Cell Division and Tumor Suppressor Genes

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Questions and Answers

What is the role of CTLA-4 in the immune system?

It enhances T-cell activation

It serves as a co-inhibitory molecule (correct)

It presents antigens to T-cells

It stimulates the production of antibodies

Which component is primarily responsible for presenting antigens to T-cells?

T-cell receptor (TCR)

Cytotoxic T-lymphocyte antigen-4 (CTLA-4)

Programmed cell death protein 1 (PD-1)

Major histocompatibility complex (MHC) (correct)

Which monoclonal antibodies have been developed targeting CTLA-4?

Anti-PD-1

Anti-CTLA-4 (correct)

Anti-TCR

Anti-PD-L1

What is the primary function of the T-cell receptor (TCR)?

To recognize antigens on APCs Signup and view all the answers

Which agency is responsible for the approval of monoclonal antibodies in the United States?

Food and Drug Administration (FDA) Signup and view all the answers

What role does cyclin B play in the cell cycle?

It complexes with CDK1 to drive mitosis. Signup and view all the answers

Which gene is an example of a gatekeeper in tumor suppression?

p53 Signup and view all the answers

How do caretaker genes contribute to cancer prevention?

By maintaining genome stability through DNA repair. Signup and view all the answers

What distinguishes landscaper genes from gatekeeper and caretaker genes?

They affect the tumor microenvironment. Signup and view all the answers

What connection did Kinzler and Vogelstein make in their model of tumorigenesis?

The classification of tumor-promoting genes into gatekeepers, caretakers, and landscapers. Signup and view all the answers

What is a common consequence of mutations in gatekeeper genes?

Higher risk of abnormal cell growth and cancer. Signup and view all the answers

Which phase of the cell cycle does CDK1 primarily impact when associated with cyclin B?

M phase Signup and view all the answers

What results from the inactivity or mutation of caretaker genes?

Accumulation of mutations and genetic instability. Signup and view all the answers

What is a primary function of BRCA1 during the cell cycle?

Promoting miotic spindle assembly Signup and view all the answers

Which protein does BRCA2 bind to at the junction between ssDNA and dsDNA?

RPA Signup and view all the answers

How do BRCA1 and BRCA2 contribute to the G2 checkpoint?

Both A and C Signup and view all the answers

What does the C-terminal DNA binding domain of BRCA2 interact with?

Both ssDNA and dsDNA Signup and view all the answers

During cytokinesis, what role does BRCA2 play?

Participates in the abscission step Signup and view all the answers

What is the length of the BRCA2 protein in amino acids?

3418 Signup and view all the answers

What mechanism does BRCA1 utilize to trigger end resection during DNA repair?

Displacing 53BP1 Signup and view all the answers

Which of the following best describes the role of RAD51 in the context of BRCA1 and BRCA2?

It recruits and stabilizes DNA during repair Signup and view all the answers

What does Tis indicate in tumor classification?

Cancer cells are localized to the surface layer of the tissue. Signup and view all the answers

In the TNM classification system, what does an N0 designation indicate?

Nearby lymph nodes do not contain cancer. Signup and view all the answers

What does the presence of M1 signify in cancer staging?

Distant metastasis to organs has occurred. Signup and view all the answers

If a tumor is classified as T4, what can be inferred about it?

It has spread to nearby tissues or structures. Signup and view all the answers

What is indicated by a designation of TX in the tumor category?

There is insufficient information about the primary tumor. Signup and view all the answers

Which statement is true regarding the N category in the TNM classification?

N1 indicates the presence of cancer in the examined lymph nodes. Signup and view all the answers

What does an indication of M0 represent in terms of cancer progression?

There is no distant spread of cancer. Signup and view all the answers

How are the T categories generally numbered in the TNM system?

Higher numbers indicate larger tumors or more extensive spread. Signup and view all the answers

What best describes the condition of breast cancer in the scenario provided?

Primary tumor of 5.5 cm, spread to nearby lymph nodes, no metastasis. Signup and view all the answers

How is the prostate cancer described in this context?

Medium-grade with a PSA level of 15 ng/mL, no lymph node involvement. Signup and view all the answers

What does not characterize the bladder tumor situation presented?

Lymph node involvement. Signup and view all the answers

What is significant about the melanoma described?

