The tumor microenvironment is known to have a profound effect on tumor progression in a highly context-specific manner. We have investigated whether peritoneal inflammation plays a causative role in ovarian tumor metastasis, a poorly understood process. Implantation of human ovarian tumor cells into the ovaries of severe combined immunodeficient mice resulted in peritoneal inflammation that corresponds temporally with tumor cell dissemination from the ovaries. Enhancement of the inflammatory response with thioglycolate accelerated the development of ascites and metastases. Suppression of inflammation with acetyl salicylic acid delayed ascites development and reduced tumor implant formation. A similar prometastatic effect for inflammation was observed when tumor cells were injected directly into the peritoneum of severe combined immunodeficient mice, and in a syngeneic immunocompetent mouse model. Inflammationmodulating treatments did not affect primary tumor development or in vitro tumor cell growth. Depletion of peritoneal macrophages, but not neutrophils or natural killer cells, reduced tumor progression, as assessed by ascites formation and peritoneal metastasis. We conclude that inflammation facilitates ovarian tumor metastasis by a mechanism largely mediated by macrophages, and which may involve stromal vascular endothelial growth factor production. The confirmation of these findings in immunocompetent mice suggests relevance to human disease. Identifying the mechanisms by which macrophages contribute to tumor metastasis may facilitate the development of new therapies specifically targeting immune cell products in the tumor microenvironment. [Cancer Res 2007;67(12):5708-16]
Recent studies have implicated inflammation in the initiation and progression of ovarian cancer, though the mechanisms underlying this effect are still not clear. Toll-like receptors (TLRs) allow immune cells to recognize pathogens and to trigger inflammatory responses. Tumor cell expression of TLRs can promote inflammation and cell survival in the tumor microenvironment. Here we sought to characterize the expression of TLRs in normal human ovaries, benign and malignant ovarian tumors from patients, and in established ovarian tumor cell lines. We report that TLR2, TLR3, TLR4, and TLR5 are strongly expressed on the surface epithelium of normal ovaries. In contrast to previous studies of uterus and endocervix, we found no cyclic variation in TLR expression occurred in murine ovaries. TLR2, TLR3, TLR4, and TLR5 are expressed in benign conditions, epithelial tumors, and in ovarian cancer cell lines. Variable expression of TLR6 and TLR8 was seen in benign and malignant epithelium of some patients, while expression of TLR1, TLR7, and TLR9 was weak. Normal and malignant ovarian stroma were negative for TLR expression. Vascular endothelial cells, macrophages, and occasional fibroblasts in tumors were positive. Functional activity for TLRs was demonstrated by stimulation of cell lines with specific ligands and subsequent activation and translocation of NFkappaB and release of the proinflammatory cytokines interleukin-6 and CCL-2. These studies demonstrate expression of multiple TLRs in the epithelium of normal ovaries and in ovarian tumor cells, and may indicate a mechanism by which epithelial tumors manipulate inflammatory pathways to facilitate tumor progression.
Overexpression of the DEK gene is associated with multiple human cancers, but its specific roles as a putative oncogene are not well defined. DEK transcription was previously shown to be induced by the high-risk human papillomavirus (HPV) E7 oncogene via E2F and Rb pathways. Transient DEK overexpression was able to inhibit both senescence and apoptosis in cultured cells. In at least the latter case, this mechanism involved the destabilization of p53 and the decreased expression of p53 target genes. We show here that DEK overexpression disrupts the normal differentiation program in a manner that is independent of either p53 or cell death. DEK expression was distinctly repressed upon the differentiation of cultured primary human keratinocytes, and stable DEK overexpression caused epidermal thickening in an organotypic raft model system. The observed hyperplasia involved a delay in keratinocyte differentiation toward a more undifferentiated state, and expansion of the basal cell compartment was due to increased proliferation, but not apoptosis. These phenotypes were accompanied by elevated p63 expression in the absence of p53 destabilization. In further support of bona fide oncogenic DEK activities, we report here up-regulated DEK protein levels in both human papilloma virus-positive hyperplastic murine skin and a subset of human squamous cell carcinomas. We suggest that DEK up-regulation may contribute to carcinoma development at least in part through increased proliferation and retardation of differentiation. The human DEK protein was originally identified as a fusion with the NUP214/CAN nucleoporin in a subset of patients with acute myeloid leukemia 1 and was independently purified as a protein that modulates the topology of SV40 minichromosomes.2 DEK is abundantly expressed in proliferating cells, and a majority of the protein is bound to chromatin, whereas a small fraction is bound to RNA.3 The 43-kDa nuclear phosphoprotein is the only member of its family, and contains a conserved central SAP DNA binding domain with homology to SAF-A/B, acinus, and PIAS, 4 and a second DNA binding motif within the C-terminus.5,6 DNA binding as well as DEK self-association can be regulated by C-terminal phosphorylation and N-terminal acetylation. 7,8 Preferential DEK association with structured DNA templates and its ability to induce positive supercoils into circular DNA templates in vitro have led to the notion that DEK serves as an architectural protein.9 -12 Multiple reports have implicated DEK in replication, 2 positive and negative regulation of transcription [13][14][15][16][17][18][19] as well as mRNA processing. 20 -22 How these activities translate into putative oncogenic DEK functions is presently unclear.
Twenty-two patients with invasive cervical cancer had ovarian transposition. Fifteen patients received whole pelvic external radiation therapy via a teletherapy unit, and nine patients also received one or two intracavitary insertions. Ovarian function was measured by serum gonadotropins, FSH, and LH. We were unable to measure gonadotropin levels in four patients because they were lost to follow-up after completion of radiation therapy. Five patients developed postmenopausal symptoms; in two the ovaries were not shielded and they received radiation by lateral ports with an average dose above 2500 cGY. Therefore, ovarian function was preserved in seven of 11 patients (64%), all of whom received = 500 cGY with an average dose of 250 cGY to the ovaries via external radiation and intracavitary insertion(s). FSH values ranged from 3.3 to 38.8 mlU ml-1 (mean = 17.7 mlU ml-1). Two patients developed symptomatic ovarian cysts. Ovarian function can be preserved by transposing the ovaries at the time of surgery prior to radiation with adequate treatment planning which limits the radiation dose to the ovaries to =300 cGY.
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