(4.7) CANCER BIOLOGY AND METASTASIS

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Questions and Answers

Which of the following defines a protooncogene?

A gene that inhibits cell division

A gene that causes apoptosis

A normal gene that can become an oncogene (correct)

A mutant gene that promotes benign growth

What is a key feature of malignant growth compared to benign growth?

Limited ability to invade neighboring tissues

Ability to metastasize to distant sites (correct)

Presence of encapsulated structures

Higher degree of differentiation

What does genomic instability in cancer refer to?

The stabilization of telomere length

Decreased cellular replication rates

The consistent structure of chromosomes

Increased mutations and chromosomal rearrangements (correct)

Which statement best describes the role of telomeres in cancer progression?

Telomerase activation helps prevent the shortening of telomeres Signup and view all the answers

What is one of the mechanisms involved in the process of metastasis?

Intravasation into nearby blood vessels Signup and view all the answers

How do protooncogenes typically contribute to cancer when mutated?

They stimulate uncontrolled cell growth Signup and view all the answers

Which factor is commonly associated with the limitless replicative potential of cancer cells?

Activation of telomerase Signup and view all the answers

What indicates the oncogenic potential of a gene when introduced into a nonmalignant cell?

Loss of contact inhibition Signup and view all the answers

What is a direct result of telomere shortening due to the end replication problem?

A decrease in cellular lifespan Signup and view all the answers

Genomic instability in cancer can result from which of the following?

Chromosomal rearrangements Signup and view all the answers

What role do signal transducing proteins from protooncogenes play in the development of cancer?

They convey 'GO' signals for growth. Signup and view all the answers

What is the significance of contact inhibition in cancer cells?

It promotes uncontrolled cell growth. Signup and view all the answers

How does genomic instability influence cancer progression?

It leads to increased mutations that may activate oncogenes. Signup and view all the answers

What is the role of telomerase in cancer cells?

It helps maintain telomere length, allowing limitless division. Signup and view all the answers

What is intravasation in the context of cancer metastasis?

The entrance of tumor cells into the bloodstream. Signup and view all the answers

Which of the following statements about tumor suppressor genes is true?

They regulate the cell cycle and prevent uncontrolled growth. Signup and view all the answers

What does extravasation refer to in cancer metastasis?

The exit of tumor cells from the bloodstream. Signup and view all the answers

What is the key characteristic of oncogenes?

They are mutated protooncogenes that lead to cancer. Signup and view all the answers

Which process allows tumor cells to invade surrounding tissues?

Intravascular Growth Signup and view all the answers

Renal carcinoma is known for what characteristic in its cancer progression?

It often demonstrates early invasiveness. Signup and view all the answers

What characterizes benign tumors compared to malignant tumors?

Slow growth Signup and view all the answers

Which of the following statements about cancer inheritance is true?

Only 5 to 10% of cancers are considered familial. Signup and view all the answers

The process of carcinogenesis primarily involves which of the following stages?

Progression and invasion Signup and view all the answers

Which of the following events is typical of the transition from normal cells to invasive cancer?

Loss of differentiation in cells Signup and view all the answers

Genomic instability in cancer relates to which of the following concepts?

An increased frequency of mutations and chromosomal changes. Signup and view all the answers

The progression to malignancy commonly follows which sequence of events?

Initiation, Dysplasia, Invasion Signup and view all the answers

What defines the transition from hyperplasia to dysplasia during cancer progression?

Alteration of cell structure without abnormal growth. Signup and view all the answers

Proto-oncogenes and their role in cancer can be described as:

Normal genes that can become oncogenes when mutated. Signup and view all the answers

What distinguishes malignant tumors from benign tumors in terms of growth characteristics?

Malignant tumors have the ability to invade surrounding tissues. Signup and view all the answers

Which of the following is true regarding the genetic risk factors associated with most cancers?

Sporadic mutations often occur with no notable family history. Signup and view all the answers

What is a key understanding of how carcinomas, one of the most common cancer types, originate?

They mainly develop from epithelial cells. Signup and view all the answers

Which process best describes the capability of cancer cells to grow autonomously without external signals?

Autonomous growth. Signup and view all the answers

How does genomic instability contribute to the development of cancer?

It increases the likelihood of mutations being passed to daughter cells. Signup and view all the answers

What role do cyclins play in the regulation of the cell cycle?

They activate cyclin-dependent kinases (CDKs) to regulate cell cycle phases. Signup and view all the answers

How do sporadic cancers differ from inherited familial cancers?

Familial cancers often present with earlier onset and more unusual cancer types. Signup and view all the answers

Dysregulation of CDK activity primarily contributes to which of the following cellular processes?

Uncontrolled cell growth and cycle progression. Signup and view all the answers

Which statement accurately describes the role of family history in assessing cancer risk?

