Name: how retroviruses lead to cancer
Uploaded: 2023-04-30T18:28:51.000Z
Duration: 1 min 51 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Life Science

SC.912.L.16

SC.912.L.16.8

Mechanisms of Retrovirus-induced Cancers

Retroviruses are a group of single-stranded RNA viruses with the ability to integrate their genome into the host-cell DNA.
Upon infection into a suitable host cell, the retroviral core enters the host-cytoplasm. The core contains the viral-genetic material and viral-enzymes like reverse transcriptase and integrase.
Once inside the host-cytoplasm, the core disassembles to release its contents. Then, the viral reverse transcriptase enzyme reverse-transcribes the viral-RNA into single-stranded complementary DNA or cDNA.
The cDNA replicates to generate double-stranded DNA that enters the host nucleus along with the viral-integrase enzyme. The integrase enzyme catalyzes the incorporation of the double-stranded viral-DNA, called provirus into the host-DNA.
The integration of the provirus into the host genome can activate or transform a normal cell into a cancerous cell via several different mechanisms. Such retroviruses are called cancer-causing or oncogenic viruses.
For example, the promoter and enhancer sequences present in the provirus may activate the neighboring host genes and trigger abnormal cell growth.
Expression of some viral proteins inside the host cell may also indirectly ac

mechanisms of retrovirus-induced cancers

Retroviruses are RNA viruses that have been shown to cause cancers in diverse species, including chickens, mice, cats, and monkeys. The RNA genomes of these viruses are first reverse-transcribed into single and then double-stranded DNA (dsDNA) copies. This dsDNA called proviral DNA then integrates into the host genome. Subsequently, the host cell transcribes the proviral DNA in concert with the chromosomal DNA. This leads to the production of viral RNA and proteins that assemble at the host cell surface, forming new viral particles. When the viral genes or products interfere with host genes that regulate cell growth and progression, it leads to cancer progression.
Acute vs. non-acute retroviruses
Some retroviruses called acute viruses can cause cancer after short latent periods. For example, the Rous sarcoma virus can induce sarcomas in the host within three weeks of infection. In contrast, some non-acute retroviruses only cause cancer after long latent periods. Such non-acute viruses induce cancer in only some of the infected hosts. For example, Rous-associated virus-60 induces lymphomas in only 50% of the infected hosts after five to nine months of infection.
However, additional events and host factors such as immunosuppression, somatic mutations, genetic predisposition, and exposure to carcinogens play an important role in cancer progression upon viral infections.

Retroviruses are RNA viruses that have been shown to cause cancers in diverse species, including chickens, mice, cats, and monkeys. The RNA genomes of ...

Education

JoVE Core

Cell Biology

Unit 1

Cancer

KEY TERMS AND CONCEPTS

how retroviruses lead to cancer

Retroviruses can lead to cancer by changing how cells grow and divide. They are RNA viruses, and their genetic material is copied into DNA after infection. That DNA can then affect the host cell in ways that promote tumor formation.

A key idea is the activation of proto-oncogenes. Proto-oncogenes are normal genes that help control cell growth, but they can become oncogenes, or cancer-causing genes, when their activity is altered. Retroviruses can contribute to this change and push infected cells toward uncontrolled growth.

Retroviruses may also cause cancer through insertion near important genes in the host genome. This insertion can disturb normal gene control and create conditions that favor cell division. The result is a pathway from viral infection to cancer development that depends on how the virus interacts with host DNA.

How Retroviruses Lead to Cancer

what is cancer?

How Cancer Cells Grow and Spread

Cancer is a disease in which cells grow and divide in an uncontrolled way. In healthy tissue, cell growth is regulated so the body can stay balanced and repair itself. In cancer, that control is lost. Cancer can start when cells in a specific tissue begin to divide too often. These abnormal cells may form a mass called a tumor. Some cancers stay in one place, while others spread to other parts of the body. The term cancer covers many diseases, not just one condition. Different cancers can...

cancers originate from somatic mutations in a single cell

cancers-originate-from-somatic-mutations-in-a-single-cell

Single-Cell Mutations Can Lead to Cancer

Cancer can begin when a somatic mutation appears in a single cell. A somatic mutation is a DNA change that is not inherited from a parent. It happens in a body cell during life and can give that cell a growth advantage. When the altered cell keeps dividing, its descendants carry the same mutation. Over time, this clone of cells can expand and form a tumor. This process helps explain how a cancer can start from one original cell rather than from the whole tissue at once. The idea also shows...

tumor progression

Tumor Growth and Spread

Tumor progression describes how a tumor changes over time. It includes tumor growth and, in some cases, spread to other parts of the body. These changes help explain why cancer can become more serious. As tumor cells divide, the tumor can increase in size. Some tumors stay in one place, while others become more aggressive. When a tumor spreads, cancer cells move away from the original site and start new tumors in other tissues. This process is linked to disease advancement and is a key part of...

