Hi. In this video, I'm going to be talking about carcinogens. We have talked about the fact that cancer begins with mutations in the DNA of a cell. The cell gets those mutations through things called carcinogens, which are substances, molecules that induce DNA damage, potentially leading to cancer in some cases. There are two types of carcinogens. The first is an initiator, and these carcinogens directly damage the DNA. They interact with the DNA and damage it directly. Then we have tumor promoters, which are carcinogens that don't cause mutations but promote cancer that already has some type of mutated DNA. Remember, cancer isn't just one mutation; it's an accumulation of mutations and other factors such as proteins and extracellular factors that can lead to cancer. Initiators are the ones that actually damage the DNA, causing those mutations, whereas promoters don't cause mutations but promote the cell to turn into cancer if it already has mutations. Here's an example of a tumor initiator: we have a carcinogen, it interacts with the DNA, causes damage. There's some type of DNA repair deficiency. For instance, a tumor promoter could act here, removing factors like calcium that would signal for DNA repair. There's some type of deficiency here, and the combination of DNA damage and the lack of repair causes more DNA damage, and all of this will eventually lead to cancer. Again, not just one factor, but multiple factors are involved.
When talking about DNA damage, I refer to things like the loss of the DNA repair system, telomere shortening. Remember, the telomeres at the end of chromosomes are replicated differently, which can induce the shortening over time. If you're losing a part of the telomere, then it's obviously some type of DNA damage. This could also include viral genome integration. We know that some viruses, when they infect a cell, integrate their genome into the cell, which could be a type of DNA damage. Examples of carcinogens that you're probably familiar with include tobacco, a significant carcinogen that can directly damage the DNA itself. Viral exposure, viruses that can lead to cancer such as human papillomavirus, hepatitis B, and hepatitis C can lead to cancer. Additionally, there are some diet and lifestyle choices. These are more controversial, but generally, eating healthily and engaging in some type of exercise can help significantly in cancer prevention for the population as a whole. This covers a general overview of carcinogens, how they work, and some examples.
So with that, let's now turn the page.
