The Role of BCL2 Protein in Chronic Lymphocytic Leukemia

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BCL-2 (B-cell lymphoma 2) protein is defined as a regulatory protein that controls programmed cell death or apoptosis (Johnson 2012, p. 20). It is determined by the BCL-2 gene, a gene that encodes for the BCL-2 family of regulatory proteins, whose function is up-regulation or down-regulation apoptosis (Nambiar et al. 2011, p. 437). The BCL-2 protein is specifically crucial for anti-apoptosis to occur. The protein has been noted to be useful in chronic lymphocytic leukemia (CLL) treatment.

Additionally, BCL-2 is in the group of proteins identified to be the reason for translocations of chromosome 14 and 18 seen in follicular lymphomas (Luciani et al. 2013, p. 19). Some orthologs, including BCL-2, are demonstrated in certain mammals, such as mice, where complete data about genome is available. BCL-2 has a clinical consequence in lymphomas, similar to other BCL proteins.

Functions of the BCL-2 Group of Proteins

The aim of this paper is to elucidate the effect of BCL-2 protein in the process of apoptosis and the consequence of the development of malignancies, primarily CLL. The BCL-2 groups of proteins function in a manner that they are expressed in the mitochondrial outer membrane, where they promote cell survival and inhibit the actions of pro-apoptotic proteins. Proteins of the BCL-2, including Bax and Bak, act as the mitochondrial membrane to improve permeability and output of cytochrome C and ROS (reactive oxygen species), which are parts of the apoptotic sequel. Pro-apoptotic proteins are the sole proteins that can be blocked by BCL-2 protein and its BCL-XI relative (Hardwick and Soane 2013, p. 43).

Some supplementary BCL-2 functions have been studied. Such functions include BCL-2 regulation of mitochondrial dynamics and participation in modifying mitochondrial fusion and fission. Furthermore, BCL-2 and BCL-XI are shown to control metabolic activity and secretion of insulin, while inhibiting BCL-2/XI, therefore, showing the growing metabolic activity and additional ROS creation (Luciani et al. 2013, p. 176). The assertion proposes that it has a defensive metabolic result in great demand scenarios (Aharoni-Simon et al. 2016, P. 2279).

The Function of the BCL-2 Proto-oncogene in CLL and Apoptosis

One needs to first realize that cancer is normally a consequence of disruption in the homeostasis that exists between cell growth and apoptosis to understand the role of the BCL-2 proto-oncogene in leukemia and apoptosis. BCL-2 protein, as earlier explained, functions by regulation of the process of apoptosis by inducing or deterring cell death. The ways in which they impact cells to cause CLL and how they are modulated is not completely understood. It is however known that when BCL-2 proteins do not cause sufficient apoptosis or do cause excess restriction of cell death, malignancy occurs (Ola, Nawaz and Ahsan 2011, p. 43). Damage done to the BCL-2 gene is shown to result in causation certain cancers, in addition to chronic lymphocytic leukemia. These include melanoma, prostate cancer, breast cancer, and lung cancer (Adams and Cory 2007, p. 1328).

The family of BCL-2 proteins that conduct pro-apoptosis and anti-apoptosis are crucial for control of programed cell death and caspase activation by mitochondria (Ola, Nawaz and Ahsan 2011, p. 48). Within its family, BCL-2 was the initial one to be characterized and recognized. Unusual expression of its gene is frequently observed in chronic lymphocytic leukemia (CLL) cases. Such faulty expression also correlates with poor chemotherapeutic response and reduced survival as a result. BCL-2 protein expression is, therefore, of prognostic usefulness in CLL. The existence or lack of BCL-2 staining in a biopsy has a bearing on the prognostication or probability of relapse in a patient (Adams and Cory 2007, p. 1332).

Regarding practicality in cancer treatment, BCL-2 genes and proteins provide potential points of treatment for related malignancies. They are especially targeted by novel chemotherapeutic agents showing some positive responses (Roberts et al. 2016, p. 314). Antisense oligonucleotides targeting BCL-2 are useful in vitro and have been examined during clinical studies in CLL, showing positive responses as well. Small molecule inhibitors of BCL-2 are also potential treatments for CLL (Malek 2013, p. 23). Mechanisms of chemotherapy that bypass BCL-2 and cause apoptosis may be effective for CLL treatment (Ola, Nawaz and Ahsan 2011, P. 49). Quantities of apoptotic proteins, including BCL-2 can be useful in risk estimation and therapeutic processes for singular patients. Molecule-specific treatments that are targeted against faulty cellular particles, including genes or parts of genes, are also promising in the future of chemotherapy for CLL (Schimmer 2003, p. 212). Notable advances recently show that genetic, epigenetic, and micro-environmental factors have a role to play in altering BCL-2 proteins. Major progress continues to be done to target such proteins in the treatment of CLL (Buggins and CJ 2010, p. 840).


