1.1 General background
The definition for “tumor” has undergone several changes largely due to scientific advancement in our understanding of cancer and the ability to differentiate one form from another. Tumor originally applied to the swelling caused by inflammation, but the non-neoplastic usage of tumor has almost vanished; thus, the term is now equated with neoplasm, and sometimes interchangeably used with the term cancer. Currently, a tumor is generally defines as an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after cessation of the stimuli which evoked the change [1]. Over the past 5 decades, cancer research has received tremendous attention from the global scientific community with frantic efforts to answer some fundamental questions about the very nature of cancer; how different is one cancer from the other?; how do cancer evade the host’s defense surveillance and at precisely what point?; how do cancer metastasize coupled with their seemingly preference for
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As such, healthy cells undergoing replication employ several intrinsic tumor-suppressor mechanisms including apoptosis, senescence, necrosis, autophagy, and mitotic catastrophe to control the transformation process and/ or eliminate such transformed cells [11]. Notwithstanding, some of the transformed cells acquire mutations that enable them to evade these intrinsic cell antitumor protocols [9]. In an immunocompetent host, however, the immune system serves as a potent extrinsic antitumor machinery. The immune system is capable to completely eliminate and/ or keep in a dormant state (equilibrium) nascent transformed cells that have evaded the intrinsic control measures during cellular development [11,
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.
..., 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?").
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.
Cancer starts when certain cells in the body are mutated or changed and begin to divide. Cancerous cells grow differently than normal cells, instead of progressing through the normal cell lifecycle, cancer cells continue to grow and create more abnormal cells. A specific trait of cancer cells is that they have the ability to infiltrate and grow into surrounding tissues, developing out of control and causing serious damage to the host (Vincent, 2008). Cells become cance...
To understand how immunotherapy works it helps to know how your immune system works to fight against cancer. Cancer cells have substances on their surfaces called tumor antigens that raise an alarm in the immune system that says cancer is present. Antigen presenting cells ( APCs) roam the body seeking out and ingesting tumor antigens. The APCs then activate B cells and T cells. The B cells differentiate into plasma cells and secrete antibodies that bind to the tumor cell and mark them for elimination ( a humoral immune response). When T cells are activated they proliferate and undergo expansion, seek out, and destroy cells bearing the specific tumor antigens ( a cellular immune response). Sometimes your immune response does not destroy all of the cancer cells and this r...
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,...
According to “Medical News Today” cancer is a disease that is caused by an over growth of anomalous cells on one or more lungs. Cells often go up the air pipes which can cause difficulty to breath. Due to the over production of cells the tissue cells often begin to over produce; which results in tumors. There are two types of tumors: malignant and benign. Malignant tumors are the more dangerous of the two due to its invasive nature; which makes it cancerous. While benign is not invasive in other words non-cancerous. This is why cancer spreads to multiple areas and can be sometimes very difficult to fight. Cancer cells are abnormal not only because of their evasive nature, but also because of its irregular life cycle. Rather than expire like a regular cell, they continuously grow and duplicate which causes the disease to spread. This makes cell abnormal in shape and other qualities; known as a sickle cell. Due to the large growth and reproduction rate of the cells this makes the spreading of the cancer more rapid. Each cancer has specific symptom, for lung cancer the sympto...
Our immune system protects our bodies from pathogens like bacteria and viruses very efficiently in most cases. One big question that has come up is why does the immune system not respond to cancerous cells in the same way? Why are cancer cells not eradicated like other dangerous foreign cells? This seems very strange, especially since the immune system has cells that are specific to destroying cancer cells and virus-infected cells, called natural killer cells. To begin to answer this question it is useful to examine cancer cells and their interactions with the immune system in more detail.
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...
There are two types of tumors, benign tumors and malignant tumors. Benign tumors are not cancerous. These types of tumors can usually be removed and do not come back in most cases. Benign tumors do not spread to other parts of the body and the cells do not invade other tissues. Unlike b...
Laughter is often said to reduce stress and produce pain reliving hormones. It is the ‘fountain of youth’, the secret ingredient to longevity. A person who laughs all the time is, more often than not, healthier and happier than a person who rarely laughs at all. Laughter is known as a natural form of medicine. However, like many other things, some people take the laughter and the jokes too far. This is the case in the story, “The Approximate Size of My Favorite Tumor,” by Sherman Alexie.
When a cell in our body has become infected or has become cancerous it’s surface changes. This is how the immune system can tell good cells from bad ones (the markings on the surface.) Once a bad cell has been recognized our bodies sends cells to destroy the damaged cell and prevent the spread of whatever caused the damage in the first place. The next step our body takes is to have the affected cells start to produce interferons and other helpful substances. These help to fight off unwanted organisms, and also to warn other cells of the invaders and prepare them to resist them therefore preventing the spread of disease.
Cancer develops when cells in a part of the body begin to grow out of
Cancer is a disease that affects human somatic cells. It causes the cells to divide uncontrollably and form masses known as tumors. There are two different types of cancer tumors. Some tumors are benign and other tumors are malignant. Benign tumors look similar to the tissues that they came from and develop slowly. The tumor remains in the same area that the tumor originated in. Malignant tumors are formed from cells that do not resemble the tissue that they came from. They vary in shape and size. This enables pieces of the tumor to break off and spread to other places in the body. Over the past few decades cancer has become a very prominent disease. There are many different types of cancer and many different causes for the the disease. Most cancers are because of a genetic mutation. The most common type occur when a cell is dividing. Proto-oncogenes, which are alleles in a normal cells, mutate to form oncogenes. 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.
Different characteristics of tumours may point to malignancy in some organs but in other locations may indicate a benign growth. For example, Thieme indicates that “an echopenic halo suggests metastasis in the liver but suggests a...