Wednesday, February 16, 2011

Cancer

Cancer or malignant neoplasm is a disease characterized by typical cell cycle abnormalities that cause the cells' ability to:

    * Growing out of control (cell division beyond the normal limits)
    * Attacking the nearby biological tissue.
    * Migrating to other body tissues through blood circulation or lymphatic system, called metastasis.


Three characters that distinguish this malignant cancer from benign tumors. Most cancers form tumors, but some do not, such as leukemia. Branch of medical science relating to the study, diagnosis, treatment, and prevention of cancer is called Oncology.
In general, cancer cells form a tumor, except in leukemia. The reaction between acid tetraiodotiroasetat integrin is inhibiting hormone activity of thyroxine and tri-iodotironina which is one of the factors that play a role in angiogenesis and tumor cell proliferation. [1] uncontrolled growth caused damage to DNA, causing mutations in vital genes that control cell division . Some mutations may be required to change normal cells into cancer cells. These mutations are often caused by chemical or physical agents called carcinogens. Mutations can occur spontaneously (obtained) or inherited (germline mutation). Cancer can cause many different symptoms, depending on the location and character of malignancy, and presence or absence of metastasis. The diagnosis usually requires microscopic examination of tissue obtained by biopsy. Once diagnosed, cancer is usually treated with surgery, chemotherapy, or radiation.

Most cancers cause death. Cancer is one of the leading causes of death in developing countries. Most cancers can be treated and many cured, especially if treatment is started early. Many forms of cancer associated with environmental factors that could have been avoided. Smoking can cause cancer than many other environmental factors. Tumor (Latin: swelling) appoint an abnormal mass of tissue, but can be a "malignant" (cancerous) or "benign" (not cancerous). Only malignant tumors are capable of attacking other networks or metastasize. Cancer can spread through the lymph nodes and blood vessels to other organs.


Classification
The development of normal cells into cancer cells
In general, cancer was referred by type of organ or cells where they are incurred. For example, cancer that begins in the colon are referred to as colon cancer, while cancer that occurs in basal cells of the skin referred to as basal cell carcinoma. The classification of cancer and then performed on the more general category, for example:

     * Carcinoma, a cancer that occurs in epithelial tissues, such as skin or tissue that envelops an organ, such as organ or gland in the digestive system. Examples include skin cancer, cervical carcinoma, anal carcinoma, esophageal cancer, hepatocellular carcinoma, laryngeal cancer, hipernefroma, gastric cancer, testiskular cancer and thyroid cancer.
     * Sarcoma, a cancer that occurs in bone, such as osteosarcoma, cartilage like kondrosarkoma, like rabdomiosarcoma muscle tissue, adipose tissue, blood vessels and tissues Conductor or other support.
     * Leukemia, Lymphoma and myeloma cancer that occurs in the blood tissue
     * Melanoma arises from melanocytes.
     * mesotheliomas in the pleura or pericardium.
   

The characteristics of cancer cells 
Cancer tissue has a very distinctive morphological features when observed with a microscope. Among a large number of cells undergoing mitosis, variations in the number and size of the nucleus, variations in size and shape of the cell, there were no distinctive features of cellular, mobile coordination does not occur normally visible in normal tissue and there were no clear network boundary.

Immunohistochemistry and other molecular methods used to find morphological features typical of cancer cells / tumor, as the referral diagnosis and prognosis.

Hahn and colleagues used an ectopic expression of telomerase reverse transcriptase combined with h-ras oncogene and T antigen of SV40 virus to induce conversion tumorigenik on fibroblast cells and human epithelial cells, which occur due to disruption of intracellular metabolic path. Phenotype characteristic of cancer cells after experiencing a transformation from normal cells, among others:
Transformation in vitro

    
* There was cytological changes such as in cancer cells in vivo that increased cytoplasmic basophils, increased number and size of nuclei
    
* Changes in cell growth characteristics:

          a. difficult to have undergone differentiation to death despite repeated
          
b. that does not stop growing, although it has been squeezed by the surrounding cells, so that cancer tissue has a high density
          
c. require serum and growth factors less
          
d. no longer need the interface layer to multiply, and can grow as a free colony in semi-solid medium.
          
e. has no control over the cell cycle
          
f. difficult experience apoptosis

    
* Changes in the structure and function of cell membranes, including the increase due to lectins herbal aglutinabilitas
    
* Changes in the composition of the interface cell, glycoproteins, proteoglycans, glycolipid and mucin, tumorik antigen expression and increased absorption of amino acids, and nucleoside heksos.
    
