CHARACTERISTICS OF CANCER CELLS - PRELIMS

topic: CHARACTERISTICS OF CANCER CELLS, TUMOR GROWTH, 7 FUNDAMENTAL CHANGES IN CELL PHYSIOLOGY THAT DETERMINE MALIGNANT CELL GROWTH

Answer

Question

The process by which cells become more specialized and acquire specific structural and functional characteristics as they mature.

What is cell differentiation in normal growth?

Altered differentiation occurs due to changes in appearance, metabolism, tumor-specific antigens, and loss of normal function.

What happens to differentiation when a normal cell becomes malignant?

Variation in cell sizes and shapes.

What is pleomorphism in cancer cells?

Abnormal arrangements of chromosomes.

What is aneuploidy?

The extent to which cancer cells resemble normal cells.

What does differentiation mean in cancer?

Cells that appear more mature and closely resemble normal cells.

What are well-differentiated cancer cells?

They may produce surface enzymes that aid invasion and metastasis.

How do cell membrane changes affect cancer metabolism?

Causes loss of cell-to-cell adhesion and increases cell mobility.

How does loss of glycoproteins affect cancer cells?

Because they have higher rates of anaerobic glycolysis.

Why are cancer cells less dependent on oxygen?

They may independently signal cells to grow and increase sensitivity to normal growth factors.

What role do abnormal growth factor receptors play in cancer?

Signs and symptoms caused by inappropriate secretion of hormones by cancer cells in tissues that don’t normally produce them.

What are paraneoplastic syndromes?

Small cell carcinoma of the lung producing ADH, leading to hyponatremia.

Give an example of a paraneoplastic syndrome.

Excess or new antigens produced by tumors that mark cells as non self

What are tumor-specific antigens?

Prostate-specific antigen (PSA).

Example of a tumor-specific antigen?

Possible prostate cancer.

What does elevated PSA indicate?

As tumor markers for diagnosis and monitoring treatment effectiveness.

How can tumor antigens be used clinically?

The need for cell renewal or replacement.

What normally stimulates cell proliferation?

Cell production stops, maintaining a balance between production and loss.

What happens to normal cell proliferation after the stimulus ends?

Myocardium, neurons, and cartilage.

In which tissues does cellular proliferation not occur?

It continues uncontrolled even after the stimulus ends.

How does cancer cell proliferation differ from normal?

Normal cells stop dividing when they come into contact with others.

What is contact inhibition?

They lack/decrease it, continuing to divide and piling up on each other.

How do cancer cells behave with contact inhibition?

Due to abnormal chromosome arrangements and chromosomal instability.

Why are cancer cells genetically unstable?

New malignant mutants resistant to therapy.

What does chromosomal instability in cancer cause?

Spread of cancer cells from a primary site to distant secondary sites.

What is metastasis?

Enzymes on their surface aiding invasion.

What helps cancer cells metastasize?

Duration of the cell cycle, number of actively dividing cells, and cell loss.

What 3 factors affect tissue growth rate?

Coordinated events leading to DNA duplication and cell division.

What is the cell cycle?

G1, S, G2, M.

What are the 4 main phases of the cell cycle?

RNA and protein synthesis in preparation for DNA replication.

What happens in G1 phase?

Hours to days or longer.

How long does G1 last?

DNA replication.

What happens in S phase?

10 to 20 hours.

How long does S phase last?

DNA synthesis stops, RNA and protein synthesis continue.

What happens in G2 phase?

2 to 10 hours.

Duration of G2 phase?

Cell division (mitosis).

What happens in M phase?

30 to 60 minutes.

How long does M phase last?

Prophase, prometaphase, metaphase, anaphase, telophase.

What are the 5 stages of mitosis?

Daughter cells enter G1 or resting phase (G0).

What happens after mitosis?

Resting phase where cells perform normal functions but do not proliferate.

What is G0 phase?

Yes, when stimulated for renewal.

Can G0 cells re-enter the cycle?

Time required for a cell to go from one mitosis to the next (M+G1+S+G2).

What is cell cycle time?

No, that is a misconception.

Do cancer cells always proliferate faster than normal?

Time for a tumor to double its volume.

What is doubling time?

About 2 months.

Average doubling time of primary solid tumors?

Testicular cancer (doubles monthly).

Example of a rapidly growing tumor?

About 10 years.

How long can it take for a tumor to reach 1 cm?

About 1 year.

How fast can a 1 cm tumor grow to 8 cm?

Cell cycle, growth fraction, cell loss, differentiation, metastasis.

What factors affect doubling time?

Ratio of dividing cells to total tumor cells.

What is growth fraction?

Larger growth fraction = faster tumor growth.

Why is growth fraction important?

They have abnormal regulation of appearance, protein expression, growth, reproduction, and death.

How do cancer cells differ in molecular pathogenesis?

(1) Self-sufficiency in growth signals (2) Insensitivity to growth-inhibitory signals (3) Evasion of apoptosis (4) Defects in DNA repair (5) Limitless replication potential (6) Sustained angiogenesis (7) Ability to invade & metastasize.

What are the 7 fundamental changes in cell physiology of cancer?

Oncogene activation.

What causes self-sufficiency in growth signals?

Normal genes regulating cell growth and repair.

What are proto-oncogenes?

Altered proto-oncogenes promoting autonomous cancer growth.

What are oncogenes?

Act as brakes, inhibiting cell growth and regulating apoptosis.

What role do tumor suppressor genes play?

Failure to inhibit tumor growth.

What happens when tumor suppressor genes are altered?

Categories of tumor suppressor genes.

What are gatekeepers and caretakers in tumor suppressor genes?

Mutations in apoptosis-regulating genes.

How do cancer cells evade apoptosis?

Normal cells repair DNA damage from environment or replication errors.

Why is DNA repair important?

Increased mutation and cancer risk.

What happens if DNA repair is defective?

Chromosome end structures that shorten with each cell division.

What are telomeres?

Proliferation stops or apoptosis occurs.

What happens when telomeres shorten too much?

By producing angiogenic factors like VEGF.

How do tumors achieve sustained angiogenesis?

To invade and metastasize.

What is the hallmark ability of malignant tumors?

Tumor cells break away, enter blood/lymph, and form distant tumors.

How does metastasis occur?