TGF-␤ can signal by means of Smad transcription factors, which are quintessential tumor suppressors that inhibit cell proliferation, and by means of Smad-independent mechanisms, which have been implicated in tumor progression. Although Smad mutations disable this tumor-suppressive pathway in certain cancers, breast cancer cells frequently evade the cytostatic action of TGF-␤ while retaining Smad function. Through immunohistochemical analysis of human breast cancer bone metastases and functional imaging of the Smad pathway in a mouse xenograft model, we provide evidence for active Smad signaling in human and mouse bonemetastatic lesions. Genetic depletion experiments further demonstrate that Smad4 contributes to the formation of osteolytic bone metastases and is essential for the induction of IL-11, a gene implicated in bone metastasis in this mouse model system. Activator protein-1 is a key participant in Smad-dependent transcriptional activation of IL-11 and its overexpression in bone-metastatic cells. Our findings provide functional evidence for a switch of the Smad pathway, from tumor-suppressor to prometastatic, in the development of breast cancer bone metastasis.IL-11 ͉ Smad4 ͉ TGF-␤ T GF-␤ plays a crucial role as a growth-inhibitory cytokine in many tissues (1, 2). The cytostatic effect of TGF-␤ is mediated by a serine͞threonine kinase receptor complex that phosphorylates Smad2 and Smad3, which then translocate into the nucleus and bind Smad4 to generate transcriptional regulatory complexes (3). SMAD4 (also known as Deleted in Pancreatic Carcinoma locus 4 or DPC4) and, to a lesser extent, SMAD2 suffer mutational inactivation in a proportion of pancreatic and colon cancers (1, 2). However, tumor cells that evade this antiproliferative control by other mechanisms may display an altered sensitivity to TGF-␤ and undergo tumorigenic progression in response to this cytokine (1, 2). Patients whose pancreatic or colon tumors express TGF-␤ receptors fare less well than those with low or absent TGF-␤ receptor expression in the tumor (4). In mouse models of breast cancer, TGF-␤ signaling promotes lung (5, 6) and bone metastasis (7). In the case of osteolytic bone metastasis by breast cancer cells, it has been proposed that TGF-␤ released from the decaying bone matrix stimulates neighboring tumor cells, establishing a vicious cycle that exacerbates the growth of the metastatic lesion (8).The TGF-␤ signaling mechanisms that foster metastasis in human cancer are an important open question and a subject of debate. Because Smad factors are quintessential tumor suppressors, the basis for the protumorigenic effects of TGF-␤ has been sought in the Smad-independent signaling pathways that may be triggered by TGF-␤. Results obtained by means of overexpression of dominant negative mutant components of the Rho pathway (9, 10) or pharmacologic inhibitors of p38 mitogen-activated protein kinase (11, 12) have implicated these pathways in the proinvasive and metastatic effects of TGF-␤ in transformed cells. In contrast, results obta...

Goals: Circulating tumor cells (CTCs) have been introduced as a biomarker in detecting advanced Epithelial Ovarian Cancer (EOC). The goals are to examine the prevalence of the invasive subpopulation of CTCs (iCTCs) in patients at high risk of EOC and to compare this biomarker to serum CA125. Methods: We used a unique Cell Adhesion Matrix (CAM)-based, functional cell enrichment and identification platform to isolate iCTCs from 129 preoperative patients. We confirmed the identity of iCTCs using positive epithelial (Epi+) markers and negative hematopoietic lineage (HL-) markers. Sensitivity and specificity of the assays were examined and iCTCs / CA125 were correlated with overall survival (OS), progression-free survival (PFS) and clinical parameters. Results: We found a 41.2% sensitivity, 95.1% specificity and 77.8% positive predictive value (PPV) of the iCTC assay in detecting patients with stage I and II EOC malignancy, and a 83% sensitivity and 97.3% PPV in detecting all stages of EOC malignancy. However, a positive CA125 test provided weak evidence to detect stage I and II malignancy (61.6% PPV) and all EOC (92.1% PPV), because of its 76.2% specificity. A significantly stronger concordance in OS and PFS of clinical factors (tumor stage, debulking and platinum sensitivity) was noted for elevated iCTCs than for serum CA125. Conclusion: The CAM-initiated CTC enrichment / identification method enabled the detection of early stage EOC. iCTCs were better correlated with worse OS and PFS, more specific and better PPV than CA125 in detecting EOC malignancy in patients at high risk of EOC.

Goals Contemporary management of epithelial ovarian cancer (EOC) uses biomarkers to monitor response to therapy. This study evaluates the role of invasive circulating tumor cells (iCTCs) in monitoring EOC treatment in comparison with serum cancer antigen 125 (CA125). Methods Molecular and microscopic analyses were used to identify seprase and CD44 as tumor progenitor (TP) markers. The iCTC flow cytometry assay was optimized using blood donated by 64 healthy donors, 49 patients with benign abdominal diseases and 123 EOC patients. Serial changes in iCTCs and CA125 were measured in 129 blood and 169 serum samples, respectively, from 31 EOC patients to assess their concordance during therapy and their relationship with risk of progressive disease (PD). Results The assay had 97% specificity and 83% sensitivity for detecting iCTCs in blood of EOC patients. iCTCs were detected in each monitoring patient (31/31, 100%) and in 110 of the 129 blood samples (85.3%). The concordance between changes in iCTCs / CA125 levels and changes in the intervals associated with no evidence of disease (NED) were markedly stronger (specificity: CA125 93.8%; iCTCs 90.6%), whereas increases in iCTCs (79.5%) were more sensitive than increases in CA125 (67.6%) to predict PD or relapse. Among the six patients who had greater than 6 measurements, iCTCs but not CA125 antedated changes in clinical status from PD to NED during and after chemotherapy, and predated relapse. Conclusion Serial measurements of iCTCs could predict therapeutic responsiveness in 31 EOC patients who underwent standard taxol / carboplatin therapy.