Cancer-associated fibroblasts suppress SOX2-induced dysplasia in a lung squamous cancer coculture.

Tumorigenesis depends on intricate interactions between genetically altered tumor cells and their surrounding microenvironment. While oncogenic drivers in lung squamous carcinoma (LUSC) have been described, the role of stroma in modulating tissue architecture, particularly cell polarity, remains unclear. Here, we report the establishment of a 3D coculture system of LUSC epithelial cells with cancer-associated fibroblasts (CAFs) and extracellular matrix that together capture key components of the tumor microenvironment (TME). Single LUSC epithelial cells develop into acinar-like structures with 0.02% efficiency, and addition of CAFs provides proper tumor-stromal interactions within an appropriate 3D architectural context. Using this model, we recapitulate key pathological changes during tumorigenesis, from hyperplasia to dysplasia and eventually invasion, in malignant LUSC spheroids that undergo phenotypic switching in response to cell intrinsic and extrinsic changes. Overexpression of SOX2 is sufficient to mediate the transition from hyperplasia to dysplasia in LUSC spheroids, while the presence of CAFs makes them invasive. Unexpectedly, CAFs suppress the activity of high SOX2 levels, restore hyperplasia, and enhance the formation of acinar-like structures. Taken together, these observations suggest that stromal factors can override cell intrinsic oncogenic changes in determining the disease phenotype, thus providing fundamental evidence for the existence of dynamic reciprocity between the nucleus and the TME of LUSC.

The effects of size and shape of the ovarian cancer spheroids on the drug resistance and migration.

BACKGROUND: High fatality in ovarian cancer is attributed to metastasis, propagated by the release of multi-cellular aggregates/spheroids into the peritoneal cavity and their subsequent mesothelial invasion of peritoneal organs. Spheroids are therefore a common and clinically relevant in vitro model for ovarian cancer research. Spheroids in patients vary significantly in size and shape and display enhanced resistance to anti-cancer drugs compared to monolayers. However, there is no consensus on how spheroid size and shape affect drug resistance. Moreover, existing data regarding the influence of epithelial-to-mesenchymal transition (EMT) profile on spheroid shape and migration is inconclusive. METHODS: We formed spheroids with OVCAR-3 and OVCAR-8 cells, chosen for their established genetic similarity to the patient tumor samples. We monitored their morphology using confocal microscope with dipping objective and fluorescent microscope. We characterized important EMT biomarkers; E-cadherin, Vimentin and Slug through western blotting in monolayers and spheroids. We treated these spheroids with Taxol and Cisplatin and investigated their migratory profile based on their morphology. RESULTS: We report two distinct multicellular structures: loose aggregates (OVCAR-3) and compact spheroids (OVCAR-8). We attribute these different morphologies to the expression of the EMT biomarkers, and their changes upon spheroid formation. Importantly, we did not observe a difference in resistance to the anti-cancer drugs as a function of spheroid size and shape. However, migration capacity of compact spheroid (OVCAR-8) was 15-fold higher compared to that of loose aggregates (OVCAR-3). CONCLUSIONS: These results highlight the importance of spheroid size and shape on anti-cancer drug resistance and migration profiles. The results of this study can, therefore, help to elucidate general rules for ovarian cancer studies based on 3D samples.

Intertumoral heterogeneity in patient-specific drug sensitivities in treatment-naïve glioblastoma.

