BRCA Gene Mutation and Breast Cancer

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Abstract

Cancer remains one of the major threats to human health. It occurs as a result of gene mutation. Breast cancer is the most prevalent cancer among women. Additionally, breast cancer affects men, though in rare cases. The disease occurs as a result of mutations in breast cancer susceptibility genes 1 and 2. The genes produce proteins that facilitate the restoration of damaged DNA. Mutations in the BRCA 1 and BRCA 2 genes inhibit the recovery of DNA leading to subsequent alterations in the DNA. The changes result in the cells growing and splitting uncontrollably causing cancer. Breast cancers are classified based on the available hormone receptors. Physicians use radiotherapy, operation or chemotherapy to assist individuals suffering from breast cancer. The operation entails the amputation of the infected breast. On the other hand, chemotherapy and radiation therapy kill the cancer cells or prevent them from multiplying.

Introduction

Cancer is the leading killer disease in the world. Easton, Ford and Bishop (2005) maintain that cancer refers to a collection of illnesses that involve irregular cell growth and are likely to attack different parts of the body. According to Easton et al. (2005), it is important to understand that not all cell growths are cancerous. They cite benign tumors as one of the diseases that are not cancerous. Cancer accounts for at least 20% to 46% of the deaths. Currently, cancer is prevalent in developed countries. The risk factors associated with the disease include old age, ethnicity, environmental conditions, diet, and lifestyle. Breast cancer is one of the leading killer diseases among women. Cancer results from a hereditary gene mutation. Easton et al. (2005) cite breast cancer susceptibility genes 1 and 2 (BRCA 1 and BRCA 2) as the common types of gene mutations that lead to breast cancer. BRCA 1 and BRCA 2 mutations can be acquired from either parent and can result in both men and women suffering from cancer. Prevention is the ultimate way of dealing with cancer. Environmental factors contribute to at least 70% of cancer cases. Lifestyle change can go a long way towards combating the disease.

Research Objective

The primary objective of this study is to determine how BRCA 1 and BRCA 2 gene mutations contribute to breast cancer. The study will also analyze the role of BRCA1 and BRCA 2 in the restoration of the damaged DNA as well as the different categories of breast cancer.

Literature Review

Breast Cancer

Breast cancer occurs as a result of irregular duplication of cells in the breast leading to a tumor. Breast cancer is prevalent in women. However, it does not mean that men cannot suffer from breast cancer. Mostly, breast cancer occurs as a result of the irregular reproduction of the cells that surround the milk ducts. Breast cancer is hard to detect during the early stages because it does not cause pain (Fackentha & Olopade, 2007). As the disease progresses, the signs become apparent. The symptoms include nipple discharge, change in the shape of the breast, a lump in the breast, and skin irritation among others. Nonetheless, the symptoms may differ due to numerous conditions. A person may exhibit these symptoms and not be diagnosed with breast cancer. In the United States, at least, 12% of the women suffer from breast cancer. Researchers claim that in 2015, the United States reported over 230,000 new cases of breast cancer. The gene transformations that lead to breast cancer are common among particular communities. Besides, the gene mutations are prevalent in particular geographic zones.

Classification of Breast Cancer

After the biopsy, the breast tissues are analyzed to establish if they have breast cancer. The medical practitioners use progesterone receptors (PR) and estrogen receptors (ER) to classify breast cancer. Gayther et al. (2011) hold that receptors refer to proteins found in the cells. The proteins get fastened on particular substances like hormones that distribute the blood. The ordinary breast cells and some cancer cells constitute receptors that embed to progesterone and estrogen. The progesterone and estrogen often hasten the development of breast cancer cells. A critical step in assessing breast cancer entails examining the tumor extracted from surgery or biopsy to determine if it contains progesterone or estrogen receptors. The breast cancers that constitute estrogen receptors are known as ER-positive (ER+) cancers. On the other hand, those that have progesterone receptors are referred to as PR-positive (PR+) cancers. The doctors must test the presence of these hormone receptors in all kinds of breast cancers. According to Gayther et al. (2011), over 67% of the breast cancers contain one of the receptors.

Breast cancers are categorized according to the hormone receptor present. Additionally, the doctors consider if cancer comprises too much of human epidermal growth factor receptor 2 (HER2). The breast cancers that do not constitute the hormone receptors are referred to as hormone receptor-negative. At times, the doctors use the term hormone-negative to apply to these types of cancer (Gayther et al., 2011). Such tumors are hard to cure using hormone therapy drugs. The hormone-negative tumors grow rapidly and affect women who have not reached the menopause stage. Some breast cancers constitute either progesterone or estrogen. Such tumors are referred to as hormone receptor-positive. The diseases can be cured using hormone therapy drugs. The drugs minimize estrogen intensity or obstruct estrogen receptors. Hormone receptor-positive cancers develop slowly. However, they may recur after an extended period.

