Molecular and Cellular Basis of Cancer

Questions and Answers

What are the primary risk factors that can lead to the development of cancer?

Risk factors include genetic predisposition, environmental exposures such as carcinogens, lifestyle choices like smoking, and infections.

How do cancer cells differ from normal cells in terms of growth regulation?

Cancer cells ignore growth signals, bypass growth suppressors, and can proliferate indefinitely, unlike normal cells which are regulated by feedback mechanisms.

List three common characteristics of cancer cells.

Common characteristics include sustained proliferative signaling, evasion of growth suppressors, and resistance to cell death.

Why is understanding tumor heterogeneity important in cancer research?

Tumor heterogeneity complicates treatment strategies and affects patient prognosis, as different tumor cells may respond differently to therapies. Signup and view all the answers

Explain the central dogma of molecular biology concerning cancer.

The central dogma illustrates that DNA is transcribed to mRNA, which is then translated into protein; mutations at any of these stages can lead to cancer cell formation. Signup and view all the answers

What role do oncogenes play in cancer development?

Oncogenes promote cell growth and division, often through mutations or overexpression, leading to uncontrolled proliferation and tumor development. Signup and view all the answers

Describe the function of tumor suppressor genes and provide an example.

Tumor suppressor genes regulate cell division and promote apoptosis; an example is the p53 gene, which acts as a checkpoint to prevent damaged DNA from replicating. Signup and view all the answers

How do epigenetic changes contribute to cancer?

Epigenetic changes, such as DNA methylation and histone modifications, can silence tumor suppressor genes or activate oncogenes, thus contributing to cancer progression. Signup and view all the answers

What are the primary differences between benign and malignant tumors?

Benign tumors do not invade surrounding tissues and do not spread to other parts of the body, while malignant tumors are cancerous and can invade tissues and metastasize. Signup and view all the answers

Identify two genetic factors that can contribute to the development of cancer.

Genetic susceptibility and epigenetic alterations are two genetic factors that can contribute to cancer development. Signup and view all the answers

List three lifestyle factors that can increase the risk of developing cancer.

Smoking, alcohol consumption, and physical inactivity can increase the risk of developing cancer. Signup and view all the answers

Explain the term 'tumour heterogeneity' and its significance in cancer treatment.

Tumour heterogeneity refers to the differences among cancer cells within the same tumor, making some cells more resistant to treatment, which complicates effective management. Signup and view all the answers

What role do environmental factors play in cancer risk?

Environmental factors such as sunlight, radiation, and pollution can increase cancer risk and are often preventable. Signup and view all the answers

Differentiate between carcinoma and sarcoma.

Carcinoma originates from epithelial tissues, while sarcoma develops from connective tissues such as bones and muscles. Signup and view all the answers

How can viral infections contribute to cancer, and provide an example?

Viral infections can alter cell function leading to cancer, with HPV causing genital tumors and hepatitis B linked to hepatocellular carcinoma. Signup and view all the answers

Describe the characteristics of cancer cells compared to normal cells.

Cancer cells never stop growing and dividing, becoming immortal, whereas normal cells grow, divide, and die in a regulated manner. Signup and view all the answers

Study Notes

Cancer Overview

Uncontrolled cell growth leads to invasion of surrounding tissues and metastasis.
Tumors are categorized as benign (non-cancerous, such as moles) or malignant (cancerous, capable of spreading).
Approximately 10% of cancers are inherited, while the rest are acquired.
Recurrence of cancer is common after treatment.

Cancer Classifications

CSMLLM: Carcinoma, Sarcoma, Myeloma, Leukaemia, Lymphoma, Mixed types.
- Carcinoma: Originates from epithelial cells; common types include colon adenocarcinoma and squamous cell carcinoma.
- Sarcoma: Develops in connective tissues like bones, tendons, and muscles; includes gliomas.
- Myeloma: Arises in bone marrow from plasma cells.
- Leukaemia: Cancer affecting blood cells, such as myeloid leukaemia.
- Lymphoma: Cancer of lymphatic glands or nodes.
- Mixed Types: Include adenosquamous carcinoma and teratocarcinoma.

Cancer Risk Factors

Biomedical Factors: Non-preventable risks such as genetic susceptibility, hormonal factors (e.g., breast and ovarian cancer), age, ethnicity (nasopharyngeal carcinoma more prevalent in Asians), and gender.
Lifestyle Factors: Preventable risks include smoking, alcohol consumption, physical inactivity leading to obesity, chronic infections (e.g., HPV for cervical cancer), and diet (high red meat intake linked to prostate cancer).
Environmental Factors: Preventable influences include excessive sunlight, radiation exposure, occupational hazards, and pollution.

Differences Between Normal and Cancer Cells

Normal Cells: Grow, divide, and undergo programmed cell death.
Cancer Cells: Characterized by uncontrolled proliferation, immortality, and invasion disrupting normal bodily functions.

Molecular and Cellular Basis of Cancer

Cancer arises from molecular and cellular abnormalities leading to errors in the cell cycle.
Genetic and epigenetic alterations, such as RNA changes, result in tumor initiation and progression.
Cancer is heterogenous, with varying characteristics among tumors, complicating treatment.

Hallmarks of Cancer

Sustaining Proliferative Signaling: Oncogenes promote increased cell growth; influenced by growth factors like EGF, HER2, RAS, and transcription factors (e.g., MYC).
Evading Growth Suppressors: Loss of function in tumor suppressor genes (e.g., p53, retinoblastoma) allows uncontrolled cell division.
Resisting Cell Death: Cancer cells often express anti-apoptotic proteins (e.g., BCL2) and lose p53 function, evading programmed cell death.

Central Dogma of Biology

DNA encodes instructions (cookbook analogy) that are transcribed into mRNA (recipe) and translated into proteins (product).
Mutations in DNA or RNA alter the protein expression, potentially leading to cancer.

Genetic and Epigenetic Alterations

Point Mutations: Lead to cancer via various mechanisms including nonsense and missense mutations.
RNA Alterations: Include changes in coding RNA (alternative splicing), epigenetic alterations (DNA methylation), and non-coding RNA, such as long non-coding and circular RNAs impacting regulation.

Understanding Tumor Heterogeneity

Tumor diversity leads to varying resistance to treatments, necessitating a comprehensive approach to targeting cancer cells.

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Description

Explore the critical risk factors that contribute to cancer development and the fundamental differences between normal and cancer cells. This quiz delves into the characteristics of cancer cells and the significance of tumor heterogeneity in understanding cancer's molecular and cellular origins.