Epithelial-mesenchimal Transition Research Articles

Abstract 5626: FKBP51 is a crucial modulator of melanoma plasticity and promising molecular target for preventing melanoma metastasis

Abstract FKBP51, a protein with a relevant role in developmental stages in mammals and other organisms, is highly expressed in melanoma and correlates with tumor aggressiveness and resistance to therapy. We found that FKBP51 positively regulates melanoma cancer stem cell (CSC) phenotype at the transcriptional level. We also found that melanoma CSCs are endowed with epithelial to mesenchimal transition (EMT) traits. The immunochemistry study of 10 primitive cutaneous and 20 brain melanoma metastases showed that melanocytic cells capable of extravasation and subverting the architecture of metastatic tissue display intense FKBP51 nuclear signal and cytoplasmic positivity for the CSC marker nestin. These findings support the conclusion that the genetic programs of cancer stemness and invasiveness overlap in melanoma, and that FKBP51 plays a pivotal role in sustaining such a program. To confirm the role of FKBP51 in melanoma invasion, we utilized an experimental metastasis model. Animal studies were performed in accordance with NIH recommendations and the approval of the local institutional animal research committee. Injecting SAN melanoma cells into the tail vein of IL2γ-NOD-SCID mice produced prominent multifocal lesions in lungs and liver. We systemically administered two separate doses of FKBP51 siRNA to mice after the injection of melanoma cells. Organ colonization was evaluated both in live animals and post mortem. Qualitative PET/CT image analysis demonstrated low FDG uptake limited to small areas in lungs and liver. By contrast, untreated mice had diffuse metastatic liver and lung lesions and high FDG uptake in the same organs. Quantitative analysis performed on PET/CT images revealed that mean standardized uptake values (SUV) in treated mice were significantly lower than in untreated mice, both for lungs and liver. High Frequency Ultrasound examination revealed few or no liver metastases in treated mice versus untreated mice. Post-mortem organ examination showed a dramatic difference between the morphologically preserved organs dissected from treated mice, and severely compromised organs from untreated mice. The histological examination confirmed these findings. Most interestingly, invading cells co-expressed FKBP51 and nestin. Our study suggests a prominent role for FKBP51 in the pathogenesis of metastatic melanoma; we envision that targeting this protein for melanoma metastasis prevention may produce a successful outcome. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5626. doi:1538-7445.AM2012-5626

Epithelial-to-mesenchymal transition possible role in meningiomas

Epithelial-to-mesenchimal transition (EMT) is a process involved in invasion and metastasis of tumors. The occurrence of EMT during tumor progression resembles the developmental scenario and sheds light on important mechanisms for the initial step of metastasis - invasion where noninvasive tumor cells acquire motility and ultimately disseminate to distant organs. The hallmark of EMT is the loss of expression of the cell-cell adhesion molecule E-cadherin. The numerous reports by many authors as well as our own results indicate that E-cadherin plays a role in CNS tumors - meningiomas. Our studies showed that 73 % of meningiomas had downregulation of E-cadherin. Moreover, loss of heterozygosity of E-cadherin was observed in 32 % of meningiomas. Bound to E-cadherin in adherens junctions is beta-catenin, whose translocation to the nucleus is yet another molecular event involved in EMT. In our study beta-catenin was progressively upregulated from meningothelial to atypical, while 60 % of anaplastic meningiomas showed upregulation and nuclear localization of the protein. The elucidation of molecular mechanisms that govern EMT will offer new approaches and targets to restrain metastasis.

