Cancer Cells: Morphology, Development, Types and Differences from Normal Cells

Introduction to Cancer Cells

Cancer cells are cells that undergo uncontrolled growth and division, resulting in development of abnormal tissue mass referred to as tumor.

Unlike normal cells, which follow regulated life cycle involving growth, division, and programmed cell death, cancer cells evade these processes.

Additionally, cancer cells can invade surrounding tissues and, in some cases, spread to other parts of body. Understanding characteristics and behavior of cancer cells is crucial for developing effective strategies for cancer diagnosis, treatment, and prevention.

Morphology of Cancer Cells

Nuclear Morphology

• Cancerous cells have unique features, including large nucleus with irregular shape and prominent nucleoli.
• Changes in chromatin, including heterochromatin reduction and increased nuclear membrane pores are observed.
• Other ultrastructural changes such as nucleus segmentation, invaginations, and formation of inclusions.

Mitotic Characteristics

• Cancer cells have increased number of mitoses with atypical mitosis forms, such as defects in mitotic spindle and dissymmetrical structures.

Cytoplasmic Changes

• Cytoplasm of cancer cells is scarce and undergoes notable changes including appearance of new structures.
• It is basophilic due to accumulation of ribosomal and messenger RNA.

Organelle Changes

• In cancer cells, Golgi apparatus is poorly developed, and there is reduction in volume of mitochondria as tumor develops.
• Show simplified granular endoplasmic reticulum structure with frequent fragmentation and degranulation.
• Changes in amount and structure of both granular and agranular endoplasmic reticulum are observed.

Cytoskeletal Changes

• Cytoskeletal components such as microfilaments, intermediate filaments, and microtubules appear in different proportions in tumor cells.
• Composition and arrangement can affect ability of tumor cells to move and invade surrounding tissues.

Cell Membrane Changes

• Changes in cell membrane affect tumor evolution and host responses.
• Include modified surface receptors, new molecules, and abnormal antigens that trigger immune responses.
• Cell surface shows atypical structures with highly active enzymes, contributing to malignant cell characteristics.

Metabolic Changes

• Cancer cells have abnormal energy metabolism processes.
• Show poor use of oxygen and massive use of glucose, behaving like metabolic parasites.
• Abnormal glycolysis processes in mitochondrial membranes, known as Warburg phenomenon are present.

Development of Cancer Cells

Development involves series of genetic and cellular changes including genetic mutations and disruptions in normal cell growth regulation.

• Form due to genetic mutations that may be inherited or caused by external factors such as exposure to carcinogens like smoking, radiation, viruses, and certain chemicals.

• Normal cell growth is regulated, with precise mechanisms controlling growth, division, and death.

• However, mutations can disrupt normal regulation of cell growth and division leading to formation of tumors.

• Cancerous tumors can evade normal programmed cell death mechanism called apoptosis and continue to divide further.

• Can also escape immune detection and destruction.

• Can also stimulate angiogenesis, forming new blood vessels to supply nutrients and eventually these malignant cells can invade and spread to other parts of body.

Types of Cancer Cells

Cancer cells come in various types, each originating from different parts of body.

Carcinoma

Originates in epithelial cells covering external surfaces and internal organs. It can occur in various organs like skin, lungs, breast, prostate, and colon.

Types of carcinomas include:

• Adenocarcinoma - develops in epithelial cells producing fluids or mucus, commonly found in glandular tissues like breast, colon, and prostate.
• Basal cell carcinoma - occurs in lower or basal layer of skin's epidermis.
• Squamous cell carcinoma - affects squamous epithelial cells beneath skin and lining various organs.

Sarcomas

Arise in connective tissues, including muscles, fat, blood vessels, bone, or cartilage, which are supporting tissues of body.

Examples include:

• Osteosarcoma is most common bone cancer.
• Leiomyosarcoma is tumor that occurs in smooth muscle tissue.
• Kaposi Sarcoma occurs in skin, lymph nodes, and internal organs.

Leukemia

Originates in blood-forming cells. While most cases involve cancerous transformations of white blood cells, some leukemias may originate from other types of blood cells.

• Can be classified primarily as acute or chronic leukemia affecting either myeloid or lymphoid blood cells.

Lymphoma

Blood cancer that affects lymphatic system. It affects lymph glands or other organs connected to lymphatic system.

