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p53 Attenuates Cancer Cell Migration and Invasion through Repression of SDF-1/CXCL12 Expression in Stromal Fibroblasts

The p53 tumor suppressor acts as a major barrier against cancer. To a large extent, this is due to its ability to maintain genome stability and to eliminate cancer cells from the replicative pool through cell-autonomous mechanisms. However, in addition to its well-documented functions within the malignant cancer cell, p53 can also exert non-cell-autonomous effects that contribute to tumor suppression. We now report that p53 can suppress the production of the chemokine SDF-1 in cultured fibroblasts of both human and mouse origin. This is due to a p53-mediated down-regulation of SDF-1 mRNA, which can be exacerbated on activation of p53 by the drug Nutlin-3. SDF-1 promotes the migration and invasiveness of cells that express its cognate receptor CXCR4. Indeed, medium conditioned by p53-deficient fibroblasts induces cancer cells towards increased directional migration and invasiveness, which are largely reversed by CXCR4 antagonist peptides. Because SDF-1 produced by stromal fibroblasts plays an important role in cancer progression and metastasis, our findings suggest that the ability of p53 to suppress stromal SDF-1 production may be an important mechanism whereby it does its non-cell-autonomous tumor suppressor function.

Systemic dysregulation of CEACAM1 in melanoma patients.

It was previously shown that CEACAM1 on melanoma cells strongly predicts poor outcome. Here, we show a statistically significant increase of serum CEACAM1 in 64 active melanoma patients, as compared to 48 patients with no evidence of disease and 37 healthy donors. Among active patients, higher serum CEACAM1 correlated with LDH values and with decreased survival. Multivariate analysis with neutralization of LDH showed that increased serum CEACAM1 carries a hazard ratio of 2.40. In vitro, soluble CEACAM1 was derived from CEACAM1(+), but neither from CEACAM1(−) melanoma cells nor from CEACAM1(+) lymphocytes, and directly correlated with the number of CEACAM1(+) melanoma cells. Production of soluble CEACAM1 depended on intact de novo protein synthesis and secretion machineries, but not on metalloproteinase function. An unusually high percentage of CEACAM1(+) circulating NK and T lymphocytes was demonstrated in melanoma patients. CEACAM1 inhibited killing activity in functional assays. CEACAM1 expression could not be induced on lymphocytes by serum from patients with high CEACAM1 expression. Further, expression of other NK receptors was impaired, which collectively indicate on a general abnormality. In conclusion, the systemic dysregulation of CEACAM1 in melanoma patients further denotes the role of CEACAM1 in melanoma and may provide a basis for new tumor monitoring and prognostic platforms.

Repression of the MSP/MST-1 gene contributes to the antiapoptotic gain of function of mutant p53

Tumor-associated mutant forms of p53 can exert an antiapoptotic gain of function activity, which confers a selective advantage upon tumor cells harboring such mutations. We report that mutant p53 suppresses the expression of the MSP (MST-1/HGFL) gene, encoding the ligand of the receptor tyrosine kinase RON, implicated in a variety of cellular responses. Mutant p53 associates with the MSP gene promoter and represses its transcriptional activity, leading to a decrease in mRNA levels and a subsequent decrease in the levels of secreted MSP protein. Forced downregulation of MSP expression in H1299 cells, derived from a large-cell lung carcinoma, confers increased resistance against etoposide-induced cell death. These antiapoptotic consequences of MSP downregulation seemingly conflict with the well-documented ability of the RON receptor to promote cell survival and tumor progression when aberrantly hyperactive. Yet, they are consistent with the fact that reduced MSP expression was observed in many types of human cancer, including large-cell lung carcinoma. Thus, repression of MSP gene expression by mutant p53 may contribute to oncogenesis in a cell type-specific manner.

Cancer cells suppress p53 in adjacent fibroblasts

The p53 tumor suppressor serves as a crucial barrier against cancer development. In tumor cells and their progenitors, p53 suppresses cancer in a cell-autonomous manner. However, p53 also possesses non-cell-autonomous activities. For example, p53 of stromal fibroblasts can modulate the spectrum of proteins secreted by these cells, rendering their microenvironment less supportive of the survival and spread of adjacent tumor cells. We now report that epithelial tumor cells can suppress p53 induction in neighboring fibroblasts, an effect reproducible by tumor cell-conditioned medium. The ability to suppress fibroblast p53 activation is acquired by epithelial cells in the course of neoplastic transformation. Specifically, stable transduction of immortalized epithelial cells by mutant H-Ras and p53-specific short inhibitory RNA endows them with the ability to quench fibroblast p53 induction. Importantly, human cancer-associated fibroblasts are more susceptible to this suppression than normal fibroblasts. These findings underscore a mechanism whereby epithelial cancer cells may overcome the non-cell-autonomous tumor suppressor function of p53 in stromal fibroblasts.

