markers located on chromosome 16 in a set of morphologically different papillary breast lesions. LOH at TP53 locus was also analyzed throughout lesions. Materials and methods. Fifteen cases were analyzed. Sections including a malignant papillary lesion, a benign lesion (when available), and normal breast tissue were selected. Fifteen malignant and twelve benign areas were microdissected using the Leica laser microdissection system (AS LMD). After DNA extraction samples were tested for the following markers: TP53, D16S423, D16S310, DS163210 and D16S476, and analyzed on ABI PRISM 3100 (Applied Biosystems, Foster city CA). Results. Fourteen malignant lesions and twelve paired benign areas appeared to be informative for at least one of the four markers on chromosome 16. In particular, LOH at loci 16p13 and 16q21 was detected in both benign and malignant lesions, whereas LOH at locus 16q23 was limited to malignant lesions. Nine malignant and seven benign lesions were informative for LOH at TP53 locus, that was found to be significantly associated (p=0.01) with the malignant phenotype. Conclusions. Our data suggest an involvement of chromosome 16 mutations in the early steps of breast papillary tumorigenesis. TP53 deletion and possibly LOH at 16q23 appear to play a role as progression factors, being they significantly associated with malignant transformation of breast papilloma.

Nuclear Expression of Hypoxia-inducible Factor-1?? in Clear Cell Renal Cell Carcinoma is Involved in Tumor Progression

ObjectivesThe most frequent genomic abnormality in clear cell renal cell carcinoma (cc-RCC) is inactivation of Von Hippel-Lindau gene (VHL). pVHL19 is a ligase promoting proteosomal degradation of hypoxia-inducible factor-1alfa (HIF-1α); pVHL30 is associated with microtubules. VHL exert its oncogenetic action both directly and through HIF-1α activation. TNM classification is unable to define a correct prognostic evaluation of intracapsular cc-RCC. The nucleo-cytoplasmic trafficking in VHL/HIF-1α pathway could be relevant in understanding the molecular pathogenesis of renal carcinogenesis. This study analyzes VHL/HIF-1α proteins in a large series of intracapsular cc-RCCs, correlating their expression and cellular localization with prognosis. Materials and MethodsTwo anti-pVHL (clones Ig32 and Ig33) and 1 anti-HIF-1α were used on tissue microarrays from 136 intracapsular cc-RCCs (mean follow-up: 74 mo). Clone 32 recognizes both pVHLs, whereas clone 33 only pVHL30. Results were matched with clinicopathologic variables and tumor-specific survival (TSS). ResultsA strong cytoplasmic positivity was found for all antibodies in the largest part of cases, associated to a strong nuclear localization in the case of HIF-1α. All pVHL-negative cases were associated with high HIF-1α expression. pVHL negativity and HIF-1α nuclear positivity significantly correlated with shorter TSS. In multivariate analysis both pVHL negativity and HIF-1α nuclear expression were independent predictors of TSS. ConclusionsThe localization of the proteins well matches with their role and with the supposed tumor molecular pathways. The correlation with prognosis of VHL/HIF-1α alterations confirms the relevance of their molecular pathway and of the cellular trafficking of their products in the pathogenesis of renal cancer.

PIK3CA in Breast Carcinoma: A Mutational Analysis of Sporadic and Hereditary Cases

The PI3K-Akt cascade is a key signaling pathway involved in cell proliferation, survival, and growth. Activating PIK3CA mutations have been reported in breast carcinoma (BC). The aim of this study was to characterize the PIK3CA mutations at exons 9 and 20 in a series of 176 sporadic and 22 hereditary BCs and to correlate the results with clinicopathologic parameters and survival. In sporadic BC, 68 missense mutations were detected. PIK3CA mutations were significantly associated with ER+ in HER2-negative cases. A higher frequency of PIK3CA mutations was present in lobular carcinoma compared with ductal carcinoma (50% vs. 35%). There was no association between the survival and PIK3CA mutational status. In hereditary BC, PIK3CA mutations were found only in the BRCA2 group. The PIK3CA mutation seems to characterize the luminal-type BC, in both sporadic and BRCA2 mutated forms, and is absent in the basal-type BC, in both the sporadic and BRCA1 mutated forms.

Genome analysis and gene expression profiling of neuroblastoma and ganglioneuroblastoma reveal differences between neuroblastic and Schwannian stromal cells

Neuroblastic tumours are a group of paediatric cancers with marked morphological heterogeneity. Neuroblastoma (Schwannian stroma‐poor) (NB‐SP) is composed of undifferentiated neuroblasts. Ganglioneuroblastoma intermixed (Schwannian stroma‐rich) (GNBi‐SR) is predominantly composed of Schwannian stromal (SS) and neuroblastic (Nb) cells. There are contrasting reports suggesting that SS cells are non‐neoplastic. In the present study, laser capture microdissection (LCM) was employed to isolate SS and Nb cells. Chromosome 1p36 deletion and MYCN gene amplification were found to be associated in two out of seven NB‐SPs, whereas no abnormalities were observed in five GNBi‐SRs. In some cases, loss of heterozygosity (LOH) at 1p36 loci was detected in Nb cells but not in the bulk tumour by LCM; furthermore, LOH was also identified in both SS and tumour tissue of a GNBi‐SR. DNA gain and loss studied by comparative genomic hybridization were observed at several chromosome regions in NB‐SP but in few regions of GNBi‐SR. Finally, gene expression profiles studied using an oligo‐microarray technique displayed two distinct signatures: in the first, 32 genes were expressed in NB‐SP and in the second, 14 genes were expressed in GNBi‐SR. The results show that NB‐SP is composed of different morphologically indistinguishable malignant cell clones harbouring cryptic mutations that are detectable only after LCM. The degree of DNA imbalance is higher in NB‐SP than in GNBi‐SR. However, when the analysis of chromosome 1p36 is performed at the level of microdissection, LOH is also observed in SS cells. These data provide supportive evidence that SS cells have a less aggressive phenotype and play a role in tumour maturation. Copyright

