Mast Cells Positive to Tryptase Correlate with Angiogenesis in Early Breast Cancer

Background: Literature data indicate that mast cells (MCs) are involved in tumor angiogenesis due to the release of several pro-angiogenetic factor among which tryptase, a serine protease stored in MCs granules, is one of the most active. In benign breast lesions and in primary breast cancer, tryptase-positive MCs are more numerous as compared to chymase-positive MCs. Recently, it has been demonstrated that tryptase-positive MCs are involved in angiogenesis in sentinel lymph nodes with micrometastases from patients with breast cancer. However no data has been published regarding the correlations between MCs positive to tryptase and angiogenesis in primary breast cancer tissue. In the present study, we have evaluated the correlations between the number of MCs positive to tryptase (MCDPT), the area occupied by MCs positive to tryptase (MCAPT), microvascular density (MVD) and endothelial area (EA) in a series of T1-3, N0-2, MO female breast cancer, by means of immunohistochemistry and image analysis methods.Material and Methods: Bioptic specimens were collected from 88 female breast cancer patients who had undergone breast cancer surgery. For the evaluation of MCDPT, MCAPT, MVD and EA, a three layer biotin-avidin-peroxidase system was utilized. Briefly, six-micrometers thick serial sections of formalin-fixed and paraffin-embedded bioptic tumor samples were obtained. Then sections were microwaved at 500 W for 10 min. and treated with a 3% hydrogen peroxide solution. Sections were incubated with human-specific monoclonal antibodies anti-CD34 (QB-END 10; Bio-Optica Milan, Italy) diluted 1:50 for 1h at room temperature and anti-tryptase (clone AA1; Dako, Glostrup, Denmark) diluted 1:100 for 1h at room temperature. The bound antibody was visualised using biotinylated secondary antibody, avidin-biotin peroxidase complex, and and 3-amino-9-ethylcarbazole. The five most vascularized areas ("hot spot") were selected at low magnification and both individual vessels were counted at x 400 magnification. In serial sections each single tryptase-positive MC was counted. Single brown stained endothelial cells and red MCs positive to tryptase were also evaluated in terms of immunostained area at x 400 magnification.Results: Our data demonstrated a significantly (r= ranging from 0.78 to 0.89; p: ranging from 0.001 to 0.002 by Pearson's analysis respectively) correlation between MCDPT, MCAPT, MVD, EA each to other, whereas no correlation concerning MCDPT, MCAPT, MVD, EA and the main clinical pathological features was found.Discussion: These preliminary results suggest that tryptase-positive MC play a key role in breast cancer angiogenesis and that inhibition of tryptase may be a new antiangiogenic strategy for the treatment of breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2159.

Induction of minisatellite DNA rearrangements by genotoxic carcinogens in mouse liver tumors

We investigated whether somatic rearrangements in minisatellite DNA are more frequent in chemically induced mouse liver tumors than they are in spontaneous tumors. CD-1 mouse liver tumors were induced by either a single dose or 15 consecutive daily doses of 7,12-dimethylbenz[alpha]anthracene, 4-aminoazobenzene, N-hydroxy-2-acetyl-aminofluorene or diethylnitrosoamine (DEN). Using DNA fingerprinting analysis, we found that the single- and multiple-dose carcinogen treatments caused a 2- to 5-fold higher frequency of minisatellite DNA rearrangements compared with that found in spontaneous tumors--with the exception of single-dose DEN tumors, which showed no increase in rearrangements. Our results suggest that DNA fingerprinting may be a valuable assay for differentiating certain chemically induced tumors from spontaneous tumors.

Activation of immediate-early gene expression by peroxisome proliferators in vitro

The hepatocarcinogenicity of peroxisome proliferators (PPs) in rodents has been attributed both to oxidative DNA damage resulting from excessive leakage of peroxisomal H2O2 and to increased hepatocellular replication that may be independent of peroxisome proliferation. Because of the growing association between tumor promotion and alterations in growth-regulatory signal transduction pathways, we investigated whether PPs can modulate these pathways in a mouse liver epithelial cell line, BNL-CL.2. We tested two PPs that differ markedly in rodent tumorigenicity for their ability to activate immediate-early proto-oncogene expression. 4-Chloro-6-(2,3-xylidino)-2-pyrimidinylthioacetic acid (Wy-14643), a highly tumorigenic PP, was an exceptionally strong inducer of c-fos expression. Wy-14643 was also stronger than DEHP in stimulating c-jun expression, whereas both PPs were fairly strong inducers of jun-B and jun-D. The induction of fos and jun expression by Wy-14643 was specifically inhibited by the protein kinase C inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperizine dihydrochloride (H-7). DEHP-induced gene expression was strongly inhibited by H-7, but was also partially inhibited by an inhibitor of protein kinase A. The activation of fos and jun gene expression by PPs was independent of peroxisome proliferation since it was an immediately-early response not requiring protein synthesis and since the cell lines used in this study do not undergo peroxisome proliferation. Our r results raise the possibility that the carcinogenicity of PPs may be due, in part, to epigenetic modulation of growth-regulatory signal transduction pathways.

