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Carcinogenesis

About: Carcinogenesis is a research topic. Over the lifetime, 60368 publications have been published within this topic receiving 3192599 citations. The topic is also known as: oncogenesis & tumorigenesis.


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Journal ArticleDOI
TL;DR: The findings of this work support the original hypothesis, derived previously from mathematical modeling of crypt dynamics, that progressive colonic SC overpopulation occurs during colon tumorigenesis and drives CRC development.
Abstract: Although the concept that cancers originate from stem cells (SC) is becoming scientifically accepted, mechanisms by which SC contribute to tumor initiation and progression are largely unknown. For colorectal cancer (CRC), investigation of this problem has been hindered by a paucity of specific markers for identification and isolation of SC from normal and malignant colon. Accordingly, aldehyde dehydrogenase 1 (ALDH1) was investigated as a possible marker for identifying colonic SC and for tracking them during cancer progression. Immunostaining showed that ALDH1 + cells are sparse and limited to the normal crypt bottom, where SCs reside. During progression from normal epithelium to mutant ( APC ) epithelium to adenoma, ALDH1 + cells increased in number and became distributed farther up the crypt. CD133 + and CD44 + cells, which are more numerous and broadly distributed in normal crypts, showed similar changes during tumorigenesis. Flow cytometric isolation of cancer cells based on enzymatic activity of ALDH (Aldefluor assay) and implantation of these cells in nonobese diabetic–severe combined immunodeficient mice ( a ) generated xenograft tumors (Aldefluor − cells did not), ( b ) generated them after implanting as few as 25 cells, and ( c ) generated them dose dependently. Further isolation of cancer cells using a second marker (CD44 + or CD133 + serially) only modestly increased enrichment based on tumor-initiating ability. Thus, ALDH1 seems to be a specific marker for identifying, isolating, and tracking human colonic SC during CRC development. These findings also support our original hypothesis, derived previously from mathematical modeling of crypt dynamics, that progressive colonic SC overpopulation occurs during colon tumorigenesis and drives CRC development. [Cancer Res 2009;69(8):3382–9]

1,000 citations

Journal ArticleDOI
TL;DR: This review considers the potential role of tumor suppressors as metabolic regulators and a number of well-established tumor suppressers play critical roles in suppressing growth and/or proliferation when intracellular supplies of essential metabolites become reduced.
Abstract: Growing tumors face two major metabolic challenges-how to meet the bioenergetic and biosynthetic demands of increased cell proliferation, and how to survive environmental fluctuations in external nutrient and oxygen availability when tumor growth outpaces the delivery capabilities of the existing vasculature. Cancer cells display dramatically altered metabolic circuitry that appears to directly result from the oncogenic mutations selected during the tumorigenic process. An emerging theme in cancer biology is that many of the genes that can initiate tumorigenesis are intricately linked to metabolic regulation. In turn, it appears that a number of well-established tumor suppressors play critical roles in suppressing growth and/or proliferation when intracellular supplies of essential metabolites become reduced. In this review, we consider the potential role of tumor suppressors as metabolic regulators.

994 citations

Journal ArticleDOI
16 Feb 2012-Nature
TL;DR: The discovery of microRNAs almost two decades ago established a new paradigm of gene regulation, and during the past ten years these tiny non-coding RNAs have been linked to virtually all known physiological and pathological processes, including cancer.
Abstract: MicroRNAs (miRNAs) are small, evolutionarily conserved, non-coding RNAs of 18–25 nucleotides in length that have an important function in gene regulation. Mature miRNA products are generated from a longer primary miRNA (pri-miRNA) transcript through sequential processing by the ribonucleases Drosha and Dicer1 (ref. 1). The first description of miRNAs was made in 1993 in Caenorhabditis elegans as regulators of developmental timing 2,3 . Later, miRNAs were shown to inhibit their target genes through sequences that are complementary to the target messenger RNA, leading to decreased expression of the target protein 1 (Box 1). This discovery resulted in a pattern shift in our understanding of gene regulation because miRNAs are now known to repress thousands of target genes and coordinate normal processes, including cellular proliferation, differentiation and apoptosis. The aberrant expression or alteration of miRNAs also contributes to a range of human pathologies, including cancer. The control of gene expression by miRNAs is a process seen in virtually all cancer cells. These cells show alterations in their miRNA expression profiles, and emerging data indicate that these patterns could be useful in improving the classification of cancers and predicting their behaviour. In addition, miRNAs have now been shown to behave as cancer ‘drivers’ in the same way as protein-coding genes whose alterations actively and profoundly contribute to malignant transformation and cancer progression. Owing to the capacity of miRNAs to modulate tens to hundreds of target genes, they are emerging as important factors in the control of the ‘hallmarks’ of cancer 4 . In this Review, we summarize the findings that provide evidence for the central role of miRNAs in controlling cellular transformation and tumour progression. We also highlight the potential uses of miRNAs and miRNA-based drugs in cancer therapy and discuss the obstacles that will need to be overcome. miRNAs are cancer genes In 2002, Croce and colleagues first demonstrated that an miRNA cluster was frequently deleted or downregulated in chronic lymphocytic leukaemia 5 . This discovery suggested that non-coding genes were contributing to the development of cancer, and paved the way for the closer investigation of miRNA loss or amplification in tumours. Subsequently, miRNAs were shown to be differentially expressed in cancer cells, in which they formed distinct and unique miRNA expression patterns 6 , and whole classes of miRNAs could be controlled directly by key oncogenic transcription factors 7 . In parallel, studies with mouse models established that miRNAs were actively involved in tumorigenesis

992 citations

Journal ArticleDOI
TL;DR: It now appears that type I and type II ovarian tumors develop independently along different molecular pathways and that both types develop outside the ovary and involve it secondarily, leading to the conclusion that the only true primary ovarian neoplasms are gonadal stromal and germ cell tumors analogous to testicular tumors.

983 citations

Journal ArticleDOI
TL;DR: A recent outcome of whole exome sequencing of thousands of human cancers has been the unexpected discovery of many inactivating mutations in genes that control the epigenome, which contributes to cancer.

983 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20239,028
20227,271
20213,536
20203,486
20193,433
20183,073