VEGF-A-independent and angiogenesis-dependent tumour growth in patients with metastatic breast cancer

GROWTH FACTORS AND COX2 IN WOUND HEALING: AN EXPERIMENTAL STUDY WITH EHRLICH TUMORS

Background

Healing is an innate biological phenomenon, and carcinogenesis acquired, but with common humoral and cellular elements. Carcinogenesis interferes negatively in healing.

Aim

To evaluate the histological changes in laparotomy scars of healthy Balb/c mice and with an Ehrlich tumor in its various forms of presentation.

Methods

Fifty-four mice were divided into three groups of 18 animals. First group was the control; the second had Ehrlich tumor with ascites; and the third had the subcutaneous form of this tumor. Seven days after tumor inoculation, all 54 mice were submitted to laparotomy. All of the animals in the experiment were operated on again on 7th day after surgery, with resection of the scar and subsequent euthanasia of the animal. The scars were sent for histological assessment using immunohistochemical techniques to evaluate Cox-2 (cyclooxygenase 2), VEGF (vascular endothelial growth factor) and FGF (fibroblast growth factor). Semi-quantitatively analysis was done in the laparotomy scars and in the abdominal walls far away from the site of the operation.

Results

Assessing the weight of the animals, the correct inoculation of the tumor and weight gain in the group with tumoral ascites was observed. The histological studies showed that groups with the tumor showed a statistically significant higher presence of Cox-2 compared to the control. In the Cox-2 analysis of the abdominal wall, the ascites group showed the most significant difference. VEGF did not present any significant differences between the three groups, regardless of the site. The FGF showed a significant increase in animals with the tumor.

Conclusion

Histological findings in both laparotomy scar and the abdominal wall showed that with Ehrlich's neoplasia there was an exacerbated inflammatory response, translated by more intense expression of Cox-2 and greater fibroblast proliferation, translated by more intense expression of FGF, that is, it stimulated both the immediate inflammatory reactions, observed with Cox-2 reactions, and late scarring by fibroblasts and FGF.

VEGF, HIF-1α expression and MVD as an angiogenic network in familial breast cancer

Angiogenesis, which plays an important role in tumor growth and progression of breast cancer, is regulated by a balance between pro- and anti-angiogenic factors. Expression of vascular endothelial growth factor (VEGF) is up-regulated during hypoxia by hypoxia-inducible factor-1α (HIF-1α). It is known that there is an interaction between HIF-1α and BRCA1 carrier cancers, but little has been reported about angiogenesis in BRCA1-2 carrier and BRCAX breast cancers. In this study, we investigated the expression of VEGF and HIF-1α and microvessel density (MVD) in 26 BRCA1-2 carriers and 58 BRCAX compared to 77 sporadic breast cancers, by immunohistochemistry. VEGF expression in BRCA1-2 carriers was higher than in BRCAX cancer tissues (p = 0.0001). Furthermore, VEGF expression was higher in both BRCA1-2 carriers and BRCAX than the sporadic group (p<0.0001). VEGF immunoreactivity was correlated with poor tumor grade (p = 0.0074), hormone receptors negativity (p = 0.0206, p = 0.0002 respectively), and MIB-1-labeling index (p = 0.0044) in familial cancers (BRCA1-2 and BRCAX). The percentage of nuclear HIF-1α expression was higher in the BRCA1-2 carriers than in BRCAX cancers (p<0.05), and in all familial than in sporadic tumor tissues (p = 0.0045). A higher MVD was observed in BRCA1-2 carrier than in BRCAX and sporadic cancer tissues (p = 0.002, p = 0.0001 respectively), and in all familial tumors than in sporadic tumors (p = 0.01). MVD was positively related to HIF-1α expression in BRCA1-2 carriers (r = 0.521, p = 0.006), and, in particular, we observed a highly significant correlation in the familial group (r = 0.421, p<0.0001). Our findings suggest that angiogenesis plays a crucial role in BRCA1-2 carrier breast cancers. Prospective studies in larger BRCA1-2 carrier series are needed to improve the best therapeutic strategies for this subgroup of breast cancer patients.