Humanization of Tumor Stroma by Tissue Engineering as a Tool to Improve Squamous Cell Carcinoma Xenograft.

The role of stroma is fundamental in the development and behavior of epithelial tumors. In this regard, limited growth of squamous cell carcinomas (SCC) or cell-lines derived from them has been achieved in immunodeficient mice. Moreover, lack of faithful recapitulation of the original human neoplasia complexity is often observed in xenografted tumors. Here, we used tissue engineering techniques to recreate a humanized tumor stroma for SCCs grafted in host mice, by combining CAF (cancer associated fibroblasts)-like cells with a biocompatible scaffold. The stroma was either co-injected with epithelial cell lines derived from aggressive SCC or implanted 15 days before the injection of the tumoral cells, to allow its vascularization and maturation. None of the mice injected with the cell lines without stroma were able to develop a SCC. In contrast, tumors were able to grow when SCC cells were injected into previously established humanized stroma. Histologically, all of the regenerated tumors were moderately differentiated SCC with a well-developed stroma, resembling that found in the original human neoplasm. Persistence of human stromal cells was also confirmed by immunohistochemistry. In summary, we provide a proof of concept that humanized tumor stroma, generated by tissue engineering, can facilitate the development of epithelial tumors in immunodeficient mice.

Establishing a cryopreservation protocol for patient-derived xenografts of prostate cancer.

BACKGROUND: Serially transplantable patient-derived xenografts (PDXs) are invaluable preclinical models for studying tumor biology and evaluating therapeutic agents. As these models are challenging to establish from prostate cancer specimens, the ability to preserve them through cryopreservation has several advantages for ongoing research. Despite this, there is still uncertainty about the ability to cryopreserve PDXs of prostate cancer. This study compared three different cryopreservation protocols to identify a method that can be used to reproducibly cryopreserve a diverse cohort of prostate cancer PDX models. METHODS: One serially transplantable prostate cancer PDX from the Melbourne Urological Research Alliance cohort was used to compare three cryopreservation protocols: slow freezing in fetal calf serum (FCS) with 10% dimethyl sulfoxide (DMSO), FCS with 10% DMSO supplemented with the Rho-associated kinase (ROCK) inhibitor Y-27632 and vitrification. The efficiency of the slow freezing protocols was then assessed in 17 additional prostate cancer PDXs. Following cryopreservation, PDXs were re-established in host mice that were either intact and supplemented with testosterone or castrated. Graft take rate, tumor growth, histological features, and transcriptome profiles before and after cryopreservation were compared. RESULTS: Slow freezing maintained the viability and histological features of prostate cancer PDXs, and the addition of a ROCK inhibitor increased their growth following cryopreservation. Using the slow freezing method, we re-established 100% of PDXs grown in either testosterone-supplemented or castrated host mice. Importantly, the long-term tumor growth rate and transcriptome profile were maintained following cryopreservation. CONCLUSION: This study has identified a protocol to reliably cryopreserve and re-establish a diverse cohort of serially transplantable PDXs of prostate cancer. This study has the potential to significantly improve the practicality of maintaining PDX models. Cryopreservation may also increase the accessibility of these important resources and provide new opportunities for preclinical studies on a broader spectrum of prostate tumors.

How cancer cells attach to urinary bladder epithelium in vivo: study of the early stages of tumorigenesis in an orthotopic mouse bladder tumor model.

The majority of bladder cancers in humans are non-muscle-invasive cancers that recur frequently after standard treatment procedures. Mouse models are widely used to develop anti-tumor treatments. The purpose of our work was to establish an orthotopic mouse bladder tumor model and to explore early stages of implantation of cancerous MB49 cells in vivo using various labeling and microscopic techniques. To distinguish cancer cells from normal urothelial cells in mouse urinary bladders, we performed molecular characterization of MB49 cells before intravesical injection experiments. In this new approach we applied internalized metal nanoparticles to unequivocally discriminate cancer cells from normal cells. This method revealed that cancer cells attached to the urothelium or basal lamina within just 1 hour of intravesical injection, whereas small tumors and localized hyperplastic urothelial regions developed within two days. We found that cancer cells initially adhere to normal urothelial cells through filopodia and by focal contacts with basal lamina. This is the first in vivo characterization of intercellular contacts between cancerous and normal urothelial cells in the bladder. Our study yields new data about poorly known early events of tumorigenesis in vivo, which could be helpful for the translation into clinic.

