Cell Cycle and Tumor Biology Quiz

Cancer Biology

• Cancer is a genetic disease, caused by uncontrolled cell division in a part of the body.
• Cancer cells tend to cause death and deterioration.
• They are invasive, metastasize, and can terminate a malignant tumor.
• Changes in DNA sequence of key genes (cancer genes) cause abnormal behavior of cancer cells.
• Biopsy is the only way to confirm uncontrolled cell division.
• KI 67 is a marker of cell division.

Hallmarks of Cancer

• Self-sufficiency in growth signals
• Insensitivity to antigrowth signals
• Evading apoptosis
• Limitless replicative potential
• Sustained angiogenesis (formation of new blood vessels)
• Tissue invasion and metastasis

Cancer Cells

• Cancer cells arise from single cells.
• Their genomes are altered.
• They lose contact inhibition.
• They are usually clonal in origin (replicated clones).

Normal vs. Cancer Cells

• Normal cells exhibit contact inhibition, while cancer cells do not.
• Normal cells have large cytoplasm, single nucleus, and fine chromatin.
• Cancerous cells have multiple nuclei, coarse chromatin, and small cytoplasm.

Tumour Cell Biological Markers

• Substances produced by cancer cells or found on plasma cell membranes, in blood, CSF, or urine.
• These include hormones, enzymes, genes, antigens and antibodies.

Neoplasia

• Any abnormal new growth of cells.
• Increased number of cells in one area describes hyperplasia.
• Increased size of cells describes hypertrophy.
• Disordered proliferation of cells, and changed cell form is called dysplastic.

In Situ Cancer

• Cancer-looking cells are present in the original site, but no spread to nearby tissue.
• These cells may become cancerous and spread into nearby tissue eventually.

Benign Tumors

• Benign tumor cells grow locally and cannot spread by invasion or metastasis.

Malignant Tumors

• Cancer cells invade surrounding tissues.
• They enter blood vessels and become metastasized.
• Primary tumor development is linear, arising from a single dominant clone.
• Parallel tumor development occurs with multiple groups of cancer cells that arise simultaneously.

Clonal Selection

• A change from identical cells can become a tumor.
• One cell, with a characteristic, is selected and copied many times, replacing the original population.
• When a cell trait is replicated enough, it can become the dominant cell/trait.

Invasion

• Tumour invasion involves steps including cellular multiplication.
• Altered mitotic rate, lytic enzymes release, and decreased cell-cell adhesion increase mobility in tumour cells.
• Intravasation and extravasation processes allow entry and exit from blood vessels.

Benign Colonic Neoplasms

• Tubular adenomas and villous adenomas are precancerous polyps.
• About 15-25% of villous adenomas and 10% of tubular adenomas become cancerous.
• Hyperplastic polyps are located in the colon rectum and sigmoid colon.
• Dysplastic polyps display abnormal cell characteristics.

Essential TNM

• A registry tool to reduce errors in cancer staging.
• Metastasis is checked for using M status (M0 or M1) and determined
• Tumor size (T status) is checked
• Lymph node involvement is checked (N status)

Oncogenes, Protooncogenes, Tumor Suppressor Genes

• Mutations in oncogenes increase the frequency of cancer.
• Protooncogenes can become oncogenes.
• Tumor suppressor genes usually suppress tumors.

p53

• Master regulator of cell cycle.
• Regulates DNA replication and repair.

Germline and Somatic Mutations

• Germline mutations can be inherited from parents.
• Somatic mutations are present in all body cells, except reproductive cells.

DNA Damage Repair Mechanisms

• Base excision repair, mismatch repair, and nucleotide excision repair.

Chromosomal Mutations

• Rearrangements include inversions and translocations; deletions, insertions, and duplications and substitutions; aneuploidy; and polyploidy.

Aneuploidy

• Irregular number of chromosomes.

Mutagens, Carcinogens, Clastogens, Teratogens

• Mutagens cause mutations.
• Carcinogens cause cancer.
• Clastogens produce chromosome breaks.
• Teratogens cause congenital malformations.

Cell Cycle

• A series of events that occur in a cell as it grows and divides.

Checkpoints

• Control points in the cell cycle to ensure DNA replication and cell division proceed accurately.

Cyclins and CDKs

• Cyclins are proteins that regulate CDKs (cyclin-dependent kinases) which are involved in regulating the cell cycle.
• Phosphorylation activates proteins, thus enabling cell cycle progression.

Apoptosis

• Regulated cell death (and sometimes an unregulated process), with mechanisms that destroy cells.

Intrinsick and Extrinsic Pathways to Apoptosis

• Intrinsic - signals that trigger programmed cell death from inside the cell.
• Extrinsic - signals outside of the cell trigger programmed cell death.

Cancer Cells and Membrane Flipping

• Tumor Cells are often associated with membrane flipping.