3D bioprinted vascularized lung cancer organoid models with underlying disease capable of more precise drug evaluation

Despite encouraging progress in the development of in vitro cancer models, in vitro cancer models that simultaneously recapitulate the complexity of the tumor microenvironment and its diverse cellular components and genetic properties remain lacking. Here, an advanced vascularized lung cancer model is proposed, which includes patient-derived lung cancer organoids (LCOs), lung fibroblasts, and perfusable vessels using 3D bioprinting technology. To better recapitulate the biochemical composition of native lung tissues, a porcine lung-derived decellularized extracellular matrix (LudECM) hydrogel was produced to offer physical and biochemical cues to cells in the lung cancer microenvironment. In particular, idiopathic pulmonary fibrosis-derived lung fibroblasts (iLFs) were used to implement fibrotic niches similar to actual human fibrosis. It was shown that they increased cell proliferation and the expression of drug resistance-related genes in LCOs with fibrosis. In addition, changes in resistance to sensitizing targeted anti-cancer drugs in LCOs with fibrosis were significantly greater in LudECM than in that Matrigel. Therefore, assessment of drug responsiveness in vascularized lung cancer models that recapitulate lung fibrosis can help determine the appropriate therapy for lung cancer patients accompanied by fibrosis. Furthermore, it is expected that this approach could be utilized for the development of targeted therapies or the identification of biomarkers for lung cancer patients accompanied by fibrosis.

Abstract P5-01-25: Potential prognostic value of exosomal Beta Protein 1 in breast cancer

Background: Beta protein 1 (BP1), discovered in our lab, is an isoform protein of the DLX4 gene that is a member of the homeobox gene family. Previous work showed BP1 mRNA was activated in 80% of invasive ductal breast (IDC) tumors, where 100% of estrogen receptor (ER) negative tumor tissues and 73% of ER positive tumor tissues were BP1 positive. Moreover, high BP1 levels were associated with tumor cell survival, breast cancer aggressiveness and metastasis. BP1 overexpression was found to stimulate known oncogenes including BCL2 and c-Myc. Exosomes are nano-sized membrane-bound vesicles released by various cells and play important roles in intercellular communication. In addition, researchers found that exosomal proteins have unique characteristics compared to traditional biomarkers for carcinoma diagnosis and prognosis. Therefore, we hypothesized that BP1 protein may be packed in exosomes, and analysis of exosomal BP1 protein could provide a novel biomarker for diagnosis or prognosis of breast cancer.

Materials and Methods: Exosomes were isolated using the commercially available Exosome Precipitation Solution. In cell line experiments, fluorescent immunohistochemistry was used to detect the location of BP1 protein. Levels of BP1 protein were determined in cell extracts (CE) and conditioned media (CM) using Western Blot analysis. The hypothesis that exosomal BP1 protein may be related to the development of breast cancer was investigated with clinical serum samples purchased from Capital Bioscience. Total exosomal protein levels in the serum were analyzed using BCA assay, and exosomal BP1 protein levels were determined using Western blot. In order to develop a method that could be easily used in the clinic, an ELISA assay was also designed to assess exosomal BP1 protein concentrations in the serum from metastatic breast cancer patients and normal controls.

Results: It was observed that BP1 protein is localized to the nucleus, the cytoplasm and the conditioned media of MCF-7 cells. In addition, experiments with cell lines showed that the secreted BP1 protein could be internalized by cells and exhibited mitogenic activity, which is related to cancer metastasis. Moreover, it was observed that exosomal BP1 is included in secreted BP1 protein in the conditioned media. Experiments with serum samples demonstrated that the total exosomal protein levels have no significant differences between that in breast cancer patients and in normal controls. However, the results of Western blot and ELISA both showed exosomal BP1 protein levels were significantly higher in breast cancer samples compared to normal controls (P < 0.05). Moreover, Western blot results suggested that ER positive patients have much more (P < 0.05) exosomal BP1 protein in the serum compared to ER negative patients.

Conclusion: It was shown for the first time that BP1 protein is exosomally packaged in breast cancer patients’ serum. The significant difference in the exosomal BP1 protein levels between the serum from women with metastatic breast cancer and that from normal controls indicated that exosomal BP1 protein in the serum could be a potential prognostic biomarker for breast cancer. Furthermore, the ELISA assay, designed to be easily used for exosomal BP1 protein quantification, may have many uses in the clinic through aiding in prognosis, monitoring therapy and early detection.

