Cancer cells: how they arise and characteristics.


Cancer cells are very different from normal cells in the body. Normal cells become cancerous when a series of mutations causes the cell to continue to grow and divide uncontrollably and, in a sense, a cancer cell is a cell that has achieved a kind of immortality. Also, unlike normal cells, which remain in the area where they originated, cancer cells have the ability to invade nearby tissues and spread to distant areas of the body. We will look at the process that leads to the development of a cancer cell, some of the ways cancer cells differentiate from normal cells, and why the body may not recognize cancer cells and destroy them like other "foreign" cells. / Stock Photo © vitanovski


There are as many types of cancer cells as there are types of cancer. Of the more than 100 cancers, most are named after the type of cancer cells in which they started. Carcinomas are cancers that develop in the epithelial cells that line the body cavities. Sarcomas are cancers that arise in the mesenchymal cells of bones, muscles, blood vessels, and other tissues. Leukemias, lymphomas, and myeloma are "blood-related cancers" that arise from the bone marrow (leukemias and multiple myelomas) or lymphoid tissues (lymphomas) and are "fed" on nutrients in the bloodstream and lymphatic fluid so that they do not they work. "There is no need to form tumors. Just as cancers can behave differently, not all cancer cells behave in the same way.

How do they start?

Cancer cells are the result of a series of genetic and epigenetic changes. Some of these changes can be inherited or, more commonly, caused by carcinogens (substances that cause cancer) in our environment. Normally, solid tumors contain several mutations. Interestingly, the metastatic process, which is the main culprit for the high mortality from advanced cancer, is believed to be primarily caused by epigenetic changes, as no specific genetic changes have been found in metastases. It also helps explain genetic predisposition to cancer. Genetic predisposition does not mean that you will have cancer, but simply put, if there are already multiple mutations, it is likely that fewer acquired mutations are required for the cell to become malignant.

The process of turning normal cells into cancer often goes through stages in which cells become increasingly abnormal. These stages can include hyperplasia, dysplasia, and eventually cancer. You can also hear it described as differentiation. At an early stage, a cell may look very similar to normal cells in that organ or tissue, but as it develops, the cell becomes increasingly undifferentiated. In fact, this is why it is sometimes impossible to determine the origin of cancer.

What makes them divide and grow?

A cancer cell can have thousands of mutations, but only a certain number of these genetic changes in cancer cells cause the cancer to divide and grow. Mutations that lead to cancer cell growth are called "driver mutations," while other mutations are considered "transient mutations." Normal genes, called proto-oncogenes, can become " oncogenes " when they mutate and encode proteins that stimulate cancer growth and give it immortality. Tumor suppressor genes , by contrast, are genes within a cell that tell cells to slow down and stop growing, repair damaged DNA, or tell cells to die.

Most cancer cells have mutations in both oncogenes and tumor suppressor genes that determine their behavior.

Cancer cells versus normal cells

There are many important differences between cancer cells and normal cells . Some of these include:

  • Growth : Normal cells grow as part of growth and development, such as during childhood, or to repair damaged tissue. Cancer cells continue to grow (reproduce) even when other cells are not needed. Cancer cells also cannot hear the signals that tell them to stop growing or to kill themselves (apoptosis) as cells age or become damaged.
  • The ability to penetrate nearby tissues : Normal cells respond to signals from other cells that tell them that they have reached the edge. Cancer cells do not respond to these signals and spread to nearby tissues, often sticking out like fingers. This is one of the reasons that it is sometimes difficult to remove a cancerous tumor with surgery. The word cancer actually comes from the Greek word carcinos , meaning crab, which means these claw-like extensions on adjacent tissues.
  • The ability to spread (metastasize) to other areas of the body : Normal cells produce substances called adhesion molecules that cause them to adhere to neighboring cells. Some cancer cells, devoid of the stickiness caused by these adhesion molecules, can break free and move to other parts of the body. They can travel to nearby tissues or through the bloodstream and lymphatic system to areas of the body that are far from the original cancer cell; for example, lung cancer cells can travel ( metastasize ) to lymph nodes, the brain, liver, or bones. …
  • Immortality : Most normal cells, like human cells, have a limited lifespan. When they reach a certain age, they die. In contrast, cancer cells have developed a way of "defying" death. At the end of our chromosomes is a structure known as telomeres . Every time a cell divides, its telomeres shorten. When telomeres get short enough, cells die. Cancer cells have found a way to repair their telomeres so that they do not continue to shorten as the cell divides, thus, in a sense, making them immortal.

