IL-27-engineered CAR.19-NK-92 cells exhibit enhanced therapeutic efficacy.

Chimeric antigen receptor (CAR) engineering of natural killer (NK) cells has shown promising results in early-phase clinical studies. However, advancing CAR-NK cell therapeutic efficacy is imperative. In this study, we investigated the impact of a fourth-generation CD19-targeted CAR (CAR.19) coexpressing IL-27 on NK-92 cells. We observed a significant improvement in NK-92 cell proliferation and cytotoxicity activity against B-cell cancer cell lines, both in vitro and in a xenograft mouse B-cell lymphoma model. Our systematic transcriptome analysis of the activated NK-92 CAR variants further supports the potential of IL-27 in fourth-generation CARs to overcome limitations of NK cell-based targeted tumor therapies by providing essential growth and activation signals. Integrating IL-27 into CAR-NK cells emerges as a promising strategy to enhance their therapeutic potential and elicit robust responses against cancer cells. These findings contribute substantially to the mounting evidence supporting the potential of fourth-generation CAR engineering in advancing NK cell-based immunotherapies.

Evaluation of human adipose-derived mesenchymal stromal cell Toll-like receptor priming and effects on interaction with prostate cancer cells.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) are a multipotent cell population of clinical interest because of their ability to migrate to injury and tumor sites, where they may participate in tissue repair and modulation of immune response. Although the processes regulating MSC function are incompletely understood, it has been shown that stimulation of Toll-like receptors (TLRs) can alter MSC activity. More specifically, it has been reported that human bone marrow-derived MSCs can be "polarized" by TLR priming into contrasting immunomodulatory functions, with opposite (supportive or suppressive) roles in tumor progression and inflammation. Adipose-derived MSCs (ASCs) represent a promising alternative MSC subpopulation for therapeutic development because of their relative ease of isolation and higher abundance compared with their bone marrow-derived counterparts; however, the polarization of ASCs remains unreported. METHODS: In this study, we evaluated the phenotypic and functional consequences of short-term, low-level stimulation of ASCs with TLR3 and TLR4 agonists. RESULTS: In these assays, we identified transient gene expression changes resembling the reported pro-inflammatory and anti-inflammatory MSC phenotypes. Furthermore, these priming strategies led to changes in the functional properties of ASCs, affecting their ability to migrate and modulate immune-mediated responses to prostate cancer cells in vitro. CONCLUSIONS: TLR3 stimulation significantly decreased ASC migration, and TLR4 stimulation increased ASC immune-mediated killing potential against prostate cancer cells.

Skeletal muscle signal peptide optimization for enhancing propeptide or cytokine secretion.

We have utilized hidden Markov models using HMMER software to predict and generate putative strong secretory signal peptide sequences for directing efficient secretion of cytokines from skeletal muscle for therapeutic applications. The results show that this approach can analyze signal sequences of a skeletal muscle secretome dataset and classify them, emitting new sequences that are strong candidate skeletal muscle-enriched signal peptides. The emitted signal peptides also were analyzed for their hydropathy and secondary structure profiles as compared to native signal peptides. The emitted signal peptides had a higher degree of hydropathy and helical composition relative to native sequences, which may suggest that these new sequences may hold promize for promoting enhanced secretion of proteins including cytokines or propeptides from skeletal muscle.

Histamine-induced Ca²âº signalling is mediated by TRPM4 channels in human adipose-derived stem cells.

Intracellular Ca2+ oscillations are frequently observed during stem cell differentiation, and there is evidence that it may control adipogenesis. The transient receptor potential melastatin 4 channel (TRPM4) is a key regulator of Ca2+ signals in excitable and non-excitable cells. However, its role in human adipose-derived stem cells (hASCs), in particular during adipogenesis, is unknown. We have investigated TRPM4 in hASCs and examined its impact on histamine-induced Ca2+ signalling and adipogenesis. Using reverse transcription (RT)-PCR, we have identified TRPM4 gene expression in hASCs and human adipose tissue. Electrophysiological recordings revealed currents with the characteristics of those reported for the channel. Furthermore, molecular suppression of TRPM4 with shRNA diminished the Ca2+ signals generated by histamine stimulation, mainly via histamine receptor 1 (H1) receptors. The increases in intracellular Ca2+ were due to influx via voltage-dependent Ca2+ channels (VDCCs) of the L-type (Ca(v)1.2) and release from the endoplasmic reticulum. Inhibition of TRPM4 by shRNA inhibited adipogenesis as indicated by the reduction in lipid droplet accumulation and adipocyte gene expression. These results suggest that TRPM4 is an important regulator of Ca2+ signals generated by histamine in hASCs and is required for adipogenesis.