Citation Format: Yaoxian Lou, Paul Goldsmith, Jinguen Rheey, Patricia E. Berg. Potential prognostic value of exosomal Beta Protein 1 in breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-01-25.

Abstract 3338: BP1 induces an epithelial to mesenchymal transition in breast cancer cells by modulating the Twist/IL6 pathway

Background. BP1 (Beta Protein 1) belongs to the Distal-less family of homeobox genes. We have demonstrated that BP1 is activated in over 80% of invasive ductal breast tumors, where it is associated with breast cancer progression. The mechanism(s) of BP1 involvement in breast cancer progression, invasion and metastasis are still not known. Homeobox genes contribute to the epithelial to mesenchymal transition (EMT). During EMT, epithelial cells acquire mesenchymal features which lead to motility, invasiveness and resistance to apoptosis. EMT is also characterized by changes in apico-basal polarity and a dramatic remodeling of the cytoskeleton. During progression toward metastasis, cancer cells acquire a mesenchymal gene expression phenotype and increased motility. This transition allows the tumor cells to metastasize and establish secondary tumors at distant sites. One of the drivers of the EMT is the transcription factor Twist. Twist is a member of highly conserved family of basic helix-loop-helix transcription factors and is involved in the specification and differentiation of mesenchymal tissue in embryos. Twist overexpression can induce EMT, generate cancer stem cells, and promote metastasis in vivo. We hypothesized that BP1 might promote cancer metastasis and invasiveness mediated though Twist and the EMT.

Methods. We generated BP1 overexpressing cell lines, MCF-7/BP1 and HS578T/BP1, along with the associated vector controls. Expression of BP1 was tested by both protein and transcript levels by Western blotting and qRT-PCR, respectively. BP1 binding to Twist was assayed by chromatin immunoprecipitation. Confocal microscopy was used to localize BP1 expression and Boyden chamber assays were employed to assess the migratory and invasive ability of these cells. ELISA assays were employed to study IL6 expression in BP1 expressing cells.

Results. BP1 expression led to an increase in Twist expression. Mechanistically, we demonstrated that BP1 bound proximally to the Twist promoter and regulated its expression. BP1 induced an EMT in both cell lines as seen by (a) lack of expression of E-cadherin, and an increase of vimentin and fibronectin expression, as well as (b) morphological changes, including a spindle-like, and more migratory phenotype. We also observed that BP1 induced expression of the cytokine IL6 in both cell lines. We conclude that BP1 regulates the EMT in breast cancer cells via the Twist and IL6 pathways.

Citation Format: Farhad Vesuna, Bin-Jin Hwang, Jinguen Rheey, Mamta Giri, Mandeep Gill, Sidney W. Fu, Ashley Irving, Ala Lisok, Yehudit Bergman, Venu Raman, Patricia E. Berg. BP1 induces an epithelial to mesenchymal transition in breast cancer cells by modulating the Twist/IL6 pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3338.

FoxM1 Promotes Stemness and Radio-Resistance of Glioblastoma by Regulating the Master Stem Cell Regulator Sox2

Glioblastoma (GBM) is the most aggressive and most lethal brain tumor. As current standard therapy consisting of surgery and chemo-irradiation provides limited benefit for GBM patients, novel therapeutic options are urgently required. Forkhead box M1 (FoxM1) transcription factor is an oncogenic regulator that promotes the proliferation, survival, and treatment resistance of various human cancers. The roles of FoxM1 in GBM remain incompletely understood, due in part to pleotropic nature of the FoxM1 pathway. Here, we show the roles of FoxM1 in GBM stem cell maintenance and radioresistance. ShRNA-mediated FoxM1 inhibition significantly impeded clonogenic growth and survival of patient-derived primary GBM cells with marked downregulation of Sox2, a master regulator of stem cell phenotype. Ectopic expression of Sox2 partially rescued FoxM1 inhibition-mediated effects. Conversely, FoxM1 overexpression upregulated Sox2 expression and promoted clonogenic growth of GBM cells. These data, with a direct binding of FoxM1 in the Sox2 promoter region in GBM cells, suggest that FoxM1 regulates stemness of primary GBM cells via Sox2. We also found significant increases in FoxM1 and Sox2 expression in GBM cells after irradiation both in vitro and in vivo orthotopic tumor models. Notably, genetic or a small-molecule FoxM1 inhibitor-mediated FoxM1 targeting significantly sensitized GBM cells to irradiation, accompanying with Sox2 downregulation. Finally, FoxM1 inhibition combined with irradiation in a patient GBM-derived orthotopic model significantly impeded tumor growth and prolonged the survival of tumor bearing mice. Taken together, these results indicate that the FoxM1-Sox2 signaling axis promotes clonogenic growth and radiation resistance of GBM, and suggest that FoxM1 targeting combined with irradiation is a potentially effective therapeutic approach for GBM.