• Hodgkin lymphoma and non-Hodgkin lymphoma (NHL) are main types.

Multiple Myeloma

• Also called plasma cell myeloma, affects plasma cells, which are immune cells producing antibodies.
• Occurs in bone marrow and forms tumors in bones.
• Also known as Kahler disease.

Cancer Cells vs Normal Cells - 7 Differences

1. Growth

• Normal cells stop dividing when specific signals indicate growth should stop.
• Cancer cells undergo uncontrolled growth. They do not respond to signals that inhibit cell division.

2. Regulatory Mechanisms

• Normal cells have well-regulated mechanisms controlling proliferation, differentiation, and survival.
• Cancer cells show abnormalities in these regulatory mechanisms, leading to uncontrolled growth.

3. Density-Dependent Inhibition

• Normal cells display density-dependent inhibition, stopping proliferation when reaching finite cell density.
• Cancer cells are insensitive to density-dependent inhibition, continuing to grow to high cell densities.

4. Immune Response

• In normal cells, immune system detects and removes damaged cells.
• Cancer cells evade immune system, escaping detection.

5. Contact Inhibition

• Normal cells inhibit further proliferation upon cell-cell contact.
• Cancer cells lack sensitivity to contact inhibition. They grow in disordered patterns even after contact with neighboring cells.

6. Angiogenesis

• Normal cells do not instruct blood vessels to grow toward them.
• Cancer cells promote angiogenesis, leading to formation of new blood vessels necessary for tumor growth and metastasis.

7. Cell Death - Apoptosis

• Normal cells undergo apoptosis in response to signals from growth factors or extracellular matrix.
• Cancer cells evade process of apoptosis, leading to prolonged survival compared to normal cells.

What is Cancer?

Cancer is group of diseases that involves uncontrolled growth of abnormal cells and in some cases spread to different parts of body.

Normally, cells follow regulated process of growth, division, and death. However, abnormal cancer cells proliferate uncontrollably, forming tumors that can be either malignant or benign.

• Malignant tumors are cancerous cells that can invade surrounding tissues and have potential to metastasize or spread to other body parts.
• Benign tumors are non-cancerous cells that cannot invade other tissues and usually do not recur after removal. Although they can be large and, in some cases, pose serious health risks, they lack capacity for invasion and metastasis as seen in cancerous tumors.

Cancer is genetic disease that can start anywhere in body and is of different types based on cells or organs of their origin.

Diagnostic process involves different screening methods, and treatment includes options such as surgery, chemotherapy, radiation, and immunotherapy.

Cancer is one of major causes of death worldwide. Advancements in early detection and treatment can positively impact patient outcomes.

Summary

Cancer cells undergo uncontrolled growth and division forming tumor mass evading regulated growth and apoptosis. Morphology shows large irregular nucleus with prominent nucleoli, heterochromatin reduction, increased nuclear pores, segmentation and inclusions, increased atypical mitoses with spindle defects, scarce basophilic cytoplasm rich in rRNA and mRNA, poorly developed Golgi, reduced mitochondria, fragmented degranulated granular and agranular endoplasmic reticulum, altered microfilaments intermediate filaments microtubules affecting invasion, modified membrane receptors abnormal antigens with active enzymes, and Warburg phenomenon with poor oxygen use and massive glucose use. Development involves inherited or carcinogen induced mutations from smoking, radiation, viruses, chemicals disrupting growth regulation, evading apoptosis and immune detection and stimulating angiogenesis for nutrient supply and metastasis. Types include carcinoma from epithelial cells including adenocarcinoma in glandular tissues, basal cell carcinoma in epidermal basal layer, squamous cell carcinoma in squamous epithelia; sarcomas in connective tissue including osteosarcoma bone, leiomyosarcoma smooth muscle, Kaposi sarcoma skin lymph nodes; leukemia from blood forming cells acute chronic myeloid lymphoid; lymphoma Hodgkin and non-Hodgkin of lymphatic system; multiple myeloma or plasma cell myeloma or Kahler disease forming bone tumors. Compared to normal cells, cancer cells lack growth inhibition, show abnormal regulatory mechanisms, lack density-dependent and contact inhibition, evade immune response, induce angiogenesis and evade apoptosis. Cancer includes malignant invasive metastatic and benign non-invasive tumors, diagnosed by screening and treated by surgery chemotherapy radiation immunotherapy.

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