Spontaneous and induced levels of chromosomal aberration and sister-chromatid exchange in neurofibromatosis: no evidence of chromosomal hypersensitivity

Chromosomal aberration (CA) and sister-chromatid exchange (SCE) frequencies have been assessed in 9 patients with von Recklinghausen's neurofibromatosis (NF1) and 8 apparently healthy controls. In separate experiments over a 5-year period, blood lymphocytes, skin fibroblast cell strains, and lymphoblastoid lines from both groups were treated with X-rays or mitomycin C (MMC) to determine whether the NF1 group was more sensitive to these agents than the control group. No difference between cells from NF1 patients and controls was observed with respect to spontaneous or X-ray-induced CA. Spontaneous or X-ray- and MMC-induced SCE frequencies were also similar in NF1 patients and controls.

Radiation sensitivity of cell strains from families with genetic disorders predisposing to radiation-induced cancer

This investigation was designed to test the hypothesis that skin fibroblasts from patients with genetic disorders characterized by hypersusceptibility to X-ray-induced cancer are sensitive to the cytotoxic or clastogenic effects of X-irradiation in vitro. Cell strains were established from 28 specifically ascertained patients from families with nevoid basal cell carcinoma syndrome, retinoblastoma, or other disorders apparently predisposing to radiation-induced cancer. These included 10 patients with a clear personal or family history of radiation-induced tumors. These cell strains were examined for the cytotoxic effects of X-irradiation in 3 distinct series of separate, blinded experiments, along with a group of 9 similarly coded cell bank controls. Cells from 11 of these patients and 6 controls were studied for sensitivity to X-ray-induced chromosomal aberrations. Seven of the 37 cell strains were moderately hypersensitive to radiation-induced cell killing; 2 of these were from patients with radiation-induced tumors and 1 was a cell bank control. These results suggest that such isolated cases of hypersensitivity probably do not relate to the underlying genetic disorder. Overall, the X-ray response of cells from affected individuals in this study showed no systematic difference from that of cells from nonaffected relatives or cell bank controls for either cytotoxicity or clastogenicity.

Normal cytotoxic response of skin fibroblasts from patients with Li-Fraumeni familial cancer syndrome to DNA-damaging agents in vitro

Skin fibroblasts from patients with the Li-Fraumeni familial cancer syndrome have been reported to show abnormalities in their response to X-irradiation. We have examined the response of fibroblasts from affected and nonaffected individuals in three families to treatment with four DNA-damaging agents: X-rays, UV light, N-methyl-N'-nitro-N-nitrosoguanidine, and mitomycin C. Test cells along with additional cell bank control strains were received coded and blinded. The same strains were studied on 2 or 3 separate occasions; each of these groups was coded differently. The cytotoxic effects of the four agents were examined by a colony formation assay. Sensitivity to the induction of chromosomal aberrations by X-rays was also measured. In all cases, the response of cells from affected individuals did not differ significantly from that of cells from unaffected (not a risk) family members nor of cell bank controls. The response of somatic cells from members of Li-Fraumeni cancer families to DNA-damaging agents does not appear to be a fruitful approach to the detection of at-risk individuals.

Hypersensitivity of cells from a new chromosomal-breakage syndrome to DNA-damaging agents

Cells derived from a patient with severe chromosomal breakage, immunodeficiency, and growth retardation were found to resemble those from individuals with ataxia telangiectasia (A-T) in terms of their sensitivity to cell killing and the induction of cytogenetic abnormalities by X-rays. Their response to other DNA-damaging agents, including 254-nm UV light, mitomycin C, MNNG, and bleomycin was also A-T-like. In contrast to classical A-T, however, X-irradiated cells exhibited a G1 block after release from density inhibition of growth that was not significantly different from that of normal controls.