Human adipose-derived mesenchymal stromal cell pigment epithelium-derived factor cytotherapy modifies genetic and epigenetic profiles of prostate cancer cells.

BACKGROUND AIMS: Adipose-derived mesenchymal stromal cells (ASCs) are promising tools for delivery of cytotherapy against cancer. However, ASCs can exert profound effects on biological behavior of tumor cells. Our study aimed to examine the influence of ASCs on gene expression and epigenetic methylation profiles of prostate cancer cells as well as the impact of expressing a therapeutic gene on modifying the interaction between ASCs and prostate cancer cells. METHODS: ASCs were modified by lentiviral transduction to express either green fluorescent protein as a control or pigment epithelium-derived factor (PEDF) as a therapeutic molecule. PC3 prostate cancer cells were cultured in the presence of ASC culture-conditioned media (CCM), and effects on PC3 or DU145. Ras cells were examined by means of real-time quantitative polymerase chain reaction, EpiTect methyl prostate cancer-focused real-time quantitative polymerase chain reaction arrays, and luciferase reporter assays. RESULTS: ASCs transduced with lentiviral vectors were able to mediate expression of several tumor-inhibitory genes, some of which correlated with epigenetic methylation changes on cocultured PC3 prostate cancer cells. When PC3 cells were cultured with ASC-PEDF CCM, we observed a shift in the balance of gene expression toward tumor inhibition, which suggests that PEDF reduces the potential tumor-promoting activity of unmodified ASCs. CONCLUSIONS: These results suggest that ASC-PEDF CCM can promote reprogramming of tumor cells in a paracrine manner. An improved understanding of genetic and epigenetic events in prostate cancer growth in response to PEDF paracrine therapy would enable a more effective use of ASC-PEDF, with the goal of achieving safer yet more potent anti-tumor effects.

Granular Hydrogels Improve Myogenic Invasion and Repair after Volumetric Muscle Loss.

Skeletal muscle injuries including volumetric muscle loss (VML) lead to excessive tissue scarring and permanent functional disability. Despite its high prevalence, there is currently no effective treatment for VML. Bioengineering interventions such as biomaterials that fill the VML defect to support cell and tissue growth are a promising therapeutic strategy. However, traditional biomaterials developed for this purpose lack the pore features needed to support cell infiltration. The present study investigates for the first time, the impact of granular hydrogels on muscle repair - hypothesizing that their flowability will permit conformable filling of the defect site and their inherent porosity will support the invasion of native myogenic cells, leading to effective muscle repair. Small and large microparticle fragments are prepared from photocurable hyaluronic acid polymer via extrusion fragmentation and facile size sorting. In assembled granular hydrogels, particle size and degree of packing significantly influence pore features, rheological behavior, and injectability. Using a mouse model of VML, it is demonstrated that, in contrast to bulk hydrogels, granular hydrogels support early-stage (satellite cell invasion) and late-stage (myofiber regeneration) muscle repair processes. Together, these results highlight the promising potential of injectable and porous granular hydrogels in supporting endogenous repair after severe muscle injury.

Interleukin-27 expression modifies prostate cancer cell crosstalk with bone and immune cells in vitro.