BACKGROUND: A major barrier to effective treatment of glioblastoma (GBM) is the large intertumoral heterogeneity at the genetic and cellular level. In early phase clinical trials, patient heterogeneity in response to therapy is commonly observed; however, how tumor heterogeneity is reflected in individual drug sensitivities in the treatment-naïve glioblastoma stem cells (GSC) is unclear. METHODS: We cultured 12 patient-derived primary GBMs as tumorspheres and validated tumor stem cell properties by functional assays. Using automated high-throughput screening (HTS), we evaluated sensitivity to 461 anticancer drugs in a collection covering most FDA-approved anticancer drugs and investigational compounds with a broad range of molecular targets. Statistical analyses were performed using one-way ANOVA and Spearman correlation. RESULTS: Although tumor stem cell properties were confirmed in GSC cultures, their in vitro and in vivo morphology and behavior displayed considerable tumor-to-tumor variability. Drug screening revealed significant differences in the sensitivity to anticancer drugs (p < 0.0001). The patient-specific vulnerabilities to anticancer drugs displayed a heterogeneous pattern. They represented a variety of mechanistic drug classes, including apoptotic modulators, conventional chemotherapies, and inhibitors of histone deacetylases, heat shock proteins, proteasomes and different kinases. However, the individual GSC cultures displayed high biological consistency in drug sensitivity patterns within a class of drugs. An independent laboratory confirmed individual drug responses. CONCLUSIONS: This study demonstrates that patient-derived and treatment-naïve GSC cultures maintain patient-specific traits and display intertumoral heterogeneity in drug sensitivity to anticancer drugs. The heterogeneity in patient-specific drug responses highlights the difficulty in applying targeted treatment strategies at the population level to GBM patients. However, HTS can be applied to uncover patient-specific drug sensitivities for functional precision medicine.

Extracellular vesicles carry microRNA-195 to intrahepatic cholangiocarcinoma and improve survival in a rat model.

The cancer microenvironment plays a central role in cancer development, growth, and homeostasis. This paradigm suggests that cancer fibroblasts support cancers, probably in response to stimuli received from the cancer cells. We aimed at investigating whether extracellular vesicles (EVs) can shuttle microRNA (miR) species between cancer-associated fibroblasts (CAFs) and cancer cells. To this end, we extracted EVs according to published protocols. EVs were studied for their miR content by quantitative reverse-transcription polymerase chain reaction. EVs were transfected with select miR species and utilized in vitro as well as in vivo in a rat model of cholangiocarcinoma (CCA). We found that miR-195 is down-regulated in CCA cells, as well as in adjoining fibroblasts. Furthermore, we report that EVs shuttle miR-195 from fibroblasts to cancer cells. Last, we show that fibroblast-derived EVs, loaded with miR-195, can be administered in a rat model of CCA, concentrate within the tumor, decrease the size of cancers, and improve survival of treated rats. CONCLUSION: EVs play a salient role in trafficking miR species between cancer cells and CAFs in human CCA. Understanding of these mechanisms may allow devising of novel therapeutics. (Hepatology 2017;65:501-514).

Experimental estimation of stored stress within spherical microtissues : What can and cannot be inferred from cutting experiments.

Biological tissues accumulate mechanical stress during their growth. The mere measurement of the stored stress is not an easy task. We address here the spherical case and our experiments consist in performing an incision of a spherical microtissue (tumor spheroid) grown in vitro. On the theoretical part we derive a compatibility condition on the stored stress in spherical symmetry, which imposes a relation between the circumferential and radial stored stress. The numerical implementation uses the hyperelastic model of Ciarlet and Geymonat. A parametric study is performed to assess the influence of each parameter on the shape of the domain after the incision. As a conclusion, the total radial stored stress can be confidently estimated from the measurement of the opening after incision. We validate the approach with experimental data.

Endothelin-1 receptor blockade as new possible therapeutic approach in multiple myeloma.

New effective treatments are needed to improve outcomes for multiple myeloma (MM) patients. Receptors with restricted expression on plasma cells (PCs) represent attractive new therapeutic targets. The endothelin-1 (EDN1) axis, consisting of EDN1 acting through EDN-receptor A (EDNRA) and B (EDNRB), was previously shown to be overexpressed in several tumours, including MM. However, there is incomplete understanding of how EDN1 axis regulates MM growth and response to therapy. Besides EDNRA, the majority of MM cell lines and primary malignant PCs express high levels of EDNRB and release EDN1. Similarly, bone-marrow microenvironment cells also secrete EDN1. Investigating the extent of epigenetic dysregulation of EDNRB gene in MM, we found that hypermethylation of EDNRB promoter and subsequent down-regulation of EDNRB gene was observed in PCs or B lymphocytes from healthy donors compared to EDNRB-expressing malignant PCs. Pharmacological blockade with the dual EDN1 receptor antagonist bosentan decreased cell viability and MAPK activation of U266 and RPMI-8226 cells. Interestingly, the combination of bosentan and the proteasome inhibitor bortezomib, currently approved for MM treatment, resulted in synergistic cytotoxic effects. Overall, our data has uncovered EDN1-mediated autocrine and paracrine mechanisms that regulate malignant PCs growth and drug response, and support EDN1 receptors as new therapeutic targets in MM.

