Suppression of Her2/Neu mammary tumor development in mda-7/IL-24 transgenic mice

Independent organelle and organelle-organelle interactions: essential mechanisms for malignant gynecological cancer cell survival

Different eukaryotic cell organelles (e.g., mitochondria, endoplasmic reticulum, lysosome) are involved in various cancer processes, by dominating specific cellular activities. Organelles cooperate, such as through contact points, in complex biological activities that help the cell regulate energy metabolism, signal transduction, and membrane dynamics, which influence survival process. Herein, we review the current studies of mechanisms by which mitochondria, endoplasmic reticulum, and lysosome are related to the three major malignant gynecological cancers, and their possible therapeutic interventions and drug targets. We also discuss the similarities and differences of independent organelle and organelle-organelle interactions, and their applications to the respective gynecological cancers; mitochondrial dynamics and energy metabolism, endoplasmic reticulum dysfunction, lysosomal regulation and autophagy, organelle interactions, and organelle regulatory mechanisms of cell death play crucial roles in cancer tumorigenesis, progression, and response to therapy. Finally, we discuss the value of organelle research, its current problems, and its future directions.

PERP-ing into diverse mechanisms of cancer pathogenesis: Regulation and role of the p53/p63 effector PERP

The tetraspan plasma membrane protein PERP (p53 apoptosis effector related to PMP22) is a lesser-known transcriptional target of p53 and p63. A member of the PMP22/GAS3/EMP membrane protein family, PERP was originally identified as a p53 target specifically trans-activated during apoptosis, but not during cell-cycle arrest. Several studies have since shown downregulation of PERP expression in numerous cancers, suggesting that PERP is a tumour suppressor protein. This review focusses on the important advances made in elucidating the mechanisms regulating PERP expression and its function as a tumour suppressor in diverse human cancers, including breast cancer and squamous cell carcinoma. Investigating PERP's role in clinically-aggressive uveal melanoma has revealed that PERP engages a positive-feedback loop with p53 to regulate its own expression, and that p63 is required beside p53 to achieve pro-apoptotic levels of PERP in this cancer. Furthermore, the recent discovery of the apoptosis-mediating interaction of PERP with SERCA2b at the plasma membrane-endoplasmic reticulum interface demonstrates a novel mechanism of PERP stabilisation, and how PERP can mediate Ca²⁺ signalling to facilitate apoptosis. The multi-faceted role of PERP in cancer, involving well-documented functions in mediating apoptosis and cell-cell adhesion is discussed, alongside PERP's emerging roles in epithelial-mesenchymal transition, and PERP crosstalk with inflammation signalling pathways, and other signalling pathways. The potential for restoring PERP expression as a means of cancer therapy is also considered.

Fli-1 Activation through Targeted Promoter Activity Regulation Using a Novel 3', 5'-diprenylated Chalcone Inhibits Growth and Metastasis of Prostate Cancer Cells

The friend leukemia integration 1 (Fli-1) gene is involved in the expression control of key genes in multiple pathogenic/physiological processes, including cell growth, differentiation, and apoptosis; this implies that Fli-1 is a strong candidate for drug development. In our previous study, a 3′,5′-diprenylated chalcone, (E)-1-(2-hydroxy-4-methoxy-3,5-diprenyl) phenyl-3-(3-pyridinyl)-propene-1-one (C10), was identified as a novel anti-prostate cancer (PCa) agent. Here, we investigated the molecular mechanisms underlying the anti-cancer effects of C10 on the growth, metastasis, and invasion of PC3 cells in vitro. Our results show that C10 exhibited a strong inhibitory effect on proliferation and metastasis of PC3 cells via several cellular and flow cytometric analyses. Further mechanism studies revealed that C10 likely serves as an Fli-1 agonist for regulating the expression of Fli-1 target genes including phosphatidylinositol 3-kinase (P110), murine double minute2 (MDM2), B-cell lymphoma-2 (Bcl-2), Src homology-2 domain-containing inositol 5-phosphatase 1 (SHIP-1), and globin transcription factor-1 (Gata-1) as well as the phosphorylation of extracellular-regulated protein kinases 1 (ERK1). Further, we confirmed that C10 can regulate the expressions of vascular endothelial growth factor 1 (VEGF-1), transforming growth factor-β2 (TGF-β2), intercellular cell adhesion molecule-1 (ICAM-1), p53, and matrix metalloproteinase 1 (MMP-1) genes associated with tumor apoptosis, migration, and invasion. Thus, C10 exhibits stronger anticancer activity with novel molecular targets and regulatory molecular mechanisms, indicating its great potency for development as a novel targeted anticancer drug.

