Hi. In this video, I'm going to be talking to you about cancer treatments. There are many different types of cancer treatments. I've summarized them in this graph for you, or this table for you. So let me go through a couple of them. First, there's the traditional therapies. These are the ones we're most used to: Surgery, radiation, chemotherapy. Surgery just removes the tumor, and radiation and chemotherapy work by damaging the DNA, which will hopefully lead to the tumor's death.
Then you have a second class called immunotherapy, which involves using immune system mechanisms. Passive immunotherapy uses antibodies against tumors to kill them. We introduce these tumor antibodies to either the cells or the body, and they target the tumors for destruction. On the other hand, active immunotherapy is different because it provides the patients with certain molecules or drugs that stimulate their own immune system to either produce those antibodies or kill the tumor in some way. So, passive is just giving the body some immune system assistance, and active is stimulating the person's own immune system.
Next, we have anti-angiogenic therapies, which work on destroying the blood vessels that support tumor growth. Finally, we have molecular targeting. These are small molecules or drugs that specifically target cancer-causing genes. We might say, for example, "This tumor has one type of mutation; let's develop a drug or give a drug that will target that one mutation." These are becoming very important in the buzzword of personalized medicine; finding the exact treatment that will help treat your tumor mutation, your tumor type.
Unfortunately, we all know that cancer cells develop resistance against the treatment. This happens for every treatment, and there are many different ways that a cancer cell does this. One of the most important is through multi-drug resistance. Multi-drug resistance occurs when a cancer cell exposed to one treatment can develop resistance or not respond to multiple treatments, even treatments to which it has never been exposed. How does it do this? Well, there's this one gene called the MDR1 gene, and this gene encodes for an ABC transporter. This type of transporter moves things into or out of the cell. When the cell becomes resistant, it can actually amplify this gene, overexpressing the gene.
When there's a lot of MDR1 on the surface, it will actually transport those cancer-killing drugs out of the cell, and therefore, they can't do their work and make them ineffective. So, this is what this process looks like. If we have a cell here with the MDR1 gene, and we treat the cell with, let's say, chemotherapy or radiation or antibodies, represented here as black dots, these are the cancer treatments. Normally, this is going to get into the cell. The problem is that the MDR1 transporters pick this up so fast and export it out that it can't perform its function because it's being exported so quickly out of the cell. This is a major way that cancer cells develop resistance. It's not the only way, but it is a significant one, especially in terms of multi-drug resistance. So with that, let's now move on.
