Synthetic analogs of vitamin D3 have inhibitory effects on breast cancer cell lines.

BACKGROUND: 1,25-dihydroxycholecalciferol has been previously reported to negatively regulate human breast cancer cell growth. MATERIAL AND METHODS: The antiproliferative effect of 1,25-dihydroxycholecalciferol (Ro 21-5535) and of the two non hypercalcemic analogs (1a,25-dihydroxy-16-ene-23-yne-26,27-hexafluorocholecalciferol+ ++, Ro 24-5531 and 1a,25-dihydroxy-16-ene-23-yne-26,27-hexafluoro-19-nor-cholec alciferol, Ro 25-6760) was studied in MCF-7 and MDAMB-468 human breast cancer cell lines. Cell cycle distribution and apoptosis were evaluated by flow cytometry. Steroid receptor modulation was investigated by radioligand assay. RESULTS: The most effective drug was the Ro 25-6760 which at concentrations ranging between 1-100 nM caused a dose dependent growth inhibition apparently due to accumulation in G0/G1. Vitamin D3 analogs (10 nM) significantly counteracted the growth stimulation induced by TGF-a and IGF-I as well as the paracrine stimulation observed in co-cultures. They antagonized estradiol-promoted growth stimulation and progestrone receptor induction in MCF-7 cells. CONCLUSION: Vitamin D3 analogs represent a class of clinically attractive drugs for treatment of breast cancer due to their ability to counteract estradiol and growth factor-induced growth stimulation.

Receptor status variation in primary breast cancer and subsequent accessible relapse.

To better understand the prognostic relevance of change in steroid receptor status, during the clinical course of breast cancer, we analysed the variation of estrogen and progesterone receptor (ER, PgR) status in a series of 532 primary tumors and metachronous accessible recurrences in individual patients. A more consistent variation was observed in patients with a receptor-positive primary (ER(+) or PgR(+)) than in those with a receptor-negative tumor (ER(-) or PgR(-)). Forty-four percent of PgR(+) and 24% of ER(+) tumors became negative, whereas only 20% of ER(-) or PgR(-) became positive. The changes were independent of tumor stage and menopausal status. However, steroid receptor variation appeared to be related to the interval between the primary tumor and relapse. In fact, the changes from ER(+) to ER(-) were more frequent in patients with a disease-free survival of less than 1 year, whereas changes from ER(-) to ER(+) occurred more often in patients with a disease-free survival of more than 3 years. Moreover, we observed a decrease in the number of ER(+) tumors following hormone treatment and a decrease in ER(-) tumors following chemotherapy. However, such variations did not reach statistical significance. Irrespective of the type of adjuvant therapy, the presence of at least one receptor (in particular, PgR) in the metachronous lesion was correlated with a long median time to relapse and to death. Our results confirmed the predictive relevance of receptor status of the primary lesion on relapse and survival and suggest the predictive relevance of receptor status of the metachronous lesion on post-relapse survival.

Combined effects of lonidamine and tamoxifen in human breast-cancer cell-lines.

The antiproliferative activity of lonidamine, alone or in combination with the antiestrogen tamoxifen, was studied on estrogen receptor-positive and estrogen receptor-negative human breast cancer cell lines. Lonidamine by itself induced an appreciable cytotoxic effect on all five cell lines, with 50% inhibitory concentrations (IC50) ranging from 19.5 to 54 mu M. The combination of lonidamine and tamoxifen, simultaneously administered or in sequence, provided additive effects on the estrogen receptor-negative MCF/DX cell line and a sub-additive interaction in the estrogen receptor-positive MCF7 cells. The negative interference between the two drugs could be ascribed to the marked reduction induced by lonidamine in the expression of estrogen receptor in the MCF7 cells.

P53 and cathepsin-d are independent of established prognostic factors in breast-cancer.

p53 and cathepsin D expression was investigated in 300 primary breast cancers by the avidin-biotin immunoperoxidase method using two murine monoclonal antibodies: PAb1801 and anti-procathepsin D, respectively. The frequency of p53- and cathepsin D-positive cells varied widely among different tumors and most tumors (82% and 86%) at least occasionally showed positive cells. The two biological markers were unrelated to one another, to cell proliferative rate and ploidy and were differently related to other biological and pathological features. In particular, p53 was directly related to tumor size and nodal involvement and inversely related to the presence of steroid receptors. Conversely, cathepsin D was directly related only to nodal involvement.