Prognosis of breast cancer: evidence for interaction between c-erbB-2 overexpression and number of involved axillary lymph nodes

The prognostic significance of c-erbB-2 oncogene amplification or overexpression in relation to axillary lymph node metastasis is controversial. We investigated this question in 159 cases of operable breast cancer: 56 patients with node negative disease and 103 patients with pathological involvement of axillary lymph nodes. c-erbB-2 overexpression was assessed by immunohistochemistry using a polyclonal antibody raised against a synthetic peptide fragment of the oncoprotein. The overall incidence of c-erbB-2 overexpression was 35%. c-erbB-2 overexpression was significantly related to survival when all patients were considered (P = 0.0124), and also for patients with positive axillary lymph nodes (P = 0.0026). c-erbB-2 overexpression had no influence on survival of node negative patients (P = 0.7972). A multivariate survival analysis using the Cox proportional hazard model revealed that number of involved lymph nodes, c-erbB-2 overexpression, ER status, and tumour size were independently related to prognosis (P = 0.0000, 0.0012, 0.0112, and 0.0204, respectively). When an interaction term was introduced in the Cox model between c-erbB-2 overexpression and number of involved axillary lymph nodes, a statistically highly significant interaction between these two factors was observed (P = 0.0002), suggesting that the expression of prognostic power of c-erbB-2 overactivity is related to the number of involved axillary lymph nodes. The 159 patients were then subdivided into three groups: node negative (-ve) (56); 1-6 node positive ( + ve) (55); and ≥7 node +ve (48). This cutoff criterion gave the most numerically equitable distribution of the 159 patients into three groups. The relative risk of death increased stepwise from 0.86 (95% CI 0.26-2.78) for node negative patients, to 1.95 (95% CJ 0.82-63) for 1-6 node positive patients, to 2.23 (95% Cl 1.15-4.35) for >7 node positive patients. Our results suggest that the prognostic influence of c-erbB-2 overexpression increases arithmatically with increasing number of involved axillary lymph nodes

Malignant transformation of Syrian hamster embryo (SHE) cells in culture by malachite green: An agent of environniental importance

904-918Malachite green (MG), consisting of green crystals with a metallic lustre, is very soluble in water and is highly cytotoxic to mammalian cells in culture and also acts as a liver tumour promoter. In view of its industrial importance and possible exposure to human beings, MG poses a potential environmental health hazard. Accordingly, we have studied the effect of MG on the formation of free radicals using Electron Spin Resonance (ESR) analysis with 5, 5-dimethyl-1-pyrroline N-oxide (DMPO) as-a spin trapping agent. ESR analysis showed formation of reactive free radicals during exposure of MG to Syrian hamster embryo (SHE) cells. As per mechanism-based toxicology in cancer risk assessment, the chemicals that have the potential to be metabolized to active free radical species could be human cancer hazards. So, we have investigated the effect of MG on the formation of Type II and Type III morphologically transformed foci using SHE cell transformation assay. MG induced dose related transformed foci. Some of these transformed foci were taken out using selective trypsinisation and established immortal cell lines. One of these immortal cell lines was characterized extensively. This immortal cell line showed enhanced DNA synthesis in the form of BrdU incorporation, increased presence of proliferating cell nuclear antigen (PCNA), bcl-2 and p53 proteins by immunohistochemistry. When these immortal cells were injected subcutaneously into nude mice, they developed tumors which were transplantable and histopathologically sarcomas. The present studies indicate that MG could be a potential candidate for two year chemical carcinogenesis rodent bioassays