Peptides can be detected by immune system via binding to major histocompatibility complex (MHC). The minimum length of peptide chain is 8~9 amino acid for MHCI binding, and 12~16 for MHC II binding. As to our JS-1 with 5 amino acids on average, it will not be recognized by the immune system [1, 2].

Moreover, JS-1, as a peptide-based polymer, can be degraded by polypeptidase. Its component, glutamate, will be metabolised via GABA shunt [3].

As a result, JS-1 has lower cytotoxicity compared with other HuR protein inhibitors.

Reference:

1. Hemmer, B., Fleckenstein, B. T., Vergelli, M., Jung, G., McFarland, H., Martin, R. and Wiesmuller, K. H. 1997. Identification of high potency microbial and self ligands for a human autoreactive class II-restricted T cell clone. J. Exp. Med. 185:1651.
2. Hemmer, B., Vergelli, M., Pinilla, C., Houghten, R. and Martin, R. 1998. Probing degeneracy in T-cell recognition using combinatorial peptide libraries. Immunol. Today 19:163.
3. Olsen, R.W., DeLorey, T.M. (1999). "GABA Synthesis, Uptake and Release." Basic Neurochemistry: Molecular, Cellular and Medical Aspects. 6th edition.

In recent years, nanoparticles have drawn much attention because of their great potential as cell targeting drug nanocarriers [1]. The distributions of traditional small molecule drugs in human body mostly depend on the methods of administration and their own chemical properties. In contrast, nanoparticles are distinctively modified and at different length scales, resulting in the differences in the drug uptake rates by various cells [2-4].

We can notice that JS-1 was almost fully consumed by macrophages in the previous experiment. Also, macrophages endocytose more efficiently when it comes to nanoparticles during inflammations [5]. As a result, JS-1 is effective in treating overreacting immune system.

What's more, as a nanoparticle, JS1 can act as a drug nanocarrier and carry hydrophobic drugs into target cells. Small molecule drugs which have no targeting ability can thus be transported into cells more directly and side effects can then be reduced drastically.

Reference:

1. Erkki Ruoslahti, Sangeeta N. Bhatia, and Michael J., Targeting of drugs and nanoparticles to tumors, J Cell Biol. 2010 Mar 22; 188(6): 759–768.
2. Champion JA, Walker A, Mitragotri S., Role of particle size in phagocytosis of polymeric microspheres., Pharm Res. 2008 Aug;25(8):1815-21. doi: 10.1007/s11095-008-9562-y. Epub 2008 Mar 29.
3. Walkey CD, Olsen JB, Guo H, Emili A, Chan WC., Nanoparticle size and surface chemistry determine serum protein adsorption and macrophage uptake., J Am Chem Soc. 2012 Feb 1;134(4):2139-47. doi: 10.1021/ja2084338. Epub 2012 Jan 23.
4. Owens DE 3rd, Peppas NA., Opsonization, biodistribution, and pharmacokinetics of polymeric nanoparticles., Int J Pharm. 2006 Jan 3;307(1):93-102. Epub 2005 Nov 21.
5. Rogers WJ, Basu P., Factors regulating macrophage endocytosis of nanoparticles: implications for targeted magnetic resonance plaque imaging., Atherosclerosis. 2005 Jan;178(1):67-73.

In addition to promoting inflammation, HuR protein is also highly associated with cell carcinogenesis [1-4]. To prove that JS-1 has the potential to treat other diseases, "Lipopolysaccharide / D-galactosamine (LPS / D-Gal)-induced acute liver inflammation model" will also be conducted to evaluate its therapeutic effect on acute inflammation [5]. Additionally, LL2 cells-inoculated C57BL / 6 mice lung cancer model will also be used to evaluate its therapeutic effect on delaying the process of cancer [6].

We can expect JS-1's significant breakthrough in anti-inflammatory and anticancer field.