The PI3K inhibitor LY294002 prevents p53 induction by DNA damage and attenuates chemotherapy-induced apoptosis

The p53 tumor suppressor plays a key role in the natural protection against cancer. Activation of p53 by DNA-damaging agents can contribute to successful elimination of cancer cells via chemotherapy-induced apoptosis. The phosphatidylinositol-3 kinase (PI3K) pathway, triggered in normal cells upon exposure to growth factors, regulates a cascade of proliferation and survival signals. The PI3K pathway is abnormally active in many cancers, thus making it an attractive target for inactivation in an attempt to achieve better cancer therapy. We report here that exposure to LY294002, a potent PI3K inhibitor, aborts the activation of p53 by several drugs commonly used in cancer chemotherapy. Concomitantly, LY294002 attenuates p53-dependent, chemotherapy-induced apoptosis of cancer cells. These findings invoke an unexpected positive role for PI3K in p53 activation by anticancer agents, and suggest that the efficacy of PI3K inhibitors in cancer therapy may be greatly affected by the tumor p53 status.

Targeted drug delivery strategies to treat lung metastasis

Background: Most cancer patients die of metastatic disease, and in a high proportion of cases, from lung metastasis. Methods to target therapy to metastatic disease in general and specifically to lung metastasis are required. Objective: To describe the current and potential tools for the treatment of lung metastasis. Methods: Literature search tools were used with no predefined limitations to encompass the main tumor targeting methods. Methods in standard clinical use, in clinical trials and in preclinical development are reviewed. Data about treatment of lung metastasis and solid tumors are emphasized. Results: Physically targeting therapies to lung metastasis is feasible by aerosol-carried agents, magnetic targeting and intravascular devices. Biological targeting includes methods such as polymers and liposomes, which are based on the principle of enhanced permeability and retention of large molecules in tumor vascular field. Ligand-targeted treatments depend on cancer-specific antibodies or receptors. Few of these methods are in clinical trials or in standard clinical use. However, promising techniques are in advanced preclinical or early clinical studies. The authors believe that targeted treatments will be one the major anticancer tools in the near future.

Involvement of stromal p53 in tumor-stroma interactions

p53 is a major tumor-suppressor gene, inactivated by mutations in about half of all human cancer cases, and probably incapacitated by other means in most other cases. Most research regarding the role of p53 in cancer has focused on its ability to elicit apoptosis or growth arrest of cells that are prone to become malignant owing to DNA damage or oncogene activation, i.e. cell-autonomous activities of p53. However, p53 activation within a cell can also exert a variety of effects upon neighboring cells, through secreted factors and paracrine and endocrine mechanisms. Of note, p53 within cancer stromal cells can inhibit tumor growth and malignant progression. Cancer cells that evolve under this inhibitory influence acquire mechanisms to silence stromal p53, either by direct inhibition of p53 within stromal cells, or through pressure for selection of stromal cells with compromised p53 function. Hence, activation of stromal p53 by chemotherapy or radiotherapy might be part of the mechanisms by which these treatments cause cancer regression. However, in certain circumstances, activation of stromal p53 by cytotoxic anti-cancer agents might actually promote treatment resistance, probably through stromal p53-mediated growth arrest of the cancer cells or through protection of the tumor vasculature. Better understanding of the underlying molecular mechanisms is thus required. Hopefully, this will allow their manipulation towards better inhibition of cancer initiation, progression and metastasis.

Lymph node ratio may predict the benefit of postoperative radiotherapy in non-small-cell lung cancer.

Introduction: The use of postoperative radiotherapy (PORT) after resection of non–small-cell lung cancer (NSCLC) is controversial, with some evidence suggesting a benefit in patients with N2 disease. We assessed lymph node ratio (LNR) as a predictor of PORT benefit. Methods: By using the Surveillance, Epidemiology and End Results database, we analyzed resected, node-positive (N1–N2) NSCLC patients diagnosed between 1998 and 2009. LNR, (number of positive nodes/number of resected nodes) was categorized into four groups: LNR less than 12.5%, 12.5 to 24.9%, 25 to 49.9%, and 50% or more. Results: Of 11,324 node-positive NSCLC patients identified, 6551 (57.9%) had N1 disease. The LNR was prognostic for survival in the entire cohort and within each nodal stage. The median survival in LNR groups 1, 2, 3, and 4 was 43, 40, 30, and 23 months in N1 disease and 40, 32, 27, and 22 months in N2 disease, respectively. PORT was associated with a worse survival on univariate analysis (hazard ratio [HR] =1.09; confidence interval [CI] 1.03–1.15; p = 0.002) but no effect on multivariate analysis (HR = 0.96; CI 0.90–1.02; p = 0.201). When analyzed by nodal stage, the benefit of PORT was limited to N2 disease (HR = 0.9; CI 0.84–0.99; p= 0.026) with no benefit in N1 disease (HR = 1.06; CI 0.97–1.15; p=0.2). After stratifying by LNR, the survival benefit of PORT was limited to those with N2 disease and an LNR of 50% or more. Conclusion: A high LNR is associated with a poorer survival in resected, node-positive NSCLC. The survival benefit associated with PORT in this disease seems to be limited to those with an LNR of 50% or more. This warrants further investigation in other cohorts and prospective studies.