adaptive mechanisms in cancer cells

Cancer Cells Under Stress

Cancer cells survive by adjusting to stressful conditions in the body. They can change how they use energy, how they grow, and how they handle limited resources. These adaptive changes help the cells keep dividing even when their environment is harsh. One major example is hypoxia, which means low oxygen. Many tumors grow faster than their blood supply, so the cells must cope with oxygen shortage. Cancer cells can also use the Warburg effect, a way of making energy that relies heavily on...

the tumor microenvironment

Tumor Microenvironment: Cells Around Cancer

The tumor microenvironment includes the cells and materials that surround a tumor. It is an active part of cancer growth, not just a background setting. These nearby cells and signals can influence how a tumor develops and spreads. One important part of the tumor microenvironment is the extracellular matrix, or ECM. The ECM is the network of proteins and other materials outside cells that helps hold tissue together. Cancer cells can interact with this matrix as they grow and invade nearby...

metastasis

How Cancer Spreads: Metastasis

Metastasis is the spread of cancer cells from the original tumor to other parts of the body. It is a key step in cancer progression and helps explain why cancer can become more difficult to treat.

cancer-critical genes i: proto-oncogenes

Proto-oncogenes and Cell Growth Control

Proto-oncogenes are cancer-critical genes that help control normal cell growth. They play an important role in the signals that tell cells when to grow and divide. In healthy cells, these genes support regular cell behavior. Problems can begin when a proto-oncogene changes. A changed proto-oncogene may push a cell to divide too often or at the wrong time. This shift can contribute to cancer development. This topic focuses on proto-oncogenes as one class of cancer-related genes. It shows how...

cancer-critical genes ii: tumor suppressor genes

cancer-critical-genes-ii-tumor-suppressor-genes

Tumor Suppressor Genes in Cancer

Tumor suppressor genes help keep cell growth under control and can limit cancer development. These genes act as safeguards by slowing the cell cycle, repairing damage, or triggering cell death when cells are too abnormal to continue dividing. When tumor suppressor genes are changed or lost, cells may divide when they should not. That loss of control can contribute to tumor growth. Understanding how these genes work helps explain why some cells become cancerous while others stay normal. The...

loss of tumor suppressor gene functions

Tumor Suppressor Gene Loss in Cancer

Tumor suppressor gene loss can help cancer cells grow and survive. Tumor suppressor genes normally help control cell growth and keep cells from dividing too quickly. When these gene functions are lost, that protection is reduced. This topic also includes how tumor suppressor genes can be turned off without changing the DNA code itself. Epigenetic changes are chemical changes that affect gene activity. They can silence a tumor suppressor gene and lower its function in the cell. Understanding...

the retinoblastoma gene

Retinoblastoma Gene and Cell Cycle Control

The retinoblastoma gene helps control the cell cycle. It is a tumor suppressor gene, which means it helps prevent cells from dividing when they should not. Its role is closely tied to normal cell growth and the checks that keep division under control. The gene is often discussed in relation to cancer because changes in its function can remove this control. When that happens, cells may keep dividing in an unregulated way. That loss of control can contribute to tumor formation.

Retroviruses can lead to cancer by changing how cells grow and divide. They are RNA viruses, and their genetic material is copied into DNA after infection. That DNA can then affect the host cell in ways that promote tumor formation. A key idea is the activation of proto-oncogenes. Proto-oncogenes are normal genes that help control cell growth, but they can become oncogenes, or cancer-causing genes, when their activity is altered. Retroviruses can contribute to this change and push infected...

rous sarcoma virus (rsv) and cancer

Rous Sarcoma Virus and the Src Gene

Rous sarcoma virus (RSV) is a cancer-causing virus linked to a specific gene called src. The virus is known for its role in helping scientists understand how some cancers develop at the molecular level. The src gene is a proto-oncogene, which means it is a normal gene with the potential to become cancer-related when altered. In RSV, this gene becomes the viral v-src version. That change is important because it connects a normal cellular gene to cancer-forming activity. RSV helped reveal that...

the ras gene

Ras Gene in Cell Signaling

The Ras gene helps control cell signaling. Ras proteins act as switches that pass signals inside a cell. These signals can affect growth and other cell responses. Ras is important in many cells because it helps move information from the cell surface to the cell interior. When this signaling system is working normally, the cell can respond in an organized way. Changes in Ras can disrupt that control.

mtor signaling and cancer progression

mTOR Pathway in Cancer Growth

mTOR signaling helps control cell growth, and changes in this pathway can support cancer progression. The mTOR protein is a key part of this signaling system. It helps cells respond to signals that tell them when to grow and divide. The transcript focuses on how mTOR signaling connects to cancer. When this pathway is altered, it can affect the behavior of cancer cells. Understanding this link helps explain why mTOR is an important topic in cancer biology. mTOR signaling is studied as part of...

