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Carcinomas of unknown primary origin constitute 3% to 5% of all newly diagnosed metastatic cancers, with the primary source difficult to classify with current histological methods. Effective cancer treatment depends on early and accurate identification of the tumor; patients with metastases of unknown origin have poor prognosis and short survival. Because miRNA expression is highly tissue specific, the miRNA profile of a metastasis may be used to identify its origin. We therefore evaluated the potential of miRNA profiling to identify the primary tumor of known metastases. Two hundred eight formalin-fixed, paraffin-embedded samples, representing 15 different histologies, were profiled on a locked nucleic acid–enhanced microarray platform, which allows for highly sensitive and specific detection of miRNA. On the basis of these data, we developed and cross-validated a novel classification algorithm, least absolute shrinkage and selection operator, which had an overall accuracy of 85% (CI, 79%–89%). When the classifier was applied on an independent test set of 48 metastases, the primary site was correctly identified in 42 cases (88% accuracy; CI, 75%–94%). Our findings suggest that miRNA expression profiling on paraffin tissue can efficiently predict the primary origin of a tumor and may provide pathologists with a molecular diagnostic tool that can improve their capability to correctly identify the origin of hitherto unidentifiable metastatic tumors and, eventually, enable tailored therapy.

Ligation of two oligonucleotide probes hybridized adjacently to a DNA template has been widely used for detection of genome alterations. The multiplex ligation-dependent probe amplification (MLPA) technique allows simultaneous screening of multiple target sequences in a single reaction by using pairs of probes that carry tails for binding of common amplification primers. Resolution of the various targets is achieved by electrophoresis on the basis of predefined differences in amplicon length. In the conventional MLPA approach, one of the two target probes is generated by cloning in a single-stranded bacteriophage vector to introduce a sequence of defined length between the primer binding site and the specific target sequence. Here we demonstrate that differences in amplicon length can be achieved by using multiple short synthetic probes for each target sequence. When joined by a DNA ligase, these probes will form a single amplifiable template whose length is defined by the number and lengths of the individual probes. We have used this principle to establish a methylation-specific MLPA (MS-MLPA) assay that simultaneously determines the methylation status of five promoter CpG islands, and we have used this assay to analyze DNA from tumor tissue and corresponding urine samples from patients with bladder cancer. Our data show that the use of multiple short synthetic probes provides a simple means for custom-designed MS-MLPA analysis.

Recent studies have characterized the ABC half-transporter associated with mitoxantrone resistance in human cancer cell lines. Encoded by the ABCG2 gene, overexpression confers resistance to camptothecins, as well as to mitoxantrone. We developed four polyclonal antibodies against peptides corresponding to four different epitopes on the mitoxantrone resistance-associated protein, ABCG2. Three epitopes localized on the cytoplasmic region of ABCG2 gave rise to high-affinity antibodies, which were demonstrated to be specific for ABCG2. Western blot analysis of cells with high levels of ABCG2 showed a single major band of the expected 72-kDa molecular size of ABCG2 under denaturing conditions. Immunoblot analysis performed under non-reducing conditions and after treatment with cross-linking reagents demonstrated a molecular weight shift from 72 kDa to several bands of 180 kDa and higher molecular weight, suggesting detection of dimerization products of ABCG2. Evidence of N -linked glycosylation was also obtained using tunicamycin and N -glycosidase F. Finally, both by light, fluorescence and electron microscopic immunohistochemical staining, we demonstrate cytoplasmic and predominantly plasma membrane localization of ABCG2 in cell lines with high levels of expression. Plasma membrane staining was observed on the surface of the chorionic villi in placenta. These results support the hypothesis that ABCG2 is an ABC half-transporter that forms dimers in the plasma membrane, functioning as an ATP-dependent outward pump for substrate transport.

