Some changes are not so good -Oncogenes

As mentioned earlier post, two types of genes are being responsible for the development of cancers.Those being oncogenes and tumour supressor genes.
Onco genes are formed by the changes happen in normal genes in the genome, which are called the Proto -oncogenes.Proto-oncogenes regulate the normal processes of the cell, including, cell proliferation, differentiation, adhesion, cell cycle control and apoptosis.
So, not unexpectedly, the mutations in these genes will lead to the formation of malignant tissue.

Activation of oncogenes:
The proto-oncogene can become an oncogene by a relatively small modification of its original function. There are three basic activation types:

1. A mutation within a proto-oncogene can cause a change in the protein product
2. An increase in protein concentration caused by,

• increased gene expression or
• by increased protein(mRNA) stability in the cell

3. A chromosomal translocation causing,

• an increased gene expression in the wrong cells at wrong times or
• an expression of an hybrid abberent protein

Hoping to talk about the types of of oncogenes in the next post............

Keeps growing: Cancer

When talking about hottest topics in molecular biology, i think cancer has become one in the top of the chart recently.So, i thought of getting a head start by discussing something about cancer.





At this particular moment, i have some statistics in my hand showing that the corresponding estimates for total cancer deaths in 2007 are 7.6 million.It's about 20,000 cancer deaths per day. It also suggests that by 2050,the global burden will grow to 27 million cancer deaths and 17.5 million cancer deaths simply due to the growth and aging of the population.

so,there's no doubt that it has become one of the hottest topics in molecular biology.





cancer is a growth disorder of cells. It starts when an apperently normal cell begins to grow in an uncontrolled and invasive way.


The result is a cluster of cellls,called a tumour,that constantly expands in size.


As the mass of cells grows, it invades the surrounding tissues, penetrating the blood and lymphatic vessels.


These vessels carry cancer cells throughout the body, wher they lodge and grow,forming new masses of cancerous tissue. These cells that leave the tumour and spread thoughout the body, forming new tumours at distant sites are called metastases.

So, scientists have made a great deal of progress in the last 20 years using molecular biology techniques, and we know that cancer is a gene disorder of somatic tissue, in which damaged genes fail to properly control cell proliferation.
The celll division cycle is regulated by a sophisticated group of proteins and cancer results from the mutation of the genes encoding these proteins.
These mutations may be induced by chemicals that mutate DNA or in some cases by viruses.

Uncontrollled cell proliferation is activated in two ways. In some cases, cancerous growth is initiated by the inappropriate activation of proteins that regulate the cell cycle; in other cases it is initiated by the inactivation of proteins that suppress the cell cycle.
Basically, you can accelerate by stepping on the gas or by the removal of the brakes.

Acceleration happens sometimes by the unrestrained supply of the signals for the cell division cycle. These signals are coded by signalling genes which sometimes mutate.
The normal non mutated forms of these genes are called proto oncogenes and they can mutate to produce tumour forming onco genes.
For example, k-ras: cause lung and colon cancer
N-ras: cause leukemia

Removal of the brakes happens, when genes encoding for proteins, which turn off the cell division cycle are mutated. Those genes are called tumour-suppressor genes.
For example, p53: cause a wide range of cancers
BRCA 1/2 : cause breast cancer

I'm hoping to talk a lot more details about these genes in my next few posts.