Normal Cells vs. Cancer Cells

Normal Cells

• Normal cells are the basic structural and functional units of the body
• They grow, divide, and die in a controlled manner
• They have specialized functions depending on the tissue or organ they belong to
• Normal cells communicate with each other to maintain tissue homeostasis
• They exhibit contact inhibition, which means they stop growing when they come into contact with other cells

Cancer Cells

• Cancer cells are cells that have undergone genetic mutations, causing them to grow and divide uncontrollably
• They can invade surrounding tissues and spread to other parts of the body (metastasis)
• Cancer cells do not have specialized functions and do not contribute to tissue homeostasis
• They do not respond to normal growth signals or signals to stop growing
• Cancer cells evade apoptosis (programmed cell death) and continue to proliferate
• Due to rapid proliferation, cancer cells require a lot of nutrients and oxygen
• Angiogenesis, the formation of new blood vessels, helps supply nutrients to cancer cells
• The tumor microenvironment consists of cancer cells along with nearby blood vessels, immune cells, fibroblasts, and signaling molecules

Genetic Mutations

• Mutations in genes that control cell growth, division, and DNA repair can lead to cancer
• Proto-oncogenes are genes that promote cell growth, and when mutated, they become oncogenes, which can cause cells to grow excessively
• Tumor suppressor genes normally inhibit cell growth and division, and when mutated, they lose their function, allowing cells to grow uncontrollably
• DNA repair genes correct errors that occur during DNA replication, and when mutated, they can lead to an accumulation of mutations, increasing the risk of cancer

Differences in Growth

• Normal cells grow in response to signals from other cells and stop growing when they receive signals to stop
• Their growth is tightly regulated to maintain a balance between cell division and cell death
• Cancer cells grow uncontrollably, regardless of signals from other cells
• They can divide indefinitely and form tumors, which are masses of abnormal cells

Differences in Differentiation

• Normal cells differentiate into specialized cell types with unique functions
• This differentiation is tightly controlled and is essential for tissue and organ development
• Cancer cells often lose their ability to differentiate and remain in an immature state
• This lack of differentiation can contribute to uncontrolled growth and invasion

Differences in Cell Signaling

• Normal cells communicate with each other through cell signaling pathways
• These pathways regulate cell growth, division, differentiation, and apoptosis
• Cancer cells often have altered cell signaling pathways, which can lead to uncontrolled growth and evasion of apoptosis
• Some cancer cells produce their own growth factors, while others have mutations in receptor proteins that make them constitutively active

Differences in Apoptosis

• Apoptosis is a programmed cell death process that eliminates damaged or unwanted cells
• This process is essential for maintaining tissue homeostasis and preventing cancer
• Cancer cells often evade apoptosis by inactivating genes involved in the apoptotic pathway or by activating genes that inhibit apoptosis
• Resistance to apoptosis allows cancer cells to survive and proliferate even when they are damaged or exposed to harmful conditions

Differences in Metabolism

• Normal cells have a defined metabolic pathway that converts nutrients into energy
• Cancer cells often have altered metabolic pathways that allow them to grow and divide rapidly
• They exhibit aerobic glycolysis, also known as the Warburg effect, where they prefer to use glycolysis even in the presence of oxygen
• This allows them to produce energy and building blocks for cell growth more efficiently

Differences in Angiogenesis

• Angiogenesis is the formation of new blood vessels from pre-existing vessels
• It is essential for normal tissue growth and repair
• Cancer cells produce growth factors that stimulate angiogenesis, allowing them to form new blood vessels to supply nutrients to the tumor
• Angiogenesis also allows cancer cells to metastasize to other parts of the body

Differences in Metastasis

• Metastasis is the spread of cancer cells from the primary tumor to other parts of the body
• It is a complex process that involves several steps, including detachment from the primary tumor, invasion of surrounding tissues, entry into the bloodstream or lymphatic system, and colonization of distant sites
• Cancer cells often have mutations that allow them to detach from the primary tumor and invade surrounding tissues
• They also produce enzymes that can break down the extracellular matrix, making it easier for them to invade

Immune System Interaction

• Normal cells are monitored by the immune system, which can recognize and destroy damaged or abnormal cells
• Cancer cells can evade the immune system by suppressing immune cell activity or by expressing proteins that inhibit immune recognition
• Some cancer cells can even recruit immune cells to the tumor microenvironment to promote tumor growth and angiogenesis

Telomeres

• Telomeres are protective caps on the ends of chromosomes that shorten with each cell division
• Normal cells have a limited number of divisions before their telomeres become too short, triggering senescence or apoptosis
• Cancer cells often express telomerase, an enzyme that maintains telomere length, allowing them to divide indefinitely

Chromosomal Differences

• Normal cells have a defined number of chromosomes
• Cancer cells often have an abnormal number of chromosomes (aneuploidy) or other chromosomal abnormalities, such as translocations or deletions
• These chromosomal abnormalities can lead to mutations that drive cancer progression.