Christian Marin-Muller

Current advances in research and clinical applications of PLGA-based nanotechnology

Co-polymer poly(lactic-co-glycolic acid) (PLGA) nanotechnology has been developed for many years and has been approved by the US FDA for the use of drug delivery, diagnostics and other applications of clinical and basic science research, including cardiovascular disease, cancer, vaccine and tissue engineering. This article presents the more recent successes of applying PLGA-based nanotechnologies and tools in these medicine-related applications. It focuses on the possible mechanisms, diagnosis and treatment effects of PLGA preparations and devices. This updated information will benefit to both new and established research scientists and clinical physicians who are interested in the development and application of PLGA nanotechnology as new therapeutic and diagnostic strategies for many diseases.

MicroRNAs: Control and loss of control in human physiology and disease

Analysis of the human genome indicates that a large fraction of the genome sequences are RNAs that do not encode any proteins, also known as non-coding RNAs. MicroRNAs (miRNAs) are a group of small non-coding RNA molecules 20–22 nucleotides (nt) in length that are predicted to control the activity of approximately 30% of all protein-coding genes in mammals. miRNAs play important roles in many diseases, including cancer, cardiovascular disease, and immune disorders. The expression of miRNAs can be regulated by epigenetic modification, DNA copy number change, and genetic mutations. miRNAs can serve as a valuable therapeutic target for a large number of diseases. For miRNAs with oncogenic capabilities, potential therapies include miRNA silencing, antisense blocking, and miRNA modifications. For miRNAs with tumor suppression functions, overexpression of those miRNAs might be a useful strategy to inhibit tumor growth. In this review, we discuss the current progress of miRNA research, regulation of miRNA expression, prediction of miRNA targets, and regulatory role of miRNAs in human physiology and diseases, with a specific focus on miRNAs in pancreatic cancer, liver cancer, colorectal cancer, cardiovascular disease, the immune system, and infectious disease. This review provides valuable information for clinicians and researchers who want to recognize the newest advances in this new field and identify possible lines of investigation in miRNAs as important mediators in human physiology and diseases.

Mesothelin overexpression promotes autocrine IL-6/sIL-6R trans-signaling to stimulate pancreatic cancer cell proliferation

Mesothelin (MSLN) overexpression in pancreatic cancer (PC) leads to enhanced cell survival/proliferation and tumor progression. After screening for a number of growth factors/cytokines, we found that the MSLN expression correlated closely with interleukin (IL)-6 in human PC specimens and cell lines. Stably overexpressing MSLN in different PC cell lines (MIA-MSLN and Panc1-MSLN) led to higher IL-6 production. Silencing MSLN by small interfering RNA (siRNA) significantly reduced IL-6 levels. Blocking the observed constitutive activation of nuclear factor-kappaB (NF-κB) with IKK inhibitor wedelolactone in MIA-MSLN cells also reduced IL-6. Silencing IL-6 by siRNA reduced cell proliferation, cell cycle progression and induced apoptosis with significant decrease of c-myc/bcl-2. Interestingly, recombinant IL-6-induced proliferation of MIA-MSLN cells but not MIA-V cells. Although messenger RNA/protein levels of IL-6R did not vary, soluble IL-6R (sIL-6R) was significantly elevated in MIA-MSLN and was reduced by treatment with the TACE/ADAM17 inhibitor TAPI-1, indicating intramembrane IL-6R cleavage and IL-6 trans-signaling may be operative in MIA-MSLN cells. Blocking the IL-6/sIL-6R axis using sIL-6R antibody abrogated basal proliferation/survival as well as recombinant human IL-6-induced cell proliferation. Our data suggest that MSLN-activated NF-κB induces elevated IL-6 expression, which acts as a growth factor to support PC cell survival/proliferation through a novel auto/paracrine IL-6/sIL-6R trans-signaling. In addition, using a panel of PC cells with varying MSLN/IL-6 expressions, we showed that MSLN/IL-6 axis is a major survival axis in PC supporting tumor cell growth under anchorage-dependent and independent conditions. The close correlation between MSLN and IL-6 provides a new rationale for combination therapy for effective control of MSLN-overexpressing PCs.