Studies on the models of gene expression have resulted in novel ways of grouping breast cancer. Today, doctors classify breast cancer based on the appearance of tumors when observed using a microscope. Doctors have come up with four groups of breast cancers depending on the molecular characteristics of the tumor. The mode of examining breast cancer based on the molecular structure of the tumor is referred to as Prosigna Breast Prognostic Gene Signature Assay (PAM50). The method is useful in testing HER2 and hormone receptors. The four groups of cancer are luminal A, luminal B, HER 2 type and basal type. According to Gayther et al. (2011), luminal A and luminal B types of breast cancer are ER+. Godlewski and Kapu[ciDska (1996) allege that the structure of the gene expression in the tumors is akin to standard cells that cover the milk ducts. The luminal A tumors do not develop rapidly and are easy to diagnose. Conversely, the luminal B cancers develop rapidly. The tumors have a hideous appearance (Godlewski & Kapu[ciDska, 1996). The HER2 types constitute additional copies of the human epidermal growth factor receptor 2. These types of breast cancer have a nice facade when observed through a microscope. The cancers grow fast and can be healed through targeted therapies. The basal types of breast cancers do not have both the progesterone and the estrogen receptors. Further, the cancers have a standard amount of human epidermal growth factor receptor 2. The basal type of breast cancer mostly affects women with BRCA 1 gene mutations.

The Function of BRCA Genes

The breast cancer susceptibility genes fix proteins that facilitate in genome protection. According to King, Marks and Mandell (2003), BRCA 1 protein and BRCA 2 protein are two types of protein that work in diverse phases of the DNA restoration course. King et al. (2003) argue that the breast cancer susceptibility gene 1 protein is a DNA damage reaction protein. The protein plays key roles on both checkpoint activation and DNA restoration. On the other hand, BRCA 2 protein facilitates the conciliation of the crucial processes of homologous recombination. The scientists are yet to understand the relationship between the two proteins. However, researchers claim that the two proteins have to be available to elucidate the striking association of human cancer vulnerability that results from germline mutations in BRCA 1 and BRCA 2. Apart from DNA restoration, BRCA genes help in transcription management in reaction to DNA damage. Latest studies hold that BRCA1 and BRCA 2 proteins are vital in the preservation of chromosomal equilibrium, therefore ensuring that the genome remains unaffected. Research shows that BRCA 1 and BRCA 2 proteins transcriptionally control several genes that facilitate apoptosis and the cell cycle (Yoshida & Miki, 2004). A majority of these functions are made possible through the interaction between BRCAs and numerous cellular proteins. Rennert et al. (2007) claim that BRCA proteins also facilitate several phosphorylation processes. Nonetheless, scientists are yet to understand how phosphorylation-triggered molecular conduits help to prevent tumor.

Genes Associated with Breast Cancer

Rennert et al. (2007) argue that cancer arises as a result of accumulation of mutations in vital genes, which lead to cells developing and splitting uncontrollably forming a growth. In the case of breast cancer, the genetic transformations arise in the course of an individuals life and are found in specific cells in the breast. The affected genes are those that manage cell development and division. The mutation may also arise in the genes that restore damaged DNA. The genetic transformations are referred to as somatic mutations and are not hereditary. Breast cancer occurs mainly due to somatic mutation of different genes. The common gene mutations that occur in other body cells do not significantly contribute to the development of breast cancer. The genetic transformations that occur in most cells of the body are known as germline mutations. The mutations are hereditary. Most breast cancers that affect members of the same family are as a result of genetic mutations in some genes like BRCA 1 or BRCA 2. The BRCA 1 and BRCA 2 are regarded as high penetrance since they are disposed to causing ovarian cancer, breast cancer and many other varieties of cancer particularly in women with mutations (Roy, Chun & Powell, 2012). Besides, men with mutations in BRCA 1 and BRCA 2 genes are also likely to suffer from breast cancer and other types of cancer.

The BRCA 1 and BRCA 2 manufacture proteins that facilitate the repair of spoilt DNA. On the other hand, the DNA guarantees the constancy of genetic information of the cells. The proteins help to stem tumor by preventing cells from developing and splitting uncontrollably. Mutations in BRCA 1 and BRCA 2 inhibit the restoration of DNA, thus enabling devastating mutations to occur in DNA. Increased mutations in the DNA result in the cells growing and splitting uncontrollably to form a growth (Roy et al., 2012). Breast cancer can come as a result of other numerous exceptional genetic syndromes. They include Cowden syndrome that happens due to mutations in the phosphatase and tensin homolog (PTEN) genes and a Li-Fraumeni syndrome that occurs as a result of mutations in the tumor protein p53 (TP53) genes.