Xenon induces transcription of ADNP in neonatal rat brain

Xenon and other inhalational agents induce cell and organ protection through different and only partially elucidated molecular mechanisms. Anesthesia induced or pharmacologic preconditioning is a recognized mechanism of cell protection. In this study we explored the gene transcription of activity-dependent neuroprotective protein (ADNP) in neonatal rat brain as consequence to xenon exposure, comparing the noble gas to nitrogen. Seven-day-old Sprague Dawley rats were exposed for 120 min to 75% xenon and 25% oxygen or control condition consisting of 75% nitrogen and 25% oxygen (Air). ADNP was found to be differentially expressed by SSH, validated by Relative Real-Time PCR (RT-PCR) and confirmed by western blot and immunohistochemistry. The differential expression of ADNP in the rat neonatal brain may account for the preconditioning and neuroprotective effects exerted by gas xenon.

Xenon up-regulates several genes that are not up-regulated by nitrous oxide

Xenon and other inhalational agents induce cell and organ effects through different and only partially elucidated molecular mechanisms. In this study, we explored the gene transcription consequences of xenon exposure compared with nitrogen or nitrous oxide exposure in rat brain. Seven-day-old Sprague Dawley rats (n=24, 8 for each group) were exposed for 120 minutes to 75% xenon and 25% oxygen, 75% nitrogen and 25% oxygen (air), or 75% nitrous oxide and 25% oxygen. Using suppression subtractive hybridization, relative real-time polymerase chain reaction, and northern blot analyses of on/off gene expression, we were able to identify a set of genes that are significantly up-regulated by xenon exposure. These genes may help explain some of the molecular mechanisms that account for the neuropreconditioning effects exerted by xenon relative to nitrous oxide and air.

Loss of Heterozygosity Status of D9S105 Marker Is Associated with Downregulation of Krüppel-Like Factor 4 Expression in Pancreatic Ductal Adenocarcinoma and Pancreatic Intraepithelial Lesions

The transcription factor Krüppel-like factor 4 (KLF4) may act both as an oncogene and a tumor suppressor in a tissue-dependent manner, and further studies on its role in pancreatic ductal adenocarcinoma (PDAC) progression and clinical outcome are warranted. Therefore, we investigated the loss of heterozygosity (LOH) in the 9q22.3–32 region and loss of KFL4 gene expression in epithelial cells from 35 PDAC, 6 pancreatic intraductal neoplasias (PanINs) and 6 normal ducts, isolated by laser microdissection, as well as their correlation with overall survival (OS) in patients treated with gemcitabine in the adjuvant setting. LOH was evaluated with 4 microsatellite markers and in situ hybridization, while KLF4 expression was studied by reverse transcription-PCR and immunohistochemistry. LOH in at least 1 locus was observed in 25 of 35 PDAC cases and in 5 of 6 PanINs, respectively. In particular, the loss of the D9S105 marker was present in 46.9% of PDAC and 83.3% of PanINs, becoming the most deleted marker, while no LOH in D9S105 was observed in normal Wirsung pancreatic duct. Lack of KLF4 mRNA expression was significantly associated with: (1) genomic deletion flanking KLF4 in PDAC and in PanINs (with LOH of D9S105), (2) low-grade PDAC-associated PanIN, (3) lack of KLF4 protein expression, and (4) shorter OS. These results strongly suggest a relationship between D9S105 deletion and downregulation of KLF4 gene expression as an early event in PDAC progression, as well as a possible role of KLF4 as a prognostic biomarker in gemcitabine-treated patients.

Establishment and characterization of 4 new human pancreatic cancer cell lines: evidences of different tumor phenotypes.

Objectives: Pancreatic cancer still remains a challenge for its biological complexity and lack of effective therapeutic strategies. Establishing new pancreatic cancer cell lines is therefore of paramount importance to clarify its biology. Methods: We established and characterized 4 new pancreatic cancer cell lines (PP78, PP109, PP117, and PP161) according to their genetic (K-Ras, TP53, CDKN2A, and MADH4; DNA fingerprinting; karyotype), cytostructural (cytokeratins 7, 8, 18, and 19 vimentin, and ezrin), and functional profiles (doubling time; migration assay). Results: K-Ras, TP53, and CDKN2A gene alterations were detected in all 4 of them. Each cell line had a unique DNA profile revealed by DNA fingerprinting. A complex karyotype with numerous structural and numeric chromosomal abnormalities was present in each cell line. All 4 cell lines showed positivity for cytokeratins 7, 8, and 18. All but PP78 expressed cytokeratin 19, whereas vimentin was expressed only in PP117 and PP78 cells. A different ezrin cellular distribution was noticed in PP78 and PP117, being mostly located at membrane ruffles. This peculiar distribution was associated with the strongest migratory capability. Conclusions: Our results seem to confirm the pancreatic ductal adenocarcinoma heterogeneity; in fact, the same genetic abnormalities (K-Ras, TP53, and CDKN2A) may have different effects on tumor biology depending on cellular differentiation.