A tumorigenic factor interactome connected through tumor suppressor microRNA-198 in human pancreatic cancer.

Purpose: The majority of pancreatic cancers overexpress mesothelin (MSLN), which contributes to enhanced proliferation, invasion, and migration. However, the MSLN regulatory network is still unclear. Here, we investigated the regulation of a panel of tumorigenic factors and explored the potential of MSLN-regulated miR-198 treatment in vivo. Experimental Design: The expression and functional regulation of the tumorigenic factors MSLN, NF-κB, and the homeobox transcription factors (TF) POU2F2 (OCT-2), Pre-B-cell leukemia homeobox factor 1 (PBX-1), valosin-containing protein (VCP), and miR-198 were studied in pancreatic cancer cell lines, patient tumor samples, and xenograft pancreatic cancer mouse models. Results: We found that miR-198 is downregulated in pancreatic cancer and is involved in an intricate reciprocal regulatory loop with MSLN, which represses miR-198 through NF-κB–mediated OCT-2 induction. Furthermore, miR-198 repression leads to overexpression of PBX-1 and VCP. The dysregulated PBX-1/VCP axis leads to increased tumorigenicity. Reconstitution of miR-198 in pancreatic cancer cells results in reduced tumor growth, metastasis, and increased survival through direct targeting MSLN, PBX-1, and VCP. Most interestingly, reduced levels of miR-198 in human tissue samples are associated with upregulation of these tumorigenic factors (MSLN, OCT-2, PBX-1, VCP) and predict poor survival. Reduced miR-198 expression links this tumor network signature and prognosticates poor patient outcome. High miR-198 disrupts the network and predicts better prognosis and increased survival. Conclusions: miR-198 acts as a central tumor suppressor and modulates the molecular makeup of a critical interactome in pancreatic cancer, indicating a potential prognostic marker signature and the therapeutic potential of attacking this tumorigenic network through a central vantage point. Clin Cancer Res; 19(21); 5901–13. ©2013 AACR.

Current understanding and potential immunotherapy for HIV-associated squamous cell carcinoma of the anus (SCCA).

Squamous cell carcinoma of the anus (SCCA) is a rare disease in the average population but is an increasing concern among immunocompromised individuals, such as the HIV-seropositive. Coinfection with human papillomavirus (HPV) in this population is common. HPV infection is difficult to clear with a compromised immune system, which results in a greater risk of tumor development and a more aggressive progression of the disease. The recent approval of a prophylactic HPV vaccine for cervical cancer has sparked an interest in a search for improved immunotherapeutic multimodality therapies to combat anogenital tumors associated with the virus. In this review, we discuss the known mechanisms of action of HIV-associated SCCA, examine the current treatments for the disease, and focus on the potential of an immunotherapeutic vaccine approach for both prophylactic and therapeutic application.

Complete and repeatable inactivation of HIV-1 viral particles in suspension using a photo-labeled non-nucleoside reverse transcriptase inhibitor

A method is described for achieving repeatable, complete inactivation of HIV, based on photo-inactivation of HIV reverse transcriptase (RT) with a non-nucleoside reverse transcriptase inhibitor (NNRTI), photoactive 4-[[4-[(4-azido-2,6-dimethylphenyl) amino]-2-pyrimidinyl]amino]benzonitrile (PA-DAPYa). These results show that PA-DAPYa inactivated completely a suspension of cell-free HIV-1 viral particles in a dose and time-dependent manner. Using an ELISA assay for p24, it is demonstrated that a 500nM concentration of PA-DAPYa is able to inactivate 500 TCID50 of HIV viral particles in suspension when irradiated with non-microbicidal wavelength UV light for 30min. No active p24 was detected on days 7, 14, and 21 days after culturing the inactivated HIV in peripheral blood mononuclear cells (PBMCs). Several batches of large quantities of HIV viral particles were demonstrated to be inactivated completely and repeatedly by this method. Therefore, a reliable method has been developed to inactivate HIV viral particles in a reproducible manner using an optimal concentration of PA-DAPYa and duration of UV exposure time of the treated particles. The inactivation of viral particles in suspension allows for large-scale production of an injectable formulation of inactivated HIV viral particles for vaccine development which should preserve the conformational and antigenic integrity of viral surface proteins.