WF10 is a stabilized chlorite matrix with immunosuppressive effects. In vitro studies have demonstrated its ability to suppress T cells and delay or abolish antigen presentation. Hence, WF10 may prove useful to prolong graft survival after transplantation. In this study, we evaluated the use of high dose WF10 as a single drug regimen in the hamster-to-rat xenotransplantation model and searched for possible cardiotoxic side effects. WF10 prolonged cardiac xenograft survival, but did not induce tolerence or inhibit pathological signs of acute rejection. Hamsters from the donor population, receiving high dose WF10 for 5 days, were compared with a matched control group. Ultrastructural examination of cardiac tissue as well as biochemical analysis of the cardiac enzymes troponin I, myoglobin and MB isoenzyme of creatine kinase showed no signs of damage. Thus, while prolonging graft survival, high dose WF10 seems to be non-cardiotoxic and as such should not contribute to the differential diagnosis of acute graft failure.

We have recently shown that interferon-γ (IFN-γ) stimulated immunocytochemical staining of the intercellular adhesion molecule ICAM-1 may be dependent on inositol phosphate formation in the human renal carcinoma cell line CaKi-1. In the present study we investigated the possible role of GTP-binding proteins (G-proteins) during IFN-γ signalling. Preincubation of CaKi-1 cells for 24 h with increasing amounts of pertussis toxin (PT) or cholera toxin (CT), two regulators of G-protein activity, inhibited IFN-γ induced ICAM-1 staining. Preincubation with PT or CT for 24 h also inhibited IFN-γ induced inositol 1-monophosphate (Ins 1-P), inositol 1,4 bisphosphate (Ins 1,4-P2) and inositol 1,4,5 trisphosphate (Ins 1,4,5-P3) formation. Our findings suggest that IFN-γ induced ICAM-1 staining and inositol phosphate formation in CaKi-1 cells is dependent on a PT and CT sensitive signalling pathway. This may reflect a role for G-proteins in the coupling of IFN-γ receptor activation and phospholipase C catalyzed phosphoinositide hydrolysis.

In two cases of solid and papillary neoplasm of the pancreas (SPN), positive staining for argyrophil granules, chromogranin-A, neuron-specific enolase, chymotrypsin, α1-antitrypsin, vimentin, cytokeratin, and estrogen receptors was present. Ultrastructurally, neurosecretory as well as zymogenlike granules were demonstrated. Measurements of mean nuclear volume and volume-corrected mitotic index discriminated between SPN and well-differentiated ductal adenocarcinoma of the pancreas, with notably lower values being seen in SPN. Silver-stained nucleolar organizer region counts showed wide overlaps. The results suggest that SPN is a tumor with mixed endocrine and exocrine features. Its low malignant potential compared to ductal adenocarcinoma is reflected in the mean nuclear volume and volume-corrected mitotic index. The presence of estrogen receptors may prove therapeutically useful.

Incubation of the human renal carcinoma cell line CaKi-1 with tumour necrosis factor α (TNFα) or the phorbol ester phorbol-12-myristate 13 acetate (PMA) strongly enhanced the immunocytochemical staining of the intercellular adhesion molecule ICAM-1, in a non-linear manner. Since PMA is capable of activating Ca2+/phospholipid-dependent protein kinase C (PKC), we investigated the role of this kinase during TNFα signal transduction. Calcium ionophore A23187 significantly enhanced PMA, but not TNFα-induced ICAM-1 staining. The PKC inhibitors H7, staurosporine and sphingosine abrogated the action of PMA, while TNFα was unaffected. Simultaneous incubation with TNFα and PMA resulted in maximal ICAM-1 staining significantly above values obtained when cultures were treated with either agent alone. Finally, chronic PMA treatment with subsequent TNFα stimulation enhanced ICAM-1 staining above values from cultures where TNFα was omitted. Our findings suggest that the immunocytochemical staining of ICAM-1 in CaKi-1 cells can be induced by TNFα through mainly PKC-independent mechanisms or by PMA through PKC-dependent mechanisms. The two agents may work synergistically in this respect.