Reference:

1. Lopez de Silanes, I.; Fan, J.; Yang, X.; Zonderman, A. B.; Potapova, O.; Pizer, E. S.; Gorospe, M. Oncogene 2003, 22, (46), 7146-54.
2. Denkert, C.; Koch, I.; von Keyserlingk, N.; Noske, A.; Niesporek, S.; Dietel, M.; Weichert, W. Mod Pathol 2006, 19, (9), 1261-9.
3. Yi, X.; Zhou, Y.; Zheng, W.; Chambers, S. K. Aust N Z J Obstet Gynaecol 2009, 49, (1), 93-8.
4. Lim, S. J.; Kim, H. J.; Kim, J. Y.; Park, K.; Lee, C. M. Int J Gynecol Pathol 2007, 26, (3), 229-234.
5. Mignon, A.; Rouquet, N.; Fabre, M.; Martin, S.; Pages, J. C.; Dhainaut, J. F.; Kahn, A.; Briand, P.; Joulin, V. Am J Resp Crit Care 1999, 159, (4), 1308-1315.
6. Duś D, Budzyński W, Radzikowski C., LL2 cell line derived from transplantable murine Lewis lung carcinoma--maintenance in vitro and growth characteristics., Arch Immunol Ther Exp (Warsz). 1985;33(6):817-23.

Hu proteins are mammalian embryonic lethal abnormal visual system (ELAV)-like neuronal RNA-binding proteins, including HuA (HuR), HuB (Hel-N1), HuC (Ple-21), and HuD.

The one that is our focus in this study, HuR, is ubiquitously expressed. Rather, HuB is expressed in ovaries, testes and neurons, and HuC and HuD are expressed only in neurons [1, 2].

HuB, HuC, and HuD all promote neuronal development in the central and peripheral nervous systems [3]. Take HuB for example, low expression of it is associated with autism spectrum disorders (ASD) [4]. However, over-expression of these three may also lead to cell lesions, for instance:

1. HuB can induce the formation of neurites in human embryonic teratocarcinoma (hNT2) cells [5].
2. HuC serves as autoantigen in the patients with paraneoplastic encephalomyelitis and Limbic Encephalitis, causing inflammation [6].
3. HuD is expressed in 100% of (SCLC) tumor cells and more than 50% of neuroblastoma (NB) cells, suggesting HuD can be the target of the immunotherapy of both cancers [7].

And Hu protein family have similar three RRM structures [1], which happens to be binding target of JS1, so our study of HuR inhibitors is expected to be used for the development of other Hu protein inhibitors.

Reference:

1. Good PJ., A conserved family of elav-like genes in vertebrates., Proc Natl Acad Sci U S A. 1995 May 9;92(10):4557-61.
2. Antic D, Keene JD., Embryonic lethal abnormal visual RNA-binding proteins involved in growth, differentiation, and posttranscriptional gene expression., Am J Hum Genet. 1997 Aug;61(2):273-8.
3. Wado Akamatsu, Hirotaka J. Okano, Noriko Osumi, Takayoshi Inoue, Shun Nakamura, Shin-Ichi Sakakibara, Masayuki Miura, Nobutake Matsuo, Robert B. Darnell, and Hideyuki Okano, Mammalian ELAV-like neuronal RNA-binding proteins HuB and HuC promote neuronal development in both the central and the peripheral nervous systems, Proc Natl Acad Sci U S A. 1999 Aug 17; 96(17): 9885–9890.
4. Berto S, Usui N, Konopka G, Fogel BL., ELAVL2-regulated transcriptional and splicing networks in human neurons link neurodevelopment and autism., Hum Mol Genet. 2016 Jun 15;25(12):2451-2464. Epub 2016 Jun 3.
5. Dragana Antic, Ning Lu, and Jack D. Keene, ELAV tumor antigen, Hel-N1, increases translation of neurofilament M mRNA and induces formation of neurites in human teratocarcinoma cells, Genes Dev. 1999 Feb 15; 13(4): 449–461.
6. Kumagai T, Kitagawa Y, Hirose G, Sakai K., Antibody recognition and RNA binding of a neuronal nuclear autoantigen associated with paraneoplastic neurological syndromes and small cell lung carcinoma., J Neuroimmunol. 1999 Jan 1;93(1-2):37-44.
7. Debra Ehrlich, Bo Wang, Wei Lu, Peter Dowling, and Ruirong Yuan, Intratumoral anti-HuD immunotoxin therapy for small cell lung cancer and neuroblastoma, J Hematol Oncol. 2014; 7: 91.

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