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ClinicI significance of ras oncogene activation in human hmg cancer Rodmhuis S, Slebos RJC. Division ofExperimental 7herapy. Deparhnent of Medical Oncology. Netherlands Cancer Institute, Plesmanlaaa 121, 1066 CXAmsterdam. Cancer Res 1992;52:Suppl. 26659-9s.

Activation of ras oncogenes is commonly found in human neoplasms. We have investigated 280 human lung cancer specimens for ras activation, including 38 that have not been reported previously, using an oligonucleotidedetection assay. Froma total of 141 adenocarcinoma samples from smokers, 41 tested positive for a paint mutation in codon 120f K-ms (30%). whilethreetumors had another typeof rasactivation. Only two of 40 cases from nonsmokers had a K-ras mutation (5 46). suggesting that K-ras mutations may be directly caused by exposure to carcinogens in tobacco smoke. The majority of the point mutations in adenocarcinomas were guanine to thymine transversions in codon 12 of the K-ras oncogene. Occasional point mutations in ras oncogenes were detected in adenoquamous carcinomas (one of five. cases) and large cell carcinoma (one of 24 cases), but no ras activations were found in small cell carcinomas (six cases), squamous carcinomas (48 cases), carcinoid carcinomas (15 cases), or thymoma (one case). Analysis of the clinical and pathological features of the adenocarcinoma cases showed no apparent associations behveen the K-ras activation and age at diagnosis, sex, disease stage, and the occurrence of other neoplasms. K-ras- positive adenocarcinomas tended to be less differentiated than the K-ras- negative ones (P = 0.044, chi’ test for trend). K-ras mutations identify a subgroup of patients with adenocarcinoma of the lung who have a very poor prognosis despite radical resection of their tumor. Although K-ras has been proposed as a target for antitumor therapy, its major clinical significance could be to aid in the selection of patients for specific therapeutic interventicns, such as adjuvant chemotherapy.

Primary lung tumors in mice: An experimentally manipulable model of human adenocarcinoma Malkinson AM. Molecular Toxicology and EHS Program, Univ. of Colorado School of Pharmacy, Campus Box 297, Boulder, CO BO309- 0297. Cancer Res 1992;52:Suppl. 267Os-6~.

The paucity of premalignant material available for study makes it difficulttoassignpathogenicroles to&myriad phenotypic abnormalities found in lung cancer. Chemically and transgenically induced primary lung tumors in mice, however, share many of the morphological, histogenic, and biochemical featuresofhumau adenocarcinoma. Genetic factors guide the susceptibility to these tumors in both mice and humans. The reproducible natural history of these investigator-initiated lesions allows molecular characterization at each stage of progression, as well as delineation of pharmacological agents which encourage or retard their appearance. Experimental tools which can be used with this mouse model include inbred and recombinant inbred strains that vary in susceptibility to lung turn&genesis, sensitivity to tumor-promoting agents, and tumor growth characteristics; the ability to isolate the cells of tumor origin with a high degree of purity; immortalized but nontumorigenic cell lines for comparison with neoplastic cell lines; and transgenic mice with an accelerated rate of tumorigenesis for the study of benign to malignant progression over a conveniently short time course. Among the relevant information thus far garnered about mouse lung tumors is the fact that K-ras protooncogene polymorphisms predict susceptibility to tumor development; K-ras mutation is an early event, and the nature of this mutation may determine the benign or malignant fate of the tumors; and the autonomous growth of neoplastic lung apithelial cells is maintained by a resistance to growth-inhibitory signals, and this is mediated by depletion of intracellular receptors and altered signal transduction pathways.

Kinetic analysis of combination etTect of navelbine (KW-2307) with cisplatin agaimt human lung adenocarcinoma PC-12 cells in culture Gomi K, Ohno H, Nomum K, Okabe M, Kohayashi K, Niitani H. Phannaceut. ResearchLab., Kyowa Hawlo Kogyo Co., L.td., Shimotognri 1188, Nagaizumi-cho,Shbuokn_ken411. JplJCaucerRes1992;83:532- 9.

The combination effect of ??avelbine (NVB, KW-2307), a newly synthesized vinca alkaloid, and cisplatin (CDDP) was compared with that of vindesine (VDS) and CDDP using human lung adamcarcinoma PC-12 cells. The growth-inhibitory activity of NVB or VDS was time- dependent, whereas that of CDDP was AUC (area under the curve)- dependent. When NVB or VDS was used in combination with CDDP simultaneously for 24 h, antagonism was observed in temw of growth- inhibitory activity. However, additive combination effect was observed when NVB or VDS treatment was followed by CDDP treatment. On this treatment schedule, a synergistic combination effect was observed in terms ofthecell-killing activity assessed by colony fonuationassay. The growth-inhibitory activity of NVB or VDS was detected 24 h after the treatment, whereas that of CDDP became significant 72 h after the treatment. NVB and VDS caused cell accumulation in G2M phase at IO times tbeir’IC %), values, and cells with less than diploid DNA content were detected after 24 hat IC,. CDDP caused accumulation of cells in S phase, and the effect became detectable 16 h after the treatment. The DNA histogram of cells treated with NVB or VDS in combination with CDDP was a superposition of those of cells treated with each drug alone. Significant differences in thecharacteristics of anticellular activity were not detected behwen NVB and VDS, although NVB inhibited cell growth at a slightly lower concentration than VDS at the short exposure time of 1-8 h.

Alternative splicing of neuralcell-adhesion mole&e mRNA in human small-cell lung-cancer cell line H69 Moolenaar CEC, Pieneman C, Walsh FS, Mooi WJ, Michalides RJAM. Division of Tumor Biology, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CXAmsterdam. Int J Cancer 1992;51:238-43.

The neural-cell-adhesion molecule (NCAM) is expressed in all small- cell lung cancers (SCLC) and in approximately 20% of non-small-cell lung tumors (non-SCLC). These NCAM-positive lung tumors have a poor prognosis compared with NCAM-negative tumors. Multiple NCAM protein isoforms are expressed from a singlesopy gene. as a result of alternative splicing and/or post-translational modifications. Therefore, we studied the NCAM isoforms expressed in a human small- cell lung-cancer cell line, H69. NCAM mRNA transcripts of 7.2, 6.7, 4.3 and 4.0 were detected in these. cells on Northern blots. Since the various NCAM isoforms may have different biological properties, we performed a more p&se examination of NCAM mRNAs, using polymerase chain reactions (PCR) with primers flanking the various NCAM exon boundaries. The shortest alternatively spliced sequence. that we found was the trinucleotide AAG located behveen exon 12 and 13 in the so-called hinge region of the NCAM protein. This AAG trinucleotide was present in the majority of the NCAM mRNAs. A second alternatively spliced 30 nt-exon VASE (immunoglobulin variable domain-like alternatively spliced won) was present in all NCAM transcript isofonns at the exon 7lexon 8 junction. VASE resulted in the insertion of IO amino acids into the 4th immunoglobulin-like loop of the NCAM protein. Within tbelimitsofthePCR methodology, noevidence for the presence of mRNA containing exon 15, encoding the glycosyl- phosphatldylinositol-linked (GPI-linked) NCAM isoforrn in H69 cells was obtained. Considering that H69 cells express 2 major NCAM protein classes (NCAM-180 and NCAM-140). and that the VASE and AAG alternative mRNA splice variants result in minor differences in protein sizes, at least 8 polypeptide isoforms of NCAM might be expressed in H69 cells that contribute to the binding interactions of NCAM.