Protein Sam68 regulates the alternative splicing of survivin DEx3.

Messenger RNA alternative splicing (AS) regulates the expression of a variety of genes involved in both physiological and pathological processes. AS of the anti-apoptotic and proliferation-associated survivin (BIRC5) gene generates six isoforms, which regulate key aspects of cancer initiation and progression. One of the isoforms is survivin DEx3, in which the exclusion of exon 3 generates a unique carboxyl terminus with specific anti-apoptotic functions. This isoform is highly expressed in advanced stages of breast and cervical tumors. Therefore, understanding the mechanisms that regulate survivin DEx3 mRNA AS is clearly important. To this end, we designed a minigene (M), and in combination with a series of deletions and site-directed mutations, we determined that the first 22 bp of exon 3 contain cis-acting elements that enhance the exclusion of exon 3 to generate the survivin DEx3 mRNA isoform. Furthermore, using pulldown assays, we discovered that Sam68 is a possible trans-acting factor that binds to this region and regulates exon 3 splicing. This result was corroborated using a cell line in which the Sam68 binding site in the survivin gene was mutated with the CRISPR/Cas system. This work provides the first clues regarding the regulation of survivin DEx3 mRNA splicing.

Comparison of hock- and footpad-injection as a prostate adenocarcinoma model in rats.

BACKGROUND: Objective of this study is a feasibility-test comparing hock- and footpad-injection in rats with inoculated MatLyLu - adenocarcinoma tumor model. This study compares the development of an adenocarcinoma model (MatLyLu) in 12 Copenhagen rats. Two groups (n = 6) of animals were inoculated with 1 × 106 MatLyLu tumor cells solved in 0.1 ml NaCl either by footpad or hock injection. All animals were examined before tumor inoculation and before euthanasia using a 3.0 Tesla MRI. Histological evaluation of all organs was performed post mortem. RESULTS: Both types of injection were able to induce the adenocarcinoma model using MatLyLu tumor cells. The primary tumor could be visualized in MRI and confirmed histologically. Comparing the risk of reflux and the maximum injection volume during injection, the hock injection was superior to the footpad injection (less reflux, less anatomical restrictions for larger volumes). The hock injection induces a faster tumor growth compared to the footpad injection. As consequence the maximum level of long term discomfort after hock injection was reached earlier, even if it grew on a not weight bearing structure. Early lymph node tumor metastasis could not be observed macroscopically nor detected histologically. Therefore the reproducibility of the MatLyLu tumor model is questionable. CONCLUSION: Hock injection is a feasible alternative technique compared with footpad-injection in rats. It provides a save and easy injection method for various early-terminated applications with the potential to increase animal welfare during tumor models in rats.

Inhibitor of DNA binding 2 is a novel therapeutic target for stemness of head and neck squamous cell carcinoma.

BACKGROUND: Head and neck squamous cell carcinomas (HNSCCs) are highly lethal epithelial tumours containing self-renewal cancer stem cells (CSCs). CSCs in HNSCCs are strongly associated with tumour initiation, invasion, and chemoradiation resistance. However, the important factors regulating stemness in HNSCCs remain unclear. Here, we investigated the molecular roles and clinical significance of inhibitor of DNA binding 2 (Id2) protein to determine if it constitutes a novel therapeutic target for ablating HNSCC cells with stemness. METHODS: We performed in vitro and in vivo studies of Id2 function and its effects on stemness using HNSCC cells. We also examined whether Id2 expression could be used as a prognostic indicator through immunohistochemical staining of 119 human HNSCC tumours. RESULTS: Expression of Id2 was higher in HNSCC cells with stemness compared with differentiated HNSCC cells. Overexpression of Id2 increased proliferation, self-renewal, and expression of the putative stemness marker CD44 in HNSCC cells in vitro and in vivo. In contrast, silencing of Id2 using short hairpin RNA attenuated the stemness phenotype of HNSCC cells by reducing self-renewal, CD44 expression, cisplatin chemoresistance, and xenograft tumourigenicity. Most importantly, increased expression of Id2 was closely associated with poorer post-treatment survival rates in HNSCC patients. CONCLUSIONS: Inhibitor of DNA binding2 represents a novel and promising therapeutic target for treating and improving the clinical outcomes for patients with HNSCC.

An original patient-derived xenograft of prostate cancer with cyst formation.

