Targeted Inhibition of lncRNA Malat1 Alters the Tumor Immune Microenvironment in Preclinical Syngeneic Mouse Models of Triple-Negative Breast Cancer

Article

作者: Zhang, Xiang H-F ; Shen, Yichao ; Adewunmi, Oluwatoyosi ; Rosen, Jeffrey M

AbstractLong noncoding RNAs (lncRNA) play an important role in gene regulation in both normal tissues and cancer. Targeting lncRNAs is a promising therapeutic approach that has become feasible through the development of gapmer antisense oligonucleotides (ASO). Metastasis-associated lung adenocarcinoma transcript (Malat1) is an abundant lncRNA whose expression is upregulated in several cancers. Although Malat1 increases the migratory and invasive properties of tumor cells, its role in the tumor microenvironment (TME) is still not well defined. We explored the connection between Malat1 and the tumor immune microenvironment (TIME) using several immune-competent preclinical syngeneic Tp53-null triple-negative breast cancer (TNBC) mouse models that mimic the heterogeneity and immunosuppressive TME found in human breast cancer. Using a Malat1 ASO, we were able to knockdown Malat1 RNA expression resulting in a delay in primary tumor growth, decreased proliferation, and increased apoptosis. In addition, immunophenotyping of tumor-infiltrating lymphocytes revealed that Malat1 inhibition altered the TIME, with a decrease in immunosuppressive tumor-associated macrophages (TAM) and myeloid-derived suppressor cells (MDSC) as well as an increase in cytotoxic CD8+ T cells. Malat1 depletion in tumor cells, TAMs, and MDSCs decreased immunosuppressive cytokine/chemokine secretion whereas Malat1 inhibition in T cells increased inflammatory secretions and T-cell proliferation. Combination of a Malat1 ASO with chemotherapy or immune checkpoint blockade (ICB) improved the treatment responses in a preclinical model. These studies highlight the immunostimulatory effects of Malat1 inhibition in TNBC, the benefit of a Malat1 ASO therapeutic, and its potential use in combination with chemotherapies and immunotherapies.

2023-05-26·Oncotarget

Deconstructing the role of MALAT1 in MAPK-signaling in melanoma: insights from antisense oligonucleotide treatment.

Article

作者: Feichtenschlager, Valentin ; Callanan, Ciara ; Rappersberger, Klemens ; Ho, Wilson ; Zheng, Yixuan James ; Ortiz, Jose ; Lee, Albert ; Chen, Christopher ; Chen, Linan ; Ortiz-Urda, Susana

The long non-coding RNA (lncRNA) MALAT1 is a regulator of oncogenesis and cancer progression. MAPK-pathway upregulation is the main event in the development and progression of human cancer, including melanoma and recent studies have shown that MALAT1 has a significant impact on the regulation of gene and protein expression in the MAPK pathway. However, the role of MALAT1 in regulation of gene and protein expression of the MAPK-pathway kinases RAS, RAF, MEK and ERK in melanoma is largely unknown. We demonstrate the impacts of antisense oligonucleotide (ASO)-based MALAT1-inhibition on MAPK-pathway gene regulation in melanoma. Our results showed that MALAT1-ASO treatment decreased BRAF RNA expression and protein levels, and MALAT1 had increased correlation with MAPK-pathway associated genes in melanoma patient samples compared to healthy skin. Additionally, drug-induced MAPK inhibition upregulated MALAT1-expression, a finding that resonates with a paradigm of MALAT1-expression presented in this work: MALAT1 is downregulated in melanoma and other cancer types in which MALAT1 seems to be associated with MAPK-signaling, while MALAT1-ASO treatment strongly reduced the growth of melanoma cell lines, even in cases of resistance to MEK inhibition. MALAT1-ASO treatment significantly inhibited colony formation in vitro and reduced tumor growth in an NRAS-mutant melanoma xenograft mouse model in vivo, while showing no aberrant toxic side effects. Our findings demonstrate new insights into MALAT1-mediated MAPK-pathway gene regulation and a paradigm of MALAT1 expression in MAPK-signaling-dependent cancer types. MALAT1 maintains essential oncogenic functions, despite being downregulated.

2023-05-17·Bioconjugate chemistry

Propensities of Fatty Acid-Modified ASOs: Self-Assembly vs Albumin Binding.

Article

作者: Portmann, Michaela ; Worm, Jesper ; Reinhart, Anne-Gaelle ; Hau, Jean-Christophe ; Sladojevich, Filippo ; Kusznir, Eric-Andre ; Ringler, Philippe ; Lauer, Matthias ; Falivene, Fabio ; Bleicher, Konrad ; Huber, Sylwia ; Keller, Michael ; Ross, Alfred ; Bastien, Jessica

We conducted a biophys. study to investigate the self-assembling and albumin-binding propensities of a series of fatty acid-modified locked nucleic acid (LNA) antisense oligonucleotide (ASO) gapmers specific to the MALAT1 gene.To this end, a series of biophys. techniques were applied using label-free ASOs that were covalently modified with saturated fatty acids (FAs) of varying length, branching, and 5'/3' attachment.Using anal. ultracentrifugation (AUC), we demonstrate that ASOs conjugated with fatty acids longer than C16 exhibit an increasing tendency to form self-assembled vesicular structures.The C16 to C24 conjugates interacted via the fatty acid chains with mouse and human serum albumin (MSA/HSA) to form stable adducts with near-linear correlation between FA-ASO hydrophobicity and binding strength to mouse albumin.This was not observed for the longer fatty acid chain ASO conjugates (>C24) under the exptl. conditions applied.The longer FA-ASO however adopted self-assembled structures with increasing intrinsic stabilities proportional to the fatty acid chain length.For instance, FA chain lengths smaller than C24 readily formed self-assembled structures containing 2 (C16), 6 (C22, bis-C12), and 12 (C24) monomers, as measured by anal. ultracentrifugation (AUC).Incubation with albumin disrupted these supramol. architectures to form FA-ASO/albumin complexes mostly with 2:1 stoichiometry and binding affinities in the low micromolar range, as determined by isothermal titration calorimetry (ITC) and anal. ultracentrifugation (AUC).Binding of FA-ASOs underwent a biphasic pattern for medium-length FA chain lengths (>C16) with an initial endothermic phase of particulate disruption, followed by an exothermic binding event to the albumin.Conversely, ASO modified with di-palmitic acid (C32) formed a strong, hexameric complex.This structure was not disrupted when incubated with albumin under conditions above the critical nanoparticle concentration (CNC; <0.4μM).It is noteworthy that the interaction of parent, fatty acid-free malat1 ASO to albumin was below detectability by ITC (KD ≫150μM).This work demonstrates that the nature of mono- vs multimeric structures of hydrophobically modified ASOs is governed by the hydrophobic effect.Consequently, supramol. assembly to form particulate structures is a direct consequence of the fatty acid chain length.This provides opportunities to exploit the concept of hydrophobic modification to influence pharmacokinetics (PK) and biodistribution for ASOs in two ways: (1) binding of the FA-ASO to albumin as a carrier vehicle and (2) self-assembly resulting in albumin-inert, supramol. architectures.Both concepts create opportunities to influence biodistribution, receptor interaction, uptake mechanism, and pharmacokinetics/pharmacodynamics (PK/PD) properties in vivo, potentially enabling access to extrahepatic tissues in sufficient concentration to treat disease.

100 项与 MALAT1 ASO(Baylor College of Medicine) 相关的药物交易

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