Decreased performance in IDUA knockout mouse mimic limitations of joint function and locomotion in patients with Hurler syndrome

BACKGROUND

Mucopolysaccharidosis type I (MPS I) is caused by the deficiency of alpha-L-iduronidase (IDUA), which is involved in the degradation of glycosaminoglycans (GAGs), such as heparan sulfate and dermatan sulfate in the lysosome. It has been reported that joint symptoms are almost universal in MPS I patients, and even in the case of attenuated disease, they are the first symptom that brings a child to medical attention. However, functional tests and biological markers have not been published for the evaluation of the limitations in joint and locomotion in animal model-mimicking MPS.

METHODS

We generated IDUA knockout (KO) mice to observe whether they present impairment of joint function. KO mice were characterized phenotypically and tested dual-energy X-ray absorptiometry analysis (DEXA), open-field, rotarod, and grip strength.

RESULTS

The IDUA KO mice, generated by disruption between exon 6 and exon 9, exhibited clinical and laboratory findings, such as high urinary GAGs excretion, GAGs accumulation in various tissues, and significantly increased bone mineral density (BMD) in both female and male mice in the DEXA of the femur and whole bone. Remarkably, we observed a decrease in grasp function, decreased performance in the rotarod test, and hypo-activity in the open-field test, which mimic the limitations of joint mobility and decreased motor performance in the 6-min walk test in patients with MPS I.

CONCLUSIONS

We generated a new IDUA KO mouse, tested open field, rotarod and grip strength and demonstrated decrease in grip strength, decreased performance and hypo-activity, which may be useful for investigating therapeutic approaches, and studying the pathogenesis of joint and locomotion symptoms in MPS I.

Wnt/β-catenin signaling is a key downstream mediator of MET signaling in glioblastoma stem cells

BACKGROUND

Glioblastoma (GBM) is the most lethal and common type of primary brain tumor. Recent evidence suggests that a subpopulation of GBM cells (glioblastoma stem cells [GSCs]) is critical for tumor progression, invasion, and therapeutic resistance. We and others have demonstrated that MET, a receptor tyrosine kinase, positively regulates the stemness phenotype and radioresistance of GSCs. Here, we interrogated the downstream effector pathways of MET signaling in GSCs.

METHODS

We have established a series of GSCs and xenograft tumors derived from freshly dissociated specimens from patients with GBM and characterized a subpopulation enriched with MET activation (MET(high/+)). Through global expression profiling and subsequent pathways analysis, we identified signaling pathways that are enriched in MET(high/+) populations, one of which is Wnt/β-catenin signaling pathway. To determine molecular interaction and the biological consequences of MET and Wnt/β-catenin signaling, we used pharmacological and shRNA-mediated genetic inhibition and performed various molecular and cellular analyses, including flow cytometry, immunohistochemistry, and clonogenicity assays.

RESULTS

We found that Wnt/β-catenin signaling is highly active in MET(high/+) cells, compared with bulk tumor cells. We also showed that Wnt/β-catenin signaling activities in GBM are directly modulated by the addition of ligand-mediated MET activation or MET inhibition. Furthermore, the ectopic expression of active-β-catenin (S37A and S45Y) rescued the phenotypic effects caused by MET inhibition.

CONCLUSION

These data suggest that Wnt/β-catenin signaling is a key downstream effector of MET signaling and contributes to the maintenance of GSC and GBM malignancy.

Cell non-autonomous functions of homeoproteins in neuroprotection in the brain

Homeoproteins transcription factors can transfer between cells and play important roles in development. However, some of these homeoproteins are expressed in the adult, but their function is unknown. The loss of mesencephalic dopaminergic (mDA) neurons is the cause of Parkinson's disease. In mice lacking a functional allele for the Engrailed 1 homeoprotein, mDA neurons progressively die starting about 6 weeks after birth. Infusion of recombinant Engrailed stops the death of these neurons demonstrating that homeoproteins can be neuroprotective. This has been extended to retinal ganglion cell neurons (RGCs), which die in glaucoma and optic neuropathies. The homeoprotein Otx2 promotes the survival of injured adult RGCs both in vitro and in vivo. These examples raise the possibility that homeoproteins may provide neuroprotection to neurons vulnerable in other neurodegenerative diseases.