Prostate cancer is frequently associated with bone metastases, where the crosstalk between tumor cells and key cells of the bone microenvironment (osteoblasts, osteoclasts, immune cells) amplifies tumor growth. We have explored the potential of a novel cytokine, interleukin-27 (IL-27), for inhibiting this malignant crosstalk, and have examined the effect of autocrine IL-27 on prostate cancer cell gene expression, as well as the effect of paracrine IL-27 on gene expression in bone and T cells. In prostate tumor cells, IL-27 upregulated genes related to its signaling pathway while downregulating malignancy-related receptors and cytokine genes involved in gp130 signaling, as well as several protease genes. In both undifferentiated and differentiated osteoblasts, IL-27 modulated upregulation of genes related to its own signaling pathway as well as pro-osteogenic genes. In osteoclasts, IL-27 downregulated several genes typically involved in malignancy and also downregulated osteoclastogenesis-related genes. Furthermore, an osteogenesis-focused real-time PCR array revealed a more extensive profile of pro-osteogenic gene changes in both osteoblasts and osteoclasts. In T-lymphocyte cells, IL-27 upregulated several activation-related genes and also genes related to the IL-27 signaling pathway and downregulated several genes that could modulate osteoclastogenesis. Overall, our results suggest that IL-27 may be able to modify interactions between prostate tumor and bone microenvironment cells and thus could be used as a multifunctional therapeutic for restoring bone homeostasis while treating metastatic prostate tumors.

Poly I:C-priming of adipose-derived mesenchymal stromal cells promotes a pro-tumorigenic phenotype in an immunocompetent mouse model of prostate cancer.

Introduction: Mesenchymal stromal cells (MSC) are envisioned as a potential cellular vehicle for targeted cancer therapies due to their tumor tropism and immune permissiveness. An obstacle in their use is the duality in their interactions within tumors, rendering them pro-tumorigenic or anti-tumorigenic, in a context dependent manner. MSC preconditioning, or priming, has been proposed as a strategy for directing the effector properties of MSC at tumor sites. Methods: We primed human MSC derived from adipose tissues (ASC), a clinically advantageous MSC source, utilizing toll-like receptor agonists. Subsequently, we explored the consequences in tumor progression and transcriptome upon the interaction of tumor cells with primed or unprimed ASC in an in vivo model of prostate cancer, the second most common cancer and second leading cause of cancer related death in men in the USA. Results and discussion: In the studied model, poly I:C-primed ASC were found to significantly accelerate tumor growth progression. And while unprimed and LPS-primed ASC did not exert a significant effect on tumor growth at the macroscopic level, gene expression analyses suggested that all treatments promoted distinct modulatory effects in the tumor microenvironment, including altered modulation of angiogenesis, and immune response processes. However, the effects resulting from the collective interaction across these processes must be sufficiently skewed in a pro-tumorigenic or anti-tumorigenic direction for evidence of tumor progression modulation to be detectable at the macroscopic level. Our study highlights potential MSC-tumor microenvironment interactions that may be leveraged and should be considered in the development of cancer therapeutics utilizing MSC.

Cabozantinib and IL-27 combinatorial therapy for bone-metastatic prostate cancer.

Introduction: Prostate cancer is the second leading cause of cancer-related death among American men. Prostate tumor cells exhibit significant tropism for the bone and once metastasis occurs, survival rates fall significantly. Current treatment options are not curative and focus on symptom management. Immunotherapies are rapidly emerging as a possible therapeutic option for a variety of cancers including prostate cancer, however, variable patient response remains a concern. Chemotherapies, like cabozantinib, can have immune-priming effects which sensitize tumors to immunotherapies. Additionally, lower doses of chemotherapy can be used in this context which can reduce patient side effects. We hypothesized that a combination of chemotherapy (cabozantinib) and immunotherapy [Interleukin-27 (IL-27)] could be used to treat bone-metastatic prostate cancer and exert pro-osteogenic effects. IL-27 is a multi-functional cytokine, which promotes immune cell recruitment to tumors, while also promoting bone repair. Methods: To test this hypothesis, in vivo experiments were performed where syngeneic C57BL/6J mice were implanted intratibially with TRAMP-C2ras-Luc cells that are able to form tumors in bone. Immunotherapy was administered in the form of intramuscular gene therapy, delivering plasmid DNA encoding a reporter gene (Lucia), and/or a therapeutic gene (IL-27). Sonoporation was used to aid gene delivery. Following immunotherapy, the animals received either cabozantinib or a vehicle control by oral gavage. Bioluminescence imaging was used to monitor tumor size over time. Results: Combinatorial therapy inhibited tumor growth and improved survival. Further, RNA sequencing was used to investigate the mechanisms involved. Microcomputed tomography and differentiation assays indicated that the combination therapy improved bone quality by enhancing osteoblast differentiation and inhibiting osteoclast differentiation. Discussion: Our conclusion is that a chemo-immunotherapy approach such as the one examined in this work has potential to emerge as a novel therapeutic strategy for treating bone-metastatic prostate cancer. This approach will enable a significant reduction in chemotherapy-associated toxicity, enhance sensitivity to immunotherapy, and improve bone quality.

