Whole-Exome Sequencing Identifies Somatic Mutations Associated With Mortality in Metastatic Clear Cell Kidney Carcinoma.

Clear cell renal cell carcinoma (ccRCC) is among the most aggressive histologic subtypes of kidney cancer, representing about 3% of all human cancers. Patients at stage IV have nearly 60% of mortality in 2-3 years after diagnosis. To date, most ccRCC studies have used DNA microarrays and targeted sequencing of a small set of well-established, commonly altered genes. An exception is the large multi-omics study of The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma (TCGA-KIRC), which identified new ccRCC genes based on whole exome-sequencing (WES) data, and molecular prognostic signatures based on transcriptomics, epigenetics and proteomics data. Applying WES to simultaneously interrogate virtually all exons in the human genome for somatic variation, here we analyzed the burden of coding somatic mutations in metastatic ccRCC primary tumors, and its association with patient mortality from cancer, in patients who received VEGF receptor-targeting drugs as the first-line therapy. To this end, we sequenced the exomes of ten tumor-normal pairs of ccRCC patient tissues from primary biopsies at >100× mean depth and called somatic coding variation. Mutation burden analysis prioritized 138 genes linked to patient mortality. A gene set enrichment analysis evidenced strong statistical support for the abundance of genes involved in the development of kidney cancer (p = 2.31 × 10-9) and carcinoma (p = 1.22 × 10-5), with 49 genes having direct links with kidney cancer according to the published records. Two of these genes, SIPA1L2 and EIF3A, demonstrated independent associations with mortality in TCGA-KIRC project data. Besides, three mutational signatures were found to be operative in the tumor exomes, one of which (COSMIC signature 12) has not been previously reported in ccRCC. Selection analysis yielded no detectable evidence of overall positive or negative selection, with the exome-wide number of nonsynonymous substitutions per synonymous site reflecting largely neutral tumor evolution. Despite the limited sample size, our results provide evidence for candidate genes where somatic mutation burden is tentatively associated with patient mortality in metastatic ccRCC, offering new potential pharmacological targets and a basis for further validation studies.

The Na, K-ATPase ß-Subunit Isoforms Expression in Glioblastoma Multiforme: Moonlighting Roles.

Glioblastoma multiforme (GBM) is the most common form of malignant glioma. Recent studies point out that gliomas exploit ion channels and transporters, including Na, K-ATPase, to sustain their singular growth and invasion as they invade the brain parenchyma. Moreover, the different isoforms of the ß-subunit of Na, K-ATPase have been implicated in regulating cellular dynamics, particularly during cancer progression. The aim of this study was to determine the Na, K-ATPase ß subunit isoform subcellular expression patterns in all cell types responsible for microenvironment heterogeneity of GBM using immunohistochemical analysis. All three isoforms, ß1, ß2/AMOG (Adhesion Molecule On Glia) and ß3, were found to be expressed in GBM samples. Generally, ß1 isoform was not expressed by astrocytes, in both primary and secondary GBM, although other cell types (endothelial cells, pericytes, telocytes, macrophages) did express this isoform. ß2/AMOG and ß3 positive expression was observed in the cytoplasm, membrane and nuclear envelope of astrocytes and GFAP (Glial Fibrillary Acidic Protein) negative cells. Interestingly, differences in isoforms expression have been observed between primary and secondary GBM: in secondary GBM, ß2 isoform expression in astrocytes was lower than that observed in primary GBM, while the expression of the ß3 subunit was more intense. These changes in ß subunit isoforms expression in GBM could be related to a different ionic handling, to a different relationship between astrocyte and neuron (ß2/AMOG) and to changes in the moonlighting roles of Na, K-ATPase ß subunits as adaptor proteins and transcription factors.

Alterations in IQGAP1 expression and localization in colorectal carcinoma and liver metastases following oxaliplatin-based chemotherapy.

IQGAP1 is a scaffolding protein that serves a key role in cell dynamics by integrating internal and external stimuli to distinct signal outputs. Previous studies have identified several genes that are significantly up- or downregulated in the peripheral white cells (PWCs) of patients with colorectal adenocarcinoma (CRC), who underwent oxaliplatin-based chemotherapy (CT). In addition, screening studies have reported that IQ-motif containing GTPase activating protein 1 (IQGAP1) transcriptional expression levels varied from 'off' to 'on' following oxaliplatin CT. In order to determine if variations previously described in PWCs are able to be observed at the protein level in tumors and in metastases following CT, the present study performed an immunohistochemical analysis of IQGAP1 in CRC and primary metastases. IQGAP1 expression was observed in the nuclear envelope and in lateral cell membranes and cytoplasm in normal colon tissue. However, in tumor tissue, cells exhibited a diffuse pattern, with variable expression levels of staining in the nuclear membrane and cytoplasm, with the highest expression intensity observed at the invasive front. In healthy and metastasized liver tissue and in the metastases themselves, expression levels varied from cell to cell from no expression to a high level. In the majority of cells, IQGAP1 co-localized with microtubules at the cytoplasmic face of the nuclear envelope. Strong positive expression was observed in areas of the lesion where cells were detaching from the lesion into the lumen. Despite the homogeneous IQGAP1 staining pattern observed in healthy colon tissue sections, CRC demonstrated heterogeneity in staining, which was more marked in metastasized liver tissue resected following CT. However, the most notable findings were the observed effects on the cellular and subcellular distribution and its implications for cancer biology. These results suggest that IQGAP1 may be a putative biomarker, a candidate for clinical diagnostics and a potential novel target for anti-cancer therapeutics.

