Jay D. Hunt

TP53 and KRAS Mutation Load and Types in Lung Cancers in Relation to Tobacco Smoke: Distinct Patterns in Never, Former, and Current Smokers

TP53 mutations are common in lung cancers of smokers, with high prevalence of G:C-to-T:A transversions generally interpreted as mutagen fingerprints of tobacco smoke. In this study, TP53 (exons 5-9) and KRAS (codon 12) were analyzed in primary lung tumors of never (n = 40), former (n = 27), and current smokers (n = 64; mainly heavy smokers). Expression of p53, cyclooxygenase-2 (Cox-2), and nitrotyrosine (N-Tyr), a marker of protein damage by nitric oxide, were analyzed by immunohistochemistry. TP53 mutations were detected in 47.5% never, 55.6% former, and 77.4% current smokers. The relative risk for mutation increased with tobacco consumption (P(linear trend) < 0.0001). G:C-to-T:A transversions (P = 0.06, current versus never smokers) and A:T-to-G:C transitions (P = 0.03, former versus never smokers) were consistently associated with smoking. In contrast, G:C-to-A:T transitions were associated with never smoking (P = 0.02). About half of mutations in current smokers fell within a particular domain of p53 protein, suggesting a common structural effect. KRAS mutations, detected in 20 of 131 (15.3%) cases, were rare in squamous cell carcinoma compared with adenocarcinoma [relative risk (RR), 0.2; 95% confidence interval (95% CI), 0.07-1] and were more frequent in former smokers than in other categories. No significant differences in Cox-2 expression were found between ever and never smokers. However, high levels of N-Tyr were more common in never than ever smokers (RR, 10; 95% CI, 1.6-50). These results support the notion that lung tumorigenesis proceeds through different molecular mechanisms according to smoking status. In never smokers, accumulation of N-Tyr suggests an etiology involving severe inflammation.

8‐Hydroxy‐2′‐deoxyguanosine (8‐OH‐dG) as a potential survival biomarker in patients with nonsmall‐cell lung cancer

8‐Hydroxy‐2′‐deoxyguanosine (8‐OH‐dG) is 1 of the most abundant oxidative products of cellular DNA. Accumulation of impaired 8‐OH‐dG could lead to increased genomic instability that in turn could lead to a more malignant phenotypic behavior of tumors. Therefore, the effects of 8‐OH‐dG on survival in 99 resected nonsmall‐cell lung cancer (NSCLC) patients was evaluated.

Platelet-activating factor (PAF) induces activation of matrix metalloproteinase 2 activity and vascular endothelial cell invasion and migration

Tumor‐induced angiogenic responses lead to complex phenotypic changes in vascular endothelial cells, which must coordinate the expression of both proteases and protease inhibitors prior to the proliferation and invasion of surrounding stroma. Matrix metalloproteinase 2 (MMP2), which degrades Type IV collagen, is produced as proMMP2. proMMP2 is activated in part through its interactions with membrane Type 1 MMP (MT1‐MMP) and tissue inhibitor of matrix metalloproteinase 2 (TIMP2). In this study, we demonstrate that platelet‐activating factor (PAF) is a potent inducer of human umbilical vein endothelial cell (HUVEC) migration and invasion, which is attenuated by PAF receptor antagonists, and that PAF receptor antagonists inhibit the migration and invasion of HUVEC mediated by medium conditioned by a prostatic carcinoma cell line. We confirm that PAF receptor antagonists inhibit proliferation of HUVEC grown in rich growth medium. We show that PAF increases mRNA levels for MT1‐MMP and TIMP2, followed by increased temporal conversion of latent proMMP2 to MMP2. Finally, we demonstrate that the ratio of MT1‐MMP to TIMP2 in membrane preparations from PAF‐stimulated HUVEC is 1.6:1, approximating the hypothesized ideal ratio of 2:1 necessary for the conversion of proMMP2 to MMP2. Our data support the involvement of PAF in vascular endothelial cell migration and invasion.