* No interaction matrix cells and cell-extracellular, so there is no decrease in the rate of differentiation
    
* Cancer cells do not respond to stimulation of substances that induce differentiation, because the interface changes in the composition of the cell, including the molecular composition of substances pencerap concerned.
    * Changes in cellular signal transduction mechanisms, including the track that is very fundamental, in addition to regulations that control the trajectory pencerap function of growth factors, levels of phosphorylation and defosforilasi.
    
* The ability to induce tumors in the model. This capability is a sine qua non that defines the word "fierce" in transformation in vitro. However, cancer cells that do not have the ability like this, still has the character "tumorigenik" on other models.

Transformation in vivo Transformation in human cells requires the accumulation of genetic changes that lead to genomic instability, [4] such as:

    
* Increased protein expression of oncogenes as a result of translocation, amplification and mutation on the chromosome.
    * There was no protein expression of the gene "tumor suppressor".
    
* Changes in DNA methylation.
    
* There is a transcription of genetic disorders that cause overproduction of growth supporting substances, such as IGF-2, TGF-α, tumor angiogenesis factor, PDGF, and hematopoietic growth factors such as CSF and interleukin.
    
* There was no genetic balance, which becomes increasingly uncontrolled proliferation, increased the likelihood of metastasis.
    * Changes in the pattern of enzyme and increase enzymes that play a role in the synthesis of nucleic acids and enzymes that are lytic, such as protease, collagenase and glikosidase.
    
* Production onkofetal antigens, such antigens plasentis karsinoembrionik and hormones (eg, chorionic gonadotropin), or phosphatase isoenzymes as alkalina plasentis.
    
* The ability to avoid the host antitumor response.


Of the various genetic changes, in tumors in humans, frequently found chromosomal translocation that produces the product kimerik transformation into cells with the ability of tumor / cancer or change the expression of oncogenes.
 



Characteristics and symptoms 
Paraklinis trait common in tumors and cancer cells is the production of lactic acid and pyruvic acid are high, low glucose oxidation, although not always accompanied simtoma hypoxia, glycolysis path acceleration and deceleration rate of oxidative phosphorylation, and a shift in trajectory from anaerobic to aerobic glycolysis, which is known as the Warburg effect. Cancer cells have a tendency to produce ATP as an energy source of the trajectory path of glycolysis than oxidative phosphorylation. ETS transcription factor-1 is enhanced by the secretion of H2O2 by mitochondria is one of the shift in control of metabolism in cancer cells. Another feature is the low plasma levels of vitamin C are found in various cancer patients, both from patients with smoking habit, or not.
In general, cancer symptoms can dibadi into groups:

    
* Local Symptoms: enlargement or unusual swelling of the tumor, bleeding (hemorrhage), pain and / or peptic ulcers / ulceration. Compression of surrounding tissue can cause symptoms jaundis (yellowing of skin and eyes).
    
* Symptoms of enlarged lymph nodes (lymph nodes), cough, haemoptysis, hepatomegaly (enlarged liver), bone pain, fractures in the bones are affected, and neurological symptoms. Despite the advanced stage cancer causes pain, often times it's not the first symptom.
    
* Systemic symptoms: weight loss, decreased appetite significantly, fatigue and kakeksia (emaciated), excessive sweating during sleep / night sweats, anemia, certain paraneoplastik phenomenon that is caused by specific conditions such as thrombosis, active cancer and hormonal changes. Each symptom on the list above can be caused by various conditions (a list of conditions is called differential diagnosis.) Cancer is probably the main cause or not the primary cause of any symptom.
    * Symptoms of angiogenesis which is the interaction between tumor cells, stromal cells, endothelial cells, fibroblasts and extracellular matrix. In cancer, decrease the concentration of compounds inhibiting the growth of new blood vessels, such as trombospondin, angiostatin and glioma-derived angiogenesis inhibitory factor, and excess expression proangiogenik factors, such as vascular endothelial growth factor, which allows cancer cells to metastasize. Therapy of tumor in general, always involves two important roles, namely the use of anti-vascular endothelial growth factor monoclonal antibodies to offset proangiogenik factor overexpression, and the provision of angiogenesis inhibitor compounds, such as endostatin and angiostatin.
    * Symptoms of tumor cell migration, which is characterized by degradation of extracellular matrix (ECM), connective tissue that supports the cell structure, by the MMP enzymes. Until now has been known to file 26 MMP genes that play a role in cancer, [with the exception that occurs among others in hepatocellular carcinoma.  