IL-24 inhibits endometrial cancer cell proliferation by promoting apoptosis through the mitochondrial intrinsic signaling pathway

BACKGROUND

Endometrial cancer is a type of malignant tumor of the female reproductive system. Preserving fertility in endometrial cancer patients is currently a formidable challenge. Interleukin-24 (IL-24) is a unique cytokine tumor suppressor gene belonging to the IL-10 cytokine family. IL-24 has broad-spectrum antitumor activity through different signaling pathways but does not affect normal cells. IL-24 gene therapy may provide a new method for the treatment of endometrial cancer.

METHODS

Transfection was used for gene transfer. The expression of IL-24 and related pathway proteins in endometrial cancer tissue and the Ishikawa cell line was detected by immunohistochemistry and Western blotting, respectively. The antitumor function of IL-24 was examined in vitro and in vivo. Cell proliferation was determined by CCK-8 assay, cell migration was shown by wound-healing assay, and cell invasion was detected by Transwell assay. Apoptosis was analyzed by TUNEL assay, and HE staining was performed to observe the morphology of the samples.

RESULTS

Immunohistochemical analysis showed different expression levels of IL-24 in human endometrial cancer tissues and normal endometrial tissues. IL-24 increased protein expression of BAX and Cytochrome C, while BCL-2, MMP-3, VEGF, Caspase-9 and Caspase-3 expression was decreased. Overexpression of IL-24 inhibited cell proliferation, migration and invasion, but increased cell apoptosis in endometrial cancer. Mechanistically, we demonstrated that IL-24 inhibited endometrial cancer cell growth by inducing cell apoptosis through the mitochondrial intrinsic signaling pathway. In addition, IL-24 inhibited tumor development by inducing cell apoptosis and inhibiting angiogenesis, as shown in xenograft tumor experiments.

CONCLUSIONS

Our study demonstrates the antitumor effect of IL-24 on endometrial cancer and shows that IL-24 may be a promising therapeutic gene for endometrial cancer gene therapy.

Recent insights into apoptosis and toxic autophagy: The roles of MDA-7/IL-24, a multidimensional anti-cancer therapeutic

Apoptosis and autophagy play seminal roles in maintaining organ homeostasis. Apoptosis represents canonical type I programmed cell death. Autophagy is viewed as pro-survival, however, excessive autophagy can promote type II cell death. Defective regulation of these two obligatory cellular pathways is linked to various diseases, including cancer. Biologic or chemotherapeutic agents, which can reprogram cancer cells to undergo apoptosis- or toxic autophagy-mediated cell death, are considered effective tools for treating cancer. Melanoma differentiation associated gene-7 (mda-7) selectively promotes these effects in cancer cells. mda-7 was identified more than two decades ago by subtraction hybridization showing elevated expression during induction of terminal differentiation of metastatic melanoma cells following treatment with recombinant fibroblast interferon and mezerein (a PKC activating agent). MDA-7 was classified as a member of the IL-10 gene family based on its chromosomal location, and the presence of an IL-10 signature motif and a secretory sequence, and re-named interleukin-24 (MDA-7/IL-24). Multiple studies have established MDA-7/IL-24 as a potent anti-cancer agent, which when administered at supra-physiological levels induces growth arrest and cell death through apoptosis and toxic autophagy in a wide variety of tumor cell types, but not in corresponding normal/non-transformed cells. Furthermore, in a phase I/II clinical trial, MDA-7/IL-24 administered by means of a non-replicating adenovirus was well tolerated and displayed significant clinical activity in patients with multiple advanced cancers. This review examines our current comprehension of the role of MDA-7/IL-24 in mediating cancer-specific cell death via apoptosis and toxic autophagy.