BACKGROUND: The high rate of failure of new agents in oncology clinical trials indicates a weak understanding of the complexity of human cancer. Recent understanding of the mechanisms underlying castration resistance in prostate cancer led to the development of new agents targeting the androgen receptor pathway; however, their effectiveness is limited. Hence, there is a need for experimental systems that are able to better reproduce the biological diversity of prostate cancer in preclinical settings. In this study, we established a unique patient-derived xenograft (PDX) model to identify biomarkers for treatment efficacy and resistance and better understand prostate cancer biology. METHODS: A prostate cancer tissue sample from a Japanese patient was transplanted subcutaneously into male, severe combined immune-deficient (SCID) mice and this PDX mouse model was named KUCaP3. Sequential tumor volume changes were observed before and after castration. Androgen receptor (AR), prostate-specific antigen (PSA), and other molecular markers were examined immunohistochemically. Sequence analysis of AR was also performed to detect mutations. Proteomic analysis of cyst fluid and sera samples of KUCaP3 mice were analyzed by mass spectrometry (MS). RESULTS: KUCaP3 cell line, derived from human tissue, was successfully and serially passaged in vivo with approximately 60% take rate. KUCaP3 exhibited cyst formation, showed androgen-dependent growth initially, and developed castration-resistant growth several months after castration of the mice. Immunohistochemical analysis showed that KUCaP3 was positive for AR, PSA, CK18, and α-methyl acyl-coenzyme A racemase, but negative for CK5/6 and ERG. The AR gene in KUCaP3 cells contained a substitution from CAT (histidine) to TAT (tyrosine) at the nucleotide positions corresponding to codon 875 (H875Y) in the ligand-binding domain. Chemiluminescent immunoassay revealed higher levels of PSA in cystic fluid and the serum of KUCaP3-bearing mice. MS analysis detected 23 proteins of human origin in cystic fluids of KUCaP3. CONCLUSIONS: We developed KUCaP3, an androgen-dependent PDX model with cyst formation. Several proteins including PSA were detected in the cystic fluid and sera of tumor-bearing mice. This original PDX model has the potential to be used as a clinically relevant model to evaluate molecular markers for prostate cancer diagnosis and treatment. Prostate 76:994-1003, 2016. © 2016 Wiley Periodicals, Inc.

Analysis of TMEFF2 allografts and transgenic mouse models reveals roles in prostate regeneration and cancer.

BACKGROUND: Previous results from our lab indicate a tumor suppressor role for the transmembrane protein with epidermal growth factor and two follistatin motifs 2 (TMEFF2) in prostate cancer (PCa). Here, we further characterize this role and uncover new functions for TMEFF2 in cancer and adult prostate regeneration. METHODS: The role of TMEFF2 was examined in PCa cells using Matrigel(TM) cultures and allograft models of PCa cells. In addition, we developed a transgenic mouse model that expresses TMEFF2 from a prostate specific promoter. Anatomical, histological, and metabolic characterizations of the transgenic mouse prostate were conducted. The effect of TMEFF2 in prostate regeneration was studied by analyzing branching morphogenesis in the TMEFF2-expressing mouse lobes and alterations in branching morphogenesis were correlated with the metabolomic profiles of the mouse lobes. The role of TMEFF2 in prostate tumorigenesis in whole animals was investigated by crossing the TMEFF2 transgenic mice with the TRAMP mouse model of PCa and analyzing the histopathological changes in the progeny. RESULTS: Ectopic expression of TMEFF2 impairs growth of PCa cells in Matrigel or allograft models. Surprisingly, while TMEFF2 expression in the TRAMP mouse did not have a significant effect on the glandular prostate epithelial lesions, the double TRAMP/TMEFF2 transgenic mice displayed an increased incidence of neuroendocrine type tumors. In addition, TMEFF2 promoted increased branching specifically in the dorsal lobe of the prostate suggesting a potential role in developmental processes. These results correlated with data indicating an alteration in the metabolic profile of the dorsal lobe of the transgenic TMEFF2 mice. CONCLUSIONS: Collectively, our results confirm the tumor suppressor role of TMEFF2 and suggest that ectopic expression of TMEFF2 in mouse prostate leads to additional lobe-specific effects in prostate regeneration and tumorigenesis. This points to a complex and multifunctional role for TMEFF2 during PCa progression.

Successful application of endoscopic ultrasound-guided fine needle biopsy to establish pancreatic patient-derived tumor xenografts: a pilot study.

