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<h4>RNA interference (RNAi) is an endogenous, ubiquitous, evolutionarily conserved and powerful method for regulating gene expression, which can cause the gene encoding messenger RNA (mRNA) degradation<sup>[1]</sup>. In this case, a medication in transcription level can be achieved. RNAi is highly effective in silencing the target gene that regulates the specific biological/pathological pathway<sup>[2]</sup>. Several in vitro and in vivo studies have shown that every human disease with over-expression of disease causing gene(s) is a potential target for RNAi-based therapeutics <sup>[3]</sup>. | <h4>RNA interference (RNAi) is an endogenous, ubiquitous, evolutionarily conserved and powerful method for regulating gene expression, which can cause the gene encoding messenger RNA (mRNA) degradation<sup>[1]</sup>. In this case, a medication in transcription level can be achieved. RNAi is highly effective in silencing the target gene that regulates the specific biological/pathological pathway<sup>[2]</sup>. Several in vitro and in vivo studies have shown that every human disease with over-expression of disease causing gene(s) is a potential target for RNAi-based therapeutics <sup>[3]</sup>. | ||
<h4>Cancer is a genetic disease of stepwise deregulation of cell death mechanisms and cell proliferation. The growth phenotype of cancer cells differs from normal cells due to proto-oncogene mutation, aberrant genetic activation, amplification, over-expression or deletion of tumor suppressor<sup>[1]</sup>. RNAi is being explored as a way to inhibit the expression of genes involved in oncogenesis. However, when it comes to cancer therapy, specifically targeting tumor cells is an important direction<sup>[1]</sup>. In our RNAi system, cancer specific target and promoters are designed which means that the strategy can selectively cause destruction of cancer cells without affecting normal cells. However, the efficiency of our system <i>in vivo</i> is also an issue that need to be concerned otherwise our gene device may not reach cancer cells to do its job. What’s more, our gene therapy strategy, if ever to become transgenic drugs, involves multiple genes transferring with two plasmids. There’s an “AND” gate system which protects the normal cells from damaging, however undesirable effects like mutagenesis lead by encoded proteins or RNA products alone (although happens relatively low in normal cells) may happens, these are indeed problems to consider. | <h4>Cancer is a genetic disease of stepwise deregulation of cell death mechanisms and cell proliferation. The growth phenotype of cancer cells differs from normal cells due to proto-oncogene mutation, aberrant genetic activation, amplification, over-expression or deletion of tumor suppressor<sup>[1]</sup>. RNAi is being explored as a way to inhibit the expression of genes involved in oncogenesis. However, when it comes to cancer therapy, specifically targeting tumor cells is an important direction<sup>[1]</sup>. In our RNAi system, cancer specific target and promoters are designed which means that the strategy can selectively cause destruction of cancer cells without affecting normal cells. However, the efficiency of our system <i>in vivo</i> is also an issue that need to be concerned otherwise our gene device may not reach cancer cells to do its job. What’s more, our gene therapy strategy, if ever to become transgenic drugs, involves multiple genes transferring with two plasmids. There’s an “AND” gate system which protects the normal cells from damaging, however undesirable effects like mutagenesis lead by encoded proteins or RNA products alone (although happens relatively low in normal cells) may happens, these are indeed problems to consider. | ||
− | <h4><font color="red">In this case, to further improve our project for future application when it comes into a drug, if possible | + | <h4><font color="red">In this case, to further improve our project for future application when it comes into a drug, if possible. Two methods which allow us to target tumor tissue <i>in vivo</i> are designed.</font> |
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<h4>Enrich the drugs in or near tumor is vital when it comes to targeting the cancer cells. Liposome is commonly used as carrier for drug delivery<sup>[4]</sup>, and some of them are in macromolecular size. | <h4>Enrich the drugs in or near tumor is vital when it comes to targeting the cancer cells. Liposome is commonly used as carrier for drug delivery<sup>[4]</sup>, and some of them are in macromolecular size. | ||
<h4>The major goal of liposomal drug delivery is to deliver the therapeutic agent preferentially to the tumor site through the enhanced permeability and retention (EPR) effect <sup>[5]</sup>. There are seven barriers in the development of cancer selective macromolecular drugs and steps to be overcome, first of which is vascular wall and blood cirrculation. ERP effect is of prime importance for this step because drug extravasation occurs in a tumor-selective manner<sup>[6]</sup>. | <h4>The major goal of liposomal drug delivery is to deliver the therapeutic agent preferentially to the tumor site through the enhanced permeability and retention (EPR) effect <sup>[5]</sup>. There are seven barriers in the development of cancer selective macromolecular drugs and steps to be overcome, first of which is vascular wall and blood cirrculation. ERP effect is of prime importance for this step because drug extravasation occurs in a tumor-selective manner<sup>[6]</sup>. | ||