Engineering NK-CAR.19 cells with the IL-15/IL-15Rα complex improved proliferation and anti-tumor effect in vivo.

Introduction: Natural killer 92 (NK-92) cells are an attractive therapeutic approach as alternative chimeric antigen receptor (CAR) carriers, different from T cells, once they can be used in the allogeneic setting. The modest in vivo outcomes observed with NK-92 cells continue to present hurdles in successfully translating NK-92 cell therapies into clinical applications. Adoptive transfer of CAR-NK-92 cells holds out the promise of therapeutic benefit at a lower rate of adverse events due to the absence of GvHD and cytokine release syndrome. However, it has not achieved breakthrough clinical results yet, and further improvement of CAR-NK-92 cells is necessary. Methods: In this study, we conducted a comparative analysis between CD19-targeted CAR (CAR.19) co-expressing IL-15 (CAR.19-IL15) with IL-15/IL-15Rα (CAR.19-IL15/IL15Rα) to promote NK cell proliferation, activation, and cytotoxic activity against B-cell leukemia. CAR constructs were cloned into lentiviral vector and transduced into NK-92 cell line. Potency of CAR-NK cells were assessed against CD19-expressing cell lines NALM-6 or Raji in vitro and in vivo in a murine model. Tumor burden was measured by bioluminescence. Results: We demonstrated that a fourth- generation CD19-targeted CAR (CAR.19) co-expressing IL-15 linked to its receptor IL-15/IL-15Rα (CAR.19-IL-15/IL-15Rα) significantly enhanced NK-92 cell proliferation, proinflammatory cytokine secretion, and cytotoxic activity against B-cell cancer cell lines in vitro and in a xenograft mouse model. Conclusion: Together with the results of the systematic analysis of the transcriptome of activated NK-92 CAR variants, this supports the notion that IL-15/IL-15Rα comprising fourth-generation CARs may overcome the limitations of NK-92 cell-based targeted tumor therapies in vivo by providing the necessary growth and activation signals.

Mutant Hras(G12V) and Kras(G12D) have overlapping, but non-identical effects on hepatocyte growth and transformation frequency in transgenic mice.

BACKGROUND: Mouse hepatocarcinogenesis is associated with mutations in Hras, but infrequently in Kras. The effect on carcinogenesis of developmental age at the time of ras mutation remains unknown. AIM: We sought to compare quantitatively the effects of expressing mutant H- or Kras genes in fetal vs. adult mouse liver. METHODS: We established an inducible system of gene expression in mouse liver to define disease pathogenesis associated with activation of oncogene expression. RESULTS: Diffuse expression of either oncogene in fetal or adult hepatocytes caused hepatomegaly. For mutant Hras(G12V), this phenotype was almost fully reversible and accompanied by apoptosis, indicating that maintenance of hepatomegaly requires continuous Hras(G12V) expression. We also examined the effect of ras expression on growth of transplanted hepatocytes in an in vivo system that allows us to quantify hepatocyte growth effects in both permissive and restrictive hepatic growth environments. Mutant Kras(G12D) had no effect on hepatocyte growth in this system. In contrast, Hras(G12V) induced increased hepatocyte focus growth in quiescent liver, the hallmark of a cell autonomous growth stimulus. Hras(G12V) also increased the fraction of donor hepatocyte foci that displayed extreme growth, a characteristic of preneoplastic lesions. CONCLUSIONS: The primary effect of diffuse, whole-liver expression of either mutant ras gene in fetal or adult mouse liver is diffuse and progressive hepatic growth. Hras(G12V) mutation influences hepatocarcinogenesis by conferring cell autonomous growth potential upon foci of expressing cells and by increasing the risk of neoplastic progression. Kras(G12D) does not share these latter carcinogenic effects in mouse liver.