Background and study aim: Typically, pancreatic patient-derived tumor xenografts (PDXs) are established by transplanting large tumor biopsies obtained through invasive surgery approaches into immunocompromised mice. We aimed to develop pancreatic PDXs by transplanting tumor tissue acquired by endoscopic ultrasound (EUS)-guided fine needle biopsies (FNB), assess take rates compared to surgery-derived PDXs, and demonstrate the histological and genetic resemblance to the original tumor. Patients and methods: Biopsies of untreated pancreatic carcinoma were collected at surgery and during EUS and processed to generate PDXs. Results: By centrifugation of FNB-derived tissue prior to engraftment, we achieved an engraftment rate of 60 % (6/10). Despite a decrease in stromal tissue, the general morphology of FNB-derived PDXs was conserved as assessed by histopathology. At the genetic level, somatic mutation and copy number profiles were largely similar to the primary tumor. Conclusion: We show that it is technically feasible to establish pancreatic PDXs using a minimally invasive sampling technique, such as EUS-FNB. Although only a limited amount of tumor tissue was acquired, we obtained results similar to those from surgery-derived PDXs.

Tumour vascularization via endothelial differentiation of glioblastoma stem-like cells.

Glioblastoma is a highly angiogenetic malignancy, the neoformed vessels of which are thought to arise by sprouting of pre-existing brain capillaries. The recent demonstration that a population of glioblastoma stem-like cells (GSCs) maintains glioblastomas indicates that the progeny of these cells may not be confined to the neural lineage. Normal neural stem cells are able to differentiate into functional endothelial cells. The connection between neural stem cells and the endothelial compartment seems to be critical in glioblastoma, where cancer stem cells closely interact with the vascular niche and promote angiogenesis through the release of vascular endothelial growth factor (VEGF) and stromal-derived factor 1 (refs 5-9). Here we show that a variable number (range 20-90%, mean 60.7%) of endothelial cells in glioblastoma carry the same genomic alteration as tumour cells, indicating that a significant portion of the vascular endothelium has a neoplastic origin. The vascular endothelium contained a subset of tumorigenic cells that produced highly vascularized anaplastic tumours with areas of vasculogenic mimicry in immunocompromised mice. In vitro culture of GSCs in endothelial conditions generated progeny with phenotypic and functional features of endothelial cells. Likewise, orthotopic or subcutaneous injection of GSCs in immunocompromised mice produced tumour xenografts, the vessels of which were primarily composed of human endothelial cells. Selective targeting of endothelial cells generated by GSCs in mouse xenografts resulted in tumour reduction and degeneration, indicating the functional relevance of the GSC-derived endothelial vessels. These findings describe a new mechanism for tumour vasculogenesis and may explain the presence of cancer-derived endothelial-like cells in several malignancies.

Parthenolide eliminates leukemia-initiating cell populations and improves survival in xenografts of childhood acute lymphoblastic leukemia.

Approximately 20% of children with acute lymphoblastic leukemia (ALL) relapse because of failure to eradicate the disease. Current drug efficacy studies focus on reducing leukemia cell burden. However, if drugs have limited effects on leukemia-initiating cells (LICs), then these cells may expand and eventually cause relapse. Parthenolide (PTL) has been shown to cause apoptosis of LIC in acute myeloid leukemia. In the present study, we assessed the effects of PTL on LIC populations in childhood ALL. Apoptosis assays demonstrated that PTL was effective against bulk B- and T-ALL cells, whereas the CD34(+)/CD19(-), CD34(+)/CD7(-), and CD34(-) subpopulations were more resistant. However, functional analyses revealed that PTL treatment prevented engraftment of multiple LIC populations in NOD/LtSz-scid IL-2Rγ(c)-null mice. PTL treatment of mice with established leukemias from low- and high-risk patients resulted in survival and restoration of normal murine hemopoiesis. In only 3 cases, disease progression was significantly slowed in mice engrafted with CD34(+)/CD19(-) or CD34(+)/CD7(-) and CD34(-) cells, but was not prevented, demonstrating that individual LIC populations within patients have different responses to therapy. These observations indicate that PTL may have therapeutic potential in childhood ALL and provide a basis for developing effective therapies that eradicate all LIC populations to prevent disease progression and reduce relapse.

Diversity of antigen-specific responses induced in vivo with CTLA-4 blockade in prostate cancer patients.

