DNA Tumor Viruses & Cancer Prevention
48 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

In less developed countries, the attributable fraction of cancer cases related to viral infections is approximately how many times higher than in developed regions?

  • 4 times higher
  • 2 times higher
  • 5 times higher
  • 3 times higher (correct)

Hepatitis B is transmitted through various means. Which of the following is NOT a typical mode of Hepatitis B transmission?

  • Sexual contact
  • Respiratory droplets (correct)
  • Perinatal transmission
  • Unsafe injections

What percentage of people with chronic HBV infections are estimated to develop progressive liver disease?

  • 50% (correct)
  • 98-100%
  • 20%
  • 1-2%

The hepatitis B vaccine provides a high level of protection against the virus. What percentage range represents the protection offered by the vaccine?

<p>98-100% (C)</p> Signup and view all the answers

Which of the following is a primary function of the HBx protein encoded by the Hepatitis B virus?

<p>Promotion of viral replication and protection from immune destruction. (D)</p> Signup and view all the answers

Which region has the highest percentage of liver cancer cases caused by chronic HBV infections?

<p>Africa and Asia (B)</p> Signup and view all the answers

Hepatitis B is considered more infectious than HIV. Approximately how many times more infectious is it?

<p>50-100 times (B)</p> Signup and view all the answers

What is the primary reason that a complete cure for chronic HBV infections remains elusive, despite available treatments?

<p>The virus integrates its DNA into the host's liver cells. (C)</p> Signup and view all the answers

In developed countries compared to less developed countries, what is the key difference in the proportion of cancer cases linked to infections?

<p>Infections contribute to a significantly higher percentage of cancer cases in less developed countries. (D)</p> Signup and view all the answers

Which of the following interventions is least likely to reduce the risk of infection-related cancers?

<p>Widespread use of antibiotics to treat viral infections. (C)</p> Signup and view all the answers

Which virus associated with cancer contains a positive-strand RNA genome?

<p>Hepatitis C virus (HCV) (C)</p> Signup and view all the answers

A new virus is discovered that appears to cause cancer through chronic inflammation. Which of the following mechanisms is least likely to be involved in its oncogenic activity?

<p>Direct integration of viral DNA into tumor suppressor genes, disabling them. (C)</p> Signup and view all the answers

In 2008, which group of infections was collectively responsible for the majority of infection-attributable cancer cases worldwide?

<p>H. pylori, Hepatitis B virus (HBV), Hepatitis C virus (HCV), and Human papillomaviruses (HPV) (C)</p> Signup and view all the answers

A researcher is studying a new strain of Epstein-Barr virus (EBV) found in a nasopharyngeal carcinoma sample. What characteristic would most strongly suggest that this strain is specifically adapted to cause carcinomas?

<p>High rate of spontaneous lytic replication and affinity for epithelial cells. (B)</p> Signup and view all the answers

A patient is diagnosed with hepatocellular carcinoma. Which viral marker would most likely be present in their blood sample?

<p>Hepatitis B surface antigen (HBsAg) (C)</p> Signup and view all the answers

Why is the percentage of infection-related cancers higher in less developed countries?

<p>There is a higher prevalence of certain infections and limited access to public health interventions. (A)</p> Signup and view all the answers

How do vaccines like Gardasil® and Cervarix® contribute to cervical cancer prevention, according to the information provided?

<p>By providing over 95% protection against high-risk HPV types, significantly reducing cervical cancer incidence. (A)</p> Signup and view all the answers

What is a key characteristic shared among PAPOVA viruses concerning their genome organization?

<p>Double-stranded, circular DNA genomes with a single origin of replication. (D)</p> Signup and view all the answers

How do early transcripts in polyomavirus contribute to cell transformation and replication?

<p>They produce three T antigens (small, middle, and large T) responsible for cell transformation and replication. (D)</p> Signup and view all the answers

How does the Large T antigen in SV40 contribute to viral replication and host cell transformation?

<p>By playing a crucial role in DNA replication and host cell transformation. (B)</p> Signup and view all the answers

What is the primary function of the HPV E6 protein in promoting cancer development?

