Oncogenes: Role in Development of Cancer
An oncogene is a gene whose main function is as a potential to cause cancer in the cell cycle. A normal cell is transformed into a cancerous cell when the cell’s proteins involved in regulating cell division are no longer able to facilitate progression from one stage of the cell cycle to the next. Cancer cells do not lack function but reproduce at an abnormally high rate bypassing the boundaries of the cell cycle. Cancer cells, with the function brought on by oncogenes, have enhanced mobility to grow and divide, produce abundant layers of cells, require fewer nutrients, and overcome the restrictions of the cell cycle. The oncogenes encode proteins involved in the cell cycle that also stimulate growth and division of the cell. These proteins accelerate the cell cycle by allowing cells to proceed directly from either the G0 or the G1 phase to the S phase or mitosis. One particular way includes cell surface receptors binding to growth factors. Growth factors include either proteins that interact with DNA to begin replication or signaling molecules that link receptors to the initiation of replication.1
Conversion of a Proto-Oncogene to an Oncogene
In a normal cell, genes coding for proteins that control cell division and growth are called proto-oncogenes. However, a mutation can permanently activate proteins that are both active and inactive. This process results in the development of an oncogene, which has protein products that facilitate the growth of tumors.1 Most human tumors are monoclonal, which indicates that they are derived from a single aberrant cell. There are many pathways that result in the transformation of a proto-oncogene into an oncogene. First, the ras proto-oncogene can be...
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...in Burkitt’s lymphoma lead to the conversion of a proto-oncogene into an oncogene.7
Other forms of human cancer that involve oncogenes are neuroblastoma and breast cancer. In neuroblastoma patients there is a large presence of abnormality of the N-myc proto-oncogene associated with a conversion to an oncogene. In neuroplastic cells there is an abnormal increase in the N-myc gene resulting from gene amplification, which is the repeating of DNA sequences multiple times. In addition, breast cancer also is caused through gene amplification resulting in the development of oncogenes. Gene amplification of the c-erb B-2 proto-oncogene results in increased production of the c-erb B-2 protein.7 Oncogenes in these two cases bypass the G phases and proceed straight to either the S phase or mitosis, initiating abnormal cell proliferation unimpeded by cell growth regulation.
Women who inherit a mutation in one copy of BRCA1 or BRCA2 are at high risk of developing breast and ovarian cancers6. This could be due to the disruption in the pathway of BRCA proteins in the cell nucleus. If BRCA1 is defective, it loses its ability to fix damaged DNA and causes tumor. It is because once the defective BRCA1 raises, it allows the cells to develop and divide uncontrollably. Since defective in BRCA1 causes cancers, it is important to understanding the function of the protein by analyzing its sequence and structure.
The acquisition of an immortalized proliferative potential is very important for human tumors because, otherwise, the tumors will not grow in number nor will they metastasize. Mutations in progenitor cells would not be transmitted too far as they have limited replication and proliferation ability. Thus, the growth of the tumors will be limited. Hence, if there is even a very small population of cells with the ability to proliferate continuously, there will be a source for productions of more cells for the tumor. Clonogenic assays have shown that, though most cells in a tumor have a limited ability to proliferate, a subset of cancer cells exist in these tumors that continuously proliferate and give rise to new tumors on transplantation.
The breast is a muscle connected to the chest wall made up of fatty tissues containing milk-forming glands that drain into the breast ducts during breast-feeding, and then leave the ducts through the nipple (Newson et al). These glands can decrease or increase in number and size. Breast lumps or cysts can form in various tissues or components that make up the breast. The English diction cyst comes from the Ancient Greek word kystis, meaning “bladder” or “pouch”. A cyst is an organ or cavity containing a liquid, semisolid or gaseous secretion. Cysts appear within tissue and can affect any part of the human body. They range in size from minuscule to the mass of team-sport balls such as tennis or baseballs. Cysts are also referred to as any normal bag or sac in the body, such as the bladder.
..., while a cell undergoes cell cycle, when a cell comes in contact with another cell, it stops reproducing. However, cancer cells continue to duplicate repeatedly until there is a mass of cells or a tumor to form (see figure 9). Lastly, in cell division when there is a mutation or abnormality in the DNA, a normal cell stops dividing. However, a cancerous cell will continue to duplicate and form mutations (“Cell Biology and Cancer”). Also, cancer cells are harmful because they grow and duplicate with complete disregard to the functions and limitations of the body (see figure 10). Also, cancerous cells have the ability to spread through metastasis throughout parts of the body through the bloodstream. In terms of similar behavior to that of normal cells, cancerous cells also duplicate, but at a very different rate ("Cancer Cells vs. Normal Cells: What's Different?").
The pancreas can be divided into two sections when studying the histology. The pancreas has exocrine and endocrine functions, each with unique cell types. The exocrine pancreas serves to secrete digestive enzymes into the duodenum. Some of the specific enzymes and secreted substances are Proteases, lipase, amylase, bicarbonate, and water (Bowen, “Exocrine Secretions”). These enzymes are used to break down protein, fat, and carbohydrates respectively. The bicarbonate simply act as an acid buffer to prevent damage of the small intestine as the stomach acid must be neutralized. The enzymes are created in acinar cells and the bicarbonate is synthesized in epithelial cells surrounding pancreatic ducts (Bowen “Exocrine
I have chosen to write about the constellation Cancer (The Crab). I chose Cancer because it is one of only a handful of constellations that I am actually able to identify in the night sky. Cancer is one of the twelve Zodiac constellations; people whose birthdays fall between June 21st and July 22nd have Cancer as their sign. Cancer is the Latin word for crab, and despite the fact that the constellation looks more like a lobster then a crab, it is still referred to as a crab. The constellation is visible from the northern hemisphere from late winter to early spring.