Immunotherapy by mesenchymal stromal cell delivery of oncolytic viruses for treating metastatic tumors.

Oncolytic viruses (OVs) have emerged as a very promising anti-cancer therapeutic strategy in the past decades. However, despite their pre-clinical promise, many OV clinical evaluations for cancer therapy have highlighted the continued need for their improved delivery and targeting. Mesenchymal stromal cells (MSCs) have emerged as excellent candidate vehicles for the delivery of OVs due to their tumor-homing properties and low immunogenicity. MSCs can enhance OV delivery by protecting viruses from rapid clearance following administration and also by more efficiently targeting tumor sites, consequently augmenting the therapeutic potential of OVs. MSCs can function as "biological factories," enabling OV amplification within these cells to promote tumor lysis following MSC-OV arrival at the tumor site. MSC-OVs can promote enhanced safety profiles and therapeutic effects relative to OVs alone. In this review we explore the general characteristics of MSCs as delivery tools for cancer therapeutic agents. Furthermore, we discuss the potential of OVs as immune therapeutics and highlight some of the promising applications stemming from combining MSCs to achieve enhanced delivery and anti-tumor effectiveness of OVs at different pre-clinical and clinical stages. We further provide potential pitfalls of the MSC-OV platform and the strategies under development for enhancing the efficacy of these emerging therapeutics.

Generation of the Chondroprotective Proteomes by Activating PI3K and TNFα Signaling.

PURPOSE: To develop a novel treatment option for Chondrosarcoma (CS) and inflammatory arthritis, we evaluated a counterintuitive approach of activating tumorigenic and inflammatory signaling for generating joint-protective proteomes. METHODS: We employed mesenchymal stem cells and chondrocytes to generate chondroprotective proteomes by activating PI3K signaling and the administration of TNFα. The efficacy of the proteomes was examined using human and mouse cell lines as well as a mouse model of CS. The regulatory mechanism was analyzed using mass spectrometry-based whole-genome proteomics. RESULTS: While tumor progression and inflammatory responses were promoted by activating PI3K signaling and the administration of TNFα to CS cells and chondrocytes, those cells paradoxically generated a chondroprotective conditioned medium (CM). The application of CM downregulated tumorigenic genes in CS cells and TNFα and MMP13 in chondrocytes. Mechanistically, Hsp90ab1 was enriched in the chondroprotective CM, and it immunoprecipitated GAPDH. Extracellular GAPDH interacted with L1CAM and inhibited tumorigenic behaviors, whereas intracellular GAPDH downregulated p38 and exerted anti-inflammatory effects. CONCLUSIONS: We demonstrated that the unconventional approach of activating oncogenic and inflammatory signaling can generate chondroprotective proteomes. The role of Hsp90ab1 and GAPDH differed in their locations and they acted as the uncommon protectors of the joint tissue from tumor and inflammatory responses.

Correction: Sun et al. Generation of the Chondroprotective Proteomes by Activating PI3K and TNFα Signaling. Cancers 2022, 14, 3039.

In the original article [...].

Enhancing Prednisone-Based Arthritis Therapy with Targeted IL-27 Gene Delivery.

