J. Stephen Haskill

IL-8 Reduced Tumorigenicity of Human Ovarian Cancer In Vivo Due to Neutrophil Infiltration

Paclitaxel is a frontline therapy for ovarian cancer. Our laboratory has shown that paclitaxel induces IL-8, a member of the C-X-C family of chemokines, in subsets of human ovarian cancer cells. However, the critical issue concerns the biological significance of this chemokine in human ovarian cancer. To study the influence of IL-8 on tumor growth, human ovarian cancer cell lines were transfected with an expression vector for human IL-8 and tested for their ability to form tumors in nude mice. IL-8 expression by the transfected cells did not alter their growth properties in vitro. In contrast, tumor growth in vivo was significantly attenuated in animals receiving IL-8-expressing cells when compared with mice injected with control cells. As additional evidence that IL-8 is a crucial factor in tumor growth, it was noted that ovarian cell lines in which constitutive IL-8 expression is elevated did not form tumors. Injection of neutralizing Ab to IL-8 reverted the phenotype and caused tumor growth in vivo. Examination of tissue from the inoculation site revealed a dramatically elevated cellularity, containing neutrophils and macrophages, in mice receiving IL-8-expressing tumor cells. These results suggest that IL-8 production by human ovarian tumor cells can play a role in reducing the rate of tumor growth; this effect may be mediated by the increased targeting of neutrophil and other mononuclear cells to the tumor injection site. These studies indicate a role for IL-8 in ovarian cancer control and suggest that chemotherapy-induced IL-8 may have a positive role in controlling tumor growth.

Effects of paclitaxel on cytokine synthesis by unprimed human monocytes, T lymphocytes, and breast cancer cells

Abstract Paclitaxel or Taxol has attracted a great deal of attention in recent years because of its immense success as a chemotherapeutic agent for numerous types of cancer. It is known that paclitaxel stabilizes microtubules, and this characteristic is the presumed primary mechanism for its antitumor activity. Recently, however, paclitaxel’s ability to regulate gene expression, particularly in the murine system, has been reported by several groups. Here, we present research examining paclitaxel’s ability to alter expression of the interleukin-1β (IL-1β) and IL-8 cytokines in primary human monocytes, T lymphocytes, and four human breast cancer cell lines: MCF-7, ZR-75-1, MDA-MB-468, and MDA-MB-231. This report shows for the first time that treatment with 5–50 μM paclitaxel increases steady-state levels of IL-1β mRNA in unprimed human monocytes, MCF-7, and ZR-75-1 cells. Monocytes from eight donors in 16 experiments showed increased IL-1β secretion upon treatment; however, the increase in IL-1β production by monocytes was predicated on culturing in the absence of fetal bovine serum or in the presence of autologous human serum. In contrast to the IL-1β results, paclitaxel did not have significant effects on IL-8 expression by monocytes, T lymphocytes, or the breast cancer cells. These data show a specific effect of paclitaxel on cytokine synthesis by both immune cells and cancer cells.

Systemic and Local Immunity in Allograft and Cancer Rejection

Studies of allograft and tumor rejection have historically been closely related. Indeed, many of thestudies on tumor immunity carried out in theearly part of this century actually dealt with tumor allograft rejection, and theconcepts derived from transplantation immunity studies have provided many useful models and concepts for tumor immunology. In this context we have reviewed theliterature covering allograft rejection as well as syngeneic graft rejection, in order to provide a more complete picture of thecurrent state of these closely interrelated areas of investigation, especially as they relate to intragraft and intratumor reactions.

Identification of the structural region of taxol that may be responsible for cytokine gene induction and cytotoxicity in human ovarian cancer cells

Purpose: Interleukin-8 (IL-8) is a pleiotropic chemokine with both chemoattractant and angiogenic properties. In addition to its cytotoxic effects on ovarian cancer cells, taxol can transcriptionally activate genes such as IL-8 that may play a role in tumorigenesis. Utilizing IL-8 as a prototypic marker of tumor-derived modulators of growth, we undertook a systematic study of taxol and 11 structurally modified taxol analogs to identify the region of the taxane skeleton responsible for IL-8 gene induction. Methods: The human ovarian cancer cell line OVCA-420 was exposed to taxol or taxol analogs. IL-8 gene induction was assessed by Northern blot analysis after 6 h and cytotoxicity after 72 h. Results: Changes in the southern hemisphere (C-1 to C-4) of the taxane skeleton had greater effects on IL-8 induction than changes in the northern hemisphere (C-7 to C-11). Some of the taxol analogs modified at positions C-1 and/or C-2 with increased hydrophobicity induced IL-8 expression more than threefold over that induced by taxol or taxotere and more than 20-fold over control cells. Cells that failed to induce IL-8 gene expression in response to taxol were only marginally responsive to the analogs unless first primed with IL-1β. Modifications to the northern hemisphere did not alter taxols effect on IL-8 expression in human cells, but did influence TNFα expression in murine macrophage cells, suggesting species and/or gene specificity. We found a direct correlation between IL-8 induction and cytotoxicity, in that analogs that dramatically upregulated IL-8 expression proved to be the most cytotoxic, inhibiting cell survival by >90%. Conclusion: Taken together our results demonstrate that changes in the southern hemisphere of the taxane skeleton influence both the gene induction and cytotoxic potential of taxol in human ovarian cancer cells.

IL-1β transcript stability in monocytes is linked to cytoskeletal reorganization and the availability of mRNA degradation factors

Monocyte extravasation initiates reorganization of the cytoskeleton (CSK) and adhesion‐dependent cytokine gene transcription. The actin CSK is thought to be crucial for compartmentalization and translation of mRNA, many of which contain AU‐rich (ARE) instability motifs in the 3′ untranslated region. We investigated regulation of adhesion‐induced IL‐1β expression by the monocyte CSK. In serum‐free adherent monocytes, the induced IL‐1β mRNA was stable and did not coextract with actin filaments. In contrast, in cells adherent in autologous serum, IL‐1β transcripts were unstable, coextracted with actin filaments and were associated with only transient activation of the mitogen‐activated protein kinases (MAPK). Under both conditions of adherence, the ARE‐binding protein AUF1/hnRNP D was readily extracted in the cytosolic fraction. Electro‐injection with AUF1/hnRNP D modified the actin CSK and, surprisingly, stabilized IL‐1β transcripts. These data suggest that the control of mRNA degradation is linked with changes in the CSK. Mitogen‐activated protein kinase activation or alterations in the availability of mRNA degradation factors may mediate these effects.