Carcinogenesis: Molecular Mechanisms and Pathology

Introduction

Carcinogenesis, or the process of cancer development, is a complex interplay of genetic and environmental factors leading to uncontrolled cell growth. Understanding its molecular mechanisms is crucial for advancements in cancer prevention and treatment.

Molecular Mechanisms of Carcinogenesis

Genetic Mutations

Cancer arises due to mutations in proto-oncogenes, tumor suppressor genes, and DNA repair genes.

• Proto-oncogenes: Gain-of-function mutations in genes such as RAS or MYC lead to oncogenic transformation.
• Tumor suppressor genes: Loss-of-function mutations in genes like TP53 and RB1 remove regulatory checks on the cell cycle.
• DNA repair defects: Mutations in genes such as BRCA1 and BRCA2 increase genomic instability.

Epigenetic Modifications

Changes in DNA methylation, histone modifications, and microRNA expression impact gene regulation and promote tumorigenesis.

Oncogenic Signaling Pathways

Dysregulation of pathways such as Wnt, PI3K/AKT, and MAPK promotes proliferation and survival of cancer cells.

Environmental and Lifestyle Factors

Carcinogenesis is influenced by external factors such as:

• Chemical carcinogens (e.g., tobacco smoke, aflatoxins)
• Radiation exposure (UV and ionizing radiation)
• Chronic inflammation (e.g., H. pylori and hepatitis infections)

Conclusion

Understanding the molecular basis of carcinogenesis provides insights into therapeutic interventions, paving the way for targeted cancer treatments and prevention strategies.