RNAi-Based Identification System and interference of Specific Cancer Cells

A “classifier” was created to classify cells by identifying specific characteristics of Cervical Cancer.[1] These characteristics were consistent with HeLa cells, which served as the target cell line for cell death.[1] Upon identifying these cells the Classifier would release specific proteins within the HeLa cell that would trigger apoptosis without killing or endangering neighboring, healthy cells.[1]

The defining characteristics of these Classifiers were defined by elements whose levels within the cells created markers that could be measured.[1] High markers and low markers were established and a “classifier molecule” was created to insert into prospective cells, and would induce apoptosis only when cells exhibit the threshold level of High or Low markers.[1] These classifiers would use a small interfering RNA which targeted the repressor and activator in the Lac operon.[1] The potential for therapeutic use, providing that an efficient delivery system can be established for in vivo DNA. In vitro applications are possible provided the classifier molecule can be safely integrated into cultured cells.[1]

Cancer cell identification and classification

Cancer cells can be classified by identifying the MicroRNA expression.[2] These mRNA expression levels can be used as a diagnostic and prognostic tool in tumor and cancer classifications, although current tumor classification methods do not incorporate experimental knowledge.[2] As is evident in experimental knowledge, different types of cancer can be associated with the irregular expression of particular miRNAs.[2] Other parameters considered to be critical are the location of the miRNAs on the strand, cancer associated genomic regions, epigenetic alteration of miRNA expression and abnormalities in processing target genes and proteins.[2] Recent evidence show that miRNAs play an important role in human malignancies and could act as a tumor/oncogene suppressor.[2]

RNAi for apoptosis

Recently it has been discovered that small RNA can trigger specific gene silencing in human cells.[3] The RNAi reaction enables a complete elimination of a specific protein which can potentially enable researchers to target pivotal structures within a cell to eliminate the cell altogether.[4] RNAi silencing can also strongly inhibit proliferation of cells with genetic mutations that encourage oncogenic activation.[3]

RNAi delivery methods

Since its discovery RNAi knowledge has grown substantially.[5] Although quite useful, RNAi in vivo delivery to tissues proves to be a challenge that still eludes science- especially to deep tissues within the body.[5] RNAi delivery is only easily accessible to surface tissues such as the eye and respiratory tract.[5] In these instances siRNA has been used in direct contact with the tissue for transport and the resulting RNAi has been extremely successful in focusing on target genes.[5] When delivering siRNA to deep tissue layers within the body measures need be taken to protect the siRNA from nucleases, but targeting specific areas becomes the main difficulty.[5] This difficulty has been combatted with high dosage levels of siRNA to ensure the tissues have been reached, however in these cases hepatotoxicity was reported.[5]

References

  1. 1 2 3 4 5 6 7 Xie Z, Wroblewska L, Prochazka L, Weiss R, Benenson Y (September 2011). "Multi-input RNAi-based logic circuit for identification of specific cancer cells". Science 333 (6047): 1307–11. doi:10.1126/science.1205527. PMID 21885784.
  2. 1 2 3 4 5 Mitra R, Bandyopadhyay S, Maulik U, Zhang MQ (2010). "SFSSClass: an integrated approach for miRNA based tumor classification". BMC Bioinformatics. 11 Suppl 1: S22. doi:10.1186/1471-2105-11-S1-S22. PMC 3009493. PMID 20122194.
  3. 1 2 Wilda M, Fuchs U, Wössmann W, Borkhardt A (August 2002). "Killing of leukemic cells with a BCR/ABL fusion gene by RNA interference (RNAi)". Oncogene 21 (37): 5716–24. doi:10.1038/sj.onc.1205653. PMID 12173041.
  4. ↑ Santo EE, Ebus ME, Koster J, Schulte JH, Lakeman A, van Sluis P, Vermeulen J, Gisselsson D, Ora I, Lindner S, Buckley PG, Stallings RL, Vandesompele J, Eggert A, Caron HN, Versteeg R, Molenaar JJ (March 2012). "Oncogenic activation of FOXR1 by 11q23 intrachromosomal deletion-fusions in neuroblastoma". Oncogene 31 (12): 1571–81. doi:10.1038/onc.2011.344. PMID 21860421.
  5. 1 2 3 4 5 6 Grimm D, Kay MA (December 2007). "Therapeutic application of RNAi: is mRNA targeting finally ready for prime time?". J. Clin. Invest. 117 (12): 3633–41. doi:10.1172/JCI34129. PMC 2096424. PMID 18060021.
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