Preclinical evaluation of the BET bromodomain inhibitor BAY 1238097 for the treatment of lymphoma.

The epigenome is often deregulated in cancer and treatment with inhibitors of bromodomain and extra-terminal proteins, the readers of epigenetic acetylation marks, represents a novel therapeutic approach. Here, we have characterized the anti-tumour activity of the novel bromodomain and extra-terminal (BET) inhibitor BAY 1238097 in preclinical lymphoma models. BAY 1238097 showed anti-proliferative activity in a large panel of lymphoma-derived cell lines, with a median 50% inhibitory concentration between 70 and 208 nmol/l. The compound showed strong anti-tumour efficacy in vivo as a single agent in two diffuse large B cell lymphoma models. Gene expression profiling showed BAY 1238097 targeted the NFKB/TLR/JAK/STAT signalling pathways, MYC and E2F1-regulated genes, cell cycle regulation and chromatin structure. The gene expression profiling signatures also highly overlapped with the signatures obtained with other BET Bromodomain inhibitors and partially overlapped with HDAC-inhibitors, mTOR inhibitors and demethylating agents. Notably, BAY 1238097 presented in vitro synergism with EZH2, mTOR and BTK inhibitors. In conclusion, the BET inhibitor BAY 1238097 presented promising anti-lymphoma preclinical activity in vitro and in vivo, mediated by the interference with biological processes driving the lymphoma cells. Our data also indicate the use of combination schemes targeting EZH2, mTOR and BTK alongside BET bromodomains.

Re-characterization of established human retinoblastoma cell lines.

Retinoblastoma (RB) is the most common malignant intraocular childhood tumor. Forty years after their first description, in the present study, we re-characterized seven established retinoblastoma cell lines with regard to their RB1 mutation status, morphology, growth pattern, endogenous apoptosis levels, colony formation efficiency in soft agar and invasiveness and dissemination capacity in chick chorioallantoic membrane (CAM) assays. All RB cell lines predominantly resemble small epithelioid cells with little cytoplasm and large nucleus, which mainly grow in cell clusters, but sometimes form chain-like structures with incident loops or three-dimensional aggregates. We observed different growth rates for the different retinoblastoma cells investigated. RBL-30, RBL-13 and RBL 383 cells grew very slowly, whereas Y-79 cells grew fastest under our culture conditions. Apoptosis rates likewise differed with highest cell death levels in RB 383 and RB 355 and lowest in WERI-Rb1 and RBL-15. Contradicting former reports, six of the seven RB cell lines analyzed were able to form colonies in soft agarose after single cell seeding within 3 weeks of incubation. Upon inoculation of four out of seven RB cell lines on the dorsal CAM, GFP-positive cells were detectable in the ventral CAM and two RB cell lines caused tumor development, indicating their intravasation and dissemination potential. All RB cell lines exhibited the potential to extravasate from the capillary system after intravenous CAM injection. Our study provides valuable new details for future therapy-related retinoblastoma basic research in vitro.

Wnt/ß-catenin pathway involvement in ionizing radiation-induced invasion of U87 glioblastoma cells.

