Cancer: Study with Video Lessons, Practice Problems & Examples

Cancer is characterized by uncontrolled cell division, leading to malignant and benign tumors. Malignant tumors are cancerous, metastasizing to other organs, while benign tumors are noncancerous and remain localized. Key genes regulating cell growth include proto-oncogenes, which promote cell division, and tumor suppressor genes, which inhibit it. Mutations in these genes can lead to oncogenes, promoting unrestrained cell growth and cancer development. Understanding these concepts is crucial for grasping cancer biology and the mechanisms of cell cycle regulation.

Cancer

In this video, we're going to begin our introduction to cancer. And so cancer is a disease characterized by uncontrollable cell division is going to lead to the development of malignant tumors. Now a tumor is defined as an overgrowth of cells, or in other words, an abnormal mass of tissue. And tumors typically can cause health complications, and there are 2 main types of tumors that you should be familiar with. The first main type of tumor is malignant tumors, which are an overgrowth of cancer cells that migrate or, in other words, metastasize to other organs. And malignant tumors are the ones that are the most dangerous because they can create a tumor in one area of the body, but then they can migrate or metastasize to a completely different organ within the body and also cause health complications in that other organ. Now benign tumors are the second type of tumor, and these are not cancerous. This is an overgrowth of cells that are not cancer cells, and they do not migrate, so they do not metastasize. Instead, benign tumors remain at the same site. And benign tumors can cause health complications, but they're not nearly as dangerous as malignant tumors are. And now below in our image, notice over here on the far left we're showing you malignant tumors, and over here on the far right, we're showing you benign tumors. So again, the malignant tumors are cancerous, and the benign tumors over here on this side are noncancerous cells. Now, the malignant tumors, that are cancerous, are actually nonencapsulated, and the benign tumors over here, are actually encapsulated. And the capsule is just this basically structure of tissue that can surround and encapsulate the cells, basically containing them in the same area. Now, malignant tumors tend to be very fast growing. They divide very fast since they are cancerous cells, whereas benign tumors are more slow-growing. And then in terms of metastasizing or migrating to other areas of the body, of course, malignant tumors are characterized by migration or metastasis. So this is, of course, going to be, yes, they do metastasize. Whereas the benign tumors, on the other hand, in terms of do they metastasize, the answer to this would be no, they do not metastasize, and partially because they are encapsulated. And so, this here concludes our introduction to cancer and the difference between malignant tumors and benign tumors. And in our next lesson video, we'll get to talk a little bit more about cancer by talking about specific genes that control the cell cycle. So I'll see you all in that video.

The difference between benign and malignant tumors is:

a) Malignant tumors do not spread to other sites.

b) Benign tumors have not lost growth control.

c)  Benign tumors have not spread to other sites.

d)  Malignant tumors have not lost growth or control.

• A. Malignant tumors do not spread to other sites.
• B. Benign tumors have not lost growth control.
• C. Benign tumors have not spread to other sites.
• D. Malignant tumors have not lost growth or control.

Types of Genes Regulating Cell Growth

In this video, we're going to introduce 2 types of genes that regulate cell growth. And so any healthy and normal cell that is not cancerous and is not part of a tumor, this healthy normal cell is going to have 2 types of genes that regulate cell growth, and we've got these 2 labeled down below, number 1 and number 2. And so the first type of gene that's going to regulate cell growth in a healthy normal cell is a proto-oncogene. And so a proto-oncogene is going to be a gene that provides signals that promote appropriate cell division. And so because it's promoting appropriate cell division, proto-oncogene is pretty much acting like the green light for cell division. And so it's going to allow cell division to proceed. Now, the second type of gene that regulates cell growth is a tumor suppressor gene. And so the tumor suppressor gene, as its name implies, is going to do pretty much the opposite of the proto-oncogene. It's going to provide signals to not promote but inhibit cell division. So it's basically acting like the red light for cell division, to inhibit cell division and to slow it down. Now a protein called p53 is an example of a protein that serves as a tumor suppressor gene. And so if we take a look at our image down below over here on the left-hand side, notice we're showing you a proto-oncogene and how it pretty much acts like the cell division gas pedal. It pretty much promotes cell division, so it acts like the green light for cell division to allow cell division to proceed normally and appropriately. And then over here on the right-hand side, notice we're showing you the tumor suppressor gene, which is pretty much acting like the cell division brakes or the brakes to cell division or the red light for cell division that slows down or inhibits cell division. And so again, within a healthy and normal cell, there are both proto-oncogenes and there are tumor suppressor genes that will either promote or inhibit cell division appropriately so that cell division will proceed appropriately. However, although proto-oncogenes and tumor suppressor genes are normal and healthy genes found in normal and healthy cells, they are susceptible to mutations. And mutations in either of these types of genes, in either proto-oncogenes or tumor suppressor genes, can lead to the development of cancer, uncontrollable cell division. And so all again, although proto-oncogenes are essential, although proto-oncogenes are essential and healthy genes that promote cell division appropriately, again, they are susceptible to mutations that can generate oncogenes. And oncogenes are different than proto-oncogenes. Proto-oncogenes are healthy and normal genes that are needed and required to promote appropriate cell division. However, oncogenes are mutated proto-oncogenes. And so that's exactly how we're defining oncogene down below. They are a mutated gene that is going to promote unrestrained cell growth. Essentially, it's going to promote cancer. And so this here concludes our introduction to the 2 types of genes that regulate cell growth, proto-oncogenes and tumor suppressor mutations that can lead to the development of cancer. And so the mutations that can lead to the development of cancer. And so this here, concludes this video and we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.

