Projects |

Adar Gene Interference for Cancer Immunotherapy

Mon, 15 Nov 2021 00:00:00 +0000

The adenosine deaminase acting on RNA (ADAR) enzymes that have been identified to specifically recognizes and edits double-stranded RNA (dsRNA), catalyze the Adenosine-to-Inosine (A-to-I) RNA editing. They are widely expressed in most of higher eukaryotes, where tens of thousands of posttranscriptional editing of A-to-I conversions happen in inverted repeats that form long dsRNAs such as the Alu element. In the ADAR family, there’re catalytically active enzymes including ADAR1, ADAR2 and the inactive ADAR3. While ADAR2’s specific substrates are mainly in the brain tissue, ADAR1 is more ubiquitously expressed, and function as the primary editing enzyme converting A-to-I mutation. Since the inherent translational machinery reads inosine as guanosine, ADAR1 mediated A-to-I RNA editing results in non-synonymous coding changes (A-to-G mutation) (Yeo et al., 2010), potentially altering the protein encoded by the mRNA. Additionally, ADAR1 can also modulate microRNA pathways independent of its editing activity, employed only as the dsRNA binding protein without editing function. Mounting evidence indicates that the level of dsRNA recognition and editing by Adar1 plays an important role in restraining autoimmunity activity and maintaining self-tolerance, in which RNA editing is pivotal for controlling the cytoplasmic antiviral immunity. Intriguingly, mutations in humans and in mice models in ADAR1 can induce autoimmunity[1] and ADAR1 has recently been shown to regulate the canonical RNA sensing pathways such as RIG-I-like receptors (retinoic acid-inducible gene-I-like receptors, RLRs) and protein kinase R (PKR) [2-4]. ADAR1 was demonstrated to leverage the sensing of endogenous dsRNA level, allowing for detection of pathogen while avoiding autoinflammation. It’s reported that when the “self” endogenous dsRNAs are not edited sufficiently by ADAR1, which would be recognized as “non- self” pathogenic dsRNAs by the dsRNA sensor MDA5 to trigger an innate immune response to lower the cellular dsRNA level. Thus, dsRNA editing activities by ADAR1 would in inhibit the activation immune response to the aberrant or chronic innate. In contract, elevated ADAR1-based editing has been found in cancer cells, where ADAR1 would be exploited to elicit hyper-editing so that escape flee immune detection[5]. To this end, three recent studies[6-9] reported that some types of tumor cells can be profoundly sensitized to cancer immunotherapy upon the depletion of ADAR1. In these cancer models, anti-tumour immunity is limited by ADAR1 checkpoint functions through preventing endogenous dsRNA sensing. Whereas loss of function of ADAR1 provokes responses to PD-1 blockade, overcoming the resistance to immunotherapy. In this project we attempted to understand the role of ADAR1 interference in modulating immune response in cancer.

References:

Lamers, M.M., B.G. van den Hoogen, and B.L. Haagmans, ADAR1:“Editor-in-Chief” of Cytoplasmic Innate Immunity. Frontiers in immunology, 2019. 10.
Rice, G.I., et al., Mutations in ADAR1 cause Aicardi-Goutieres syndrome associated with a type I interferon signature. Nature genetics, 2012. 44(11): p. 1243.
Crow, Y.J., et al., Characterization of human disease phenotypes associated with mutations in TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR, and IFIH1. American journal of medical genetics Part A, 2015. 167(2): p. 296-312.
Liddicoat, B.J., et al., RNA editing by ADAR1 prevents MDA5 sensing of endogenous dsRNA as nonself. Science, 2015. 349(6252): p. 1115-1120.
Fritzell, K., et al. ADARs and editing: the role of A-to-I RNA modification in cancer progression. in Seminars in cell & developmental biology. 2018. Elsevier.
Liu, H., et al., Tumor-derived IFN triggers chronic pathway agonism and sensitivity to ADAR loss. Nature medicine, 2019. 25(1): p. 95-102.
Ishizuka, J.J., et al., Loss of ADAR1 in tumours overcomes resistance to immune checkpoint blockade. Nature, 2019. 565(7737): p. 43-48.
Gannon, H.S., et al., Identification of ADAR1 adenosine deaminase dependency in a subset of cancer cells. Nature communications, 2018. 9(1): p. 1-10.
Hajj, K.A. and K.A. Whitehead, Tools for translation: non-viral materials for therapeutic mRNA delivery. Nature Reviews Materials, 2017. 2(10): p. 1-17.

