Cancer and The Process of Cell Division

Introduction

Cancer. As brutal as this word may sound, and as harmful as it may be on the human body, it is uncontrollable cell growth. The Internal and external changes that can occur in the body can be causes of DNA changing. These changes can result in cell multiplication and not die leading to the rapid growth of the now cancerous cells. According to Sylvia & Michael (2014), cancer, which is also known as ‘The Cell Cycle’, it occurs at multiple stages called ‘The Stages Of Interphase’ and they are G1, G2, S, and M. Each of these stages has a major role in the cell moving through that cell cycle. Apoptosis as described by Sylvia & Michael (2014) contributes to decreasing the number of cells which is known as programmed cell death.

Many types of cancer do exist today, but the most common ones are skin cancer, breast cancer, lung cancer, and prostate cancer, and they are all caused by the cell division that has gone wrong, leading to accelerated cell growth. Statistics have shown that 10 million people were diagnosed with cancer in the year 2000 and 6.2 million people have died from it worldwide, leading to an increase of 22% in comparison to 1990 (Naomi et al. 2005).

Cancer, to this day, is still known as one of the main leading causes of death.

The Cell Cycle

According to Sylvia & Michael (2014) cancer, which is also known as ‘The Cell Cycle’ is also defined as several stages that happen between the time of when the cell is dividing and the time of when that divided cell also divides. The cell cycle occurs at multiple stages called ‘The Stages Of Interphase' and they are G1, which arises before the DNA synthesis, G2, which occurs after the synthesis of the DNA, and S, which includes DNA synthesis. Each of these stages has a major role in the cell moving through that cell cycle. The stage of interphase is the period when the cell is getting ready to divide. When it divides it grows bigger, and it doubles in the number of organelles as well as the amount of DNA. The ‘G’ stage stands for growth as it occurs in that stage. During the G1 stage, the organelles of the cell double, it also acquires the materials that are essentially required for the synthesis of the DNA. The G2 stage is where the cell is synthesizing proteins required for cell division, for example, proteins that form the microtubules. During the S stage, the DNA reproduction occurs, this is where each chromosome is made up of one DNA molecule, which is known as chromatids. The end of this stage is where each of the chromosomes consists of two chromatids known as ‘sister chromatids’ which stay attached until they get separated during mitosis. This leads up to the Mitotic stage, known as M stage. This stage is divided into two parts known as mitosis and cytokinesis, where mitosis is the division of the nucleus that is also divided into five phases, and they are prophase, late prophase, metaphase, anaphase, and telophase. Cytokinesis is the division of the cytoplasm.

Cells die every day and new ones are always produced. This cell division is crucial for repairing damaged tissue after injuries. Cell division is also known to increase the number of body cells. This is in contrast to apoptosis which decreases the number of cells as it is known as ‘programmed cell death’ Sylvia & Michael (2014), apoptosis is the removal of improper tissue, which impacts on cancer and preventing it from happening, as cancer cells normally die from apoptosis, which aids in preventing the tumor from progressing and growing. Apoptosis is where the cell goes through a destruction phase, where the cell loses its interaction with the other cells. Therefore, the fragments in the nucleus and the plasma membrane produce blisters. When it comes to apoptosis, there are two types of caspases, the first one is called ‘initiators’ and the second is called ‘executioners’. Initiators are very crucial as they are the ones to receive signals in order to activate the second caspase. This then results in activating the enzymes that break up the cell.

Although we know that apoptosis is the decrease of the number of cells, Lowe & Lin (2000) describe it by its morphological characteristics, such as the blebbing of the membrane, the shrinks of cells as well as the fragmentation of the nucleus.

Controlled cell movement in the cell cycle is done through two types of gene control, they are known as ‘proto-oncogenes’ and ‘tumor suppressor genes’ Sylvia & Michael (2014). The proto-oncogene encodes the proteins that develop the cell cycle which prevents apoptosis. Contrastingly, the tumor suppressor genes encode proteins that discontinue the cell cycle and therefore assist apoptosis.

Cell Division

Understanding cell division and what makes cancer cell division very different from the normal cell division is very important to understand. Adipose tissue-derived stromal cells (ASC’s) have two division types which are asymmetrical and symmetric. The asymmetrical division is to maintain tissue homeostasis. However, symmetric division is beneficial for the extreme expansion of malignant cells which results in unbounded tumour growth. New evidence shows that restricting a switch from the symmetric division to asymmetric division in cancer cells would be beneficial as cancer therapy would then only be targeting the damaged tissue and not affecting the normal tissue homeostasis.