Stem cells help us to maintain and heal our bodies, as they are undifferentiated cells, their roles are not yet determined. They have the ability to become anything during early life and growth. Stem cells come from two sources, namely: embryonic stem cells (embryo’s formed during the blastocyst phase of embryological development) and adult stem cells (see figure 3).
Acute Myeloid Leukemia (AML) is the most common type of acute leukemia in adults. AML is a heterogeneous disease which results from genetic alterations in normal hematopoietic stem cells. These alterations induce differentiation arrest and/or excessive proliferation of abnormal leukemic cells or blasts [1]. Recent genomic studies have identified that recurrent somatic mutations in patients with AML blocks differentiation and/or enhance self-renewal by altered transcription factors [2,3]. The genetic or the epigenetic changes acquired by AML cells disrupt the key growth regulatory pathways and changes will make the normal cells to attain certain malignant characteristics which include inappropriate proliferation in the absence of normal growth signals, indefinite self-renewal in a manner analogous to a stem cell, escape from programmed cell death, inhibition of differentiation, aberrant cell cycle checkpoint control and genomic instability [4].
Thought to be an oncogene, a gene that has potential in transforming normal cells into tumor cells, p53 was regarded as the most prominent tumor suppressor gene [1]. P53 is a gene which signals apoptosis (programmed cell death) if a cell cannot be repaired due to an extensive amount of damage. As stated in the textbook, p53 regulation occurs by an E3 ubiquitin-protein ligase known as MDM2 [1]. "Controlling the controller" is a statement that describes the molecular interaction where the presence of MDM2 targets the p53 for proteosome via degradation. With three main checkpoints in cell cycle, the literature states p53 functioning from G1 into S phase in a chaotic cell [2]. The normal state of cells is to keep p53 levels low in order to prevent uncontrolled apoptosis and random cell cycle arrest from occurring. In a further note, although p53 promotes apoptosis and cell cycle arrest, cancer may result from p53 unable to recognize the problematic site. In turn, a mutation in p53 may result engaging in new activities. These activities include cellular transformation, tumor metastasis,...
“The word 'leukemia' is a very frightening word. In many instances, it's a killer and it's something that you have to deal with in a very serious and determined way if you're going to beat it” - Kareem Abdul-Jabbar. Many people, including tons of children, fight leukemia every day trying to beat this vicious cancer. Without knowing how leukemia is exactly caused, it puts a damper on how to avoid it.
Leukemia is a cancer of the white blood cells. It begins in the bone marrow, the soft tissue inside the bones. Within the bone marrow is where white blood cells are created, that help fight off bacteria, viruses, and other microorganisms within the body that cause infections. The disease develops to when the white blood cells are being produced out of control. The cells that are being produced do not work properly as they should, they grow faster than a normal cell would and don’t know when to stop growing. Overtime, if not treated properly, the white blood cells will over crowd blood cells, creating a serious problem such as anemia, bleeding and infection. Leukemia cells can spread to the lymph nodes and other organs in the body causing swelling and pain.
Healthy cells grow and divide in a way to keep your body functioning properly. But when a cell is damaged and becomes cancerous, cells continue to divide, even when new cells aren't...
These oncogenes cause cancer because they do not allow the cells to self-destruct or become epistatic. There have been several research projects which have been testing epistatis. Transfecting DNA To perform the experiments for this research, the researchers had to grow certain pieces of DNA.... ... middle of paper ...
Oral Pathology is a specialty branch of dental medicine that is concerned with the detection, treatment and management of diseases that affect the oral region. Its area of specialty also covers the oral and dental treatment of patients that present with medical conditions. Our oral cavity lies in close proximity to the brain and heart while at the same time it is inextricably connected to our lungs and stomach. If this area is being compromised by an oral disease, it can affect the overall health and wellbeing of our whole body. Extensive and prolonged damage to our oral cavity may even impair our ability for normal daily functions – and diminish our capacity to do the things that we often take for granted like eating, talking and breathing.
Tumors are formed by the alteration of the body’s own cells. This can be caused by environmental factors such as radiation, like UV exposure, chemicals or viruses 1. These can disrupt genes that control growth and cause an increase in cell division and proliferation. Proto-oncogenes are those genes that control normal but essential cell processes that keep cell growth and death in check. Two important categories are apoptosis genes, which regulate cell death, and tumor suppressor genes, which decrease cell propagation 1 . If these genes were mutated to the point where they cannot produce a functioning protein, cell division would continue far past what it was supposed to and unhealthy cells would be allowed to live and continue to multiply. This is what creates a malignant tumor. Certain conditions in the body can also promote the growth of cancer cells. One of these is a deficiency of natural killer (NK) cells, which are able to kill cancer cells by creating a pore in the cell membrane with perforin and releasing granzymes into the cell. Low levels of perforin allow for tumor growth 1. Chronic inflammation can also ...