Tumor angiogenesis and anti-angiogenic gene therapy for cancer

When Folkman first suggested a theory about the association between angiogenesis and tumor growth in 1971, the hypothesis of targeting angiogenesis to treat cancer was formed. Since then, various studies conducted across the world have additionally confirmed the theory of Folkman, and numerous efforts have been made to explore the possibilities of curing cancer by targeting angiogenesis. Among them, anti-angiogenic gene therapy has received attention due to its apparent advantages. Although specific problems remain prior to cancer being fully curable using anti-angiogenic gene therapy, several methods have been explored, and progress has been made in pre-clinical and clinical settings over previous decades. The present review aimed to provide up-to-date information concerning tumor angiogenesis and gene delivery systems in anti-angiogenic gene therapy, with a focus on recent developments in the study and application of the most commonly studied and newly identified anti-angiogenic candidates for anti-angiogenesis gene therapy, including interleukin-12, angiostatin, endostatin, tumstatin, anti-angiogenic metargidin peptide and endoglin silencing.

Enhanced tumor growth inhibition by mesenchymal stem cells derived from iPSCs with targeted integration of interleukin24 into rDNA loci

Induced pluripotent stem cells (iPSCs) are a promising source of mesenchymal stem cells (MSCs) for clinical applications. In this study, we transformed human iPSCs using a non-viral vector carrying the IL24 transgene pHrn-IL24. PCR and southern blotting confirmed IL24 integration into the rDNA loci in four of 68 iPSC clones. We then differentiated a high expressing IL24-iPSC clone into MSCs (IL24-iMSCs) that showed higher expression of IL24 in culture supernatants and in cell lysates than control iMSCs. IL24-iMSCs efficiently differentiated into osteoblasts, chondrocytes and adipocytes. Functionally, IL24-iMSCs induced in vitro apoptosis in B16-F10 melanoma cells more efficiently than control iMSCs when co-cultured in Transwell assays. In vivo tumor xenograft studies in mice demonstrated that IL24-iMSCs inhibited melanoma growth more than control iMSCs did. Immunofluorescence and histochemical analysis showed larger necrotic areas and cell nuclear aggregation in tumors with IL24-iMSCs than control iMSCs, indicating that IL24-iMSCs inhibited tumor growth by inducing apoptosis. These findings demonstrate efficient transformation of iPSCs through gene targeting with non-viral vectors into a rDNA locus. The ability of these genetically modified MSCs to inhibit in vivo melanoma growth is suggestive of the clinical potential of autologous cell therapy in cancer.

A screen for Fli-1 transcriptional modulators identifies PKC agonists that induce erythroid to megakaryocytic differentiation and suppress leukemogenesis

