Chapter 4 Cellular Oncogenes - 4.2 ~ 4.6 -
Many retroviruses carrying oncogenes have been found in chickens and mice
However, attempts undertaken during the 1970s to isolate viruses from most types of human tumors were unsuccessful. Even reverse transcriptase-containing virus particles are difficult to find in human tumor samples.
4.2 Transfection of DNA provides a strategy for detecting nonviral oncogenes (NIH3T3 cells) transformed by 3-methycholanthrene Sidebar 4.2 Figure 4.2 (part 1 of 2) The Biology of Cancer ( Garland Science 2007)
DNA from tumor cells (NIH3T3 cells) The DNA from chemical-transformed tumor cells was able to convert non-tumorigenic NIH3T3 fibroblasts into tumorigenic cells. Figure 4.2 (part 2 of 2) The Biology of Cancer ( Garland Science 2007)
DNA from human cancers also cause focus formation focus formation cells in the focus surrounding untransformed monolayer cells Transfection of DNA from T24 human bladder carcinoma cell line into NIH3T3 cells Figure 4.3 The Biology of Cancer ( Garland Science 2007)
4.3 Oncogenes discovered in human tumor cell lines are related to those carried by transforming retroviruses Southern blotting (DNA) Northern blotting (RNA)
nitrocellulose paper ( 32P-DNA) Figure 4.4 (part 2) The Biology of Cancer ( Garland Science 2007)
Figure 4.4 (part 3) The Biology of Cancer ( Garland Science 2007)
Homology between transfected oncogenes and retroviral oncogenes probe used: H-ras oncogene present in Harvey rat sarcoma virus 11 (a ~ k) NIH3T3 cell lines transfected with DNA extracted from a human bladder carcinoma cell line Figure 4.5 The Biology of Cancer ( Garland Science 2007) untransfected NIH3T3
TK : tyrosine kinase Table 4.1 The Biology of Cancer ( Garland Science 2007)
Amplification of the erbb2/her2/neu oncogene in breast cancers Kaplan-Meier plot Figure 4.6a The Biology of Cancer ( Garland Science 2007)
erbb2/her2/neu oncogene can be amplified or overexpressed in human breast carcinoma cells erbb2/neu oncogene is amplified erbb2/neu mrna is overexpressed increased level of erbb2/neu-encoded protein Figure 4.6c The Biology of Cancer ( Garland Science 2007)
Cloning of transfected human oncogenes Alu sequence present in about 106 copies scattered throughout human genome Figure 4.8 The Biology of Cancer ( Garland Science 2007)
Localization of the mutation responsible for oncogene activity cloned DNA of a human bladder carcinoma oncogene Figure 4.9 The Biology of Cancer ( Garland Science 2007)
A point mutation is responsible for H-ras oncogene activation Figure 4.10 The Biology of Cancer ( Garland Science 2007)
4.4 Proto-oncogenes can be activated by genetic changes affecting either protein expression or structure
4.5 The myc oncogene can arise via at least three distinct mechanisms homogeneous staining regions (HSR) The N-myc gene amplification is found in 30% of human childhood neuroblastoma. Astrocytoma, retinoblastoma and small-cell lung carcinomas (neuroendocrinal traits) also often exhibit amplified N-myc genes. * N-myc is a close relative of c-myc. Figure 4.11a The Biology of Cancer ( Garland Science 2007)
event - free survival Kaplan-Meier plot of childhood neuroblastoma
Table 4.3 The Biology of Cancer ( Garland Science 2007)
Activation of the myc protooncogenes 1. Gene amplification 10 ~ 30 copies or 100 ~ 150 copies shown as homogeneously staining regions (HSR) or double minutes (DM) 2. Provirus integration - insertional mutagenesis constitutive expression by insertion of retroviruses 3. Chromosomal translocation
Insertional mutagenesis transcription of myc gene is controlled by viral promoters excessive myc protein Figure 3.23b The Biology of Cancer ( Garland Science 2007)
Burkitt s lymphoma in Africa (Aedes simpsoni) Malarial infection Figure 4.12 The Biology of Cancer ( Garland Science 2007) Epstein-Barr virus (EBV) genome in Burkitt s lymphoma cells
Chromosome translocations in Burkitt s lymphoma The expression of c-myc gene is placed under control of the trancriptioncontrolling enhancer sequences of an immunoglobulin heavy chain (IgH) gene. Figure 4.13a The Biology of Cancer ( Garland Science 2007)
Genetic map of the translocation event of c-myc gene The c-myc gene is translocated into chromosome 8, under the control of the immunoglobulin heavy-chain (IgH) sequences present on human chromosome 14 Figure 4.13b The Biology of Cancer ( Garland Science 2007)
Table 4.4 The Biology of Cancer ( Garland Science 2007)
4.6 A diverse array of structural changes in proteins can also lead to oncogene activation (GF) Figure 4.14 The Biology of Cancer ( Garland Science 2007)
The great majority (> 95 %) of chronic myelogenous leukemia (CML) has t(9; 22) (q34; q11) translocation Philadelphia chromosome (Ph1) Figure 2.23a The Biology of Cancer ( Garland Science 2007)
Formation of the bcr-abl oncogene after t(9; 22) (q34; q11) translocation (Abelson murine leukemia virus) (breakpoint cluster region) Figure 4.15a The Biology of Cancer ( Garland Science 2007)
Different breakpoints in bcr results in different types of human leukemia a b c a. acute lymphocytic leukemia b. chronic myelogenous leukemia c. Bcr Abl Bcr-Abl fusion protein Figure 4.15b The Biology of Cancer ( Garland Science 2007) chronic neutrophilic leukemia
Table 4.5 The Biology of Cancer ( Garland Science 2007)
Notations used for proto-oncogenes and oncogenes Non-human (chicken, mouse, etc.) Human gene protein src, myc Src, Myc SRC, MYC SRC, MYC