Abstract 3408: Ovarian cancer stem cell cytokine microenvironment

Abstract Objectives: Epithelial ovarian cancer (EOC) is an extremely aggressive disease associated with a lack of early symptoms, rapid progression to peritoneal metastases, and poor prognosis for patients. Currently available treatments are not effective in preventing or slowing metastatic spread, and the therapeutic resistance of EOC remains a major unresolved clinical and scientific problem. Cancer stem cells (CSCs) represent the most aggressive part of the tumor. CSCs are drug resistant and are thought to be responsible for the failure of chemotherapy. Earlier, we demonstrated that chemotherapy can lead to selection of CSCs. We hypothesized that malignancy of CSCs was associated with an efficient cytokine network. Methods: Ovarian CSCs and primary adherent epithelial cultures were established from ascites from ovarian cancer patient with stage III EOC. Ovarian CSCs were isolated using magnetic beads separation columns and human CD133 and CD44 Microbead kits from Miltenyl Biotec and were grown as tumor spheres. The High Content Screening (HCS) and High Content Analysis (HCA) platform from Thermo Scientific Cellomics was applied to study the CSC markers, embryonic markers, transcription factors, epithelial mesenchimal transition markers, cytokines, chemokines, growth and angiogenetic factor receptor expression and intracellular cytokine accumulation. Multiplex xMAP technology was used for the analysis of human cytokines and growth factors in cell culture medium. An in vivo SCID mouse model was used for the analysis of tumorigenity of bulk EOC cells and CSCs. Results: We established primary EOC cell lines and CSCs from ascites of 3 EOC patients. We confirmed that cells growing in tumor spheres demonstrate all the properties of CSCs: they express high levels of CSCs markers and low levels of differentiated markers, they have capacity to self-renew and differentiate, and they are highly tumorigenic in SCID mice. The EMT and CSC phenotypes were both exhibited in ovarian CSCs. We found that ovarian CSCs have a specific cytokine microenvironment involving the up-regulation of multiple cytokine-receptor axes. Conclusions: Our findings provide new knowledge regarding ovarian CSC biology. They elucidate the important role of the specific cytokine-receptor signaling axis for the self-renewal and proliferation of ovarian CSCs. We concluded that an optimal antitumor efficacy will be achieved by inhibiting both tumor cell populations: CSCs and bulk EOC cells. We suggest that combining two treatment modalities, e.g. RTK inhibitor that targets CSCs, and cisplatin that eradicates bulk tumor cells will represent a novel paradigm in EOC therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3408. doi:10.1158/1538-7445.AM2011-3408

Abstract 5019: Loss of the ETS transcription factor ESE3 induces epithelial-mesenchimal transition and generates cells with stem cell-like properties

Abstract ETS transcription factors have emerged as important elements in the pathogenesis of prostate cancer. Most ETS factors promote cell proliferation, survival and transformation, while few others act as tumor suppressors. We have recently reported that the epithelial-specific ETS factor ESE3 is frequently down-regulated in prostate cancer, affects negatively cell proliferation and survival, and acts as tumor suppressor in prostate epithelial cells. ESE3 signatures extracted from prostate cancer clinical samples indicated a broad dedifferentiation program. Thus, we hypothesized that ESE3 maintains the differentiation state of prostate epithelial cells and that its loss leads to cell transformation. In this study, we report that stable knock-down of ESE3 in immortalized human prostate epithelial LHS cells (LHS-ESE3kd) resulted in the induction of epithelial-mesenchymal transition (EMT) with the acquisition of a fibroblast-like appearance. Concomitantly, LHS-ESE3kd cells acquired also ability to grow in anchorage-independent conditions in soft-agar and to form prostatosheres in sphere-forming assays. Expression of various stem-cell markers was also increased in LHS-ESE3kd compared to LHS cells. In a panel of prostate cell lines the ability to form prostatospheres was inversely correlated with ESE3 expression level, providing further support to the idea that the gene is an important regulator of the stem cell compartment. Consistently, re-expression of ESE3 in DU145 cells, which do not express ESE3, induced morphological changes consistent with a mesenchymal-epithelial transition, reduced the ability of the cells to migrate and to form prostatospheres. Cancer stem cells are reportedly to be drug resistant and drugs like taxol can select for drug-resistant cells with stem cell properties. We observed that resistance to taxol was inversely correlated with ESE3 expression in prostate cell lines. Furthermore, treatment of LHS-ESE3kd cells with taxol increased sphere formation, consistent with an enlargement of the stem-cell compartment by the ESE3 knock-down and increased selection by the drug. Collectively, these findings implicate that ESE3 controls the differentiation state and stem cell properties of prostate epithelial cells and that loss of ESE3 can be an important event in prostate tumorigenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5019.

Cell cycle control and adhesion signaling pathways in the development of metastatic melanoma

Metastatic melanoma is a fatal malignancy which is remarkably resistant to treatment. It is not entirely clear what determines transition from primary local to metastatic melanoma. Recent gene profiling studies shed light onto the complexity of pathogenesis of melanoma progression. An interaction between cell cycle signaling, adhesion pathways and epithelial-mesenchimal transition program appears to be critical in the development of metastatic disease. An isolated deregulation of either of those pathways may not be sufficient to initiate tumor evolution towards an aggressive phenotype. Here we review how they act in concert to make such a transition possible.