The ETS-related transcription factor Fli-1 affects many developmental programs including erythroid and megakaryocytic differentiation, and is frequently de-regulated in cancer. Fli-1 was initially isolated following retrovirus insertional mutagenesis screens for leukemic initiator genes, and accordingly, inhibition of this transcription factor can suppress leukemia through induction of erythroid differentiation. To search for modulators of Fli-1, we hereby performed repurposing drug screens with compounds isolated from Chinese medicinal plants. We identified agents that can transcriptionally activate or inhibit a Fli-1 reporter. Remarkably, agents that increased Fli-1 transcriptional activity conferred a strong anti-cancer activity upon Fli-1-expressing leukemic cells in culture. As opposed to drugs that suppress Fli1 activity and lead to erythroid differentiation, growth suppression by these new Fli-1 transactivating compounds involved erythroid to megakaryocytic conversion (EMC). The identified compounds are structurally related to diterpene family of small molecules, which are known agonists of protein kinase C (PKC). In accordance, these PKC agonists (PKCAs) induced PKC phosphorylation leading to activation of the mitogen-activated protein kinase (MAPK) pathway, increased cell attachment and EMC, whereas pharmacological inhibition of PKC or MAPK diminished the effect of our PKCAs. Moreover, in a mouse model of leukemia initiated by Fli-1 activation, the PKCA compounds exhibited strong anti-cancer activity, which was accompanied by increased presence of CD41/CD61 positive megakaryocytic cells in leukemic spleens. Thus, PKC agonists offer a novel approach to combat Fli-1-induced leukemia, and possibly other cancers,by inducing EMC in part through over-activation of the PKC-MAPK-Fli-1 pathway.

Fli-1 overexpression in erythroleukemic cells promotes erythroid de-differentiation while Spi-1/PU.1 exerts the opposite effect

The ETS transcription factors play a critical role during hematopoiesis. In F-MuLV-induced erythroleukemia, Fli-1 insertional activation producing high expression of this transcription factor required to promote proliferation. How deregulated Fli-1 expression alters the balance between erythroid differentiation and proliferation is unknown. To address this issue, we exogenously overexpressed Fli-1 in an erythroleukemic cell harboring activation of spi-1/PU.1, another ETS gene involved in erythroleukemogenesis. While the proliferation in culture remains unaffected, Fli-1 overexpression imparts morphological and immunohistochemical characteristics of immature erythroid progenitors. Fli-1 overexpression in erythroleukemic cells increased the numbers of erythroid colonies on methylcellulose and reduced tumorigenicity as evidenced by increase latency of erythroleukemogenesis in mice inoculated with these cells. Although all transplanted mice developed enlargement of the spleen and liver due to leukemic infiltration, Fli-1 overexpression altered the hematopoietic phenotype, significantly increasing the expression of regulatory hematopoietic genes cKIT, SCA-1, CD41 and CD71. In contrast, expression of Spi-1/PU.1 in a Fli-1 producing erythroleukemia cell line in which fli-1 is activated, resulted in increased proliferation through activation of growth promoting proteins MAPK, AKT, cMYC and JAK2. Importantly, these progenitors express high levels of markers such as CD71 and TER119 associated with more mature erythroid cells. Thus, Fli-1 overexpression induces a de-differentiation program by reverting CFU-E to BFU-E erythroid progenitor activity, while Spi-1/PU.1 promoting maturation from BFU-E to CFU-E.

Clinical applications of mouse models for breast cancer engaging HER2/neu

Human c-ErbB2 (HER2) has long been used as a marker of breast cancer (BC) for sub-categorization for the prediction of prognosis, and determination of therapeutic strategies. HER2 overexpressing BCs are more invasive/metastatic; but patients respond to monoclonal antibody therapy with trastuzumab or tyrosine kinase inhibitors, at least at early stages. To date, numerous mouse models that faithfully reproduce HER2(+) BCs have been created in mice. We recently reviewed different mouse models of BC overexpressing wild type or mutant neu driven by MMTV, neu, or doxycycline-inducible promoters. These mice have been used to demonstrate the histopathology, oncogenic signaling pathways initiated by aberrant overexpression of HER2 in the mammary epithelium, and interaction between oncogenes and tumor suppressor genes at molecular levels. In this review, we focus on their clinical applications. They can be used to test the efficacy of HER(2) inhibitors before starting clinical trials, characterize the tumor-initiating cells that could be the cause of relapse after therapy as well as to analyze the molecular mechanisms of therapeutic resistance targeting HER2. MMTV-human ErbB2 (HER2) mouse models have recently been established since the monoclonal antibody to HER2 (trastuzumab; Herceptin®) does not recognize the rat neu protein. It has been reported that early intervention with HER2 monoclonal antibody would be beneficial for preventing mammary carcinogenesis. MDA-7/IL-24 as well as naturally-occurring chemicals have also been tested using MMTV-neu models. Recent studies have shown that MMTV-neu models are useful to develop vaccines to HER2 for immunotherapy. The mouse models employing HER2/neu will be essential for future antibody or drug screenings to overcome resistance to trastuzumab or HER(2)-specific tyrosine kinase inhibitors.