<p>Inactivating p53, enabling cell survival and proliferation. (B)</p> Signup and view all the answers

How does the Middle T antigen encoded by polyomavirus manipulate host cell signaling pathways to promote cell transformation?

<p>It recruits kinases to activate signaling pathways such as PI3K. (B)</p> Signup and view all the answers

How do HPV E1 and E2 proteins coordinate during the viral replication process?

<p>E1 provides helicase activity to unwind DNA, while E2 regulates transcription and genome maintenance. (C)</p> Signup and view all the answers

Considering the genomic organization of PAPOVA viruses, what would be the most likely consequence of a mutation that disrupts the function of the origin of replication?

<p>Impaired viral DNA replication. (A)</p> Signup and view all the answers

How does p53 contribute to maintaining genetic stability?

<p>By activating DNA repair mechanisms, inducing cell cycle arrest, or initiating apoptosis. (A)</p> Signup and view all the answers

The interaction between adenovirus E1A oncoprotein and pRB disrupts pRB's normal function, leading to:

<p>Uncontrolled cell proliferation by preventing pRB from regulating E2F transcription factors. (A)</p> Signup and view all the answers

In Familial Adenomatous Polyposis (FAP), mutations in the APC gene lead to the development of numerous colorectal polyps. If left untreated, what is the most likely outcome?

<p>Progression to colorectal cancer. (C)</p> Signup and view all the answers

How does pRB regulate the cell cycle?

<p>By binding to and inhibiting E2F transcription factors, controlling the G1 to S phase transition. (C)</p> Signup and view all the answers

What is the primary role of Wnt proteins in the Wnt signaling pathway?

<p>To bind to Frizzled receptors and initiate a signaling cascade. (D)</p> Signup and view all the answers

What initial observation led to the discovery of phosphoinositide 3-kinase (PI3K)?

<p>The presence of PI3K activity in association with the polyomavirus middle T antigen. (B)</p> Signup and view all the answers

Which of the following is a direct consequence of PI3K activation in the signaling pathway?

<p>Production of phosphatidylinositol-3,4,5-triphosphate (PIP3) and subsequent activation of Akt. (C)</p> Signup and view all the answers

Which of the following components is NOT directly involved in the destruction complex that regulates beta-catenin degradation?

<p>LRP5/6 (low-density lipoprotein receptor-related proteins). (C)</p> Signup and view all the answers

How does the loss of tumor suppressors like PTEN contribute to oncogenic transformation?

<p>By acting as negative regulators of the PI3K pathway, leading to increased cell survival and proliferation. (A)</p> Signup and view all the answers

What event directly prevents beta-catenin degradation upon Wnt pathway activation?

<p>Disruption of the destruction complex. (C)</p> Signup and view all the answers

Following its stabilization, what is the next step for beta-catenin in the Wnt signaling pathway?

<p>Translocation into the nucleus. (A)</p> Signup and view all the answers

What is the primary mechanism by which p53 prevents the proliferation of cells with damaged DNA?

<p>Inducing cell cycle arrest to allow for DNA repair or initiating apoptosis if repair is impossible. (A)</p> Signup and view all the answers

Which of the following best describes the functional relationship between pRB and E2F transcription factors in a normal, healthy cell?

<p>pRB inhibits E2F, preventing the transcription of genes required for G1-to-S phase transition. (D)</p> Signup and view all the answers

In the nucleus, beta-catenin interacts with which transcription factors to activate the expression of Wnt target genes?

<p>TCF/LEF. (A)</p> Signup and view all the answers

Which of the following biological processes is regulated by Wnt/beta-catenin signaling during embryonic development?

<p>Cell fate determination. (A)</p> Signup and view all the answers

In the context of tumor development based on the multi-hit model, what is the MOST accurate description?

<p>Tumor development is usually a result of multiple genetic mutations accumulated over time. (D)</p> Signup and view all the answers

How does the Middle T antigen (MT) of polyomavirus contribute to cellular transformation?

