What cause mutation in cancer cells?5 answersMutations in cancer cells can be caused by various factors. Mutational processes, both endogenous and exogenous, play a significant role in the accumulation of somatic mutations in cancer cells. Endogenous mutational processes associated with aging contribute to the origination of selected variants in certain cancer types. Exogenous mutational processes, such as ultraviolet light exposure and tobacco exposure, are responsible for driving mutations in melanomas and lung cancers, respectively. Additionally, certain mutational processes, like the error-prone polymerase and spontaneous deamination of 5-methylcytosine, can induce specific mutations in cancer genes. Other factors, such as chemotherapy treatment and specific bacterial strains, can also induce mutations in healthy cells, potentially increasing the risk of cancer. Overall, a combination of mutational processes and external exposures contribute to the development of mutations in cancer cells.
Whole-Genome Duplication and Genome Instability in Cancer Cells: Double the Trouble4 answersWhole-genome duplication (WGD) is a common genomic abnormality in cancer cells that leads to genome instability. WGD provides redundant genes that buffer the deleterious effects of somatic alterations and facilitate clonal evolution. Chromosome instability resulting from WGD contributes to cancer aggressiveness and poor prognosis. Tetraploid cells that survive WGD demonstrate increased tolerance to chromosome aberrations, allowing for the evolution of chromosomal changes in colorectal tumors. WGD+ cells are more dependent on spindle assembly checkpoint signaling, DNA replication factors, and proteasome function, and loss of KIF18A, a mitotic kinesin protein, impairs the viability of WGD+ cells. These findings suggest new strategies for targeting WGD+ cancer cells while sparing normal cells.
What percentage of colorecttal cancers involve genomic instability?5 answersColorectal cancers involving genomic instability account for approximately 10% to 50% of all cases.
What are the mutations of the Chromosomal Instability subtype in Gastric Cancer?3 answersThe mutations of the Chromosomal Instability (CIN) subtype in Gastric Cancer (GC) are not clearly defined and may be a compilation of a more heterogeneous group of tumors. The CIN subtype accounts for 50% of GC cases and is characterized by chromosomal instability. However, the underlying molecular mechanisms leading to CIN are still not fully understood. The CIN subtype is associated with TP53 mutational status and is correlated with the p53 expression detected by immunohistochemistry. The CIN subtype is also correlated with microsatellite instability, hepatocyte growth factor receptor (MET), and TP53 mutational status. Further research is needed to elucidate the specific mutations and molecular characteristics of the CIN subtype in GC.
What are the mechanisms of chromosomal instability in cancer?4 answersChromosomal instability (CIN) in cancer is driven by various mechanisms, including structural chromosomal instability (S-CIN) and whole chromosomal instability (W-CIN). S-CIN leads to structural aberrations, while W-CIN is directly related to errors during mitosis resulting in chromosome mis-segregation and aneuploidy. TGFβ signaling has been identified as a key mediator for W-CIN, causing aberrant microtubule dynamics and chromosome mis-segregation in mitosis, independent of the canonical SMAD-dependent signaling, but requiring the non-SMAD MEK-ERK pathway. Additionally, non-coding RNAs, such as miR-22, miR-26a, miR-28, and miR-186, have been implicated in CIN, targeting important checkpoint proteins involved in mediating chromosomal stability. Furthermore, cancer cell CIN engenders a pro-metastatic tumor microenvironment enriched for immune-suppressive macrophages, granulocytic infiltrate, and dysfunctional T cells, highlighting the impact of CIN on the tumor microenvironment. These findings provide insights into the multifaceted mechanisms underlying chromosomal instability in cancer.
Why is DNA so stable?1 answersEl ADN es estable debido a varios mecanismos que aseguran su integridad y transmisión fiel. Un mecanismo clave es la corrección de errores y la eliminación del daño al ADN a través de la síntesis localizada utilizando una cadena no dañada como plantilla. Adicionalmente, la estructura bicatenaria del ADN juega un papel crítico tanto en la replicación como en la corrección de errores. Otro factor que contribuye a la estabilidad del ADN es la formación de estructuras altamente compactas llamadas minimancuernas (MDB). Se ha propuesto que los MDB son intermedios que conducen a un escape eficiente de reparación del ADN y repiten expansiones. Además, las células responden al daño del ADN durante la fase S al ralentizar la replicación cromosómica, implementando un punto de control de fase intra-S. Estos mecanismos aseguran colectivamente la estabilidad del ADN, lo cual es crucial para la transmisión fiel de la información genética a través de las generaciones.