In conclusion, this essay explored the pertinence of BCL-2 in apoptosis regulation, a step of cell growth modulation that influences the occurrence of cancers, the chief being CLL. The BCL-2 gene is a gene that codes for the BCL-2 protein. The BCL-2 protein is found in the outer membrane of the mitochondria where it promotes the survival of the cell and inhibits pro-apoptotic proteins (Roberts et al. 2016, p. 317). Apoptosis refers to programmed cell death. When aberrant regulation of apoptosis occurs, due to the effect of BCL-2 expression, malignancies crop up. Mostly associated with BCL-2 protein derangements, is chronic lymphocytic leukemia, and then others that include melanoma, breast, and lung cancer. BCL-2 expression is a target of new chemotherapeutic medications (Hardwick and Soane 2013, p. 27). Thorough research continues to be conducted. Molecule-specific treatments aiming at faulty cellular particles, including genes or parts of genes, are highly promising in the future of chemotherapy for CLL. Intense research and funding are required to facilitate such projects.

BCL-2 and apoptosis (Aharoni-Simon et al. 2016).


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Adams, J. M. and Cory, S. (2007) ‘The Bcl-2 apoptotic switch in cancer development and therapy’, Oncogene, pp. 1324–1337. doi: 10.1038/sj.onc.1210220.

Aharoni-Simon, M., Shumiatcher, R., Yeung, A., Shih, A., Dolinsky, V., Doucette, C., et al. (2016). Bcl-2 Regulates Reactive Oxygen Species Signaling and a Redox-Sensitive Mitochondrial Proton Leak in Mouse Pancreatic ß-Cells. Endocrinology, 157(6), 2270–2286.

Buggins, A., and CJ, P. (2010). The role of Bcl-2 family proteins in chronic lymphocytic leukaemia. Leuk Res., 34(7), 837-842.

Hardwick, J., and Soane, L. (. (2013). Multiple functions of BCL-2 family proteins. Cold Spring Harb Perspect Biol., 5(2), a008722.

Johnson, D. E., 2012. Cell Death Signaling in Cancer Biology and Treatment [recurso electrónico]. (Adams and Cory, 2007; Nambiar et al., 2011; Ola, Nawaz and Ahsan, 2011)

Luciani, D., White, S., Widenmaier, S., Saran, V., Taghizadeh, F., Hu, X., et al. (2013). Bcl-2 and Bcl-xL suppress glucose signaling in pancreatic ß-cells. Diabetes, 62(1), 170-182.

Malek, S. (2013). Advances in Chronic Lymphocytic Leukemia (1 ed.). New York: Springer-Verlag.

Nambiar, M. et al. (2011) ‘Formation of a G-quadruplex at the BCL2 major breakpoint region of the t(14;18) translocation in follicular lymphoma’, Nucleic Acids Research, 39(3), pp. 936–948. doi: 10.1093/nar/gkq824.

Ola, M. S., Nawaz, M. and Ahsan, H. (2011) ‘Role of Bcl-2 family proteins and caspases in the regulation of apoptosis’, Molecular and Cellular Biochemistry, pp. 41–58. doi: 10.1007/s11010-010-0709-x.

Roberts, A. W., Davids, M. S., Pagel, J. M., Kahl, B. S., Puvvada, S. D., Gerecitano, J. F., et al. (2016). Targeting BCL2 with Venetoclax in Relapsed Chronic Lymphocytic Leukemia. The New England Journal of Medicine, 374 (4), 311-322.

Schimmer, A., Munk-Pedersen, I., Minden, M., and Reed, J. (2003). Bcl-2 and apoptosis in chronic lymphocytic leukemia. Curr Treat Options Oncol., 4(3), 211-218.

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August 09, 2023




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Cancer Death Leukemia

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