Treatment of Breast Cancer

A person suffering from breast cancer may opt for radiotherapy. Radiotherapy entails the use of radiations to kill cancerous cells. The radiations help to prevent cancer cells from multiplying. The doctors may also treat cancer using drugs (chemotherapy). Chemotherapy involves the use of drugs to cure cancer (Yoshida & Miki, 2004). The drugs help to kill cancer cells or prevent them from multiplying. Chemotherapy is mostly administered through the mouth. However, it can also be introduced into a muscle or vein through injection. The administration of chemotherapy depends on the phase and type of breast cancer. Today, doctors also use hormone therapy to treat breast cancer. The treatment entails the deletion or obstruction of hormones that contributes to the growing of cancer cells. For instance, the doctors conduct ovarian ablation to terminate the production of estrogen, which promotes the growth of breast cancer.

Research Methodology

The study will rely on qualitative data. The researcher will gather data from peer-reviewed journals and other appropriate publications. The researcher will rely on online libraries like EBSCOhost, JSTOR, and PubMed among others.

Sampling Technique

The study will use any journal that touches on BRCA 1 and BRCA 2 and their correlation to breast cancer. The researcher will not use probability sampling because the study does not intend to come up with statistically representative samples. Besides, the researcher does not intend to make any statistical inferences from the study. The pollster will use purposive sampling to select the necessary journals.

Data Processing and Analysis Procedures

The researcher will use phenomenological method to process the data obtained from diverse journals. The researcher will go through the collected data to understand it. After understanding the data, the researcher will generate units of meaning. The pollster will be careful not to make redundant subjective judgments. The diverse units of meaning will then be merged to develop the units of significance. Later the researcher will summarize the data collected from the different journals ensuring that they capture the essential information. The pollster will then identify the themes that are common in a majority of the journals and use them to compile the findings of the study.

Conclusion

Cancer is the leading killer disease in the contemporary world. Breast cancer is the most prevalent form of cancer among women. However, breast cancer also affects men, though in rare cases. Breast cancer occurs as a result of BRCA 1 and BRCA 2 genes mutations. The cancer is classified according to the hormone receptors present. Hormone receptor-negative cancers are breast cancers that do not contain hormones. The tumors that constitute estrogen receptors are called estrogen receptor-positive cancers. Those that contain progesterone receptors are known as progesterone receptor-positive cancers. Other types of tumors include luminal A, luminal B, and HER2 types of cancer. The primary function of BRCA1 and BRCA 2 is to facilitate the restoration of damaged DNA. Breast cancer affects the genes that promote the repair of DNA. Numerous exceptional genetic syndromes can also lead to breast cancer. They include Cowden and Li-Fraumeni syndromes. Breast cancer can be cured by surgery, radiation therapy or chemotherapy. The operation entails the amputation of the infected breast. On the other hand, radiation therapy and chemotherapy target the cancer cells. The therapies either kill the cancer cells or prevent them from multiplying.

References

Easton, D., Ford, D., & Bishop, D. (2005). Breast and ovarian cancer incidence in BRCA 1-mutation carriers: Breast cancer linkage consortium. American Journal of Human Genetics, 56(1), 265-271.

Fackentha, J., & Olopade, O. (2007). Breast cancer risk associated with BRCA 1 and BRCA 2 in diverse populations. Nature Reviews Cancer, 7(3), 937-948.

Gayther, S., Mangion, J., Russell, P., Seal, S., Barfoot, R., Ponder, B., Stratton, M., & Easton, D. (2011). Variations of risks of breast and ovarian cancer associated with different germline mutations of the BRCA 2 gene. Nature Genetics, 15(2), 103-115.

Godlewski, D., & Kapu[ciDska, M. (1996). BRCA1 and BRCA2 genes: New risk factors in hereditary forms of breast cancer and ovarian carcinoma. Reports of Practical Oncology, 1(1), 53-55.

King, M., Marks, J., & Mandell, J. (2003). Breast and ovarian cancer risks due to inherited mutations in BRCA 1 and BRCA 2. Science, 302(5645), 643-671.

Rennert, G., Bisland-Naggan, S., Barnett-Griness, O., Bar-Joseph, N., Zhang, S., Rennert, H., & Narod, S. (2007). Clinical outcomes of breast cancer in carriers of BRCA 1 and BRCA 2 mutations. The New England Journal of Medicine, 357(2), 115-123.

Roy, R., Chun, J., & Powell, S. (2012). BRCA 1 and BRCA 2: Different roles in a common pathway of genome protection. Nature Reviews Cancer, 12(1), 68-78.

Thompson, D., & Easton, D. (2005). Cancer incidence in BRCA 1 mutation carriers. Journal of the National Cancer Institute, 94(18), 1358-1365.

Xu, J., Wang, B., Zhang, Y., Li, R., Wang, Y., & Zhang, S. (2012). Clinical implications of BRCA gene mutation in breast cancer. Molecular Biology Reports, 39(3), 3097-3102.

Yoshida, K., & Miki, Y. (2004). Role of BRCA 1 and BRCA 2 as regulators of DNA repair, transcription and cell cycle in response to DNA damage. Cancer Science, 95(11), 866-871.

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