Riccardo Giovanazzi

Role of HER2 in wound-induced breast carcinoma proliferation

OBJECTIVE Clinical and experimental data have suggested that surgical removal of primary tumours promotes the growth of metastatic lesions. We assessed the effect of surgery on proliferation of breast carcinomas, in particular those overexpressing HER2 oncoprotein. METHODS Proliferation of breast carcinoma cells was assessed by MIB-1 immunohistochemistry in sections of primary breast carcinomas and in residual tumour found in re-excision specimens, and in in-vitro cell lines by colorimetric assay. Epidermal growth factor (EGF)-like growth factors were measured by displacement of radiolabelled EGF from its receptor. Cellular damage was measured in terms of creatine phosphokinase level. Downmodulation of HER2 was investigated by cytoplasmic expression of anti-HER2 antibody and by inhibition with anti-HER2 antibody trastuzumab. FINDINGS Residual breast carcinomas that had been surgically removed within 48 days after first surgery showed a significant increase in proliferation if they were HER2-positive. Wound drainage fluid and postsurgical serum samples from patients stimulated in-vitro growth of HER2-overexpressing breast carcinoma cells. Removal of HER2 from the cell membrane led to a striking reduction of the induced proliferation. The amount of EGF-like growth factors in post-surgical serum samples, as well as the extent of drainage-fluid-induced proliferation, directly correlated with the amount of surgical damage assessed by creatine phosphokinase levels (r=0.77, p=0.002 and r=0.69, p=0.009, respectively). Treatment of HER2-positive tumour cells with trastuzumab before adding the growth stimulus abolished drainage-fluid-induced proliferation. INTERPRETATION HER2 overexpression by breast carcinoma cells has a role in postsurgery stimulation of growth of breast carcinoma cells.

Fluctuation of HER2 expression in breast: Carcinomas during the menstrual cycle

The hormonal milieu at time of tumor surgery seems to have a significant impact on survival in premenopausal breast cancer patients. Indeed, surgery performed during the follicular phase of the menstrual cycle was suggested to correlate with a poor prognosis. To investigate the relationship between prognosis and menstrual cycle at time of surgery, we analyzed the expression of some markers associated with tumor aggressiveness, such as the hormone receptors, HER2, p53, Bcl2, and cathepsin D in breast carcinomas obtained from 198 premenopausal women who underwent surgery during different phases of the menstrual cycle. HER2 overexpression was found to fluctuate in hormone receptor-positive tumors. In actual fact, 20% of the tumors removed during the follicular phase scored HER2-positive, versus 8% of those removed during the luteal phase. Similarly, a number of hormone receptor-positive tumor specimens, obtained from the same patients during follicular and luteal phases, were scored HER2-positive when the sample was removed during the follicular phase and HER2-negative when removed in the luteal phase. Southern blot analysis of the HER2 gene indicated that, in hormone receptor-positive cases, the overexpression of HER2 is often not associated with gene amplification. The finding that overexpression of the HER2 gene, associated with tumor aggressiveness, can fluctuate according to the hormonal milieu may explain the increased survival of patients operated during the luteal phase. It is also relevant to the selection and treatment of patients most likely to benefit from anti-HER2 antibody therapy.

Monoclonal antibody to fibulin-1 generated by genetic immunization

Fibulin‐1 (Fbln‐1) is an extracellular matrix (ECM) and plasma glycoprotein. Considering the growing evidence indicating that Fbln‐1 plays a role in cancer we sought to develop monospecific antibodies to better facilitate further studies of the function of Fbln‐1 in breast cancer. Using a plasmid expression vector encoding full‐length human Fbln‐1D as an immunogen and CpG oligodeoxyribonucleotides as adjuvant a monoclonal antibody (MAb) against Fbln‐1 was produced. This MAb, designated MEM‐2 was of IgM isotype and reacted with bacterially expressed Fbln‐1. Furthermore, MEM‐2 reacted with Fbln‐1 expressed in the ECM released by cultured human breast carcinoma SKBR‐3 cells in ELISA, and also with Fbln‐1 present in SKBR‐3 cell extract in immunoprecipitation and Western blotting. MEM‐2 also reacted with Fbln‐1 in human breast carcinoma specimens. These findings illustrate the utility of genetic immunization as a means of generating monoclonal antibodies to tumor‐related ECM proteins. MEM‐2 represents a useful new tool for the study of Fbln‐1 in breast cancer. J. Cell. Biochem. 89: 647–652, 2003.