It has ulceration penetrating 6 mm and significant nearby lymph node involvement. Signup and view all the answers

In the scenario with pancreatic cancer, what is true?

It involves more than 4 cm, with lymphatic and secondary liver tumors. Signup and view all the answers

What do TASTs and TSTAs refer to in the context of tumors?

Specific tumor antigens and transplant-related tumor antigens. Signup and view all the answers

What aspect of the immune cycle related to cancer is highlighted?

It includes both stimulatory and inhibitory feedback mechanisms. Signup and view all the answers

What is NOT a characteristic of the immune response to cancer as described?

It leads to a decrease in overall T cell responses. Signup and view all the answers

Study Notes

Cyclin B and Cell Division

Cyclin B is a regulatory protein that, when associated with CDK1, promotes entry into the M phase (Mitosis) of the cell cycle.
The cyclin B/CDK1 complex triggers mitosis.
This complex works with other kinases to drive the transition from G2 to M phase.
The cyclin B/CDK1 complex is involved in various cellular processes including:
- Mitotic progression
- Spindle assembly
- Sister chromatid separation.

Tumor Suppressor Genes

Tumor suppressor genes protect against cancer by regulating cell growth and death.
Gatekeeper genes directly regulate cell proliferation and apoptosis.
Caretaker genes are involved in DNA repair and maintain genome integrity.
Landscapers are mutated in the tumor microenvironment, not directly in the tumor cell.
Mutations in landscapers support tumor growth by providing nutrients and resources.

BRCA1 and BRCA2

These genes are caretakers that are involved in chromosome maintenance.
Both BRCA1 and BRCA2 primarily function in homologous recombination (HR) repair.
Both proteins are involved in different stages of the cell cycle.
Both proteins are also involved in DNA damage repair, particularly in DNA double-strand breaks.
Specifically, BRCA2 binds to the RAD51 recombinase, enhancing its activity which is needed for HR repair.

Immunotherapy and Cancer

Immune checkpoint inhibitors are a type of immunotherapy that stimulates the immune system to attack cancer cells.
They work by blocking the activity of inhibitory pathways that can suppress the immune system.
Examples of immune checkpoint inhibitors are:
- Anti-CTLA-4
- Anti-PD-1
- Anti-PD-L1
- They are used to treat various types of cancer, such as melanoma, lung cancer, and bladder cancer.

TNM Tumor Classification System

The TNM system is a widely used system to classify cancers based on tumor size, lymph node involvement, and metastasis.
T refers to the primary tumor's size and extent.
- T0 indicates the primary tumor cannot be found.
- Tis indicates tumor cells are confined to the layer where they originated, without spreading to deeper tissues.
- Numbers after T (e.g., T1, T2, T3, T4) indicate increasing tumor size and/or spread to nearby structures.
N refers to the involvement of nearby lymph nodes.
- N0 indicates no involvement of nearby lymph nodes.
- Numbers after N (e.g., N1, N2, N3) indicate increasing involvement in nearby lymph nodes.
M indicates the presence or absence of metastasis.
- M0 indicates no metastasis.
- M1 indicates metastasis to distant organs or tissues.

Tumor Markers

Tumor markers are substances produced by cancer cells or by the body in response to cancer.
They can be used to detect cancer, monitor treatment, and assess the risk of recurrence.
Different types of tumor markers exist, including proteins, enzymes, and hormones.

Tumor-Associated Antigens (TATAs and TSTAs)

These are targets for the immune system to identify and attack cancer cells.
TATAs are more common and are associated with cancer cells but are not specific to a particular cancer type.
TSTAs are more specific to a particular cancer type and may be absent in normal cells.

Cancer Immunology

The generation of immunity to cancer is a cyclic process.
It involves a complex interplay between immune cells, tumor cells, and the tumor microenvironment.
The cycle can be self-propagating, leading to an amplification of immune responses.
However, inhibitory factors can also limit the immune response and hinder the effectiveness of immunotherapy.

Immunotherapy Timeline

Anti-CTLA-4, Anti-PD-1, and Anti-PD-L1 antibodies have shown significant clinical success in cancer treatment.
Their development has progressed from early human clinical trials to FDA approval.

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Description

Explore the key concepts of cell division, focusing on Cyclin B and its role in M phase progression. Additionally, examine the function of tumor suppressor genes, including the importance of BRCA1 and BRCA2 in maintaining genomic integrity and preventing cancer.