Cause 
Cancer is a disease that 90-95% of cases caused by environmental factors and 5-10% due to genetic factors. Environmental factors that usually lead to death due to cancer is tobacco (25-30%), diet and obesity (30-35%), infection (15-20%), radiation, stress, lack of physical activity, environmental pollutants.

Below are some of the causes of cancer, other causes are at closely.

Chemicals
Incidence of lung cancer is highly correlated with consumption rokok.Source: NIH.
Pathogenesis of cancer can be traced back to DNA mutations that affect cell growth and metastasis. Substances that cause DNA mutations are known as mutagens, and mutagens that cause cancer called carcinogens. There are some specific substances associated with certain types of cancer. Cigarette tobacco is connected with many types of cancer, and the cause of 90% of lung cancer. Continuous exposure to asbestos fibers is associated with mesothelioma. Many mutagens are also carcinogens. However, some carcinogens are not mutagens. Alcohol is an example of carcinogenic chemicals that are not mutagens. Such chemicals can cause cancer by stimulating cell division rate. Level replication for faster, leaving little time for the enzymes to repair damaged DNA during DNA replication, thereby increasing the likelihood of mutation. Research over several decades show the links between tobacco use and cancers of the lung, larynx, head, neck, stomach, bladder, kidney, esophagus, and pancreas. Tobacco smoke has more than fifty types of carcinogens that have been identified, including nitrosamines and polycyclic aromatic hydrocarbons. Tobacco is responsible for one third of all cancer deaths in developed countries, and about one-fifth in the world. The death rate from lung cancer in the United States reflects smoking patterns, with increases in smoking patterns followed by a dramatic rise in death rates from lung cancer. Even so, the number of smokers worldwide continues to increase, so some organizations say of the tobacco epidemic. Cancer associated with the job someone is believed to have an amount of 2-20% of all cases.
Ionization Radiation
Sources of ionizing radiation, such as radon gas, can cause cancer. Constant exposure to ultraviolet radiation from the sun can cause melanoma and some skin disease dangerous. An estimated 2% of cancer in the future due to the CT scan at this time. Radio frequency radiation from mobile phones do not berion of and sources of similar radio frequencies are also considered as causes of cancer, but currently very little hard evidence to support this association.

Infection
Some cancers can be caused by infection. This not only applies to animals such as birds, but also in humans. These viruses contribute to 20% against the spread of cancer in humans worldwide. These viruses include human papillomavirus (cervical cancer), poliomavirus in humans (mesothelioma, brain tumors), Epstein-Barr virus (B-cell limfoproliferatif disease and nasopharyngeal cancer), the herpes virus causes Kaposi sarcoma (Kaposi sarcoma and primary effusion lymphoma ), the viruses hepatitis B and hepatitis C (liver cancer), virus-1 on manusis T-cell leukemia (leukemia T cells), and helicobacter pylori (stomach cancer).
Experimental and epidemiological data declared causative role for the virus and the virus seems to be the second most important risk factor in cancer development in humans, which is only exceeded by the use of tobacco. This type of tumor that caused the virus can be divided into two, the kind that transformed the acute and slowly transformed. In acutely transforming viruses, the virus carrying an overactive oncogene called viral-oncogene (v-onc), and virus-infected transformed as soon as v-onc visible. In contrast, the virus that is slowly transformed, virus genome is inserted near the proto-oncogene in the genome of the parent.
[Edit] Metabolism Imbalance Formaldehyde compound is synthesized in the body, often formed from the metabolism of compounds xenobiotik trajectory, can form covalent bonds with DNA, or bind to serum albumin and valina group of hemoglobin, and induce carcinogenesis trajectory.
Hormonal Imbalance
The high ratio of plasma hormone TGF-β, which is the regulator in wound healing process, increase the production of ROS in fibroblasts, and differentiation of fibroblasts to the phenotype miofibroblas.
Offspring
Heredity (genetics) is one important factor in the formation of cancer.
The existence of genetic factors in the formation of these cancers occur because one is a cancer-causing mutations in DNA that are inherited from parents to their children, but not all types of cancer can be derived. it is influenced by the location of mutations in DNA that is experienced and also the genotype of the mutation that occurred. [Edit] Location of DNA damage suffered by There are 2 kinds of location of the mutations that trigger the formation of cancer, namely mutations in the genes of oncogenes and mutations in genes pensupresi tumors. pensupresi gene mutations in the tumor was the one who usually triggers a decrease of cancer. this is because the zygote is experiencing oncogene mutations in the gene usually can not survive so can not be lowered.
 

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