BACKGROUND: Radiotherapy has been reported to promote the invasion of glioblastoma cells; however, the underlying mechanisms remain unclear. Here, we investigated the role of the Wnt/ß-catenin pathway in radiation-induced invasion of glioblastoma cells. METHODS: U87 cells were irradiated with 3 Gy or sham irradiated in the presence or absence of the Wnt/ß-catenin pathway inhibitor XAV 939. Cell invasion was determined by an xCELLigence real-time cell analyser and matrigel invasion assays. The intracellular distribution of ß-catenin in U87 cells with or without irradiation was examined by immunofluorescence and Western blotting of nuclear fractions. We next investigated the effect of irradiation on Wnt/ß-catenin pathway activity using TOP/FOP flash luciferase assays and quantitative polymerase chain reaction analysis of ß-catenin target genes. The expression levels and activities of two target genes, matrix metalloproteinase (MMP)-2 and MMP-9, were examined further by Western blotting and zymography. RESULTS: U87 cell invasiveness was increased significantly by ionizing radiation. Interestingly, ionizing radiation induced nuclear translocation and accumulation of ß-catenin. Moreover, we found increased ß-catenin/TCF transcriptional activities, followed by up-regulation of downstream genes in the Wnt/ß-catenin pathway in irradiated U87 cells. Importantly, inhibition of the Wnt/ß-catenin pathway by XAV 939, which promotes degradation of ß-catenin, significantly abrogated the pro-invasion effects of irradiation. Mechanistically, XAV 939 suppressed ionizing radiation-triggered up-regulation of MMP-2 and MMP-9, and inhibited the activities of these gelatinases. CONCLUSION: Our data demonstrate a pivotal role of the Wnt/ß-catenin pathway in ionizing radiation-induced invasion of glioblastoma cells, and suggest that targeting ß-catenin is a promising therapeutic approach to overcoming glioma radioresistance.

3D tumor tissue analogs and their orthotopic implants for understanding tumor-targeting of microenvironment-responsive nanosized chemotherapy and radiation.

An appropriate representation of the tumor microenvironment in tumor models can have a pronounced impact on directing combinatorial treatment strategies and cancer nanotherapeutics. The present study develops a novel 3D co-culture spheroid model (3D TNBC) incorporating tumor cells, endothelial cells and fibroblasts as color-coded murine tumor tissue analogs (TTA) to better represent the tumor milieu of triple negative breast cancer in vitro. Implantation of TTA orthotopically in nude mice, resulted in enhanced growth and aggressive metastasis to ectopic sites. Subsequently, the utility of the model is demonstrated for preferential targeting of irradiated tumor endothelial cells via radiation-induced stromal enrichment of galectin-1 using anginex conjugated nanoparticles (nanobins) carrying arsenic trioxide and cisplatin. Demonstration of a multimodal nanotherapeutic system and inclusion of the biological response to radiation using an in vitro/in vivo tumor model incorporating characteristics of tumor microenvironment presents an advance in preclinical evaluation of existing and novel cancer nanotherapies. FROM THE CLINICAL EDITOR: Existing in-vivo tumor models are established by implanting tumor cells into nude mice. Here, the authors described their approach 3D spheres containing tumor cells, enodothelial cells and fibroblasts. This would mimic tumor micro-environment more realistically. This interesting 3D model should reflect more accurately tumor response to various drugs and would enable the design of new treatment modalities.

Leukemia-initiating cells of patient-derived acute lymphoblastic leukemia xenografts are sensitive toward TRAIL.

Cancer stem cells represent the most important target cells for antitumor therapy. TRAIL (TNF-related apoptosis-inducing ligand) is a potential anticancer agent that induces apoptosis in a wide variety of tumor cells, but its ability to target cancer stem cells is currently unknown. Here we investigated whether TRAIL targets leukemia-initiating cells. Limiting dilution transplantation assays were performed on xenografts from pediatric patients with precursor B-cell acute lymphoblastic leukemia (pre-B ALL) in NSG mice. In vitro treatment of xenograft cells with TRAIL significantly reduced and delayed their engraftment and procrastinated animal death from leukemia. Systemic TRAIL treatment of mice injected with patient-derived pre-B ALL xenograft cells abrogated leukemia in 3 of 5 mice in 1 sample. In conclusion, our data suggest that TRAIL targets leukemia-initiating cells derived from pre-B ALL xenografts in vitro and in vivo, and hence constitutes an attractive candidate drug for treatment of ALL.

Increased radiosensitivity of HPV-positive head and neck cancer cell lines due to cell cycle dysregulation and induction of apoptosis.

