Neoplasia

Questions and Answers

What primarily drives clonal tumor progression in metastatic tumors?

Enhanced migratory ability

Gain of immature cell functions

Loss of growth control (correct)

Increased cell differentiation

Which of the following is NOT a characteristic of malignant cells?

Create a new biochemistry (correct)

Gain of embryonic stem cell-like phenotype

Loss of differentiation

Loss of migratory control

What occurs during the initiation stage of tumorigenesis?

Cancer stem cells acquire additional genetic changes.

Oncogenic mutations occur in a cell. (correct)

Non-dividing cells are targeted by chemotherapy.

The tumor cells begin to invade surrounding tissues.

Which of the following alterations can convert a proto-oncogene into an oncogene?

Point mutations Signup and view all the answers

What role do driver genes play in tumor progression?

They contribute to tumor progression when damaged. Signup and view all the answers

How do cancer stem cells (CSCs) contribute to tumor progression?

By enhancing self-renewal and uncontrolled proliferation. Signup and view all the answers

Which of the following is an example of a driver gene mutation?

Mutated c-myc Signup and view all the answers

What is the primary difference between chemotherapy and stem cell-targeted therapy?

Stem cell-targeted therapy can target both dividing and non-dividing cancer stem cells. Signup and view all the answers

Which statement accurately describes the second hit in the transformation from pre-cancer stem cells to cancer stem cells?

It involves additional genetic and epigenetic changes. Signup and view all the answers

What is a common epigenetic factor contributing to oral cancer?

Chronic inflammation Signup and view all the answers

What characteristic is common to pre-cancer stem cells (pre-CSC)?

They possess features of both cancer and normal stem cells. Signup and view all the answers

Which type of gene is typically associated with inhibiting tumor growth?

Tumor suppressor genes Signup and view all the answers

What role do promoters play in cancer progression?

They facilitate the malignant expansion of abnormal cells. Signup and view all the answers

Which cells have the potential to gain functions not normally present in healthy cells during tumorigenesis?

Malignant tumor cells Signup and view all the answers

What is the major risk associated with non-dividing cells in the context of chemotherapy?

They often lead to treatment resistance and relapse. Signup and view all the answers

What defines the progression stage of tumorigenesis?

The acquisition of invasive and metastatic characteristics. Signup and view all the answers

Study Notes

Neoplasia - Formation and Progression

Stem cell theory involves two key mutations:
- First hit transforms normal stem cells into pre-cancer stem cells (non-cancerous, due to genetic mutation).
- Second hit converts pre-cancer cells into cancer stem cells (CSC), leading to tumor genesis (due to genetic and epigenetic factors).

Tumorigenesis Stages

Initiation: Oncogenic mutation occurs in a single cell.
Promotion: Mutated cells gain clonal advantages, allowing expansion and accumulation of additional genetic and epigenetic changes, increasing chances of more genetic errors.
Progression: Tumor advances to increasingly malignant phenotypes.
Invasion: Tumor cells develop the ability to penetrate surrounding tissues.

Chemotherapy vs Stem Cell-Targeted Therapy

Chemotherapy targets only dividing cells, allowing non-dividing cells to survive and potentially cause relapse.
Stem cell-targeted therapy focuses on all cancer stem cells, encompassing both dividing and non-dividing cells.

Detailed Mechanisms in Initiation and Promotion

Initiation involves accumulated genetic mutations that enhance self-renewal of normal stem cells, characteristic of stem cells.
Quiescent stem cells are more prone to accumulating genetic errors.
Transformation from pre-cancer stem cells (pre-CSC) to CSC occurs after additional genetic/epigenetic changes.
Promoters disrupt differentiation, leading to the malignant proliferation of abnormal cells.

Tumor Progression Characteristics

CSCs significantly drive tumor progression, promoting uncontrolled growth and contributing to invasive/metastatic phenotypes.
Metastatic tumors undergo further clonal progression, becoming more aggressive.
Tumor progression is characterized by:
- Loss of growth control (leading to clonal growth).
- Loss of differentiation (de-differentiation, preventing maturation into functional cells).
- Loss of migratory control, enabling invasion/metastasis.
Malignant cells may lose healthy cell functions or gain abnormal functions.

Oral Cancer: Genetic and Epigenetic Disease

Caused by genetic mutations and epigenetic changes affecting stem cell growth and multiplication.
Genetic causes: Mutagenic chemicals, UV exposure, viral infections (HPV, EBV), smoking, alcohol use.
Epigenetic causes: Chronic inflammation (e.g., gum disease) and aging.

Driver Genes vs Passenger Genes

Driver Genes: Certain altered genes facilitate tumor progression (e.g., mutated p53 loses tumor suppressor function).
Passenger Genes: Majority of mutations do not contribute to tumor progression.

Classes of Genes Affected in Tumorigenesis

Proto-oncogenes: Encode proteins regulating cell growth; mutations can activate them to oncogenes via point mutations, insertions, deletions, or chromosomal translocations.
Oncogenes: Transcribe oncoproteins that stimulate tumor growth; include:
- Signal transduction (e.g., Wnt/β-catenin),
- Growth factors (e.g., SCF, EGF, PDGF, TNF-α),
- Transcription factors (e.g., c-myc, c-jun, c-fos),
- Cell cycle regulators (e.g., mutant p53).
Tumor Suppressor Genes: Wild type p53 typically inhibits tumor growth, while mutations can lead to tumor progression.

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Description

Explore the concepts of neoplasia, tumorigenesis, and stem cell theory of cancer through this quiz. Understand the differences between normal stem cells, pre-cancer stem cells, and cancer stem cells, along with their roles in tumor initiation and promotion. Test your knowledge on the genetic and epigenetic factors involved in cancer development.