Cancer video in Loki analogy

Cancer, the word comes from an ancient Greek, meaning Crab, because of the similarity of crabs to some tumors with swollen veins. In medical sense, cancer is a group of diseases caused by an uncontrolled division of abnormal cells.

How does cancer occur? In most cases, the development of cancer is a multistep process. Cancers originating from a single cell. This single cell and its lineage of daughter cells undergo a series of mutations and other genetic changes that cause the cells to grow abnormally. At an early stage, the cells form a benign tumor. This tumor doesn’t invade its healthy neighbor and just stays in its place. Next, some cells in the tumor lose their normal growth regulation and become malignant tumors. Now, we can call it cancer. They invade adjacent healthy tissues, and cancer cells may metastasize.

I will talk a little bit about the cell cycle. There are 4 phases in a cell cycle. G1: The cell increases in size S: DNA replication G2: The cell continues to grow M: mitosis meaning that a cell divides into 2 daughter cells Go: A phase where the cell has left the cycle and has stopped dividing.

In our DNA, existing both proto-oncogenes and tumors-suppressor genes. Proto-oncogenes is a normal gene encoding proteins that function in signal transduction pathways involved in cell growth. There is nothing bad until mutations in proto-oncogenes convert them to oncogenes. Oncogenes is genes that has the potential to cause cancer.

Several types of genetic changes may convert a proto-oncogene into an oncogene. First, missense mutations. A missense mutation is a point mutation in which a single nucleotide is changed, results in changing a single amino acid in a protein, alters the function of the encoded protein in a way that promotes cancer. Next, Gene Amplification Another genetic event that occurs in some cancer cells is an increase in the number of copies of a proto-oncogene. An abnormal increase in the number of genes results in too much of the encoded protein. The third type of genetic alteration that can lead to cancer is Chromosomal Translocation. This occurs when one segment of a chromosome becomes attached to a different chromosome. Fourth, Retroviral Insertion. Retroviruses insert their DNA into the chromosomal DNA of the host cell. Unfortunately, it is next to a proto-oncogene, this may result in the overexpression of the proto-oncogene. Besides, a virus may cause cancer because it carries an oncogene in its viral genome.

“A brother from another mother” of proto-oncogenes is tumor-suppressor genes, we can also call it anti-oncogenes. The functioning of non-mutant anti-oncogenes prevents cancerous growth. The first function of protein encoded by anti-oncogene is maintenance of genome integrity. They can repair broken DNA, minimize the chance that a cancer-causing mutation will occur. If damage cannot be repaired, the cell initiates programmed cell death. In some cases, the proteins prevent a cell from progressing through the cell cycle if something wrong is detected. Oh, back to the cell cycle. There are 3 main checkpoints in the cycle. G1 checkpoint: check for nutrients, growth factors, DNA damage. G2 checkpoint: check for cell size, DNA replication and M checkpoint: check for chromosome spindle attachment. The protein checkpoint can stop cell division if it senses DNA damage. The second function of anti-oncogene’s proteins is negative regulation of cell division. Some proteins work as a halt to cell division. If their function is lost, cell division is abnormally accelerated.

Cancer-causing mutations in proto-oncogenes are due to overactivity, whereas in anti-oncogenes are inactivated. The function of anti-oncogene is lost in three common ways: First, Mutation: For example, a mutation could abolish the function of the promoter for an anti-oncogene or introduce an early stop codon in its coding sequence. Either of these would prevent the expression of a functional protein. Chromosome loss is a second way. It may contribute to the progression of cancer if the missing chromosome carries one or more anti-oncogenes. Third, Epigenetic changes, it involves changes in chromatin structure that alter gene expression without altering the base sequence of DNA.

Over 300 human genes are known to be associated with cancer when they mutate. And every day, you have abnormal cells in your body. Thankfully, we have the immune system. They protect us from disease, detect and respond to a wide variety of pathogens from viruses to parasitic worms as well as cancer cells. But, cancer cells use certain proteins to disguise themselves, one protein that they use is PD-L1. When T-cells use their protein PD1 to latch on cancer cells PD-L1 proteins, they’re fooled into thinking that there are healthy ones and not attack these cells. The Nobel Prize in Physiology or Medicine 2018 was awarded jointly to James P. Allison and Tasuku Honjo “for their discovery of cancer therapy by inhibition of negative immune regulation.”Using antibody anti-PD-1 to block the interaction between PD1 and PD-L1. Now, the T cells can recognize the cancer cells then kill them.