ps7a - MIT Biology Department 7.012: Introductory Biology -...

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NAME_____________________________________________________________TA__________________ SEC____ 7.012 Problem Set 7 FRIDAY December 3, 2004 Not due unless you have had a prior agreement with Claudette Gardel Solutions will be posted on the web. Question 1 Leukemia is type of cancer characterized by the uncontrolled proliferation of white blood cells (leukocytes). Chronic Myelogenous Leukemia (CML) is a type of leukemia primarily caused by a translocation that relocates an oncogene, called abl , from the long arm of chromosome 9 to the long arm of chromosome 22 in the bcr region (breakpoint cluster region). The resulting bcr-abl fusion protein encodes a constitutively active tyrosine kinase, which when expressed, leads to the CML phenotype. a) Gleevec is an effective drug treatment of CML. What design principles were applied to the development of Gleevec? How is this approach different from that used to develop conventional cancer therapies? Rational drug design was applied to the development of Gleevec. The idea is to design a drug that specifically targets the underlying molecular defect, rather than nonspecifically target all dividing cells, as do many conventional cancer therapies b) How does Gleevec work at the molecular level? Gleevec works by binding to the ATP binding site of bcr-abl thus inhibiting its tyrosine kinase activity. c) How many protein targets does Gleevec have? Name each target. Gleevec does bind to two other tyrosine kinases: kit and the PDGF receptor. d) Besides target specificity, what other characteristics of a drug should you consider when designing a therapy? Toxicity, absorption efficiency, is it metabolized, possible reactivity of metabolites, etc. In contrast to drug treatments, gene therapy attempts to correct the defect by introducing a functional copy of the malfunctioning gene that is responsible for the disease phenotype. The functional gene copy can be introduced directly into the diseased organ or can be used to genetically modify isolated tissue that is later re-introduced into the patient. e) What do you need to know about the target disease in order to apply gene therapy? You need to know the gene involved in the disease. In particular, the disease should be caused by a defect in a single gene. MIT Biology Department 7.012: Introductory Biology - Fall 2004 Instructors: Professor Eric Lander, Professor Robert A. Weinberg, Dr. Claudette Gardel
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2 f) How could you deliver the functional gene into the diseased cells? A viral vector could be used (example: adenovirus). g) What do you think are some of the challenges facing gene therapy? Challenges include efficient uptake of the functional gene, stability of the gene, long term expression, side effects of viral vector. h) Based on your understanding of oncogenes, why would
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This note was uploaded on 11/11/2011 for the course BIO 7.012 taught by Professor Lander during the Fall '10 term at MIT.

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ps7a - MIT Biology Department 7.012: Introductory Biology -...

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