Expression and regulation of tumor necrosis factor alpha in normal and malignant ovarian epithelium

Epidemiologic studies implicate inflammatory stimuli in the development of ovarian cancer. The proinflammatory cytokine tumor necrosis factor alpha (TNF-alpha) and both its receptors (TNFRI and TNFRII) are expressed in biopsies of this malignancy. Here, we tested the hypothesis that TNF-alpha is a regulator of the proinflammatory microenvironment of ovarian cancer. A cancer profiling array showed higher expression of TNF-alpha in ovarian tumors compared with normal ovarian tissue, and cultured ovarian cancer cells expressed up to 1,000 times more TNF-alpha mRNA than cultured normal ovarian surface epithelial cells; TNF-alpha protein was only detected in the supernatant of tumor cell cultures. Treatment with TNF-alpha induced TNF-alpha mRNA via TNFRI in both malignant and normal cells with evidence for enhanced TNF-alpha mRNA stability in tumor cells. TNF-alpha induced TNF-alpha protein in an autocrine fashion in tumor but not in normal ovarian surface epithelial cells. The TNF-alpha neutralizing antibody infliximab reduced the constitutive levels of TNF-alpha mRNA in tumor cell lines capable of autocrine TNF-alpha production. Apart from TNF-alpha mRNA expression, several other proinflammatory cytokines were constitutively expressed in malignant and normal ovarian surface epithelial cells, including interleukin (IL)-1alpha, IL-6, CCL2, CXCL8, and M-CSF. TNF-alpha treatment further induced these cytokines with de novo transcription of IL-6 mRNA contrasting with the increased stability of CCL2 mRNA. RNA interference directed against TNF-alpha was highly effective in abolishing constitutive IL-6 production by ovarian tumor cells. In summary, we show that TNF-alpha is differentially regulated in ovarian cancer cells compared with untransformed cells and modulates production of several cytokines that may promote ovarian tumorigenesis. Infliximab treatment may have a role in suppressing the TNF-alpha-driven inflammatory response associated with ovarian cancer.

Novel treatment strategies in clear-cell metastatic renal cell carcinoma

Metastatic renal-cell carcinoma (mRCC) is highly resistant to cytotoxic agents or hormones and is currently mainly treated with cytokine-based therapy. Transient responses and moderate survival advantages have been achieved in a subset of patients with these aspecific biological response modifiers. Side-effects are considerable, especially with high-dose interleukin (IL)-2. Efforts made in the field of specific immunotherapy have focused on optimization of dendritic cell vaccination and on administration of monoclonal antibodies, either cold (unconjugated) or hot (radioactively labeled). Furthermore, allogeneic bone marrow transplantation is able to induce remissions but, regrettably, is related to substantial morbidity and mortality. Neutralization of the biological activity of some immunosuppressive cytokines produced by RCC (IL-6 and tumor necrosis factor-alpha) with monoclonal antibodies is currently under investigation. Insights gained into the processes and pathways underlying carcinogenesis have led to the development of new treatment strategies. These treatments can be used for clear cell RCC, since they focus on blocking gene products that are upregulated by mutations in the von Hippel-Lindau gene. Specific strategies include anti-vascular endothelial growth factor monoclonal antibody (bevacizumab) or inhibition of its receptor kinases (oral SU11248 or PTK787), or targeting the Raf kinase pathway (by BAY 43-9006) or the mammalian target of rapamycin (mTOR) pathway (by CCI-779). Early clinical results are promising, but their place in the treatment of RCC has to be determined.