The detection of malignant cells in fine-needle aspirates (FNA's) using marker genes is hampered by the fact that these markers are only expressed by certain malignancies or lack sensitivity and/or specificity. Here we report the results of a prospective pilot study examining the expression of KOC (KH-domain containing protein over expressed in cancer), a novel onco-foetal gene, in 76 patients who underwent fine-needle aspiration for further diagnosis of abdominal lesions, aszites, cysts or cerebrospinal fluid. Aspirates were examined by cytology and by a KOC RT -PCR assay. KOC expression was a highly sensitive and specific indicator of malignancy. The KOC assay could be useful to facilitate screening for malignant disease and to improve the diagnostic accuracy of FNAs. In a large-scale screen for differentially expressed genes in pancreatic cancer, we have recently identified a gene encoding a novel protein with four K-homologous (KH) domains, which is highly overexpressed in pancreatic cancer (Mueller-Pillasch et al, 1997). The new gene was named KOC (KH-domain containing protein overexpressed in cancer). Two known functions of KHdomain containing proteins are the regulation of mRNA stability and subcellular localisation, both of which are implicated in fundamental biological processes such as development, cell growth, differentiation and carcinogenesis (Ross et al, 1997). Therefore, KOC may play a role in the regulation of tumour cell proliferation by interfering with transcriptional and/or posttranscriptional processes. However, the precise role of KOC in tumour biology remains to be elucidated. Our preliminary data suggested that KOC is exclusively expressed in tumours and embryonic tissues (Mueller-Pillasch et al, 1997, 1999 and may therefore represent an ideal target for novel diagnostic approaches. To test this hypothesis, a prospective study was undertaken to determine the diagnostic accuracy of measuring KOC expression as compared to the cytological assessment in a consecutive series of fine-needle aspirates (FNAs) from abdominal lesions, aszites, various cysts and cerebrospinal fluid.
MATERIALS AND METHODS
Determination of KOC expression in cell lines and FNAsHuman Panc-1 pancreatic cancer cells were purchased from the American Type Culture Collection. Stocks were maintained in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% (v v À1 ) foetal bovine serum (FBS) in a humidified atmosphere of 5% CO 2 /95% air at 371C and passaged every 3 days. Confluent cultures of Panc-1 cells were trypsinised and resuspended in serum-free DMEM. Various numbers of Panc-1 cells were subsequently mixed with 1 ml of human serum and then immediately centrifuged at 1200 r.p.m. for 2 min. The supernatants were decanted. The remaining cell pellets were resuspended in the RNeasy Mini Kit lysis buffer (Qiagen, Hilden, Germany) and total RNA was extracted using the same kit according to the manufacturer's instructions. cDNA synthesis and PCR were performed with the one-step RT -PCR (Polymerase Chain Reaction) Kit ...