CTLA-4 is a surface receptor on activated T cells that delivers an inhibitory signal, serving as an immune checkpoint. Treatment with anti-CTLA-4 Abs can induce clinical responses to different malignancies, but the nature of the induced Ag-specific recognition is largely unknown. Using microarrays spotted with >8000 human proteins, we assessed the diversity of Ab responses modulated by treatment with CTLA-4 blockade and GM-CSF. We find that advanced prostate cancer patients who clinically respond to treatment also develop enhanced Ab responses to a higher number of Ags than nonresponders. These induced Ab responses targeted Ags to which preexisting Abs are more likely to be present in the clinical responders compared with nonresponders. The majority of Ab responses are patient-specific, but immune responses against Ags shared among clinical responders are also detected. One of these shared Ags is PAK6, which is expressed in prostate cancer and to which CD4(+) T cell responses were also induced. Moreover, immunization with PAK6 can be both immunogenic and protective in mouse tumor models. These results demonstrate that immune checkpoint blockade modulates Ag-specific responses to both individualized and shared Ags, some of which can mediate anti-tumor responses.

Tumor-associated microglia/macrophages enhance the invasion of glioma stem-like cells via TGF-ß1 signaling pathway.

The invasion of malignant glioma cells into the surrounding normal brain tissues is crucial for causing the poor outcome of this tumor type. Recent studies suggest that glioma stem-like cells (GSLCs) mediate tumor invasion. However, it is not clear whether microenvironment factors, such as tumor-associated microglia/macrophages (TAM/Ms), also play important roles in promoting GSLC invasion. In this study, we found that in primary human gliomas and orthotopical transplanted syngeneic glioma, the number of TAM/Ms at the invasive front was correlated with the presence of CD133(+) GSLCs, and these TAM/Ms produced high levels of TGF-ß1. CD133(+) GSLCs isolated from murine transplanted gliomas exhibited higher invasive potential after being cocultured with TAM/Ms, and the invasiveness was inhibited by neutralization of TGF-ß1. We also found that human glioma-derived CD133(+) GSLCs became more invasive upon treatment with TGF-ß1. In addition, compared with CD133(-) committed tumor cells, CD133(+) GSLCs expressed higher levels of type II TGF-ß receptor (TGFBR2) mRNA and protein, and downregulation of TGFBR2 with short hairpin RNA inhibited the invasiveness of GSLCs. Mechanism studies revealed that TGF-ß1 released by TAM/Ms promoted the expression of MMP-9 by GSLCs, and TGFBR2 knockdown reduced the invasiveness of these cells in vivo. These results demonstrate that TAM/Ms enhance the invasiveness of CD133(+) GSLCs via the release of TGF-ß1, which increases the production of MMP-9 by GSLCs. Therefore, the TGF-ß1 signaling pathway is a potential therapeutic target for limiting the invasiveness of GSLCs.

In vitro culture and characterization of human lung cancer circulating tumor cells isolated by size exclusion from an orthotopic nude-mouse model expressing fluorescent protein.

In the present study, we demonstrate an animal model and recently introduced size-based exclusion method for circulating tumor cells (CTCs) isolation. The methodology enables subsequent in vitro CTC-culture and characterization. Human lung cancer cell line H460, expressing red fluorescent protein (H460-RFP), was orthotopically implanted in nude mice. CTCs were isolated by a size-based filtration method and successfully cultured in vitro on the separating membrane (MetaCell®), analyzed by means of time-lapse imaging. The cultured CTCs were heterogeneous in size and morphology even though they originated from a single tumor. The outer CTC-membranes were blebbing in general. Abnormal mitosis resulting in three daughter cells was frequently observed. The expression of RFP ensured that the CTCs originated from lung tumor. These readily isolatable, identifiable and cultivable CTCs can be used to characterize individual patient cancers and for screening of more effective treatment.

Conditioning of the abdominal cavity reduces tumor implantation in a laparoscopic mouse model.

PURPOSE: The addition of 4 % O2 and 10 % N2O to the CO2 pneumoperitoneum (PP), together with slight cooling and humidification (conditioning), contributes to reducing adhesions by preventing mesothelial damage. We investigated the effect of peritoneal damage during laparoscopy on tumor implantation. METHODS: In Experiment 1, different tumor cell concentrations were injected into control mice without PP and into mice with 60-min dry CO2PP (mesothelial damage). In Experiment 2, tumor cells were injected into control mice (group I) and in mice with mesothelial damage (group II). In groups III to VI, mesothelial damage was decreased by adding humidification, humidification + 10 % N2O, humidification + 10 % N2O + 4 % O2, and conditioning, respectively. RESULTS: In Experiment 1, the tumors increased with the number of cells injected and with mesothelial damage in the abdominal cavity (p = 0.018) and abdominal wall (p < 0.0001). Experiment 2 confirmed that 60 min of dry CO2PP increased the number of tumors in the abdominal cavity and wall (p = 0.026 and p = 0.003, respectively). The number of tumors was decreased in the abdominal cavity by conditioning (p = 0.030) and in the abdominal wall using humidified CO2 (p = 0.032) or conditioning (p = 0.026). CONCLUSIONS: Tumor implantation was enhanced by peritoneal damage (60 min of dry CO2PP and desiccation), but this was prevented by conditioning. If confirmed in humans, conditioning would become important for oncologic surgery.