Propylthiouracil‐induced hypothyroidism reduces xenograft tumor growth in athymic nude mice

Thyroid hormones are endocrine modulators of several vital processes that are crucial to tumor growth and differentiation. Several anecdotal reports in the literature suggest that some histologic types of carcinoma may remain in a dormant state for prolonged periods of time in patients with hypothyroidism, with eventual progression of the disease once the decreased thyroid function is identified and corrected.

Tumor Specific Epstein - Barr Virus Infection Is Not Associated with Leiomyosarcoma in Human Immunodeficiency Virus Negative Individuals

Recent studies have suggested that the Epstein‐Barr virus (EBV) is associated with leiomyosarcoma in children with human immunodeficiency virus (HIV) and in organ transplant recipients. To determine whether EBV is associated with leiomyosarcoma in HIV negative patients, the authors examined resected leiomyosarcomas for EBV and HIV.

RECOMBINANT ONCOTOXIN AR209 (ANTI-P185erbB-2) DIMINISHES HUMAN PROSTATE CARCINOMA XENOGRAFTS

PURPOSE Prostate cancer is the most common malignancy of males in the United States. Although the overall survival rate for early stage prostate cancer is good, if cancer recurs following curative therapies there is no adequate salvage therapy. Systemic chemotherapy has never been associated with any meaningful improvement in overall survival or overall objective benefit. There is a need to develop novel therapies for prostate cancer. MATERIALS AND METHODS Two prostatic cancer cell lines, DU-145 and PC-3, were grown as subcutaneous xenografts in athymic nude mice. The recombinant oncotoxin AR209, formerly OLX-209 [e23(Fv)PE38KDEL]), has the specificity of an anti-p185erbB-2 antibody contained within a single-chain antibody domain (e23Fv) coupled to a portion of the Pseudomonas exotoxin A (PE38KDEL). Using Western blot analysis, the cell lines were shown to express p185erbB-2. The mice received either 3 i.v. injections, one every 2 days, of the recombinant oncotoxin AR209 or PBS, or were implanted with osmotic pumps that delivered a constant s.c. amount of AR209 or PBS. RESULTS The oncotoxin was effective in reducing the size of s.c. prostatic xenografts in athymic nude mice. The data demonstrated that small tumors (<200 mm.3) were effectively reduced in size. However, larger tumors (>500 mm.3) were not effectively diminished. CONCLUSIONS This study provides preliminary evidence for the utility of a recombinant oncotoxin in the treatment of prostate carcinoma. Recombinant oncotoxins may be an effective clinical addition for the management of metastatic prostate lesions in patients treated with conventional therapy.

Percutaneous implantation of non-small-cell lung carcinoma: Technique and observations

RATIONALE AND OBJECTIVES The authors performed this study to determine whether intrathoracic inoculation of non-small-cell lung carcinoma with fluoroscopic guidance would provide for more accurate implantation. MATERIALS AND METHODS A tumor cell inoculum (2 x 10(6) cells per 0.15 mL) was injected percutaneously under fluoroscopic guidance at the posterior midaxillary line in 22 athymic nude mice. The mice underwent imaging with a mammographic unit at 3, 5, and 8 weeks after implantation. The mice were sacrificed at 8 weeks, and autopsy was performed to determine tumor yield. RESULTS The use of a percutaneous technique under fluoroscopic guidance greatly facilitated the accurate implantation of xenografts. Tumor growth was seen at radiography in 18 of the 22 (82%) mice at 8 weeks. Necropsy revealed a 100% tumor yield. Histologic examination confirmed adenocarcinoma of the lung. The average number of tumors found in the lung parenchyma was 1.05 +/- 0.35; the average number of tumors found in the mediastinum was 0.59 +/- 0.67. The average tumor weight was 389 mg +/- 64.3. The average tumor size was 300 mm3 +/- 66.23. CONCLUSION With fluoroscopic guidance, percutaneous implantation of tumor cells in athymic nude mice is simple and effective.

Lipid Second Messengers and Receptors

Second messengers are organic molecules that are produced within a cell to initiate the response to a signal carried by an agonist that does not itself enter the cell.