BACKGROUND AND PURPOSE: Human Papillomavirus (HPV)-related head and neck squamous cell carcinoma (HNSCC) respond favourably to radiotherapy as compared to HPV-unrelated HNSCC. We investigated DNA damage response in HPV-positive and HPV-negative HNSCC cell lines aiming to identify mechanisms, which illustrate reasons for the increased sensitivity of HPV-positive cancers of the oropharynx. METHODS: Radiation response including clonogenic survival, apoptosis, DNA double-strand break (DSB) repair, and cell cycle redistribution in four HPV-positive (UM-SCC-47, UM-SCC-104, 93-VU-147T, UPCI:SCC152) and four HPV-negative (UD-SCC-1, UM-SCC-6, UM-SCC-11b, UT-SCC-33) cell lines was evaluated. RESULTS: HPV-positive cells were more radiosensitive (mean SF2: 0.198 range: 0.22-0.18) than HPV-negative cells (mean SF2: 0.34, range: 0.45-0.27; p = 0.010). Irradiated HPV-positive cell lines progressed faster through S-phase showing a more distinct accumulation in G2/M. The abnormal cell cycle checkpoint activation was accompanied by a more pronounced increase of cell death after x-irradiation and a higher number of residual and unreleased DSBs. CONCLUSIONS: The enhanced responsiveness of HPV-related HNSCC to radiotherapy might be caused by a higher cellular radiosensitivity due to cell cycle dysregulation and impaired DNA DSB repair.

Optimization of liquid overlay technique to formulate heterogenic 3D co-cultures models.

Three-dimensional (3D) cell culture models of solid tumors are currently having a tremendous impact in the in vitro screening of candidate anti-tumoral therapies. These 3D models provide more reliable results than those provided by standard 2D in vitro cell cultures. However, 3D manufacturing techniques need to be further optimized in order to increase the robustness of these models and provide data that can be properly correlated with the in vivo situation. Therefore, in the present study the parameters used for producing multicellular tumor spheroids (MCTS) by liquid overlay technique (LOT) were optimized in order to produce heterogeneous cellular agglomerates comprised of cancer cells and stromal cells, during long periods. Spheroids were produced under highly controlled conditions, namely: (i) agarose coatings; (ii) horizontal stirring, and (iii) a known initial cell number. The simultaneous optimization of these parameters promoted the assembly of 3D characteristic cellular organization similar to that found in the in vivo solid tumors. Such improvements in the LOT technique promoted the assembly of highly reproducible, individual 3D spheroids, with a low cost of production and that can be used for future in vitro drug screening assays.

Significantly increased CD70 up regulation on TEL-AML positive B cell precursor acute lymphoblastic leukemia cells following CD40 stimulation.

BACKGROUND: TEL-AML the most common genetic alteration in childhood precursor B acute lymphoblastic leukemia (BCP-ALL) is associated with a favorable prognosis. PATIENTS AND METHOD: We studied the expression of nerve growth factor/tumor necrosis factor receptor (NGFR/TNFR)/ligand family members on 108 primary BCP-ALL samples by flow cytometry and compared both their baseline expression and CD40-induced modulation on TEL-AML positive and negative leukemia samples. RESULTS: Our findings demonstrate that TEL-AML positive patients exhibit a significantly higher percentage of CD40, CD27 and p75NTR positive blasts at diagnosis. This might well contribute to the improved relapse-free survival of these patients assessed in Kaplan Meier analysis as CD27 and p75NTR directly mediate apoptotic signals. Furthermore CD40 ligation enhances antigen presenting and T cell stimulatory capacity via significant up regulation of CD70 while adequate response to physiological maturation signals as indicated by concomitant down regulation of CD27 is retained in TEL-AML positive leukemia. CONCLUSION: These data provide novel insights in immunological control mechanisms preserved in this leukemia subtype and suggest that not only treatment with chemicals such as HDAC inhibitors but also retained in vivo response to CD40 ligation contributes to improved immune surveillance in these patients which may add to a superior relapse-free survival observed particularly in the presence of other risk factors.

CA-S27: a novel Lewis a associated carbohydrate epitope is diagnostic and prognostic for cholangiocarcinoma.