Pro-inflammatory effect of a traditional Chinese medicine formula with potent anti-cancer activity in vitro impedes tumor inhibitory potential in vivo

Medicinal formulas are a part of the complex discipline of traditional Chinese medicine that has been used for centuries in China and East Asia. These formulas predominantly consist of the extracts isolated from herbal plants, animal parts and medicinal minerals. The present study aimed to investigate the impact of 150 formulas, used as non-prescription drugs in China, on the treatment of cancer. A formula was identified, C54, commonly used to treat sore throats, which exhibited marked growth inhibition in vitro, associated with cell cycle arrest and apoptosis. Cytotoxicity was, in part, due to the ability of C54 to inhibit the expression and function of the transcription factor, Fli-1, leading to marked inhibition of leukemic cell growth in tissue culture. However, when injected into a model of leukemia initiated by Fli-1 activation, C54 only exhibited a limited tumor inhibition. C54 also did not suppress xenograft growth of the breast cancer cell line, MDA-MB-231, orthopedically transplanted into the mammary fat pad of severe combined immunodeficiency (SCID) mice. Notably, splenomegaly and accumulation of inflammatory CD11b⁺/Gr1⁺ monocytes were observed in the tumors and spleens of C54-treated mice. As inflammation is known to accelerate tumor progression, this immune response may counteract the cell-autonomous effect of C54, and account for its limited tumor inhibitory effect in vivo. Combining C54 with an anti-inflammatory drug may improve the potency of C54 for treatment of certain cancers. The present study has highlighted the complexity of Chinese medicinal compounds and the need to thoroughly analyze their systemic effects at high concentrations in vivo.

MDA-7/IL-24 functions as a tumor suppressor gene in vivo in transgenic mouse models of breast cancer

Melanoma differentiation associated gene-7/Interleukin-24 (MDA-7/IL-24) is a novel member of the IL-10 gene family that selectively induces apoptosis and toxic autophagy in a broad spectrum of human cancers, including breast cancer, without harming normal cells or tissues. The ability to investigate the critical events underlying cancer initiation and progression, as well as the capacity to test the efficacy of novel therapeutics, has been significantly advanced by the development of genetically engineered mice (GEMs) that accurately recapitulate specific human cancers. We utilized three transgenic mouse models to better comprehend the in vivo role of MDA-7/IL-24 in breast cancer. Using the MMTV-PyMT spontaneous mammary tumor model, we confirmed that exogenously introducing MDA-7/IL-24 using a Cancer Terminator Virus caused a reduction in tumor burden and also produced an antitumor "bystander" effect. Next we performed xenograft studies in a newly created MMTV-MDA-7 transgenic model that over-expresses MDA-7/IL-24 in the mammary glands during pregnancy and lactation, and found that MDA-7/IL-24 overexpression delayed tumor growth following orthotopic injection of a murine PDX tumor cell line (mPDX) derived from a tumor formed in an MMTV-PyMT mouse. We also crossed the MMTV-MDA-7 line to MMTV-Erbb2 transgenic mice and found that MDA-7/IL-24 overexpression delayed the onset of mammary tumor development in this model of spontaneous mammary tumorigenesis as well. Finally, we assessed the role of MDA-7/IL-24 in immune regulation, which can potentially contribute to tumor suppression in vivo. Our findings provide further direct in vivo evidence for the role of MDA-7/IL-24 in tumor suppression in breast cancer in immune-competent transgenic mice.