Unit III: Concepts of abnormal cellular proliferation and differentiation

What is neoplasia?

• New growth” (abnormal cell growth)

• Cancer is a disorder of altered cell differentiation, and growth

• Growth is uncoordinated and autonomous 

• No regulatory control over cell growth and division 

• Proliferation: process of cell division 

• Differentiation: process by which cells become increasingly more specialized with each mitosis division (example: WBC differentiation)

What is a disorder of altered cell differentiation and growth. This
results in a process called neoplasia, which technically means “new growth.

cancer

What is the process of cell division?

proliferation

What is the process by which cells become increasingly more specialized with each mitosis division (example: WBC differentiation)?

differentiation

Normal Cell Cycle – A&P Review

• orderly sequence of events as a cell duplicates and divides

• Genetic information is duplicated. Duplicated genetic information is distributed to

• genetically identical new cells.

  • Phases of the Cell Cycle:

    • i. Synthesis & mitosis

    • ii. Gaps 1 & 2

    • iii. Gap 0

• d. Cyclins, Cyclin-dependent kinases (CDKs), and CDK Inhibitors (CKIs):

  • i. Cyclins, CDKs, and CKIs all regulate and “check” DNA replication.
    Important process for regulating cell cycle checkpoints where DNA
    replication mistakes can be repaired

What is the …

• Process of cell division 

• Increase in number of cells by mitotic cell division 

• Normal cellular proliferation is regulated

  • Number of new cells being created = number of cells being lost

cell proliferation

During cellular proliferation the rate of cell production may be…

increased when tissue is injured or lost.

• (Example: Bleeding stimulates the reproduction of blood-forming cells in the bone marrow)

What is being described here?

• Cells become increasingly more specialized

• Result is a fully mature adult cell with its own special functions and characteristics 

• Regulated by internal and extrernal factors 

  • I: genetics (internal)

  • II: neighboring cells 

  • III: exposure to substances 

  • IV: growth factors 

  • v: cytokines

  • VI: oxygen and nutrients 

cell differentiation

Benign and malignant neoplasms

• Tumor: Swelling that could be caused by multiple conditions.

  • i. Terms tumor and neoplasm are sometimes used interchangeably

  • ii. Usually named by adding the suffix -oma to the parenchymal tissue type where the growth originated

What is a tumor with..

• Cell characteristics: well-differentiated cells resembling the tissue of origin

• Growth rate: progressive, and slow rate of growth. Neoplasm may stop or regress

• How they grow: encapsulated and not invading the surrounding tissue. Grow by expansion. Line of demarcation. Cells keep proliferating, but they have normal differentiation. Round borders 

• Metastasis (spreading): nope

• Cause harm or death: unusual unless the location interfere with vital functions

begign neoplasm

What is a tumor with…

• Cell characteristics: undifferentiated cells. Cells with anaplasia. Cells with end atypical structure and little resemblance to the tissue of origin (cells don’t look normal)

• Growth rate: variable - depends on differentiation. More undifferentiated cells= more rapid rate of growth

• How they grow: invades surrounding tissues. Grows by invasion.  (Reach out and invade surprising tissues, look like they have little tentacles)

• Metastasis: Yes! May “break loose” by entering the circulatory or lymphatic system, spreading to other sites

• Cause harm or death: more likely to cause death due to invasion and destruction of tissue, more difficult to treat

malignant neoplasm

Cancer cells are characterized by two main features, what are they?

Rapid Proliferation and Loss of Differentiation

Cancer cell characteristics:

• genetic instability

• growth factor independence

• loss of cell density

• anchorage independence

• faulty cell-to cell communication

• life span

• antigen expression

• production of enzymes, hormones, and other substances

• cytoskeleton changes

What is the:

• Loss of cell differentiation in cancerous tissue; Cancer cells are often graded on how much they resemble comparable, normal tissue. The closer the cancer cells look to normal cells

  • the lower the grade. Graded I – IV.

anaplasia

What is the hallmark of cancer cells?

• genetic instability

  • DNA is unstable

  • mutations

What is growth factor independence?

Cancer cell characteristic; unlike normal cells, cancer cells can grow without growth factor hormones

• Normal cells cannot grow without growth factor
  hormones

Loss of cell density-dependent inhibition

Cancer cell characteristic; loss of normal cessation(end/stop) of growth once cells reach a certain density

• continue to invade

Anchorage independence:

Cancer cell characteristic; cancer cells can grow without being attached to neighboring cells, unlike normal cells which die when detached

• Normal cells need to be attached to neighboring cells in order to grow.

Cancer cells have fautly…

cell to cell communication

Cancer cell life span

• Cancer cells may divide an infinite number of times

  • can live forever

• Normal cells divide only a certain number of times.

Cancer cell antigen expression:

Express surface cell molecules that are immunologically
identified as foreign.

Cancer cell production of Enzymes, Hormones, and other Substances

can cause conditions because they produce these

Cancer cells cytoskeletal changes

Facilitate metastasis(spreading)

What is metastasis?

• Spread of cancer cells through blood or lymph pathways to invade other tissues/organs; characteristic of malignant tumors

• Characteristic of malignant tumors

• Metastatic tumors frequently retain many characteristics of the primary tumor

What are some risk factors for cancer development?

genetics and enviroment risk factors both play a role

• Genetics/Heredity, gene mutations can lead to cancer

  • b. Hormones, too much or too little can lead to cancer

  • c. Impaired Immunologic Function

  • d. Chemical carcinogens

  • e. Radiation exposure (ex: the sun)

  • f. Certain viruses (Oncogenic Viruses)

General manifestations of cancer depend on…

the area of involvement. (Ex: Lung cancer = respiratory
symptoms)

Systemic manefestations of cancer:

• anorexia(loss of apetite) and/or cachexia(wasted apperance)

• fatigue(tired) and sleep disorders

• anemia (low RBC count)

What is cachexia?

Systemic wasting syndrome (with anorexia and fatigue) associated with cancer