Early and specific diagnosis is critical for treatment of cholangiocarcinoma (CCA). In this study, a carbohydrate antigen-S27 (CA-S27) monoclonal antibody (mAb) was established using pooled CCA tissue-extract as immunogen. The epitope recognized by CA-S27-mAb was a new Lewis-a (Le(a)) associated modification of MUC5AC mucin. A Soybean agglutinin/CA-S27-mAb sandwich ELISA to determine CA-S27 in serum was successfully developed. High level of CA-S27 was detected in serum of CCA patients and could differentiate CCA patients from those of gastro-intestinal cancers, hepatomas, benign hepatobiliary diseases and healthy subjects with high sensitivity (87.5%) and high negative predictive value (90.4%). The level of serum CA-S27 was dramatically reduced after tumor removal, indicating tumor origin of CA-S27. Patients with high serum CA-S27 had significantly shorter survivals than those with low serum CA-S27 regardless of serum MUC5AC levels. Fucosyltransferase-III (FUT3) was shown to be a regulator of CA-S27 expression. Suppression of CA-S27 expression with siRNA-FUT3 or neutralization with CA-S27 mAb significantly reduced growth, adhesion, invasion and migration potentials of CCA cells in vitro. In summary, we demonstrate that serum CA-S27, a novel carbohydrate antigen, has potential as diagnostic and prognostic markers for CCA patients. CA-S27 involves in promoting cell growth, adhesion, migration and invasion of CCA cells.

Gliotoxin is a potent NOTCH2 transactivation inhibitor and efficiently induces apoptosis in chronic lymphocytic leukaemia (CLL) cells.

Chronic lymphocytic leukaemia (CLL) cells express constitutively activated NOTCH2 in a protein kinase C (PKC)- dependent manner. The transcriptional activity of NOTCH2 correlates not only with the expression of its target gene FCER2 (CD23) but is also functionally linked with CLL cell viability. In the majority of CLL cases, DNA-bound NOTCH2 complexes are less sensitive to the γ-secretase inhibitor (GSI) DAPT. Therefore, we searched for compounds that interfere with NOTCH2 signalling at the transcription factor level. Using electrophoretic mobility shift assays (EMSA), we identified the Aspergillum-derived secondary metabolite gliotoxin as a potent NOTCH2 transactivation inhibitor. Gliotoxin completely blocked the formation of DNA-bound NOTCH2 complexes in CLL cells independent of their sensitivity to DAPT. The inhibition of NOTCH2 signalling by gliotoxin was associated with down regulation of CD23 (FCER) expression and induction of apoptosis. Short time exposure of CLL cells indicated that the early apoptotic effect of gliotoxin is independent of proteasome regulated nuclear factor κB activity, and is associated with up regulation of NOTCH3 and NR4A1 expression. Gliotoxin could overcome the supportive effect of primary bone marrow stromal cells in an ex vivo CLL microenvironment model. In conclusion, we identified gliotoxin as a potent NOTCH2 inhibitor with a promising therapeutic potential in CLL.

Influence of osteopontin silencing on survival and migration of lung cancer cells.

BACKGROUND AND PURPOSE: Osteopontin (OPN) is a multifunctional protein overexpressed in many cancers and is involved in tumor progression and metastasis. In lung cancer, elevated OPN expression is associated with an unfavorable prognosis. Therefore, inhibition of OPN is an attractive approach for improving survival. MATERIALS AND METHODS: We used siRNA to specifically downregulate OPN expression in A549 lung cancer cells. OPN silencing was evaluated with quantitative reverse transcriptase polymerase chain reaction (RT-PCR) for mRNA levels and with Western blotting for protein levels. Effects on cell proliferation were measured by cell counting. The influence on tumor cell migration was detected using a modified Boyden chamber. Changes in cell cycle distribution were assessed by flow cytometry. Using the colony formation assay, we determined changes in radiosensitivity. RESULTS: A specific and effective downregulation of OPN expression was detected in both RNA and protein levels. Cell proliferation and cell migration were significantly reduced by OPN silencing after 24 h and the effects were further increased by the addition of irradiation. The cell cycle distribution showed a reduction in S phase and an increase in cells arrested in both G(0)/G(1) and G(2)/M phases. Specific enhancement of radiosensitivity was clearly shown after OPN knockdown. CONCLUSION: The combination of OPN silencing and irradiation showed a synergistic effect leading to reduced cell survival.

