Lecture 2a: Characteristics of Cancer Cells Flashcards
Main cause for cancer cells is _________
DNA Damage
Sporadic Cancer
Cancer occurring without a specific cause (Most frequent)
Inherited Cancer
Cancer, usually risk of cancer, passed down (Least frequent)
________ is a critical factor in cancer development and progression. Is prevalent in many human cancer types.
Unrepaired DNA Damage/Inefficient DNA damage repair (DDR)
Agents that can cause DNA Damage and cancer
-Inherited (Hereditary)
-Carcinogens (UV Radiation or Chemicals)
-Oncogenic Viruses (HPV)
-Lifestyle (Smoking)
-Abnormal Cell Division
Normal cells + Mutations
Cancer-initiating cells
Stem cell + Mutation
Cancer Stem Cells (CSC)
Normal cells become cancerous after mutations accumulate in the genes that control ____________ and ___________.
Cellular Proliferation and Cell Cycle
DNA copying errors: Random, unpredictable DNA “Mistakes account for __________% of mutations in cancers.
Over 60%
It is estimated that approximately _________% of cancers can be prevented if people avoided these risk factors.
40%
Cancer Stem Cells (Defintion)
Rare immortal cells within a tumor that can both self-renew by dividing and give rise to many cell types that constitute the tumor and can therefore form tumors.
Clonal Evolution in Cancer (Definition)
All tumor cells derive from one cancer cell “A” through the process of clonal expansion, genetic diversification, and clonal selection
Explanation: If a tumor is found to have neoplastic cells of both A and B types.
It must have had a multicellular origin.
Neoplasia
Clonal disease that begins as one regenerative cell and leads to genetic derivatives.
Monoclonal tumors
Only a single cell is transformed from normal to cancerous behavior to become the ancestor of the cells in a tumor.
Polyclonal tumors
Multiple cells cross over the border from normalcy to malignancy to become the ancestors of several genetically distinct subpopulations of cells within a tumor mass.
Characteristic “Signature”
Distinguishing feature of the affected cell from the surrounding population of karyotypically normal cells (Translocation)
How to find see if cancer cells have a common progenitor
The same identical translocation will be present in all cancer cells within an arising tumor.
B16 mouse melanoma (2 weeks following injection in tail vein)
B16 cells are trapped in the lung and grow into metastasis causing easy recognition due to its dark color.
Liver metastasis from intestine
Portal vein that drains blood from the colon into the liver provides a route for metastasizing colon cancer cells to migrate directly to the liver.
Morphological differences in normal cancer cells
-Large cytoplasm
-Single nucleus
-Single nucleolus
-Fine chromatin
Breast cancer if left untreated often mestasizes to the ________
Brain
Morphological differences in cancer cells
-Small cytoplasm
-Multiple nuclei
-Multiple and large nucleolus
-Coarse chromatin
Characteristics of normal (Benign) cells
-Nuclear variation in size and shape is minimal
-Diploid
-Low mitotic count (normal mitosis)
-Retention of specialization
-Structural differentiation retained
-Organized
Functional differentiation usually.
Characteristics of Cancer (Malignant) Cells
-Nuclear variation in size and shape minimal to marked, often variable
-Range of ploidy
- Low to high mitotic count, abnormal mitosis
-Loss of specialization
-Structural differentiation shows wide range of changes
-Not organized
-Functional differentiation often lost
Loss of contact inhibition
An important mechanism to local invasion and metastasis
Dedifferentiation
Reversal of differentiated cell to the phenotype of a less differentiated cell, such as its precursor.
(Cancer cells lose characteristics of a well specialized cells and tissue becoming primitive, unspecialized cells.)
Dedifferentiation toward embryonic-like stemness
One critical aspect of the changes that occur as benign lesions transition to malignant ones is the progressive acquisition of the undifferentiated state through reactivation of key classic stem cell signaling pathways.
Notable classic stem cell signaling pathways
Oct4, Sox2, Wnt, and Notch
Telomere activation for telomeres maintenance
Critical for the development of replicative immortality. Cancer cells maintain the telomere length by telomerase reactivation for stabilizing telomere length.
Benign Tumor
-Limited destructiveness
-Grows slow and has distinct borders
-Does not invade other organs
Malignant
-Eventually kill the most
-Can grow fats and have irregular borders
-Can spread to other organs (Metastasize)
Keyword: Tumor
Permanent circumscribed morbid swelling consisting of a new growth of tissue, without inflammation.
Keyword: Neoplasm
A new and abnormal growth of tissue in the body one resulting from uncontrolled proliferation of cells of a benign or malignant tumor
Keyword: Malignant
Potentially fatal: having the property of uncontrolled growth, with loss of differentiation, invasion and destruction of local tissue, and often metastasis to distant sites
Keyword: Cancer
A malignant growth or tumor in different parts of the body that tends to spread indefinitely and to reproduce itself, as also to return after removal
Adenoma
Pre-invasive growth, a tumor that is not cancer. Has yet to penetrate the basement membrane.