<p>By mimicking an activated growth factor receptor, initiating downstream signaling pathways. (D)</p> Signup and view all the answers

In adult tissues, what is the primary function of Wnt signaling?

<p>Maintenance of tissue renewal. (D)</p> Signup and view all the answers

What is the immediate consequence of Middle T antigen (MT) phosphorylation at key tyrosine residues?

<p>Recruitment and activation of cellular signaling proteins such as Src kinase, PI3K, and PLC-γ. (A)</p> Signup and view all the answers

Why is the interaction between Src kinase and protein phosphatase 2A (PP2A) critical in the formation of the MT transformation complex?

<p>It is essential for initiating downstream oncogenic signaling pathways. (D)</p> Signup and view all the answers

In the ordered assembly of the Middle T antigen transformation complex, what is the role of PP2A after MT is phosphorylated at Y250 and recruits Src kinase?

<p>PP2A binds to the phosphorylated MT, facilitating additional phosphorylations at Y315 and Y322. (A)</p> Signup and view all the answers

Once PI3K and PLC-γ are recruited during the assembly of the MT transformation complex, which cellular processes are directly activated?

<p>Survival and proliferation pathways. (C)</p> Signup and view all the answers

How does the multi-subunit architecture of protein phosphatase 2A (PP2A) contribute to its function?

<p>It allows PP2A to interact with various cellular proteins, exerting precise control over phosphorylation states. (C)</p> Signup and view all the answers

Which subunit of PP2A governs substrate specificity, enabling the phosphatase to interact with various cellular proteins?

<p>The regulatory B subunit. (A)</p> Signup and view all the answers

Flashcards

p53

A protein that acts as a tumor suppressor by maintaining genetic stability.

Tumor suppressor

Proteins that help regulate cell growth and prevent tumor formation.

p21

A Cdk-inhibitor protein activated by p53 that induces cell cycle arrest in G1 phase.

pRB

A crucial tumor suppressor that regulates the cell cycle by inhibiting E2F transcription factors.

Signup and view all the flashcards

E2F transcription factors

Proteins that promote the transition from G1 to S phase of the cell cycle.

Signup and view all the flashcards

PI3K

A lipid kinase involved in cell growth and survival, activating signal cascades.

Signup and view all the flashcards

PIP3

A lipid product of PI3K that recruits and activates downstream effectors.

Signup and view all the flashcards

PTEN

A tumor suppressor that negatively regulates the PI3K signaling pathway.

Signup and view all the flashcards

Infection-related cancers

Cancers linked to infections from viruses, bacteria, or parasites.

Signup and view all the flashcards

Helicobacter pylori

A bacterium linked to gastric cancer.

Signup and view all the flashcards

Hepatitis B virus (HBV)

Virus strongly associated with liver cancer (hepatocellular carcinoma).

Signup and view all the flashcards

Human papillomavirus (HPV)

Virus directly linked to cervical and other anogenital cancers.

Signup and view all the flashcards

Epstein-Barr virus (EBV)

Virus associated with nasopharyngeal carcinoma and some lymphomas.

Signup and view all the flashcards

Global Burden of Cancer (2008)

Approximately 2 million new cancer cases due to infections worldwide.

Signup and view all the flashcards

HCV (Hepatitis C virus)

RNA virus majorly causing liver cancer.

Signup and view all the flashcards

Public health interventions

Measures like vaccinations to reduce infection-related cancer risk.

Signup and view all the flashcards

Infectious causes of cancer

Infections that contribute to cancer development, notably in resource-limited settings.

Signup and view all the flashcards

Attributable Fraction of Cancer

Percentage of new cancer cases linked to viral infections; globally 16.1% in 2012.

Signup and view all the flashcards

Primary viruses in cancer

Key viruses linked to cancer: HBV, HCV, HPV, notably causing liver and cervical cancers.

Signup and view all the flashcards

Hepatitis B (HBV)

A highly infectious virus attacking the liver; spreads through blood and body fluids.

Signup and view all the flashcards

Chronic HBV infection

A long-lasting HBV infection that can lead to cirrhosis or liver cancer.

