Project description:Pancreatic cancer is one of the most malignant tumors with the highest mortality rates, and it currently lacks effective drugs. Aptamer-drug conjugates (ApDC), as a form of nucleic acid drug, show great potential in cancer therapy. However, the instability of nucleic acid-based drugs in vivo and the avascularity of pancreatic cancer with dense stroma have limited their application. Fortunately, VNP20009, a genetically modified strain of Salmonella typhimurium, which has a preference for anaerobic environments, but is toxic and lacks specificity, can potentially serve as a delivery vehicle for ApDC. Here, we propose an approach to synergistic therapy that utilizes the penetrative capability of bacteria and the targeting and toxic effects of ApDC by conjugating ApDC to VNP20009 via straightforward, one-step click chemistry. With this strategy, bacteria specifically target pancreatic cancer through anaerobic chemotaxis and subsequently adhere to tumor cells driven by the aptamer's specific binding. Results indicate that this method prolongs the serum stability of ApDC up to 48 hours and resulted in increased drug concentration at tumor sites compared to the free drugs group. Moreover, the aptamer's targeted binding to cancer cells tripled bacterial colonization at the tumor site, leading to increased death of tumor cells and T cell infiltration. Notably, by integrating chemotherapy and immunotherapy, the effectiveness of the treatment is significantly enhanced, showing consistent results across various animal models. Overall, this strategy takes advantage of bacteria and ApDC and thus presents an effective synergistic strategy for pancreatic cancer treatment.
Project description:Neocarzinostatin (NCS) is an anti-tumor DNA damaging agent. Conjugating NCS with EpCAM Aptamer will direct the toxin pay loads to the EpCAM positive cancer cells as a targeted therapy We used microarrays to detail the global gene expression to understand the pathways involved in EpCAM-mediated NCS drug delivery in breast cancer cells.
Project description:siRNAs have played a major role in cancer drug discovery, but their potential is hampered due to off-target effects. Thus, delivery systems like RNA aptamers have been used to enhance the specific delivery of these siRNAs to cancer stem cells. We report the efficacy of three different EpCAM aptamer siRNA chimeras, which were investigated both in vitro and in vivo for their ability to reduce cancer cell progression. Using these chimeras, we demonstrated specific gene knockdown in EpCAM positive cells which ultimately led to the apoptosis. To study the efficacy of these aptamer chimeras in vivo, retinoblastoma xenografts bearing NCC Rb C 51 cells were created for the first time. Systemic administration of these aptamer chimeras reduced tumour growth to about 50%. We further investigated the central Role of PLK1 in Cancer Progression and demonstrated the anti-cancer effects of targeted EpCAM siPLK1 approach. Using SILAC-Mass spectrometry analysis, we showed that silencing PLK 1 gene can lead to p53 mediated cell cycle arrest. Thus, we establish EpCAM-siRNA chimeras as potential markers for targeted anti-cancer applications, which paves a platform for efficient second line of therapies in addition to existing chemotherapy options.
Project description:The experiments were carried out to map the ligand binding landscape of various DNA and RNA duplexed aptamer families. Duplexed Aptamer (DA) constructs were engineered from (i) natural and synthetic DNA and RNA aptamers and (i) synthetic oligonucleotide aptamer-complementary elements synthesized on custom DNA microarrays. The aptamers tested consist of the ATP DNA aptamer, the ATP RNA aptamer, the cocaine DNA aptamer, the human alpha-thrombin DNA aptamer, and the natural add riboswitch aptamer from the pathogenic bacteria Vibrio vulnificus. Each duplexed aptamer family consists of 1000's of synthetic constructs, each formed by hybridizing the aptamer with an aptamer-complementary element (ACE) - here, ACEs consisted of various DNA oligonucleotides synthesized as a custom DNA microarray.
Project description:The experiments were carried out to map the ligand binding landscape of various DNA and RNA duplexed aptamer families. Duplexed Aptamer (DA) constructs were engineered from (i) natural and synthetic DNA and RNA aptamers and (i) synthetic oligonucleotide aptamer-complementary elements synthesized on custom DNA microarrays. The aptamers tested consist of the ATP DNA aptamer, the ATP RNA aptamer, the cocaine DNA aptamer, the human alpha-thrombin DNA aptamer, and the natural add riboswitch aptamer from the pathogenic bacteria Vibrio vulnificus. Each duplexed aptamer family consists of 1000's of synthetic constructs, each formed by hybridizing the aptamer with an aptamer-complementary element (ACE) - here, ACEs consisted of various DNA oligonucleotides synthesized as a custom DNA microarray.
