The AKT2 gene is one of the human homologues of v-akt, the transduced oncogene of the AKT8 virus, which induces lymphomas in mice. In previous studies, AKT2, which codes for a serine-threonine protein kinase, was shown to be amplified and overexpressed in some human ovarian carcinoma cell lines and amplified in primary tumors of the ovary. To confirm and extend these findings, we conducted a large-scale, multicenter study of AKT2 alterations in ovarian and breast cancer. Southern-blot analysis demonstrated AKT2 amplification in 16 of 132 (12.1%) ovarian carcinomas and in 3 of 106 (2.8%) breast carcinomas. No AKT2 alteration was detected in 24 benign or borderline tumors. Northern-blot analysis revealed overexpression of AKT2 in 3 of 25 fresh ovarian carcinomas which were negative for AKT2 amplification. The difference in the incidence of AKT2 alterations in ovarian and breast cancer suggests a specific role for this gene in ovarian oncogenesis. No significant association was found between AKT2 amplification and amplification of the proto-oncogenes MYC and ERBB2, suggesting that amplification of AKT2 defines an independent subset of breast and ovarian cancers. Ovarian cancer patients with AKT2 alterations appear to have a poor prognosis. Amplification of AKT2 was especially frequent in undifferentiated tumors (4 of 8, p = 0.019), suggesting that AKT2 alterations may be associated with tumor aggressiveness.

This study demonstrates that the flavonoid quercetin (Q), a plant-derived compound with low toxicity in vivo, greatly potentiates the growth-inhibitory activity of Adriamycin (ADR) on MCF-7 ADR-resistant human breast cancer cells. The effect of Q was dose-dependent at concentrations ranging between 1 and 10 microM. Since ADR resistance in these cells is associated with the expression of high levels of P-glycoprotein (Pgp), we evaluated the effect of Q and related flavonoids of Pgp activity in cytofluorographic efflux experiments with the fluorescent dye rhodamine 123 (Rh 123). Our results indicate that Q and 3-OMe Q (3',4',7-trimethoxyquercetin) but not the 3-rhamnosylglucoside of Q (rutin) inhibit the Pgp pump-efflux activity in a dose-related manner. Moreover, 10 microM Q reduces the expression of the immunoreactive Pgp in MCF-7 ADR-resistant cells as evaluated by cytofluorimetric assay. In conclusion, these findings provide a further biological basis for the potential therapeutic application of Q as an anti-cancer drug either alone or in combination with ADR in multidrug-resistant breast tumor cells.

Summary Recent data have demonstrated that the anti-oestrogen tamoxifen (TAM) is able to facilitate apoptosis in cancer cells not expressing oestrogen receptor (ER). In an attempt to identify the biochemical pathway for this phenomenon, we investigated the role of TAM as an oxidative stress agent. In two ER-negative human cancer cell lines, namely T-leukaemic Jurkat and ovarian A2780 cancer cells, we have demonstrated that TAM is able to generate oxidative stress, thereby causing thiol depletion and activation of the transcriptional factor NF-κB. As described for other oxidative agents, TAM was able to induce either cell proliferation or apoptosis depending on the dose. When used at the lowest dose tested (0.1 µM), a slight proliferative effect of TAM was noticed in terms of cell counts and DNA synthesis rate, whereas at higher doses (10 µM) a consistent occurrence of apoptosis was detected. Importantly, the induction of apoptosis by TAM is not linked to down-regulation or functional inactivation by phosphorylation of the antiapoptotic bcl-2 protein.

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Summary We investigated the effect of the flavonoid quercetin (Q) on the proliferation of the ovarian cancer cell line OVCA 433. Growth experiments demonstrated that Q exerted a reversible dose-dependent inhibition of cell proliferation in the range of concentrations between 10 nm and 10 M. Two other flavonoids tested, rutin and hesperidin, were ineffective in inhibiting cell growth. Cell cycle analysis showed that the growth inhibitory effect of Q was due to a blocking effect in the GO/GI phase. Using a whole cell assay with (6,7-3H) (Gabor, 1988). Recently it has been reported that in the rat uterus and in the MCF-7 human breast cancer cell line the flavonoid quercetin (Q) inhibits cell growth and the uterotrophic response to oestradiol (Markaverich et al., 1988 Growth experiments Cells were plated in six-well flat bottom plates (Falcon 3046, Becton Dickinson, Lincoln Park, NJ, USA) at a concentration of I x 105 cells ml-' in MEM supplemented as above. After 24 h, the medium was replaced with fresh medium and Q (3,3',4',5,7-pentahydroxyflavone), rutin (3-rhamnosylglucoside of Q) and hesperidin (7-rhamnosylglucoside of Hesperitin) (3'-5-3-hydroxy-4-methoxy-flavanone) (Aldrich, Steinhein, FRG) were added from an absolute ethanol (Q) or DMSO stock solution (rutin, hesperidin). Control cells were treated with the same amount of vehicle alone. The final ethanol and DMSO concentration never exceeded 1 % (v/v) and 0.5% (v/v), in either control or treated samples, respectively.Quadruplicate haemocytometer counts of triplicate culture dishes were performed at the time indicated in the figures.Cell cycle analysis OVCA 433 cells were plated at a concentration of I x 105 cells ml-' in MEM supplemented as above. Twenty-four hours after plating, medium was replaced with fresh medium containing 1O0M Q or vehicle alone (ethanol). After 3 days, cells were incubated for 30 min at 37°C in the same medium with 10ftM bromodeoxyuridine (Sigma Deisenhofen, FRG