According to (Marte 2004), cells are continually liable to mutations in their DNA, which is normally damaging to the cell. Cancer cells trigger and conquer the bloodstream as well as other tissues. Moreover, genomic instability occurring from cell division or defective DNA repair may cause an increase in the rate of possible tumorigenic mutations in which it contributes to cancer evolution.

Cell Growth

Understanding controlled cell growth and proliferation when it comes to cancer is very crucial as it is the main reason for the development of cancer. Cell growth stands for the growth of cells in size, whereas proliferation is the increase in the number of cells by division. For normal cell development, there is an accurate technique which allows each organ to reach its size, and not exceed. But, when a tissue is damaged and is unable to repair itself then the surviving cells around it therefore would divide in order to aid in repairing what is damaged. With that being said, in most organs, stem cells that are able to divide replace specific organ cells. Tumour cells are different from normal cells when comparing their response to normal control mechanisms. For example, some of those tumour cells, particularly when they have changed from normal, means that they may not divide at all.

Tumours are classified into three main types which are ‘benign tumours’ which may appear in any tissue, however, they do not spread to far-off sites. The second tumour type is ‘In situ tumours’, this tumour is normally developed in epithelium yet they remain in the epithelial layer. Lastly, ‘malignant tumours’ is the full development of a tumour with the ability to destroy the elemental mesenchyme, known as local invasion. Tumour growth is caused from the growth of blood vessels as tumours have received proteins from the bloodstream, and thus, allowing more continuous tumour growth to occur. The mutation process in cancer is caused by DNA damage that could either be unrepaired or repaired incorrectly. That DNA damage could have been caused by UltraViolet light, chemicals, or ionizing radiation. The two types of mutations are somatic or germline. Most cancers hold 1,000 up to 20,000 somatic point mutations. The identification of responsible mutation to the transformation of the DNA was done through the introduction of DNA from cancer cells to normal cells, therefore, leading to malignant transformation.

Cancer Treatment

Cancer treatment is very crucial in helping the individual resume to their normal life strong and healthy. Cancer treatment aims to destroy and remove cancer cells. Cancer treatments could come in a variety of forms, some are in the form of targeted therapy and the other as chemotherapy. Chemotherapy could have an impact on the entire body, causing fatigueness and other negative impacts. Whereas,Targeted therapy treatment is known to be less harmful to the patient as it only targets the area that is affected by cancer.

These treatments are known as monoclonal antibodies, such as Herceptin, lapatinib as well as testosterone. Herceptin, also known as trastuzumab, is a monoclonal antibody formed to target HER2 (a gene that develops breast cancer) receptors, expressed by some of the cancer cells. The function of herceptin is by the inducement of endocytic downregulation of ErbB2 by a process which could involve Cbl.

Testosterone, the other example of targeted therapy is controlled by four gene groups. The first group is the AR gene which is polymorphic and its protein product which vary in affinity for testosterone because of the variable number of microsatellite areas within that gene. The second group of the genetic control function is through cytochrome gene (which is known as CYP or CYP3A4) and is involved in the hydroxylation of testosterone. The third mechanism is by a gene affecting the conversion of testosterone to active intraprostatic androgen known as (DHT). The fourth and last mechanism occurs by the expression of genetic variants that lead to high levels of dihydrotestosterone (DHT) and therefore, it could predilection to prostate cancer. 

Conclusion

To conclude, the uncontrollable cell growth that is known as cancer, which is also known as the cell cycle has a major role in the human body negatively, causing fatigue, stress, and worry that could lead to mental health issues. However, due to the advanced technologies and treatment that only target the affected area, this has helped a lot of individuals become cancer-free. Understanding the process of cell division, which is categorized into two division types and they are symmetric and asymmetric, as well as cell growth, and the difference between it and proliferation, and cancer treatment (based on cell biology) such as the use of Herceptin and testosterone and the types of treatments such as chemotherapy and targeted therapy is very useful and beneficial as statistics have shown that one in four men, as well as one in five women, will die from cancer and one in three people will develop cancer.