Cell Cancer

Overview of Cancer

• Cancer Definition: A genetic disease characterized by uncontrolled cell division and growth.

• Cell Ecosystem: Cancer cells arise from the collaboration of cells that organize into tissues and exhibit self-sacrificing behavior for the collective survival of multicellular organisms.

Characteristics of Cancer Cells

• Reproductive Independence:

  • Cancer cells reproduce without normal constraints on growth and division.

  • They have the ability to invade and colonize new areas of the body.

• Inheritance of Cancer:

  • Cancer can be heritable, passed from parent to offspring.

  • Familial cancers may correlate with genetic predisposition.

Formation of Tumors

• Tumor Types:

  • Benign Tumors: Non-invasive growths that do not spread to surrounding tissues.

  • Malignant Tumors: Invasive and can metastasize, forming secondary tumors in different body regions.

• Neoplasia:

  • Cancer development begins with normal cells transforming into abnormal cells that produce a new growth or primary tumor.

Mutations in Cancer Development

• Accumulation of Mutations:

  • Cancer cells undergo a series of mutations that contribute to their increasingly abnormal behavior.

  • Mutagens, or carcinogens, can create DNA damage leading to cancer.

• Clonal Origin of Tumors:

  • Tumors originate from a single cell that has acquired mutations enabling its cancerous state.

Microevolution of Cancer Cells

• Process of Tumor Evolution:

  • Cancer evolves through the survival of cells with beneficial mutations, leading to heterogeneity within the tumor.

  • Unique mutations confer advantages that allow these cells to proliferate uncontrollably.

Characteristics Contributing to Cancer Progression

• Loss of Contact Inhibition:

  • Cancer cells can grow beyond normal limits and escape regulatory mechanisms that usually prevent excessive proliferation.

• Telomere Dynamics:

  • Cancer often involves the escape from replicative senescence, allowing cells to maintain telomere length through mechanisms like telomerase activity.

Metabolic Changes in Cancer

• Altered Metabolism:

  • Cancer cells exhibit abnormal metabolic processes to support rapid growth and proliferation, enhancing raw material production.

Cellular Responses to Stress

• Cell Cycle Control:

  • Cancer cells often evade normal apoptotic pathways, allowing for survival despite damage or stress, facilitating continued growth.

Invasiveness and Metastasis

• Mechanisms of Metastasis:

  • Cancer cells can disrupt normal cellular adhesion, allowing them to invade surrounding tissues and enter circulation.

  • Not all cells survive the metastatic journey; fewer than 1 in 1000 cells typically succeed in forming secondary tumors.

Genetic Drivers of Cancer

• Oncogenes and Tumor Suppressor Genes:

  • Oncogenes: Mutated proto-oncogenes that promote uncontrolled cell proliferation.

  • Tumor Suppressor Genes: Genes that normally inhibit cell division; mutations can lead to their inactivity, promoting cancer progression.

Mechanisms of Tumorigenesis

• Mutations Leading to Cancer:

  • Can involve either gain-of-function (dominant) or loss-of-function (recessive) mutations affecting cell proliferation.

Important Oncogenic Proteins

• MAPK Pathway & Receptors:

  • Overview of signaling pathways crucial in cancer.

• Ras, p53, Rb: Key proteins involved in cell cycle regulation and apoptosis, often mutated or dysfunctional in cancer.