A novel onco-miR-365 induces cutaneous squamous cell carcinoma.

The expression levels of miR-365 vary in different malignancies. Herein, we found that miR-365 was overexpressed in both cells and clinical specimens of cutaneous squamous cell carcinoma (SCC). We demonstrated that the HaCaT(pre-miR-365-2) cell line, which overexpressed miR-365, could induce subcutaneous tumors in vivo. Antagomir-365, an anti-miR-365 oligonucleotide, inhibited cutaneous tumor formation in vivo, along with G1 phase arrest and apoptosis of cancer cells. These findings suggest that miR-365 may act as an onco-miR in cutaneous SCC both in vitro and in vivo. The present study provides valuable insight into the role of miR-365 in cutaneous SCC formation, which can help develop new drug and miR-365 target-based therapies for cutaneous SCC.

High NUAK1 expression correlates with poor prognosis and involved in NSCLC cells migration and invasion.

Novel (nua) kinase family 1 (NUAK1) is a member of the human adenosine monophosphate (AMP)-activated protein kinase family that has been identified as a key tumor cell survival factor. In the present study, we investigated the role of NUAK1 in the migration and invasion of human nonsmall cell lung cancer (NSCLC) cells. Immunohistochemistry staining showed that the expression of NUAK1 correlated with the differentiation and stage of the carcinoma, as well as with lymph node metastasis. Inhibition of NUAK1 expression by small interference RNA severely impaired migration and invasion in A549 cells. In addition, we found that the knockdown of NUAK1 suppressed the expression of MMP-2 and MMP-9 and the activation of NF-kB, which can regulate the transcription of MMP-2 and MMP-9. Correspondingly, NUAK1 knockdown reduced lung metastasis in a xenograft mouse model of NSCLC. Taken together, our results suggest that NUAK1 plays an important role in NSCLC cell migration and invasion.

Activation of RalA is critical for Ras-induced tumorigenesis of human cells.

RalGEFs were recently shown to be critical for Ras-mediated transformed and tumorigenic growth of human cells. We now show that the oncogenic activity of these proteins is propagated by activation of one RalGEF substrate, RalA, but blunted by another closely related substrate, RalB, and that the oncogenic signaling requires binding of the RalBP1 and exocyst subunit effector proteins. Knockdown of RalA expression impeded, if not abolished, the ability of human cancer cells to form tumors. RalA was also commonly activated in a panel of cell lines from pancreatic cancers, a disease characterized by activation of Ras. Activation of RalA signaling thus appears to be a critical step in Ras-induced transformation and tumorigenesis of human cells.

Apolipoprotein A-I (apoA-I) and apoA-I mimetic peptides inhibit tumor development in a mouse model of ovarian cancer.

We examined whether reduced levels of Apolipoprotein A-I (apoA-I) in ovarian cancer patients are causal in ovarian cancer in a mouse model. Mice expressing a human apoA-I transgene had (i) increased survival (P < 0.0001) and (ii) decreased tumor development (P < 0.01), when compared with littermates, following injection of mouse ovarian epithelial papillary serous adenocarcinoma cells (ID-8 cells). ApoA-I mimetic peptides reduced viability and proliferation of ID8 cells and cis-platinum-resistant human ovarian cancer cells, and decreased ID-8 cell-mediated tumor burden in C57BL/6J mice when administered subcutaneously or orally. Serum levels of lysophosphatidic acid, a well-characterized modulator of tumor cell proliferation, were significantly reduced (>50% compared with control mice, P < 0.05) in mice that received apoA-I mimetic peptides (administered either subcutaneously or orally), suggesting that binding and removal of lysophosphatidic acid is a potential mechanism for the inhibition of tumor development by apoA-I mimetic peptides, which may serve as a previously unexplored class of anticancer agents.