Commitment of Scaffold Proteins in the Onco-Biology of Human Colorectal Cancer and Liver Metastases after Oxaliplatin-Based Chemotherapy.

Scaffold proteins play pivotal roles in the regulation of signaling pathways, integrating external and internal stimuli to various cellular outputs. We report the pattern of cellular and subcellular expression of scaffoldins angiomotin-like 2 (AmotL2), FK506 binding protein 5 (FKBP51) and IQ motif containing GTPase-activating protein 1 (IQGAP1) in colorectal cancer (CRC) and metastases in liver resected after oxaliplatin-based chemotherapy (CT). Positive immunostaining for the three scaffoldins was found in most cells in healthy colon, tumor, healthy liver and metastasized liver. The patterns of expression of AmotL2, FKBP51 and IQGAP1 show the greatest variability in immune system cells and neurons and glia cells and the least in blood vessel cells. The simultaneous subcellular localization in tumor cells and other cell types within the tumor suggest an involvement of these three scaffoldins in cancer biology, including a role in Epithelial Mesenchymal Transition. The display in differential localization and quantitative expression of AmotL2, FKBP51, and IQGAP1 could be used as biomarkers for more accurate tumor staging and as potential targets for anti-cancer therapeutics by blocking or slowing down their interconnecting functions. Tough further research needs to be done in order to improve these assessments.

IQGAP1 in Podosomes/Invadosomes Is Involved in the Progression of Glioblastoma Multiforme Depending on the Tumor Status.

Glioblastoma multiforme (GBM) is the most frequent and aggressive primary brain tumor. GBM is formed by a very heterogeneous astrocyte population, neurons, neovascularization and infiltrating myeloid cells (microglia and monocyte derived macrophages). The IQGAP1 scaffold protein interacts with components of the cytoskeleton, cell adhesion molecules, and several signaling molecules to regulate cell morphology and motility, cell cycle and other cellular functions. IQGAP1 overexpression and delocalization has been observed in several tumors, suggesting a role for this protein in cell proliferation, transformation and invasion. IQGAP1 has been identified as a marker of amplifying cancer cells in GBMs. To determine the involvement of IQGAP1 in the onco-biology of GBM, we performed immunohistochemical confocal microscopic analysis of the IQGAP1 protein in human GBM tissue samples using cell type-specific markers. IQGAP1 immunostaining and subcellular localization was heterogeneous; the protein was located in the plasma membrane and, at variable levels, in nucleus and/or cytosol. Moreover, IQGAP1 positive staining was found in podosome/invadopodia-like structures. IQGAP1⁺ staining was observed in neurons (Map2⁺ cells), in cancer stem cells (CSC; nestin⁺) and in several macrophages (CD31⁺ or Iba1⁺). Our results indicate that the IQGAP1 protein is involved in normal cell physiology as well as oncologic processes.

Na,K-ATPase Isozymes in Colorectal Cancer and Liver Metastases.

The goal of this study was to define Na,K-ATPase α and ß subunit isoform expression and isozyme composition in colorectal cancer cells and liver metastases. The α1, α3, and ß1 isoforms were the most highly expressed in tumor cells and metastases; in the plasma membrane of non-neoplastic cells and mainly in a cytoplasmic location in tumor cells. α1ß1 and α3ß1 isozymes found in tumor and metastatic cells exhibit the highest and lowest Na(+) affinity respectively and the highest K(+) affinity. Mesenchymal cell isozymes possess an intermediate Na(+) affinity and a low K(+) affinity. In cancer, these ions are likely to favor optimal conditions for the function of nuclear enzymes involved in mitosis, especially a high intra-nuclear K(+) concentration. A major and striking finding of this study was that in liver, metastasized CRC cells express the α3ß1 isozyme. Thus, the α3ß1 isozyme could potentially serve as a novel exploratory biomarker of CRC metastatic cells in liver.

Use of panitumumab in the treatment of acinar cell carcinoma of the pancreas: A case report.

Two cases of stage IV acinar carcinoma of the pancreas are presented. The two patients were treated with several lines of chemotherapies active against colon cancer. At last-line, both patients received panitumumab monotherapy. We describe the tumour response to the different therapies. Our findings demonstrate that panitumumab produces objective responses when used as third-line treatment in the therapy of patients with acinar cell carcinoma of the pancreas. Thus, we propose the consideration of the use of panitumumab in early lines of treatment.