Project description:The experiments were carried out to map the ligand binding landscape of various DNA and RNA duplexed aptamer families. Duplexed Aptamer (DA) constructs were engineered from (i) natural and synthetic DNA and RNA aptamers and (i) synthetic oligonucleotide aptamer-complementary elements synthesized on custom DNA microarrays. The aptamers tested consist of the ATP DNA aptamer, the ATP RNA aptamer, the cocaine DNA aptamer, the human alpha-thrombin DNA aptamer, and the natural add riboswitch aptamer from the pathogenic bacteria Vibrio vulnificus. Each duplexed aptamer family consists of 1000's of synthetic constructs, each formed by hybridizing the aptamer with an aptamer-complementary element (ACE) - here, ACEs consisted of various DNA oligonucleotides synthesized as a custom DNA microarray.
Project description:Aptamers are short single-strand oligonucleotides that can form secondary and tertiary structures, fitting targets with high affinity and specificity. They are so-called "chemical antibodies" and can target specific biomarkers in both diagnostic and therapeutic applications. Systematic evolution of ligands by exponential enrichment (SELEX) is usually used for the enrichment and selection of aptamers, and the targets could be metal ions, small molecules, nucleotides, proteins, cells, or even tissues or organs. Due to the high specificity and distinctive binding affinity of aptamers, aptamer-drug conjugates (ApDCs) have demonstrated their potential role in drug delivery for cancer-targeting therapies. Compared with antibodies which are produced by a cell-based bioreactor, aptamers are chemically synthesized molecules that can be easily conjugated to drugs and modified; however, the conventional ApDCs conjugate the aptamer with an active drug using a linker which may add more concerns to the stability of the ApDC, the drug-releasing efficiency, and the drug-loading capacity. The function of aptamer in conventional ApDC is just as a targeting moiety which could not fully perform the advantages of aptamers. To address these drawbacks, scientists have started using active nucleotide analogs as the cargoes of ApDCs, such as clofarabine, ara-guanosine, gemcitabine, and floxuridine, to replace all or part of the natural nucleotides in aptamer sequences. In turn, these new types of ApDCs, aptamer nucleotide analog drug conjugates, show the strength for targeting efficacy but avoid the complex drug linker designation and improve the synthetic efficiency. More importantly, these classic nucleotide analog drugs have been used for many years, and aptamer nucleotide analog drug conjugates would not increase any unknown druggability risk but improve the target tumor accumulation. In this review, we mainly summarized aptamer-conjugated nucleotide analog drugs in cancer-targeting therapies.
Project description:Oligonucleotide aptamers can specifically bind biomarkers on cancer cells and can be readily chemically modified with different functional molecules for personalized medicine. To target acute myeloid leukemia (AML) cells, we developed a single-strand DNA aptamer specific for the biomarker CD117, which is highly expressed on AML cells. Sequence alignment revealed that the aptamer contained a G-rich core region with a well-conserved functional G-quadruplex structure. Functional assays demonstrated that this synthetic aptamer was able to specifically precipitate CD117 proteins from cell lysates, selectively bound cultured and patient primary AML cells with high affinity (Kd < 5 nM), and was specifically internalized into CD117-expressing cells. For targeted AML treatment, aptamer-drug conjugates were fabricated by chemical synthesis of aptamer (Apt) with methotrexate (MTX), a central drug used in AML chemotherapy regimens. The formed Apt-MTX conjugates specifically inhibited AML cell growth, triggered cell apoptosis, and induced cell cycle arrest in G1 phase. Importantly, Apt-MTX had little effect on CD117-negative cells under the same treatment conditions. Moreover, exposure of patient marrow specimens to Apt-MTX resulted in selective growth inhibition of primary AML cells and had no toxicity to off-target background normal marrow cells within the same specimens. These findings indicate the potential clinical value of Apt-MTX for targeted AML therapy with minimal to no side effects in patients, and also open an avenue to chemical synthesis of new, targeted biotherapeutics.
Project description:The experiments were carried out to map the ligand binding landscape of various DNA and RNA duplexed aptamer families. Duplexed Aptamer (DA) constructs were engineered from (i) natural and synthetic DNA and RNA aptamers and (i) synthetic oligonucleotide aptamer-complementary elements synthesized on custom DNA microarrays. The aptamers tested consist of the ATP DNA aptamer, the ATP RNA aptamer, the cocaine DNA aptamer, the human alpha-thrombin DNA aptamer, and the natural add riboswitch aptamer from the pathogenic bacteria Vibrio vulnificus. Each duplexed aptamer family consists of 1000's of synthetic constructs, each formed by hybridizing the aptamer with an aptamer-complementary element (ACE) - here, ACEs consisted of various DNA oligonucleotides synthesized as a custom DNA microarray.