Quercetin and tamoxifen sensitize human melanoma cells to hyperthermia.

Hyperthermia produces regression of human cancer. Because hyperthermia has produced only limited results, attention has focused on searching for substances able to sensitize tumour cells to the effects of hyperthermia. The flavonoid quercetin has been reported to be a hyperthermic sensitizer in ovarian and uterine cervical tumours and in leukaemia. Quercetin and tamoxifen inhibit melanoma cell growth. We therefore investigated whether quercetin and tamoxifen can sensitize M10, M14 and MNT1 human melanoma cells to hyperthermia. We observed that both quercetin and tamoxifen synergize with hyperthermia (42.5 degrees C) in reducing the clonogenic activity of M14 and MNT1 and in inducing apoptotic cell death in all three cell lines. As revealed by flow cytometric and Northern blot analyses, quercetin and tamoxifen reduced heat shock protein-70 expression at both protein and mRNA levels. Our results suggest that quercetin and tamoxifen can be usefully combined with hyperthermia in the therapy of recurrent and/or metastatic melanoma.

Interleukin 1alpha and interleukin 6 promote the in vitro growth of both normal and neoplastic human cervical epithelial cells.

Interleukin 1alpha (IL-1alpha), Interleukin 6 (IL-6) and epidermal growth factor (EGF) were tested for their ability to regulate epithelial cervical cell cytokine production and secretion and to induce proliferation of human normal and neoplastic epithelial cervical cells. IL-1alpha, and IL-6 enhanced tumour and normal cell growth by 20-120%. The interleukins efficacy was similar to that of EGF for some cell lines but not for normal esocervical cells. The stimulatory effects of the interleukins were observed in both human papilloma virus (HPV)-infected and HPV-non-infected cervical cells. Normal cells constitutively expressed IL-1alpha, IL-6 and EGF mRNA. All cell lines except C33A expressed IL-1alpha mRNA. CaSki, C-4II and HT-3 expressed mRNA for IL-6. IL-1alpha induced or increased IL-6 mRNA levels in the Me-180 and HT-3 lines and in normal cervical cells. IL-6 induced: (1) the expression of its own mRNA only in Me-180 cells that constitutively lacked IL-6 mRNA; (2) the expression of IL-1alpha mRNA in C-33A and increased IL-1alpha mRNA level in the case of Me180 cells. Increased amounts of IL-6 mRNA were found in normal cells when treated with IL-1alpha. In spite of the pattern of mRNA expression, only HT-3 and normal cervical cells constitutively secreted IL-6, and only normal cells were able to produce IL-1alpha protein. A significant IL-1alpha-dependent increase of IL-6 secretion was found in Me-1 80, HT-3 and normal cells. IL-1alpha- and IL-6-driven cell proliferations were almost completely inhibited by the addition of neutralizing anti-IL-6 antibodies. Taken together, these data suggest that interleukins play a role in cervical carcinogenesis as autocrine and/or paracrine stimuli.

Phosphodiesterase in human colon carcinoma cell line CaCo-2 in culture.

In a series of in vitro experiments we characterised the relationship between DNA distribution in the G1, S and G2/M phases of cell cycle and PDE and GST activity in CaCo-2 cells. The DNA distribution in CaCo-2 cells, was assessed by flow cytometry, with fluorescent dyes at different time points of culture. The exponential increase in cell number continued until day 10 when there was cell saturation. The effect of medium replacement on PDE activity was assayed in the first 10 h after medium replacement. The 6th hour is the time at which PDE activity was found to be highest. We have assayed the PDE enzyme with cGMP and cAMP as substrates. Only cAMP was consumed from this enzyme. We found a very close correlation between the DNA distribution in the various phases of the cell cycle and the PDE activity. PDE activity was very high during the active replication phase, whereas GST activity was high after confluency.