Abstract P4-06-15: BP1 Upregulates Twist and Induces EMT in Breast Cancer Cells

Background: We have cloned a gene, BP1, which is a member of the homeobox gene family of transcription factors. Our recent studies have shown that BP1 may play a role in breast cancer cell survival, aggressiveness and metastasis. BP1 protein (pBP1) is expressed in 80% of invasive ductal breast tumors, and is associated with estrogen receptor negativity and tumors of African American women, both associated with aggressive tumors. BP1 is also expressed in metastatic tumors, shown by immunostaining of 46 samples of inflammatory breast cancer; all cases were BP1 positive. Nine cases had metastasized, and all nine metastatic lymph nodes were BP1 positive. BP1 positive cells were observed in lymph channels and blood vessels. Here, we demonstrated BP1 induces the epithelial to mesenchymal transition (EMT), resulting in increased migratory ability. EMT, a process by which cancer cells lose their epithelial features and gain mesenchymal markers, enables tumor cells become more invasive, migratory and can lead to metastasis. Twist, a basic helix-loop-helix (bHLH) transcription factor which triggers EMT, is activated by BP1.

Materials and Methods: RNA levels of markers of EMT were verified by real-time PCR and their protein levels by Western blotting and, in some cases, by confocal microscopy. Chromatin immunoprecipitation (ChIP) was performed to verify the BP1 binding site on the Twist promoter. A scratch test was used to measure migratory ability. BP1 knockdown by siRNA transfection was also performed. Recombinant BP1 (rpBP1) was produced in E. coli.

Results: Increased expression levels of Twist were observed on microarrays after probing with RNA from MCF-7 cell lines overexpressing BP1. We demonstrated that BP1 can upregulate Twist expression in two different breast cancer cell lines, MCF-7 and Hs578T cells, by binding to the Twist promoter. BP1 upregulates mesenchymal marker expression and down-regulates epithelial marker expression, consistent with EMT. BP1 also promotes breast cancer cell migratory ability, shown by the scratch test. In addition, cells grown in medium supplemented with rpBP1 showed increased Twist expression and migration. Experiments evaluating the effects of siBP1 on EMT are underway.

Conclusions: BP1 stimulates Twist expression in MCF-7 and HS578T breast cancer cells, resulting in a more mesenchymal cell phenotype. We therefore hypothesize that BP1 induces EMT by upregulating Twist expression, and may result in metastasis. If BP1 is involved in EMT, it may be a good target for therapy.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-06-15.

Abstract 2298: BP1 upregulates Twist, a trigger of EMT and cancer metastasis

BP1 Upregulates Twist, a Trigger of EMT and Cancer Metastasis

Bin-Jin Hwang, Jinguen Rheey, and Patricia E. Berg

George Washington University, Department of Biochemistry and Molecular Biology,

Washington, D.C.

Background. We have cloned a gene, BP1, which is a member of the homeobox gene family of transcription factors. Increasing evidence suggests that homeobox genes are important in malignant transformation and tumorigenesis, and our recent studies have shown that BP1 may play a role in breast cancer cell survival, aggressiveness and metastasis. BP1 protein (pBP1) is expressed in 80% of invasive ductal breast tumors, and is associated with breast cancer aggressiveness: 100% of estrogen receptor negative tumors and 89% of the tumors of African American women are BP1 positive. Now we have evidence that BP1 may regulate the epithelial to mesenchymal transition (EMT). EMT, a process in which cancer cells lose their epithelial features and gain mesenchymal markers, enables tumor cells to become more invasive and migratory, and can lead to metastasis. BP1 upregulates Twist, a basic helix-loop-helix (bHLH) transcription factor which triggers EMT. Our objective is to determine whether BP1 plays a role in induction of EMT. Materials and Methods. The expression levels of Twist, E-cadherin and vimentin were observed on microarrays after probing with RNA from MCF-7 cell lines overexpressing BP1. RNA levels were verified by real-time PCR and protein levels by Western blotting and, in some cases, by confocal microscopy. Summary. Twist mRNA expression on microarrays is higher in MCF-7 cells overexpressing BP1 compared with cells containing an empty vector. Real-time PCR confirmed that Twist mRNA is increased five-fold in cells with high levels of BP1, and Western blots demonstrated that Twist protein is also elevated in the same cells. We have discovered a potential DNA binding site for pBP1 in the Twist promoter, suggesting that BP1 may directly regulate Twist. This will be verified by ChIP. Expression of two genes regulated by Twist was also examined: Twist activates vimentin and represses E-cadherin. Cells overexpressing pBP1 also show increased vimentin and decreased E-cadherin. The effect of increased pBP1 on cell migration is under investigation. Conclusions: BP1 stimulates Twist expression in MCF-7 breast cancer cells, resulting in increased vimentin and decreased E-cadherin levels. We therefore hypothesize that BP1 is upstream of Twist and induces EMT. If BP1 is required for EMT, it may be a good target for therapy of metastatic tumors.