− | <h4>ERP was first proposed by Yasuhiro in 1986<sup>[7]</sup>, which is now becoming the most important pharmacokinetic principle at the first step of the design of macromolecular drugs or nanomedicines<sup>[8]</sup>. Clearance of macromolecules and lipids from tumor is so impaired that they remain in the tumor interstitium for along time which enables the drugs to be permanent. This phenomenon has been characterized and termed the tumor-selective EPR effect of macromolecules and lipidic particles<sup>[9]</sup>. The EPR concept is now regarded as a | + | <h4>ERP was first proposed by Yasuhiro in 1986<sup>[7]</sup>, which is now becoming the most important pharmacokinetic principle at the first step of the design of macromolecular drugs or nanomedicines<sup>[8]</sup>. Clearance of macromolecules and lipids from tumor is so impaired that they remain in the tumor interstitium for along time which enables the drugs to be permanent. This phenomenon has been characterized and termed the tumor-selective EPR effect of macromolecules and lipidic particles<sup>[9]</sup>. The EPR concept is now regarded as a ‘gold standard’ in the design of new anticancer agents<sup>[10]</sup>. |
<h4>The disease we choose to apply on, Hepatocellular carcinoma(HCC), manifest a high vascular density, so it tend to have a relatively increased EPR effect<sup>[8]</sup>. By containing our two plasmids system in a liposome size ranges between 1-200nm(the size of nanomedicines) it can enrich in the tumor owing to EPR effect and thus, having a better selectivity on HCC. | <h4>The disease we choose to apply on, Hepatocellular carcinoma(HCC), manifest a high vascular density, so it tend to have a relatively increased EPR effect<sup>[8]</sup>. By containing our two plasmids system in a liposome size ranges between 1-200nm(the size of nanomedicines) it can enrich in the tumor owing to EPR effect and thus, having a better selectivity on HCC. | ||
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<h4>Passive delivery like the delivery based on EPR effect is simple, yet its effect varies depending on a patient's pathological and physiological characteristics and clinical condition, for instance, when a patient's systolic blood pressure is low side of about 90 mm Hg instead of 120–130 mm Hg, the hydro-dynamic force pushing blood from the luminal side of a vessel into tumor tissue becomes significantly low, which results in a low EPR<sup> [8]</sup>. | <h4>Passive delivery like the delivery based on EPR effect is simple, yet its effect varies depending on a patient's pathological and physiological characteristics and clinical condition, for instance, when a patient's systolic blood pressure is low side of about 90 mm Hg instead of 120–130 mm Hg, the hydro-dynamic force pushing blood from the luminal side of a vessel into tumor tissue becomes significantly low, which results in a low EPR<sup> [8]</sup>. | ||
− | <h4>Aside from preferential accumulation in tumors, nano-particle-based drug delivery systems can also enhance the pharmacokinetic profile of therapeutic agents. Specifically, the use of polyethylene glycol (PEG) | + | <h4>Aside from preferential accumulation in tumors, nano-particle-based drug delivery systems can also enhance the pharmacokinetic profile of therapeutic agents. Specifically, the use of polyethylene glycol (PEG) "stealth" coatings greatly enhances blood circulation times by allowing the liposome to evade immune detection<sup>[12]</sup>. |
− | <h4>Nanomedicine, particularly liposomal drug delivery, has expanded considerably over the past few decades, and several liposomal drugs are already providing improved clinical outcomes. Liposomes have now progressed beyond simple, inert drug carriers and can be designed to be highly responsive in vivo, with active targeting, increased stealth, and controlled drug-release properties. Ligand-targeted liposomes (LTLs) have the potential to revolutionize the treatment of cancer<sup>[13</sup> | + | <h4>Nanomedicine, particularly liposomal drug delivery, has expanded considerably over the past few decades, and several liposomal drugs are already providing improved clinical outcomes. Liposomes have now progressed beyond simple, inert drug carriers and can be designed to be highly responsive in vivo, with active targeting, increased stealth, and controlled drug-release properties. Ligand-targeted liposomes (LTLs) have the potential to revolutionize the treatment of cancer<sup>[13]</sup>. |
<h4>In order to achieve maximum efficacy, controlled release of therapeutic agents from liposomes at the tumor site is essential<sup>[14]</sup>. Liposomes, can be surface functionalized with targeting ligands to enhance the selective targeting of tumors <sup>[15][16]</sup>. The grafting of targeting ligands to the liposome surface can further enhance tumor targeting and facilitate intracellular uptake after the liposome reaches the tumor interstitium, which indicates that a specific HCC binding protein(like HCC specific antibody) modified liposome will have a promising efficacy. | <h4>In order to achieve maximum efficacy, controlled release of therapeutic agents from liposomes at the tumor site is essential<sup>[14]</sup>. Liposomes, can be surface functionalized with targeting ligands to enhance the selective targeting of tumors <sup>[15][16]</sup>. The grafting of targeting ligands to the liposome surface can further enhance tumor targeting and facilitate intracellular uptake after the liposome reaches the tumor interstitium, which indicates that a specific HCC binding protein(like HCC specific antibody) modified liposome will have a promising efficacy. | ||
<h4>Macrophage signal regulatory protein-α (SIRPα) interacts with HCC surface molecule CD47 and resulted in low macrophage response towards HCC<sup>[17]</sup>. By binding the CD47 specific antibodies (CD47mAbs) on the surface of liposome which carries our two plasmids system, not only our system can have a more efficacy drug release, immune response towards HCC will also be increased since the interaction between SIRPα and CD47 is blocked. | <h4>Macrophage signal regulatory protein-α (SIRPα) interacts with HCC surface molecule CD47 and resulted in low macrophage response towards HCC<sup>[17]</sup>. By binding the CD47 specific antibodies (CD47mAbs) on the surface of liposome which carries our two plasmids system, not only our system can have a more efficacy drug release, immune response towards HCC will also be increased since the interaction between SIRPα and CD47 is blocked. |
Revision as of 10:12, 7 December 2018