cancer stem cells and tumor maintenance

Cancer Stem Cells in Tumor Growth

Cancer stem cells are a small group of cells inside a tumor that can support tumor growth and maintenance. They are studied because they may help explain why some cancers keep growing and return after treatment. Cancer stem cells can make new tumor cells. They also have the ability to self-renew, which means they can produce more cells like themselves. This makes them important in the long-term survival of the tumor. Some cancer stem cells may also resist therapy better than other tumor cells.

mouse models of cancer study

Mouse Models for Cancer Research

Mouse models for cancer research help scientists study how tumors form and grow in a living system. Mice are used because they can be matched to many human cancer features. They also allow researchers to test ideas before moving to clinical work. These models can include mice that naturally develop tumors and mice that are engineered to carry cancer-related changes. Some models are designed to mimic specific cancers, while others are used to study general tumor behavior. Together, they give...

cancer prevention

Lowering Cancer Risk

Cancer prevention focuses on lowering the chance that cancer will develop. It includes habits and choices that can reduce risk before disease starts. Some risks can be changed, and others cannot. The transcript describes common prevention strategies such as avoiding tobacco, limiting sun exposure, and making healthy lifestyle choices. These choices matter because they can help protect cells from damage over time. Prevention also includes knowing and reducing exposure to things that may...

cancer therapies

Cancer Treatment Options

Cancer treatment options include several ways to target cancer cells and help control the disease. Common approaches include chemotherapy, radiation therapy, surgery, and immunotherapy. Each method works in a different way, so doctors may choose one treatment or combine several. Chemotherapy uses drugs to kill fast-growing cells or stop them from dividing. Radiation therapy uses high-energy beams to damage cancer cells. Surgery removes a tumor when it can be reached safely. Immunotherapy helps...

targeted cancer therapies

How Targeted Cancer Drugs Work

Targeted cancer therapies use medicines that act on specific molecules linked to cancer cell growth. These drugs are designed to interfere with signals that help cancer cells survive and divide. The goal is to affect cancer cells more directly than many traditional treatments. The transcript highlights two examples of targeted therapy. Imatinib mesylate works by blocking a protein target involved in cancer growth. Trastuzumab is another targeted drug used in cancer treatment. These therapies...

treatment resistent cancers

Why Some Cancers Resist Treatment

Some cancers resist treatment and keep growing even after therapy. This video focuses on why that happens and how resistance changes cancer care. Treatment resistance can develop when cancer cells survive drugs that should destroy them. The cells may avoid the drug’s effects, or they may keep dividing after treatment starts. This makes the cancer harder to control. Understanding treatment-resistant cancer helps explain why some therapies work at first and then lose effect. It also shows why...

combination therapies and personalized medicine

combination-therapies-and-personalized-medicine

Personalized Cancer Treatment with Drug Combinations

Personalized cancer treatment uses drug combinations to better match therapy to a patient’s tumor. It brings together combination therapies and personalized medicine to improve how doctors choose treatment. Combination therapy means using two or more drugs at the same time or in sequence. This approach can help target cancer cells in more than one way and may reduce the chance that the tumor becomes resistant to one drug. Personalized medicine uses information about the patient and the tumor...

key terms and concepts

Explore how retroviruses can cause cancer by turning proto-oncogenes into oncogenes and by inserting viral DNA near host genes.

How Retroviruses Lead to Cancer | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

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Describe the basic process of DNA replication and how it relates to the transmission and conservation of the genetic information.

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The DNA Helix

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Mutations

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Mutation, Gene Flow, and Genetic Drift

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Explain how mutations in the DNA sequence may or may not result in phenotypic change. Explain how mutations in gametes may result in phenotypic changes in offspring.

SC.912.L.16.4

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RNA Structure

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Ribosomes

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tRNA Activation

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Termination of Translation

Improving Translational Accuracy

Nonsense-mediated mRNA Decay

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The Proteasome

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Proteins: From Genes to Degradation

Explain the basic processes of transcription and translation, and how they result in the expression of genes.

SC.912.L.16.5

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Discuss the mechanisms for regulation of gene expression in prokaryotes and eukaryotes at transcription and translation level.

SC.912.L.16.6

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SC.912.L.16.7

A. DNA stores and transmits genetic information. Genes are sets of instructions encoded in the structure of DNA.

B. Genetic information is passed from generation to generation by DNA in all organisms and accounts for similarities in related individuals.

C. Manipulation of DNA in organisms has led to commercial production of biological molecules on a large scale and genetically modified organisms.

D. Reproduction is characteristic of living things and is essential for the survival of species.

How Retroviruses Lead to Cancer

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