Signup and view all the flashcards

HBV vaccine

A vaccine providing 98-100% protection against Hepatitis B, recommended for infants.

Signup and view all the flashcards

HBV genome

HBV is a small DNA virus with a partially double-stranded genome of 3.2 kb encoding four genes.

Signup and view all the flashcards

Oncogenesis in HBV

Process by which HBV contributes to cancer development, via the HBx protein.

Signup and view all the flashcards

Gardasil® and Cervarix®

Vaccines providing over 95% protection against high-risk HPV types, reducing cervical cancer incidence.

Signup and view all the flashcards

Early screening and vaccination

Strategies essential for preventing HPV-related cancers.

Signup and view all the flashcards

Small DNA tumor viruses

Viruses like polyomavirus, SV40, and HPV associated with cancer development.

Signup and view all the flashcards

PAPOVA viruses

Group of viruses sharing genomic features like double-stranded circular DNA and reliance on host cells.

Signup and view all the flashcards

Polyomavirus genome

Genome of 5,292 bp encoding T antigens for cell transformation and replication.

Signup and view all the flashcards

Early region of polyomavirus

Encodes tumor antigens that push host cell functions towards replication.

Signup and view all the flashcards

SV40 characteristics

SV40 has early and late transcription units encoding T antigens and structural proteins.

Signup and view all the flashcards

Multi-hit model

A model explaining tumor development through accumulating genetic mutations over time, increasing cancer risk.

Signup and view all the flashcards

Middle T Antigen (MT)

A viral protein from polyomavirus essential for transforming host cells and promoting oncogenesis.

Signup and view all the flashcards

Growth factor receptor mimicry

The MT antigen mimics activated growth factor receptors, initiating cell proliferation and survival pathways.

Signup and view all the flashcards

Phosphorylation sites of MT

Key tyrosine residues (Y250, Y315, Y322) on MT that are phosphorylated to facilitate signaling pathways.

Signup and view all the flashcards

Transformation complex assembly

A stepwise process involving MT phosphorylation, Src kinase, and PP2A binding crucial for oncogenic signaling.

Signup and view all the flashcards

Src kinase

A protein that phosphorylates MT, helping to stabilize the transformation complex and enhance oncogenic signal.

Signup and view all the flashcards

PP2A (Protein Phosphatase 2A)

A multi-subunit phosphatase that regulates phosphorylation states and cellular signaling pathways.

Signup and view all the flashcards

Signaling cascades

The series of biochemical events triggered by activated growth factor receptors leading to cell transformation and survival.

Signup and view all the flashcards

Familial Adenomatous Polyposis (FAP)

A hereditary syndrome leading to numerous colorectal polyps due to APC gene mutations.

Signup and view all the flashcards

APC Gene

A gene whose mutation leads to Familial Adenomatous Polyposis and increased colorectal cancer risk.

Signup and view all the flashcards

Wnt Signaling Pathway

A crucial pathway regulating cell growth, differentiation, and survival via Wnt proteins.

Signup and view all the flashcards

Frizzled Receptors

G-protein-coupled receptors that bind Wnt proteins to initiate signaling.

Signup and view all the flashcards

Beta-Catenin

A key signaling protein whose stabilization and translocation promote cell proliferation.

Signup and view all the flashcards

Destruction Complex

A group of proteins that degrades beta-catenin when Wnt is absent, preventing signaling.

Signup and view all the flashcards

Wnt Target Genes

Genes activated by beta-catenin that promote cell growth and survival.

Signup and view all the flashcards

Tissue Homeostasis

The maintenance of tissue renewal and health, regulated by Wnt/beta-catenin signaling in adults.

