What is the role of the oncogene bcl-2 which is commonly translocated to chromosomes 14 and 18?

What is the role of the oncogene bcl-2 which is commonly translocated to chromosomes 14 and 18?

Bcl-2 is an antiapoptotic molecule whose gene is located on chromosome 18. The immunoglobulin heavy chain (IgH) gene is located on chromosome 14. The bcl-2 t(14;18) translocation brings the bcl-2 gene under the control of the IgH enhancer, resulting in deregulated bcl-2 expression.

Which of the following lymphomas is characterized by 14 18 chromosomal translocation?

The chromosomal translocation t(14;18)(q32;q21) is characteristic of follicular lymphoma and a frequent abnormality in other types of non-Hodgkin lymphoma (NHL).

What is Intrachromosomal translocation?

Intrachromosomal translocations involve the movement of a chromosomal segment from one location in the chromosome to another. This is normally non-reciprocal, that is another segment does not exchange places with the first segment.

Is bcl-2 an oncogene or tumor suppressor?

Bcl-2 is widely believed to be an apoptosis suppressor gene. Overexpression of the protein in cancer cells may block or delay onset of apoptosis, by selecting and maintaining long-living cells and arresting cells in the G0 phase of the cell cycle.

What does BCL2 positive mean?

The gene for BCL2 is found on chromosome 18, and transfer of the BCL2 gene to a different chromosome is seen in many B-cell leukemias and lymphomas. This causes the BCL2 protein to be made in larger amounts, which may keep cancer cells from dying. Also called B-cell leukemia/lymphoma 2 protein.

What is the function of BCL2?

BCL2 prevents BAX/BAK oligomerization, which would otherwise lead to the release of several apoptogenic molecules from the mitochondrion. It is also known that BCL2 binds to and inactivates BAX and other pro-apoptotic proteins, thereby inhibiting apoptosis.

What is the translocation in follicular lymphoma?

Follicular lymphoma (FL) is characterized in the majority of cases by the recurrent chromosomal translocation t(14;18)(q32;q21), which brings the BCL2 gene on chromosome 18 under the influence of the IgH promoter on chromosome 14, resulting in a constitutive overexpression of the antiapoptotic BCL2 protein [1].

What is double hit non-Hodgkin’s lymphoma?

Double-hit lymphoma (DHL) is an aggressive type of B-cell non-Hodgkin lymphoma (NHL) characterized by rearrangements (parts of genes switch places within chromosomes) in two particular genes. One rearrangement involves the MYC gene, and the other involves the BCL2 gene or, less commonly, the BCL6 gene.

Is chromosomal translocation bad?

Depending on the chromosome breakpoints, a translocation can result in the disruption or misregulation of normal gene function. These molecular rearrangements, in many cases, are considered to be the primary cause of various cancers.

What does the Bcl-2 gene do?

A protein that helps control whether a cell lives or dies by blocking a type of cell death called apoptosis. The gene for BCL2 is found on chromosome 18, and transfer of the BCL2 gene to a different chromosome is seen in many B-cell leukemias and lymphomas.

What is BCL2 gene rearrangement?

Rearrangement of the BCL2 gene with the immunoglobulin (IG) genes is the most frequent genetic abnormality in B cell lymphoid neoplasms. In the majority of cases, breakages occur at two breakpoint cluster regions; major breakpoint cluster (MBR) and minor cluster region (mcr).

What causes Bcl-2 overexpression?

The results suggest that gene amplification and translocation are at least equally common mechanisms causing bcl-2 protein overexpression in DLBCL. Bcl-2 protein overexpression as determined by IHC is associated with poor response to chemotherapy and poor survival.

What is the treatment for follicular lymphoma?

FL is generally very responsive to radiation and chemotherapy. Radiation alone can provide a long-lasting remission in some patients with limited disease. In more advanced stages, physicians may use one or more chemotherapy drugs or the monoclonal antibody rituximab (Rituxan), alone or in combination with other agents.

What are the symptoms of follicular lymphoma?

Common symptoms of FL include enlargement of the lymph nodes in the neck, underarms, abdomen, or groin, as well as fatigue, shortness of breath, night sweats, and weight loss. Often, patients with FL have no obvious symptoms of the disease at diagnosis.

What is life expectancy with double hit lymphoma?

A 2014 multicenter retrospective study of 311 patients with double-hit lymphoma showed median progression-free survival to be 11 months and median overall survival to be 22 months. At 2 years, a “tail of the curve” showed about 40% of patients were free of disease progression, and close to 50% were still alive.

Which is more serious Hodgkin’s or non-Hodgkin lymphoma?

The prognosis of Hodgkin’s lymphoma is also better than that of non-Hodgkin’s lymphoma since non-Hodgkin’s lymphoma is often diagnosed at a more advanced stage. Both forms of blood cancer are treatable when caught early, however.

What causes BCR ABL translocation?

The BCR-ABL mutation happens when pieces of BCR and ABL genes break off and switch places. The piece of chromosome 9 that breaks off includes part of the ABL gene. When this piece moves over to chromosome 22, part of the ABL gene attaches to the BCR gene. The merged gene is called the BCR-ABL fusion gene.