Lapatinib and Ketoconazole Combination Therapy using Novel Lipid Micellar Nanoparticles for Treatment of Lung Cancer

Sun, 15 Nov 2020 00:00:00 +0000

According to American Cancer Society, lung cancer was accountable for over 142,000 deaths in the USA in 2019. About 20% of all NSCLC patients are expected to harbor an EGFR activating mutation. EGFR inhibitors have been shown to provide clinical benefits over chemotherapy for lung cancer patients with EGFR activating mutations. Lapatinib is a small molecule tyrosine kinase inhibitor which acts reversibly on both Epidermal Growth Factor Receptor (EGFR) and Human Epidermal Growth Factor Receptor 2 (HER2). Drug resistance forms in the majority of patients and hampers the effectiveness of these therapies. A recently submitted work showed that cholesterol synthesis enzyme, CYP51A1, along with total cellular cholesterol was upregulated in lapatinib resistant cells. Ketoconazole, a potent inhibitor of CYP51A1, is an FDA approved broad-spectrum systemic antifungal agent and also used in the treatment of the hormone dependent prostate cancer, due to its ability to block steroidogenesis. In that study ketoconazole and EGFR TKIs were shown to act synergistically to induce apoptosis and overcome the development of EGFR resistance. Both lapatinib and ketoconazole are poorly water soluble which is responsible for their variable oral absorption. Large daily dose of lapatinib limits its clinical usage significantly due to occurrence of various side effects. Nanoparticle based formulations offer remarkable promise in delivering hydrophobic drugs and enhancing their permeability and retention (EPR) inside tumors. In this project, we developed a lipid based micellar preparation (LMN) to deliver the combination of lapatinib and ketoconazole intranasally and enhance its efficacy as a treatment.

Radioimmunotherapy for glioblastoma

Sun, 15 Nov 2020 00:00:00 +0000

GBM is the most common and lethal malignant primary brain tumor in adults, and current standardof-care treatment has only limited therapeutic efficacy. We propose to develop and test a novel radioimmunotherapy strategy by rationally combining conformal radiation, a clinically translatable neoantigen nanovaccine, and immune checkpoint blockade to promote tumor response and prolong survival in an orthotopic preclinical GBM model. If successful, this novel treatment strategy could effectively treat or even cure GBM, and eventually prolong the overall survival rates of these patients.

Preclinical Safety and Efficacy of TN1008

Fri, 15 Nov 2019 00:00:00 +0000

In the realm of cancer treatment, conventional therapies frequently fall short in achieving complete tumor eradication and preventing recurrence or metastasis in lung cancer patients. A significant contributing factor to these limitations is the presence of cancer stem cells (CSCs). These cells possess the unique ability of self-renewal and play a pivotal role in cancer drug resistance as well as cancer relapse. The focus of this project was the development of novel therapeutic agents designed to specifically target CSCs, aiming to address the challenges posed by these cells in cancer treatment.

Synthesis of Penicillin Nanoparticle Conjugates and Its Functional Characterization against Resistant Bacteria

Wed, 15 Nov 2017 00:00:00 +0000

Nanotechnology is a rapidly developing field of new therapeutic and diagnostic concept in all areas of medicine. Due to unique characteristics, nanoparticles are considered to have wide applications in detection of biomolecules, drug delivery and release. The discovery of penicillin in the 20th century was a breakthrough in the treatment of infections. However, gradual development of antibiotic resistant bacteria is producing severe global threat to infectious diseases. Nanoparticles (NPs) of TiO2, ZnO, silver, etc, are commonly known for their biocidal efficacy. Hence, NPs conjugated drug delivery has drawn attention for their greater efficacy, delivery and less toxicity. To combat antibiotic resistance, nanoparticles conjugated antibiotics might be an effective treatment approaches in future. Several strategies have been employed to conjugate antibiotics efficiently with nanoparticles. However, the efficacy and stability of nanoparticle conjugated antibiotics should be evaluated properly. In this research project we have taken an initiative to conjugate penicillin such as benzyl penicillin, ampicillin, etc with silver (Ag) nanoparticles using EDC/NHS or sodium borohydrate chemistry. The silver nanoparticle conjugated antibiotics will be evaluated for their stability and efficacy against multi drug resistance Bacteria. We have started to synthesize silver nanoparticles (AgNPs) at our own facilities followed by initial characterization using UV Visible Spectroscopy. Moreover, our collaborator at King Saud University has also provided AgNPs synthesized at their laboratory. Process development and validation for synthesis AgNPs are also going on. In the mean time, we have also initiated to screen the antibacterial activity of AgNPs co administration with ampicillin and with other antibacterial agents. A number of penicillin resistance bacteria have been isolated from clinical samples. These include both gram positive and gram negative bacteria. Once we would be able to set up optimized method for synthesizing AgNps and synergistic activity of co-administrated penicillin with AgNPs, we will target to initiate AgNP-Ampicillin conjugation in the second phase.

Mon, 01 Jan 0001 00:00:00 +0000