The Role of Mesothelin in Pancreatic Cancer

Mesothelin (MSLN) is a glycosylphosphatidylinositol (GPI)-anchored cell surface glycoprotein and differentiation antigen. MSLN gets its name from typically limited expression in the mesothelial lining of the pleural cavity, where it was first identified in 1996 by Chang and Pastan1. The human MSLN gene (localized to 16p21)2 encodes a 71-kDa precursor protein that is cleaved by furin-like proteinases to produce an amino-terminal 31 kDa soluble fragment, termed the megakaryocyte-potentiating factor (MPF), which is released to the extracellular fluid, and a carboxy-terminal 40 kDa membrane-bound fragment1,3,4.

Abstract 3960: Mesothelin overexpression promotes autocrine IL-6/sIL-6R trans-signaling to stimulate pancreatic cancer cell proliferation

Background: We have shown previously that mesothelin (MSLN) overexpression in pancreatic cancer (PC) cells leads to enhanced cell survival/proliferation in vitro & tumor progression in a xenograft mouse model. The objective of this study is to determine the underlying MSLN-induced growth factors/signaling that contribute to the PC cell proliferation. Methods: PC tissue/serum & cell lines were used to evaluate MSLN/IL-6 expression. MIA PaCa-2 & Panc1 cells stably over-expressing MSLN (MIA-MSLN, Panc1-MSLN) & vector control cell lines (MIA-V, Panc1-V) were generated by using retrovirus expression system. IL-6 was measured by BioPlex. Silencing of MSLN/IL-6 was done by using specific siRNAs. NF-κB activation was examined by western blot & reporter assay. Different forms of IL-6Rs were determined by western blot, real-time PCR & FACS. Cell proliferation was measured by MTT. Cell cycle analysis was performed using PI staining & apoptosis determination by caspase3 cleavage. Results and Conclusions: MSLN expression positively correlated with secreted IL-6 in a panel of human PC specimens (serum) & cell lines (supernatants). Both MIA-MSLN & Panc1-MSLN showed high IL-6 expression & siRNA silencing of MSLN significantly reduced the IL-6 level (p 5 day) induced apoptosis with significant decrease of c-myc/bcl-2 levels. Interestingly, exogenous rIL-6 induced proliferation of MIA-MSLN cells but not MIA-V cells. Although there were no changes in mRNA/protein levels of the IL-6R (gp80), the soluble fraction (sIL-6R) was significantly elevated in MIA-MSLN cells. Treatment with the TACE/ADAM17 inhibitor TAPI-1 significantly reduced sIL-6R levels, indicating intramembrane cleavage of IL-6R in these cells. This, along with the absence of any difference in membrane IL-6R suggested IL-6 trans-signaling operative in these cells. Consequently, blocking this IL-6/sIL-6R axis using sIL-6R specific antibody abrogated serum free survival as well as rIL-6-induced proliferation. Moreover, a rIL-6/rsIL-6R mix induced proliferation was observed even in MIA-V cells. Our data suggest MSLN-activated NF-κB induces elevated IL-6 expression, which acts as growth factor to support pancreatic cancer cell survival/proliferation through a novel auto/paracrine IL-6/sIL-6R trans-signaling. The close correlation between MSLN & IL-6 provides an opportunity for formulating a new combined therapy for effective control of MSLN-overexpressing 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 3960.