Molecular Oncogenes And Cancer Gene Therapy

By:Hussain albaharna

Oncogenes and proto-oncogenes • Scientists discovered in the late 1970s that a specific gene type plays a major role in the carcinogenesis of the cell, the so-called proto-oncogenes • Oncogenes are mutated forms of proto-oncogenes whose functions are to encourage and promote the, normal growth and division of cells. When protooncogenes mutate to become carcinogenic oncogenes, the result is excessive cell multiplication • Generally, proto-oncogenes code for cellular proteins that relay signals, to a cell's nucleus, stimulating growth

Oncogenes and proto-oncogenes (continue)

• Proto-oncogenes activation to oncogenes may result in: • overproduction of growth factors. • flooding of the cell with replication signals . • uncontrolled stimulation in the. intermediary pathways and/or • unrestrained cell growth driven by elevated levels of transcription factors.

Mode of oncogene activation • There are several ways of transforming protooncogenes into oncogenes: • Point mutation (alterations in the genetic code) • Deletion (truncated EGE receptor) • Translocation (chromosomal rearrangements, Burkitt i lymphoma) • Gene amplification (double minutes, eg. erb-B in glioblastoma) • Viral insertion (retroviral transduction)

So … proto-oncogene is Any gene that could code for: • Growth factor

So … proto-oncogene is (continue)

Any gene that could code for: • Growth factor • Growth factor receptor

So … proto-oncogene is (continue)

Any gene that could code for: • Growth factor • Growth factor receptor • Intracellular signaling molecule, or

So … proto-oncogene is (continue)

Any gene that could code for: • Growth factor. • Growth factor receptor. • Intracellular signaling molecule, or, • Molecule that alter the rate of transcription.

Apoptosis • Apoptosis or "programmed cell death" in which the cell actively participates in its demise in response to a tumor suppressor gene known as p53. • It is characterized by cell shrinkage, chromatin condensation, cytoplasmic blebbing, and DNA fragmentation whereas mitochondria and other cytoplasmic organelles remain intact during the early stages.

Are all cancers caused by ? oncogenes • The roles of Non-genetic mechanisms in cancer induction: • Some chemicals, called promoters can potentiate the activity of electrophilic carcinogens. Phorbol esters (PEs) cause non-genetic cellular changes that often mimic transformation by activating protein kinase C. Long-term treatment with PEs leads to permanent cellular alterations that may or may not be genetic. • Epigenetic alteration leading to a teratocarcinoma. These tumor cells revert to normal when they are implanted into early embryos but if they are injected into adult mice, they form lethal tumors. Thus their malignant state is conditional on their environment.

Antisense RNA for human therapy • Messenger RNA (MRNA), is single-stranded. it's sequence of nucleotides is called "sense" because it results in a gene product (protein) • Antisense RNA bind to and deactivates mRNA. • Putting antisense RNA in the ribosome, facilitates the meeting of mRNA and antisense RNA and the inactivation of the Messenger • Antisense RNA that is complementary to the proto-onccgene BCL-2 is being examine as a possible therapy for certain B-cell lymphomas and Ieukemias.