The ability to invade and metastasize is very important in differentiating a cancer cell from a normal healthy cell, but there are many other important differences as well.

Cancer cell
Normal cell

Why doesn't the body recognize cancer cells as abnormal and destroy them?

Good question: "Why doesn't our body recognize and kill cancer cells, such as bacteria or viruses?" The answer is that our immune system detects and kills most cancer cells. The cells of our immune cells, called natural killer cells , must find cells that have become abnormal so that other cells of our immune system can kill them. system. Cancer cells remain alive by evading detection (they are masked in different ways) or by inactivating immune cells that appear on the scene.

The ability of the immune system to recognize and destroy cancer cells is believed to be the cause of the unusual but well-documented phenomena in which certain cancers disappear without treatment ( spontaneous remission of cancer ). This process is also at the heart of a new area of cancer treatment known as immunotherapy .

Cancer cells keep changing

Once cancer has formed, cells do not stay the same; rather, continuous mutations can occur. This is actually why resistance to chemotherapy and targeted therapy drugs develops over time. A mutation develops in the cancer cell to avoid the destructive effects of these treatments .

Changing cancer cells is very important in treatment. For example, breast cancer that is estrogen receptor positive can be estrogen receptor negative when it comes back or spreads. This also helps explain that serum cancer cells may be different in different parts of the tumor. This is called "heterogeneity" and it is also important for diagnosis and treatment.

How are cancer cells different from precancerous cells?

Precancerous cells may appear abnormal and similar to cancer cells, but they differ from cancer cells in their behavior. Unlike cancer cells, precancerous cells do not have the ability to spread (metastasize) to other areas of the body.

The condition of carcinoma in situ (CIS) is often confusing. Carcinoma in situ consists of cells with abnormal changes found in cancer cells, but because they have not spread beyond their original location (or technically have not spread beyond something called the basement membrane), they are technically not cancer. . Because CIS can turn into cancer, it is generally treated as early cancer .

Final thoughts

A car analogy can be used to describe cancer cells. Cell growth can be thought of as a car in which the accelerator stops. In this case, the brakes do not work (the cells do not respond to tumor suppressor proteins).

We can go further in this analogy. Cancer cell invasion can be thought of as a car driving through the doors of a closed apartment building. Normal cells respond to signals from neighboring cells that say, "This is my border, stay away." Cancer cells are antisocial in other ways, too. As they 'combine' with other cancer cells, all of which become increasingly immature in their actions over time (due to rapid division), they proliferate and invade other communities as well.

But just as crime has not defeated the United States, there are many police officers (checkpoints) who control most of the cells in the body.

In fact, it is very difficult for a normal cell to become cancerous. It must be abnormal to promote growth, hinder recovery and death, ignore signals from neighbors, and achieve immortality. That is why cancer is not caused by a mutation, but by a series of mutations. But since a billion cells in our bodies divide every day, something is likely to go wrong and mutations will occur from time to time. And they do this for approximately 1.6 million people in the United States each year.

Frequently asked questions

  • Cancer is a disease in which cells in the body grow at an uncontrolled rate. Normal cells grow when they receive a signal, while cancer cells ignore the signal and continue to multiply. If cancer cells form a malignant tumor or a lump of malignant tissue, it can spread to nearby tissues and form a new tumor.

  • Cancer cells can begin to form when our DNA genes undergo certain changes. When genes are damaged by external factors such as tobacco smoke and ultraviolet rays, normal cells can behave differently and form cancer cells. Some people are more likely to develop cancer due to a trait inherited from their parents.

  • There are about 200 main types of cells in the human body. They make up the trillions of cells that allow our bodies to function.

  • In a sense, cancer cells are immortal. Unlike normal cells, cancer cells are able to reject the process that tells them to die.

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