IntroductionMultiple myeloma (MM) is a common hematologic disorder in which expansion of a malignant plasma-cell (PC) clone in the bone marrow (BM) leads to osteolytic bone destruction, impaired hematopoiesis, and renal failure. 1 Despite therapeutic progress that has been achieved through the optimization of chemotherapeutic regimens through the introduction of novel drugs, such as bortezomib and lenalidomide, most MM patients currently succumb to their disease. 2 Clinically apparent MM is assumed to evolve through a multistep transformation process leading to oncogenic deregulation of signaling pathways. Acquired genetic alterations and the microenvironment are supposed to critically support the establishment and expansion of the malignant PC clone in the BM. 3,4 In particular, the interaction between MM cells and BM stromal cells (BMSCs) has been shown to protect the former from apoptosis. 5 Additionally, osteoclasts (OCs) and endothelial cells (ECs) have recently been reported to support tumor growth. [6][7][8] The interleukin-6 receptor/signal transducer and activator of transcription 3 (IL-6R/STAT3), the Ras/mitogen-activated protein kinase (Ras/MAPK), and the phosphatidylinositol 3-kinase/Akt (PI3K/Akt) pathways are well-characterized BM microenvironment (BMM)-triggered signal transduction cascades that sustain the viability of MM cells. 9,10 It has therefore been suggested that these pathways might serve as therapeutic targets. However, we have previously demonstrated that MM cells cultured in the presence of cells from the BMM are protected from apoptosis induced by a single pathway blockade. 5 Specifically, in the presence of BMSCs, disruption of either the MAPK/extracellular signal-regulated kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) module or of the IL-6R/STAT3 pathway is not sufficient to induce apoptosis of MM cells, whereas combined targeting of both pathways induces MM-cell death. 11 This indicates that both pathways cooperate to maintain MM-cell growth and survival. To investigate the mechanism that might distinguish the fatal effects of combined pathway blockade from the benign consequences of any single pathway disruption, we performed gene chip analysis and found genes encoding for heat shock proteins 90 (Hsp90s) to feature prominently among down-regulated genes. We therefore analyzed the role of Hsp90s in MM in greater detail.The ATP-dependent chaperone Hsp90 comprises 2 homologous proteins (Hsp90␣ and Hsp90␤) that are encoded by separate genes. Hsp90 accounts for the maturation and functional stability of a plethora of polypeptides termed Hsp90 client proteins. 12,13 Hsp90s are overexpressed in many cancers, and it is presumed that they are required to sustain aberrant signaling in malignant cells. 14 Several components of tumor-cell-associated growth and survival pathways have been found to be Hsp90 clients, and Hsp90s are thus thought to sustain functional expression of oncoproteins while enabling the transformed cell to tolerate the imbalanced signaling this might ...

We investigated the differential expression of Dicer and Drosha, as well as that of microRNA (miRNA), in adjacent normal and tumour samples of patients with gastric cancer. The expression of Dicer and Drosha was studied by immunohistochemistry in 332 gastric cancers and correlated with clinico-pathological patient characteristics. Differential expression of miRNAs was studied using the Invitrogen NCode(™) Multi-Species miRNA Microarray Probe Set containing 857 mammalian probes in a test set of six primary gastric cancers (three with and three without lymph node metastases). Differential expression was validated by RT-PCR on an independent validation set of 20 patients with gastric cancer. Dicer and Drosha were differentially expressed in non-neoplastic and neoplastic gastric tissue. The expression of Drosha correlated with local tumour growth and was a significant independent prognosticator of patient survival. Twenty miRNAs were up- and two down-regulated in gastric carcinoma compared with non-neoplastic tissue. Six of these miRNAs separated node-positive from node-negative gastric cancers, ie miR-103, miR-21, miR-145, miR-106b, miR-146a, and miR-148a. Five miRNAs expressed differentially in node-positive cancers had conserved binding sites for mRNAs differentially expressed in the same set of tumour samples. Gastric cancer shows a complex derangement of the miRNA-ome, including Dicer and Drosha. These changes correlate independently with patient prognosis and probably influence local tumour growth and nodal spread.

Transcriptional signatures are an indispensible source of correlative information on disease-related molecular alterations on a genome-wide level. Numerous candidate genes involved in disease and in factors of predictive, as well as of prognostic, value have been deduced from such molecular portraits, e.g. in cancer. However, mechanistic insights into the regulatory principles governing global transcriptional changes are lagging behind extensive compilations of deregulated genes. To identify regulators of transcriptome alterations, we used an integrated approach combining transcriptional profiling of colorectal cancer cell lines treated with inhibitors targeting the receptor tyrosine kinase (RTK)/RAS/mitogen-activated protein kinase pathway, computational prediction of regulatory elements in promoters of co-regulated genes, chromatin-based and functional cellular assays. We identified commonly co-regulated, proliferation-associated target genes that respond to the MAPK pathway. We recognized E2F and NFY transcription factor binding sites as prevalent motifs in those pathway-responsive genes and confirmed the predicted regulatory role of Y-box binding protein 1 (YBX1) by reporter gene, gel shift, and chromatin immunoprecipitation assays. We also validated the MAPK-dependent gene signature in colorectal cancers and provided evidence for the association of YBX1 with poor prognosis in colorectal cancer patients. This suggests that MEK/ERK-dependent, YBX1-regulated target genes are involved in executing malignant properties.

Objective. To define gene activation patterns of monocytes (MO) in patients with rheumatoid arthritis (RA).Methods. A complementary DNA (cDNA) library was constructed from first-leukapheresis MO obtained from an RA patient with active disease; 32 P-labeled cDNA from first-leukapheresis MO (activated pool) and third-leukapheresis MO (nonactivated pool) were used as probes for differential hybridization. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to assess gene activation in MO from an additional 26 RA patients and 6 normal controls.