Regulation of the inflammatory profile of stromal cells in human breast cancer: prominent roles for TNF-α and the NF-κB pathway

IntroductionBreast cancer progression is promoted by stromal cells that populate the tumors, including cancer-associated fibroblasts (CAFs) and mesenchymal stem/stromal cells (MSCs). The activities of CAFs and MSCs in breast cancer are integrated within an intimate inflammatory tumor microenvironment (TME) that includes high levels of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β). Here, we identified the impact of TNF-α and IL-1β on the inflammatory phenotype of CAFs and MSCs by determining the expression of inflammatory chemokines that are well-characterized as pro-tumorigenic in breast cancer: CCL2 (MCP-1), CXCL8 (IL-8) and CCL5 (RANTES).MethodsChemokine expression was determined in breast cancer patient-derived CAFs by ELISA and in patient biopsies by immunohistochemistry. Chemokine levels were determined by ELISA in (1) human bone marrow-derived MSCs stimulated by tumor conditioned media (Tumor CM) of breast tumor cells (MDA-MB-231 and MCF-7) at the end of MSC-to-CAF-conversion process; (2) Tumor CM-derived CAFs, patient CAFs and MSCs stimulated by TNF-α (and IL-1β). The roles of AP-1 and NF-κB in chemokine secretion were analyzed by Western blotting and by siRNAs to c-Jun and p65, respectively. Migration of monocytic cells was determined in modified Boyden chambers.ResultsTNF-α (and IL-1β) induced the release of CCL2, CXCL8 and CCL5 by MSCs and CAFs generated by prolonged stimulation of MSCs with Tumor CM of MDA-MB-231 and MCF-7 cells. Patient-derived CAFs expressed CCL2 and CXCL8, and secreted CCL5 following TNF-α (and IL-1β) stimulation. CCL2 was expressed in CAFs residing in proximity to breast tumor cells in biopsies of patients diagnosed with invasive ductal carcinoma. CCL2 release by TNF-α-stimulated MSCs was mediated by TNF-RI and TNF-RII, through the NF-κB but not via the AP-1 pathway. Exposure of MSCs to TNF-α led to potent CCL2-induced migration of monocytic cells, a process that may yield pro-cancerous myeloid infiltrates in breast tumors.ConclusionsOur novel results emphasize the important roles of inflammation-stroma interactions in breast cancer, and suggest that NF-κB may be a potential target for inhibition in tumor-adjacent stromal cells, enabling improved tumor control in inflammation-driven malignancies.

Exhaled Breath Analysis for Monitoring Response to Treatment in Advanced Lung Cancer

Introduction: The Response Evaluation Criteria in Solid Tumors (RECIST) serve as the accepted standard to monitor treatment efficacy in lung cancer. However, the time intervals between consecutive computerized tomography scans might be too long to allow early identification of treatment failure. This study examines the use of breath sampling to monitor responses to anticancer treatments in patients with advanced lung cancer. Methods: A total of 143 breath samples were collected from 39 patients with advanced lung cancer. The exhaled breath signature, determined by gas chromatography/mass spectrometry and a nanomaterial‐based array of sensors, was correlated with the response to therapy assessed by RECIST: complete response, partial response, stable disease, or progressive disease. Results: Gas chromatography/mass spectrometry analysis identified three volatile organic compounds as significantly indicating disease control (PR/stable disease), with one of them also significantly discriminating PR/stable disease from progressive disease. The nanoarray had the ability to monitor changes in tumor response across therapy, also indicating any lack of further response to therapy. When one‐sensor analysis was used, 59% of the follow‐up samples were identified correctly. There was 85% success in monitoring disease control (stable disease/partial response). Conclusion: Breath analysis, using mainly the nanoarray, may serve as a surrogate marker for the response to systemic therapy in lung cancer. As a monitoring tool, it can provide the oncologist with a quick bedside method of identifying a lack of response to an anticancer treatment. This may allow quicker recognition than does the current RECIST analysis. Early recognition of treatment failure could improve patient care.