Rheumatoid arthritis (RA) is a chronic autoimmune disease which is characterized primarily by synovial hyperplasia and accumulation of several types of immune infiltrates that promote progressive destruction of the articular structure. Glucocorticoids are often prescribed to treat RA because of their strong anti-inflammatory and immunosuppressive effects. However, their application must be limited to the short-term due to a risk of adverse events. In the present study, we examined the potential combination of low-dose prednisone with gene delivery of an agent of promising and complementary effectiveness in RA, interleukin (IL)-27. IL-27 has been shown to have anti-inflammatory potential, while also acting as an effective bone-normalization agent in prior reports. The present report examined a version of IL-27 targeted at the C-terminus with a short 'peptide L' (pepL, LSLITRL) that binds the interleukin 6 receptor α (IL-6Rα) upregulated during inflammation. By focusing on this targeted form, IL-27pepL or 27pL, we examined whether the anti-inflammatory potential of prednisone (at a relatively low dose and short duration) could be further enhanced in the presence of 27pL as a therapy adjuvant. Our results indicate that 27pL represents a novel tool for use as an adjuvant with current therapeutics, such as prednisone, against inflammatory conditions.

Cell-cycle regulators cdk2ap1 and bicalutamide suppress malignant biological interactions between prostate cancer and bone cells.

INTRODUCTION: We examined whether the novel cell-cycle regulator cdk2-associated protein 1 (p12(cdk2ap1) or cdk2ap1), recently shown to regulate prostate cancer cell cycle and apoptosis, could have the capacity to reduce invasiveness and/or reduce malignant biological interactions between prostate cancer and bone cells. We also examined whether combining two cell-cycle arrest stimuli, cdk2ap1 plus bicalutamide (or casodex, CDX), could help enhance inhibition of prostate cancer cell phenotypes. METHODS: We stably expressed cdk2ap1 in prostate cancer cell lines using lentiviral vectors, as well as several different co-culture assays to quantify cellular invasion, migration, and the effect of the treatments on interaction with the bone microenvironment. RESULTS: We have determined that cdk2ap1 can further augment the effects of CDX on cell-cycle arrest, growth inhibition, and cellular invasion. Using a coculture model, we observed that either cdk2ap1 or cdk2ap1/CDX combination were able to reduce chemotaxis towards osteoblasts, and also reduce the osteoblastic proliferative response to prostate cancer. Also modified by cdk2ap1 and CDX were several signaling pathways associated with prostate cancer/bone crosstalk mechanisms involved in prostate cancer progression. CONCLUSIONS: These results suggest that either cdk2ap1 or the cdk2ap1/CDX combination hold promise in regulating prostate cancer growth and malignant phenotypes, and potentially also in reducing procarcinogenic interactions with a bone microenvironment model, restoring malignant phenotypes and signaling to a more benign state.

Quantifying growth and transformation frequency of oncogene-expressing mouse hepatocytes in vivo.

UNLABELLED: Gene changes can affect cancer cells in many ways, but changes that increase disease severity--by allowing cells to proliferate when they should be quiescent, by enhancing their rate of growth under growth permissive conditions, or by increasing the risk that they will accumulate additional carcinogenic alterations--must be identified so that strategies to counter their effects can be developed. We describe a novel in vivo assay system based on hepatocyte transplantation that permits us to accomplish this objective for genetically modified hepatocytes. We find that the oncogenes c-myc and transforming growth factor alpha, but not simian virus 40 T-antigen, increase the rate of hepatocyte growth under growth permissive conditions. However, no single oncogene can induce hepatocyte growth in quiescent liver. In contrast, at least one oncogene combination, transforming growth factor alpha/T-antigen, was sufficient to direct cell autonomous growth even in this nonpermissive environment. Furthermore, we could quantify risk for progression to neoplasia associated with oncogene expression; increased transformation frequency was the principal carcinogenic effect of T-antigen. CONCLUSION: This system identifies biological mechanistic role(s) in carcinogenesis for candidate genetic changes implicated in development of human liver cancer. The quantitative and comparative evaluation of gene effects on liver cancer allows us to prioritize targets for therapeutic intervention.

Reengineering Tumor Microenvironment with Sequential Interleukin Delivery.