Which of the following processes do normal proto-oncogenes typically exhibit?

a)    They normally suppress tumor growth.

b)    They enhance tumor growth.

c)    They stimulate normal cell growth and division.

d)    They are underexpressed in cancer cells.

• A. They normally suppress tumor growth.
• B. They enhance tumor growth.
• C. They stimulate normal cell growth and division.
• D. They are underexpressed in cancer cells.

When activated by signals in the cell, Protein X can stop cells from growing and dividing into new cells. What type of gene codes for Protein X?

a) Oncogene.

b) Tumor-suppressor gene.

c) Protein kinase gene.

d) Protein Vesicle gene.

e) Proto-oncogene.

• A. Oncogene.
• B. Tumor-suppressor gene.
• C. Protein kinase gene.
• D. Protein Vesicle gene.
• E. Proto-oncogene.

Here’s what students ask on this topic:

What is the difference between malignant and benign tumors?

Malignant tumors are cancerous and characterized by uncontrollable cell division that can metastasize, or spread, to other organs, causing severe health complications. They are non-capsulated and grow rapidly. In contrast, benign tumors are noncancerous, do not metastasize, and remain localized at their site of origin. They are capsulated, which helps contain the cells in one area, and they grow more slowly. While benign tumors can cause health issues, they are generally less dangerous than malignant tumors.

What are proto-oncogenes and tumor suppressor genes?

Proto-oncogenes and tumor suppressor genes are two types of genes that regulate cell growth. Proto-oncogenes act like the green light for cell division, promoting appropriate cell division. Tumor suppressor genes, on the other hand, act like the red light, inhibiting cell division to prevent uncontrolled growth. Mutations in these genes can lead to cancer. Proto-oncogenes can mutate into oncogenes, which promote unrestrained cell growth, leading to cancer development.

How do mutations in proto-oncogenes and tumor suppressor genes lead to cancer?

Mutations in proto-oncogenes and tumor suppressor genes disrupt the normal regulation of cell division. When proto-oncogenes mutate, they become oncogenes, which promote unrestrained cell growth and division, leading to cancer. Similarly, mutations in tumor suppressor genes can disable their ability to inhibit cell division, removing the 'brakes' on cell growth. This uncontrolled cell division results in the formation of malignant tumors and the development of cancer.

What role does the p53 protein play in cancer prevention?

The p53 protein is a crucial tumor suppressor gene that helps prevent cancer by regulating the cell cycle. It acts as a 'guardian of the genome' by detecting DNA damage and either repairing it or initiating apoptosis (programmed cell death) if the damage is irreparable. This prevents the propagation of mutated cells that could lead to cancer. Mutations in the p53 gene can impair its function, allowing damaged cells to proliferate uncontrollably, contributing to cancer development.

What is metastasis in the context of cancer?

Metastasis refers to the process by which cancer cells spread from the primary tumor site to other parts of the body. Malignant tumors have the ability to metastasize, meaning cancer cells can break away, travel through the bloodstream or lymphatic system, and form new tumors in different organs. This spreading makes malignant tumors particularly dangerous, as they can cause health complications in multiple areas of the body, complicating treatment and prognosis.