Lung Cancer Causes and Mechanisms Mostly Accurate
“Chronic exposure to carcinogens such as tobacco smoke, air pollution, occupational toxins, or oncogenic mutations induces DNA damage and genomic instability, and dysregulation of key signaling pathways. These include the activation of oncogenes (e.g., EGFR, KRAS, ALK, MET) and inactivation of tumor suppressor genes like TP53 and RB1. These molecular alterations, in turn, lead to uncontrolled cellular proliferation, resistance to apoptosis, metabolic reprogramming, sustained angiogenesis, and immune evasion. The tumor microenvironment consisting of cancer-associated fibroblasts, immune cells, endothelial cells, components of the extracellular matrix, and inflammatory mediators is further linked with tumor growth through promotion of chronic inflammation, angiogenesis, epithelial–mesenchymal transition (EMT), invasion, and metastasis. The gradual reconstruction of the extracellular matrix and release of matrix metalloproteinases allow these malignant cells to infiltrate neighboring tissues and spread from these tissues via the lymphatic and hematogenous systems to distant tissues including brain, liver, bone, and adrenal glands. At the same time, tumor-related hypoxia stimulates hypoxia-inducible factors (HIFs) that potentiate vascular endothelial growth factor (VEGF)-dependent angiogenesis and metabolic adaptation, further prolonging tumor growth and promoting therapeutic resistance. All in all, these interconnected molecular, cellular, and microenvironmental mechanisms contribute to the initiation, progression, metastatic spread, and clinical heterogeneity of lung cancer.”
Summary
Chronic exposure to tobacco smoke and other carcinogens induces DNA damage that generates mutations in key oncogenes such as EGFR and KRAS and in tumor‑suppressor genes like TP53, which is well documented. The tumor microenvironment—including fibroblasts, immune cells, extracellular‑matrix remodeling, hypoxia‑induced HIF/VEGF signaling, and related angiogenic and invasive processes—drives uncontrolled growth, metastasis to organs such as brain, liver, bone and adrenal glands, and therapeutic resistance. Together, these molecular and cellular mechanisms underpin lung cancer initiation, progression and clinical heterogeneity.
Sources 54 searched
- Tobacco smoke carcinogens, DNA damage and p53 mutations in smoking-associated cancers - PubMed
The available data suggest that p53 mutations in lung cancers can be attributed to direct DNA damage from cigarette smoke carcinogens rather than to selection of pre-existing endogenous mutations.
- The role of the tumor-microenvironment in lung cancer-metastasis and its relationship to potential therapeutic targets - PubMed
This review covers the principal steps involved in tumor metastasis. The role of cell-cell interactions, ECM remodeling and autocrine/paracrine signaling interactions between tumor cells and the surrounding stroma is discussed. The mechanistic basis of lung cancer metastasis to specific organs is also described.
- DNA Damage, DNA Repair and Carcinogenicity: Tobacco Smoke versus Electronic Cigarette Aerosol - PMC
Second, based on the findings that ... processing of ECA in mice and humans are similar. Third, genes that are frequently mutated in human lung cancer, such as TP53 and RAS, are also frequently mutated in mouse lung cancer, indicating that lung carcinogenesis in humans and mice are ...
- Frequent Mutations in EGFR, KRAS and TP53 Genes in Human Lung Cancer Tumors Detected by Ion Torrent DNA Sequencing - PMC
Out of the mutations identified in our sample set, BRAF (2.6%), EGFR (42.1%), ERBB2 (1.3%), KRAS (5.3%), PIK3CA (2.6%), PTEN (1.3%), SMAD4 (1.3%), and TP53 (22.4%) incurred the highest rates of mutations ( Table 2 ).
- Kras, Egfr, and Tp53 Mutations in B6C3F1/N Mouse and F344/NTac Rat Alveolar/Bronchiolar Carcinomas Resulting from Chronic Inhalation Exposure to Cobalt Metal - PMC
Given this knowledge of gene mutations associated with human lung cancers, the objective of the study reported here was to compare mutation frequencies and spectra in alveolar bronchiolar carcinomas in CMD-exposed rats and mice to the published literature on rodent and human lung cancers. Since the lung tumors from CMD exposure are morphologically indistinguishable from those arising spontaneously, the mutation profiles may provide some information to distinguish the spontaneous lung tumors from those resulting from chemical exposure. Thus, we performed extensive mutation analysis on the Kras, Egfr, and Tp53 genes in lung tumors from B6C3F1/N mice and F344/NTac rats exposed to various doses of CMD by inhalation for 2 years.
- Cancer - How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease - NCBI Bookshelf
The KRAS and TP53 mutations observed in lung cancer in smokers appear to reflect DNA damage caused by metabolically activated PAHs. However, a number of other carcinogens or toxicants, such as N-nitrosamines and aldehydes, as well as oxidative damage, are also likely to be involved.
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