Breast cancer is of particular importance among non-AIDS defining cancers (NADCs), because of its incidence in industrialized and developing countries. Here we studied the effects of a known human carcinogen, the highly persistent heavy metal cadmium, on cell proliferation, angiogenesis, and on two of the main intracellular targets of HIV, heat shock protein 90 (hsp90, targeted by Tat protein, known to be imported into the nucleus of human breast cancer cells), and poly(ADP-ribose) polymerase (PARP, involved in DNA repair and oxidative stress associated with HIV infection). The effects of nontoxic doses of cadmium (1–10 lM) on intracellular HIV targets were studied in human breast cancer cells (MCF-7) and in their normal counterpart (MCF-10A). The effects of Gc-Macrophage Activating Factor (GcMAF), a protein demonstrated to be effective in HIV and breast cancer treatment (J Med Virol 81:16–26, 2009. Int J Cancer 122: 461–7, 2008) were also studied in MCF-7 cells. Cell proliferation was studied by 5-bromo-deoxiuridine labelling and by MTT based assay. Hsp90b expression was evaluated by immunohistochemistry. PARP expression was studied by immunohistochemistry and Western blot. Angiogenesis was studied in chick embryo chorionallantoic membrane (CAM). Proliferation of normal and transformed cells in serum-starved medium was inhibited by cadmium in dose-dependent manner. GcMAF (1 ng/ml) significantly inhibited MCF-7proliferation. The effect of cadmium was partially reversed by zinc. Hsp90b and PARP expression levels were increased by cadmium in dose-dependent manner in both types of cells, thus mimicking the effects of HIV on those intracellular targets. The effects of cadmium on angiogenesis were opposite in the two cell lines; MCF-7-induced angiogenesis in CAM was inhibited, whereas MCF-10-induced angiogenesis was stimulated. GcMAF (1 ng/ml) significantly inhibited MCF-7-induced angiogenesis. These results indicate that cadmium and HIV recognize as intracellular molecular targets two of the principal regulators of cell responses to stress, i.e. hsp90 and PARP. In human breast cancer cells, increased expression of hsp90 and PARP was associated with reduced cell proliferation and inhibition of angiogenesis. Since cadmium and GcMAF exerted similar effects on MCF-7 and on MCF-7-induced angiogenesis, we hypothesize that hsp90 and PARP are involved in the GcMAF signalling pathway. These results also open the perspective of studying HIV-associated angiogenesis in NADCs with the goal of controlling the progression of NADCs via inhibition of angiogenesis.
Effects of Cadmium and GC-Macrophage Activating Factor (GcMAF) on intracellular HIV targets in normal and transformed human breast cells / G. Morucci; T. Punzi. - In: INFECTION. - ISSN 0300-8126. - STAMPA. - 39 (suppl 1):(2011), pp. 69-69. (Intervento presentato al convegno Italian Conference on AIDS and Retroviruses tenutosi a Firenze, Italia nel March 27-29, 2011) [10.1007/s15010-011-0090-z].