Familial risk can be indicated by the presence of rare cancer types within a family. Signup and view all the answers

Study Notes

Cancer Biology and Metastasis

Objectives:
- Define key terms like gain/loss of function, protooncogene, oncogene, tumor suppressor gene, fusion gene/protein, hyperplasia, dysplasia, anaplasia, benign, malignant, contact inhibition, intravasation, extravasation, carcinoma, sarcoma, leukemia/lymphoma.
- Explain differences between sporadic and inherited cancers.
- Compare and contrast characteristics of benign and malignant growths.
- Explain malignant transformation and key features of malignancy.
- Differentiate reversible and irreversible stages of cancer development/progression.
- Describe the process of metastasis, focusing on steps and vascular permeability's role.
- List typical cancer stages (0-IV) with features of each.

Principles of Cancer

LO1:
- Exhibit Malignancy
- Altered Heritability
- Autonomous Growth
- Invasion and Interference
- 85% of cancers are carcinomas (epithelial cells).
- 10% are leukemia/lymphoma (blood/lymph cells).
- 5% are sarcomas (muscle, bone, blood vessels, cartilage).

Cancer Development

Most cancers develop due to somatic changes, not inheritable predispositions.
Only 5-10% of cancers are familial or inherited, though family clustering can raise that to nearly 35%.
The majority of cancers develop somatically and sporadically.

Cancer Cells

Abnormal cells with altered processes regulating cell division.
Typically involves 4-7 unique events leading to normal cell transformation into invasive cancer.
Identifying unifying themes in varied cancer types is possible.

Differentiating Benign from Malignant

Benign:
- Noninvasive
- Highly differentiated
- Reduced cellular divisions; slow growth
- Nonmetastatic; can be cured with surgery.
Malignant:
- Invasive
- Poorly differentiated
- Rapid growth
- Potentially metastatic; requires aggressive intervention.

Malignancy (Multi-Tiered Process)

Initiation: Hyperplasia and Dysplasia (often occur together).
Hyperplasia: Excessive growth.
Dysplasia: Abnormal cell structure.
Anaplasticity (Development): Represents truly abnormal cells, losing normal function.
Invasion: Spreading to surrounding tissues, often through the basement membrane.
Metastasis: Spread to distant locations.

Carcinogenesis

Process of cellular transition to malignancy.
Reversible stages:
- Initiation
- Promotion (mild hyperplasia/dysplasia).
Irreversible stages:
- Progression (significant dysplasia/anaplasia)
- Invasion
- Metastasis

Subversion of the Norms

Growth Stimulation Dependence: Growth independent of triggers.
Contact Inhibition: No density-dependent inhibition of growth.
Balance Between Losses and Gains: Controlled aging/death is altered.
Proper Response to Stop Signals: No response to anti-growth signals.

Process of Metastasis

Adhesion to Basement Membrane
Invasion Through Basement Membrane
Passage Through Extracellular Matrix
Intravasation (passage into vessel)
Travel (tumor embolus)
Adhesion to Vessel Epithelium
Extravasation (passage out of vessel)
Passage Through Extracellular Matrix
Adhesion to Basement Membrane
Growth at Secondary Location

Cancer Stages

Stage 0: Carcinoma in situ (cancer in place).
Stage I-IV: Increasingly invasive tumor spread and potential for metastasis. Specific details on each stage are provided. Metastatic spread can be early in some types of cancer.

Hallmarks of Cancer

Perspective on the molecular biology of cancer, focusing on key features.

Objectives (Additional)

Link specific molecular changes to their corresponding hallmarks.
Explain the relationship between growth signaling and cancer development and progression.
Explain the relationship between telomere length, telomerase, and cancer development and progression.
Explain the role of chromosomal rearrangements in cancer development or progression..

Self-Sufficiency in Growth Signals

Proto-oncogenes: Normal genes that become oncogenes when overexpressed or mutated.
Oncogenes: Genes that contribute to malignant transformation.
Mutations, chromosomal translocation, and gene amplification can turn proto-oncogenes into oncogenes.
Continuous activation of growth signaling makes cells less responsive to regulatory controls.

Proto-oncogenes and Oncogenes in Signaling Pathways

Many proteins conveying or promoting signals are encoded by proto-oncogenes.
These are "GO" signals in growth.
Turned-on growth signals without needing growth factors contribute to cancer.
Overcome signals telling cells to stop growing.

Proto-oncogenes and Oncogenes - Distinguishing Factors

Introduction of an oncogene can cause the formation of foci and loss of contact inhibition.
Reduction of growth factor dependence.
Increased and independent growth in soft agar
Forming tumors in immuncompromised mice.
Additional mutations needed for full malignant progression, often in regulatory genes.

Limitless Replicative Potential

Telomeres shorten with cell division, eventually stopping further division.
Telomerase maintains telomere length, allowing for limitless replication.
Presence of telomerase is most common in malignant cells (as opposed to most normal tissues).
Lengths of telomeres in cancer can exceed those of germline cells.

Genomic Instability - Telomere and Bridge-Fusion-Breakage Cycle

Telomere shortening causes DNA damage responses which may lead to cell senescence or cell death.
Telomerase activation can reverse telomere shortening, allowing for continued division.
Chromosome fusion and breakage lead to genomic instability.

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Description

Test your knowledge on key concepts of cancer biology, including definitions of essential terms like oncogenes and tumor suppressor genes. Understand the differences between benign and malignant tumors, the process of metastasis, and cancer staging. This quiz covers fundamental principles and features associated with malignancy.