Some cytokines can reengineer anti-tumor immunity to modify the tumor micro-environment. Interleukin-27 (IL-27) can partially reduce tumor growth in several animal models, including prostate cancer. We hypothesized that addition of IL-18, which can induce the proliferation of several immune effector cells through inducing IFNγ could synergize with IL-27 to enhance tumor growth control. We describe our findings on the effects of IL-27 gene delivery on prostate cancer cells and how sequential therapy with IL-18 enhanced the efficacy of IL-27. The combination of IL-27 followed by IL-18 (27→18) successfully reduced cancer cell viability, with significant effects in cell culture and in an immunocompetent mouse model. We also examined a novel chimeric cytokine, comprising an IL-27 targeted at the C-terminus with a short peptide, LSLITRL (27pepL). This novel cytokine targets a receptor upregulated in tumor cells (IL-6Rα) via the pepL ligand. Interestingly, when we compared the 27→18 combination with the single 27pepL therapy, we observed a similar efficacy for both. This efficacy was further enhanced when 27pepL was sequenced with IL-18 (27pepL→18). The observed reduction in tumor growth and significantly enriched canonical pathways and upstream regulators, as well as specific immune effector signatures (as determined by bioinformatics analyses in the tumor microenvironment) supported the therapeutic design, whereby IL-27 or 27pepL can be more effective when delivered with IL-18. This cytokine sequencing approach allows flexible incorporation of both gene delivery and recombinant cytokines as tools to augment IL-27's bioactivity and reengineer efficacy against prostate tumors and may prove applicable in other therapeutic settings.

Comprehensive evaluation of the role of EZH2 in the growth, invasion, and aggression of a panel of prostate cancer cell lines.

BACKGROUND: Although most prostate cancers respond well to initial treatments, a fraction of prostate cancers are more aggressive and will recur and metastasize. At that point, there are few treatment options available. Significant efforts have been made to identify biomarkers that will identify these more aggressive cancers to tailor a more vigorous treatment in order to improve outcome. Polycomb Group protein enhancer of zeste 2 (EZH2) was found to be overexpressed in metastatic prostate tumors, and is considered an excellent candidate for such a biomarker. Scattered studies have found that EZH2 overexpression causes neoplastic transformation, invasion, and growth of prostate cells. However, these studies utilized different systems and cell lines, and so are difficult to correlate with one another. METHODS: In this study, a comprehensive evaluation of the phenotypic effects of EZH2 in a panel of five prostate cancer cell lines was performed. By using multiple cell lines, and examining overexpression and knockdown of EZH2 concurrently, a broad view of EZH2's role in prostate cancer was achieved. RESULTS: Overexpression of EZH2 led to more aggressive behaviors in all prostate cell lines tested. In contrast, downregulation of EZH2 reduced invasion and tumorigenicity of androgen-independent (AI) cell lines CWR22Rv1, PC3, and DU145, but not of androgen-dependent (AD) cell lines LAPC4 and LNCaP. CONCLUSIONS: Findings from this study suggest that AI prostate tumors are more dependent on EZH2 expression than AD tumors. Our observations provide an explanation for the strong correlation between EZH2 overexpression and advanced stage, aggressive prostate cancers.

Novel tumor growth inhibition mechanism by cell cycle regulator cdk2ap1 involves antiangiogenesis modulation.

We evaluated the effect of expressing the cell cycle regulator protein cdk2-associating protein1 (cdk2ap1) in inhibiting growth of squamous cell carcinoma (SCC). Expression of cdk2ap1 correlated with reduction in several SCC malignant cell phenotypes, including reduced angiogenesis. We observed several alterations in gene expression consistent with classical functions of cdk2ap1, including upregulation of cell cycle inhibitory genes, and an upregulation in expression of genes belonging to both intrinsic and extrinsic apoptotic cascades. Interestingly, we also uncovered a profile of gene expression and activation of signaling pathways that may suggest new tumor-suppressive functions for cdk2ap1 through downregulation of invasion/metastasis and modulation of antiangiogenesis by upregulation of the TGFß signaling pathway. Blocking of the TGFß1 pathway resulted in inhibition of the cdk2ap1 antiangiogenesis phenotype. In combination, these data support the role of cdk2ap1 as a tumor suppressor gene that can regulate SCC tumor growth in a cell autonomous manner through decreases in invasiveness and a non-cell autonomous manner through decreases in angiogenesis phenotypes, and these are novel phenotypes induced by cdk2ap1.