Signup and view all the flashcards

Study Notes

DNA Tumor Viruses

  • Cancer is a global health concern, with high morbidity and mortality
  • Tyrosine phosphorylation was discovered in 1979, found in polyomavirus middle T antigen and v-Src-associated kinase activities
  • Phosphorylation is a common post-translational modification, occurring on serine and threonine residues more frequently than tyrosine
  • Phosphorylation is important in regulating protein function, cell signaling and in cancer progression
  • The tumor suppressor p53 is a significant milestone in cancer research
  • p53, dubbed the "Guardian of the Genome", plays a role in maintaining genetic stability

Cancer Prevention

  • Addressing modifiable risk factors is key to cancer prevention
  • Avoiding carcinogens like tobacco smoke, reducing radiation exposure (UV light) are vital
  • Preventing infections like hepatitis B and HPV through vaccination
  • Lifestyle modifications like maintaining a healthy diet, regular exercise, and minimizing alcohol consumption reduce risk

Viruses, Bacteria, and Parasites in Cancer Development

  • Approximately 15-20% of human cancers are related to infections
  • Significant burden in less-developed regions
  • Helicobacter pylori, hepatitis B and C viruses, and HPV are notable contributors
  • These agents cause gastric, liver, and cervical cancers

Viruses Involved in Human Cancer Development

  • DNA viruses, such as HBV, HPV, and EBV, and RNA viruses like HCV and HTLV, are directly implicated in cancer
  • HBV is linked to hepatocellular carcinoma
  • HPV is associated with cervical, anal, and oropharyngeal cancers
  • EBV is connected to nasopharyngeal carcinoma and lymphomas

Global Burden of Infection-Attributable Cancers

  • In 2008, approximately 2 million of the 12.7 million new cancer cases worldwide were linked to infections
  • HBV, HCV, and HPV are significant contributors to the global cancer burden

Hepatitis B Infection

  • Highly infectious virus transmitted through blood or body fluids
  • Causes acute and chronic liver disease, is 50–100 times more infectious than HIV
  • Acute hepatitis B is asymptomatic but can lead to jaundice, dark urine, fatigue and abdominal pain
  • Chronic HBV infections cause 60% of liver cancer cases in Africa and Asia and 20% in Europe and the US
  • Hepatitis B vaccine is effective at preventing the disease

HPV Infection

  • HPV is the most common sexually transmitted infection and causes cervical, anal, vulvar, vaginal, penile, and oropharyngeal cancers
  • HPV-related cancers are nearly all cervical, 70% of oropharyngeal, and more than 90% of anal cancers
  • Vaccines like Gardasil and Gardasil 9 are highly protective
  • Most effective in young individuals before exposure to HPV

Common Cancers in Women

  • Globally, the most common cancers in women are breast, cervical, and colorectal cancer
  • Cervical cancer is significant health challenge particularly in low-income countries

Example of a Malignant Tumor: Cervical Cancer

  • Cervical cancer develops through several stages from pre-cancerous lesions (CIN1, CIN2, CIN3) to invasive carcinoma
  • Invasive carcinoma spreads to surrounding tissues and distant organs
  • Risk factors include HPV infection and lifestyle choices

The Pap Smear Technique

  • Collection of cervical cells for screening for precancerous and cancerous changes
  • Early detection is crucial in reducing cervical cancer incidence and mortality.

Cancer - Genetic mutations

  • Genetic mutations play a role in the initiation and progression of cancers

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

DNA Tumor Viruses – Ogris PDF

Description

Explore DNA tumor viruses, tyrosine phosphorylation, and the role of p53 in cancer. Understand cancer prevention through risk factor modification, avoiding carcinogens, vaccination, and lifestyle changes. Learn about maintaining genetic stability.

More Like This

Tumour Viruses and Carcinogenesis
41 questions

Tumour Viruses and Carcinogenesis

NoiselessSunflower avatar
NoiselessSunflower
Tumor Antigens and Mutated Genes Quiz
10 questions

Tumor Antigens and Mutated Genes Quiz

InstrumentalCosmos avatar
InstrumentalCosmos
Oncogenesis and Viral Proteins
81 questions

Oncogenesis and Viral Proteins

LawAbidingGreatWallOfChina avatar
LawAbidingGreatWallOfChina
Tumor Imaging Techniques Quiz
121 questions

Tumor Imaging Techniques Quiz

SweepingSapphire avatar
SweepingSapphire
Use Quizgecko on...
Browser
Open
Browser
Browser