elafin and Carcinogenesis

Desmoid tumors (TDs) are derived from mesenchymal stem cells and their pathogenesis is strongly linked to the Wingless/Wnt cascade where the deregulation of β-catenin plays a major role. A mutation of the CTNNB1 encoding β-catenin is found in the majority of sporadic TD cases and constitutional mutations of APC have been described in heritable forms in patients with familial adenomatous polyposis (FAP). Estrogens could also play a role in pathogenesis and this is the basis for the use of hormone therapy. Other signaling pathways have been involved in the development of TDs such as Notch, Hedgehog, JAK/STAT, PI3 Kinase/AKT and mTOR. Metalloproteases are expressed in TDs and play a role in invasiveness. TGF-ß, as a growth factor, stimulates the transcriptional activity of β-catenin. Future studies will need to focus on better describing and understanding the immune environment of TDs. One of the major difficulties for the experimental study of TDs is the virtual absence of a preclinical model, either in vitro or in vivo. This is partly why the interactions between the different signaling pathways presented here and their consequences for the development of TDs are still poorly understood.

Topics: Adenomatous Polyposis Coli; beta Catenin; Carcinogenesis; Elafin; Estrogens; Fibromatosis, Aggressive; Genes, APC; Hedgehog Proteins; Humans; Janus Kinases; Lymphotoxin-alpha; Metalloproteases; Mutation; Neoplasm Invasiveness; Proto-Oncogene Proteins c-akt; Receptors, Notch; Signal Transduction; STAT Transcription Factors; TOR Serine-Threonine Kinases

Elafin is an endogenous serine protease inhibitor. The majority of breast cancer cell lines lack elafin expression compared to human mammary epithelial cells. In this study, we hypothesized that elafin is downregulated during breast and ovarian tumorigenesis.. We examined elafin expression by immunohistochemistry (IHC) in specimens of normal breast tissue (n = 24), ductal carcinoma in situ (DCIS) (n = 54), and invasive breast cancer (n = 793). IHC analysis of elafin expression was also performed in normal fallopian tube tissue (n = 20), ovarian cystadenomas (n = 9), borderline ovarian tumors (n = 21), and invasive ovarian carcinomas (n = 216). To understand the significance of elafin in luminal breast cancer cell lines, wild-type or M25G elafin (lacking the protease inhibitory function) were exogenously expressed in MCF-7 and T47D cells.. Elafin expression was downregulated in 24% of DCIS and 83% of invasive breast tumors when compared to elafin expression in the normal mammary epithelium. However, the presence of elafin-positive cells in invasive breast tumors, even at low frequency, correlated with poor recurrence-free survival (RFS), reduced overall survival (OS), and clinicopathological markers of aggressive tumor behavior. Elafin-positive cells were an especially strong and independent prognostic marker of reduced RFS in IHC-defined luminal A-like tumors. Elafin was also downregulated in 33% of ovarian cystadenomas, 43% of borderline ovarian tumors, and 86% of invasive ovarian carcinomas when compared to elafin expression in the normal fallopian tube. In ovarian tumors, elafin-positive cells were correlated with reduced RFS, OS and disease-specific survival (DSS) only in stage I/II patients and not in stage III/IV patients. Notably, exogenous expression of elafin or elafin M25G in the luminal breast cancer cell lines MCF-7 and T47D significantly decreased cell proliferation in a protease inhibitory domain-independent manner.. Elafin predicts poor outcome in breast and ovarian cancer patients and delineates a subset of endocrine receptor-positive breast cancer patients susceptible to recurrence who could benefit from more aggressive intervention. Our in vitro results suggest that elafin arrests luminal breast cancer cells, perhaps suggesting a role in tumor dormancy.

Topics: Breast Neoplasms; Carcinogenesis; Carcinoma; Carcinoma, Ductal, Breast; Carcinoma, Intraductal, Noninfiltrating; Cystadenoma; Disease-Free Survival; Down-Regulation; Elafin; Female; Humans; Neoplasm Recurrence, Local; Ovarian Neoplasms; Prognosis; Receptor, ErbB-2; Receptors, Estrogen; Receptors, Progesterone; RNA, Messenger

Previously, we have shown that p55PIK, an isoform of class I(A) phosphoinositide 3-kinase (PI3K), specifically interacts with important cell-cycle regulators, such as retinoblastoma (Rb), to promote cell-cycle progression. Here, we used the glutathione S-transferase pull-down assay to identify other p55PIK-interacting proteins besides Rb in a Rb-deficient cell line and found that p55PIK interacted with proliferation cell nuclear antigen (PCNA), which plays a key role in coordinating both initiation of the leading strand DNA replication and discontinuous lagging strand synthesis. Overexpression of p55PIK increased, and knockdown decreased, DNA synthesis and DNA replication by modulating the binding of DNA polymerase δ (Polδ) to PCNA. Moreover, a cell-permeable peptide containing the N-terminal-binding domain of p55PIK (TAT-N24) disrupted the p55PIK-PCNA interaction in cancer cells, and also inhibited the DNA synthesis and tumor growth in cell culture and in vivo. Altogether, our results show that the p55PIK-PCNA interaction is important in regulating DNA synthesis and contributes to tumorigenesis. Furthermore, the p55PIK-PCNA interaction provides a potential new target for anticancer drug development.

Topics: Carcinogenesis; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; DNA; DNA Replication; Elafin; Glutathione Transferase; Humans; Neoplasms; Phosphatidylinositol 3-Kinases; Proliferating Cell Nuclear Antigen; Protein Binding; Protein Interaction Maps