Selection of brain metastasis-initiating breast cancer cells determined by growth on hard agar.

An approach that facilitates rapid isolation and characterization of tumor cells with enhanced metastatic potential is highly desirable. Here, we demonstrate that plating GI-101A human breast cancer cells on hard (0.9%) agar selects for the subpopulation of metastasis-initiating cells. The agar-selected cells, designated GI-AGR, were homogeneous for CD44(+) and CD133(+) and five times more invasive than the parental GI-101A cells. Moreover, mice injected with GI-AGR cells had significantly more experimental brain metastases and shorter overall survival than did mice injected with GI-101A cells. Comparative gene expression analysis revealed that GI-AGR cells were markedly distinct from the parental cells but shared an overlapping pattern of gene expression with the GI-101A subline GI-BRN, which was generated by repeated in vivo recycling of GI-101A cells in an experimental brain metastasis model. Data mining on 216 genes shared between GI-AGR and GI-BRN breast cancer cells suggested that the molecular phenotype of these cells is consistent with that of cancer stem cells and the aggressive basal subtype of breast cancer. Collectively, these results demonstrate that analysis of cell growth in a hard agar assay is a powerful tool for selecting metastasis-initiating cells in a heterogeneous population of breast cancer cells, and that such selected cells have properties similar to those of tumor cells that are selected based on their potential to form metastases in mice.

Differential expression of epithelial and mesenchymal proteins in a panel of prostate cancer cell lines.

PURPOSE: Epithelial to mesenchymal transition is an important process that results in increased cell migration, invasion and metastasis of many carcinomas. During epithelial to mesenchymal transition epithelial cells down-regulate cell-cell adhesion molecules (ie E-cadherin), up-regulate mesenchymal proteins (ie N-cadherin and cadherin-11), alter polarity, reorganize the cytoskeleton and become isolated. In combination this leads to greater motility. We investigated the role of E-cadherin and the associated catenin-protein complex in regulating epithelial to mesenchymal transition in prostate cancer progression. MATERIALS AND METHODS: The relative invasion index of prostate cancer cells was assessed by MTT based in vitro invasion assay. Immunoprecipitation and Western blot were done to determine cadherin-complex formation, and catenin and cadherin protein expression. RESULTS: Restoration of E-cadherin expression in nonE-cadherin expressing prostate cancer cells decreased invasive potential. However, in vitro invasive potential was tightly regulated by the interaction of cadherin proteins with the catenin complex. E and N-cadherin, cadherin-11, and the catenin proteins α, ß, γ and p120 are important for the downstream signaling associated with epithelial to mesenchymal transition in tumor cells. CONCLUSIONS: Restoration of epithelial specific proteins, such as E-cadherin, in tumor cells can inhibit invasion. However, invasion is a complex process regulated not only by E and N-cadherin but also by catenin-complex proteins. The complex signaling process associated with tumor invasion warrants further investigation since crosstalk between overlapping signaling pathways is involved in regulating prostate cancer invasion, metastasis and progression.

Selectively replicating adenoviruses targeting deregulated E2F activity are potent, systemic antitumor agents.

We have engineered a human adenovirus, ONYX-411, that selectively replicates in human tumor cells, but not normal cells, depending upon the status of their retinoblastoma tumor suppressor protein (pRB) pathway. Early and late viral gene expression as well as DNA replication were significantly reduced in a functional pRB-pathway-dependent manner, resulting in a restricted replication profile similar to that of nonreplicating adenoviruses in normal cells both in vitro and in vivo. In contrast, the viral life cycle and tumor cell killing activity of ONYX-411 was comparable to that of wild-type adenovirus following infection of human tumor cells in vitro as well as after systemic administration in tumor-bearing animals.