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 2298.

Blocking internalization of pBP1, a secreted homeoprotein, kills breast cancer cells but not normal breast epithelial cells

Abstract #3068

Background: BP1 is a member of the homeobox gene family, a highly conserved family of transcription factor genes. pBP1 is a homeotic protein that is upregulated in 80% of invasive ductal breast tumors. We have previously shown that the percentage of pBP1 positive breast cancer cases increases with the extent of cellular proliferation and carcinogenesis. BP1 expression is associated with aggressive tumors: 100% of ER negative tumors were BP1 positive, compared with 73% of ER positive tumors. pBP1 is secreted by MCF-7 cells, T47D cells, and MDA-MB-231 breast cancer cells, but not by MCF10A or H16N2 normal breast epithelial cells. In all cell lines tested, secreted pBP1 is internalized, resulting in stimulation of growth. Moreover, incubation of MCF-7 or MCF10A cells in recombinant pBP1 results in stimulation of several oncogenes, including bcl-2, Twist, and Met. These results led us to ask whether we could abrogate mitogenic stimulation by addition of anti-pBP1 antibody.
 Materials and Methods. Cells were incubated in 10 µg/ml anti-BP1 Ab (Novus) or 10 µg/ml IgG for three days. Growth was measured using MTT assays and apoptosis was assessed by flow cytometry after staining with Annexin V (Trevigen).
 Results. Addition of anti-BP1 Ab to the growth medium of MCF-7 cells, T47D cells, and MDA-MB-231 cells caused significant growth inhibition and apoptosis. In contrast, addition of anti-BP1 Ab to the growth medium of MCF10A and H16N2 cells did not lead to significant growth inhibition or apoptosis.
 Discussion. Our novel finding that pBP1 is secreted by breast cancer cells but not normal breast epithelial cells was the impetus to test the effect of adding anti-BP1 Ab to the growth media of both types of cells. Remarkably, anti-BP1 Ab kills only the breast cancer cells, suggesting they may be BP1-dependent. Our data indicate it may be possible to specifically target BP1 positive breast cancer cells in the 80% of women with BP1 positive tumors.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3068.

BP1 transcriptionally activates bcl-2 and inhibits TNFalpha-induced cell death in MCF7 breast cancer cells

INTRODUCTION

We have previously shown that the Beta Protein 1 (BP1) homeodomain protein is expressed in 81% of invasive ductal breast carcinomas, and that increased BP1 expression correlates with tumor progression. The purpose of our current investigation was to determine whether elevated levels of BP1 in breast cancer cells are associated with increased cell survival.

METHODS

Effects on cell viability and apoptosis of MCF7 cells stably overexpressing BP1 were determined using MTT and Annexin V assays, and through examination of caspase activation. TNFalpha was used to induce apoptosis. The potential regulation of apoptosis-associated genes by BP1 was studied using real-time PCR and western blot analyses. Electrophoretic mobility shift assays, site-directed mutagenesis, and transient assays were performed to specifically characterize the interaction of BP1 with the promoter of the bcl-2 gene.

RESULTS

Stable overexpression of BP1 led to inhibition of apoptosis in MCF7 breast cancer cells challenged with TNFalpha. Increased BP1 resulted in reduced processing and activation of caspase-7, caspase-8, and caspase-9, and inactivation of the caspase substrate Poly(ADP-Ribose) Polymerase (PARP). Increased levels of full-length PARP and a decrease in procaspase-8 were also associated with BP1 overexpression. The bcl-2 gene is a direct target of BP1 since: (i) BP1 protein bound to a consensus binding sequence upstream of the bcl-2 P1 promoter in vitro. (ii) MCF7 cells overexpressing BP1 showed increased levels of bcl-2 mRNA and protein. (iii) Transient assays indicated that increased bcl-2 promoter activity is due to direct binding and modulation by BP1 protein. BP1 expression also prevented TNFalpha-mediated downregulation of bcl-2 mRNA and protein.

CONCLUSION

These findings suggest mechanisms by which increased BP1 may impart a survival advantage to breast cancer cells, which could lead to increased resistance to therapeutic agents in patients.