ROS-induced near-homozygous genomes in thyroid cancer

Abstract

A near-homozygous genome (NHG) is especially seen in a subset of follicular thyroid cancer of the oncocytic type (FTC-OV). An NHG was also observed in the metabolically relatively quiescent cell lines XTC.UC1, a model for FTC-OV, and in FTC-133, -236 and -238, the latter three derived from one single patient with follicular thyroid cancer. FTC-236 subclones showed subtle whole-chromosome differences indicative of sustained reciprocal mitotic missegregations. Reactive oxygen species (ROS) scavenger experiments reduced the number of chromosomal missegregations in XTC.UC1 and FTC-236, while pCHK2 was downregulated in these cells. Treatment with antimycin A increased ROS indicated by enhanced MitoSOX Red and pCHK2 fluorescence in metaphase cells. In a selected set of oncocytic follicular thyroid tumors, increasing numbers of whole-chromosome losses were observed toward an aggressive phenotype, but with retention of chromosome 7. Together, ROS activates CHK2 and links to the stepwise loss of whole chromosomes during tumor progression in these lesions. We postulate that sequential loss of whole chromosomes is a dominant driver of the oncogenesis of a subset of follicular thyroid tumors.

Metabolic reprogramming related to whole-chromosome instability in models for Hürthle cell carcinoma

“…Metabolic adaptation plays an important role in the development of cancers characterized by abundant malfunctioning mitochondria (oncocytic phenotype), including thyroid Hürthle cell carcinoma (HCC) 32 . HCCs typically show widespread loss of entire chromosomes, leading to a near-homozygous genome (NHG) [7][8][9]13,21 . The loss of entire chromosomes has been attributed to aberrant interactions with reactive oxygen species (ROS) 21 .…”

“…HCCs typically show widespread loss of entire chromosomes, leading to a near-homozygous genome (NHG) [7][8][9]13,21 . The loss of entire chromosomes has been attributed to aberrant interactions with reactive oxygen species (ROS) 21 . Interestingly, recent findings showed that ROS vary with the cell cycle phase and reach their highest levels during mitosis 33 .…”

“…oncocytic cells such as XTC.UC1, mitosis might lead to greater cellular stress, increased levels of ROS and subsequent ROS-induced aneuploidy by chromosomal missegregation 34,35 . This mechanism may be regulated via enhanced CHK2 phosphorylation, as seen in mitotic cells after AMA treatment 21 , which could in turn contribute to lagging chromosomes and missegregation 36 .…”

“…We recently suggested that NHGs in HCC are the net result of a continuous process of whole-chromosome instability (w-CIN). w-CIN may be driven by factors such as increased intracellular production of reactive oxygen species (ROS) as a by-product of metabolic changes 21 following the loss of CI functionality 22 . Interestingly, a recent study of renal oncocytomas found that recurrent CI loss was the earliest detected genetic alteration accompanied by altered metabolism and affected the production of the ROS scavenger glutathione 23 .…”

Inhibition of PARP Sensitizes Chondrosarcoma Cell Lines to Chemo- and Radiotherapy Irrespective of the IDH1 or IDH2 Mutation Status

“…CH2879, JJ012, and SW1353 cells were seeded on sterilized 3-Aminopropyltriethoxysilane (APES) coated slides (5 × 10 5 to 1 × 10 6 cells/slide). After overnight attachment, cultures were irradiated at 0 or 5 Gy of y-radiation using a 137 C source (YXLON, Comet Technologies, Shelton, CT, USA), and were allowed to recover for 2 h or 24 h. Slides were fixed with 4% formaldehyde at 37 • C, washed with PBS/0.05% Tween20, and permeabilized with 100% ice-cold methanol at −20 • C as described previously [59]. Blocking was performed with PBS/1% BSA/0.05% Tween20 for 30 min at 37 • C. Slides were stained with primary antibodies against geminin (1:500, 10802-1-AP, Proteintech, Manchester, UK) and RAD51 (1:500, clone 14B4, GeneTex, Irvine, CA, USA) for 1 h at 37 • C. After washing, slides were incubated with an Alexa Fluor 488/549 secondary antibody mix supplemented with 0.5 µM Hoechst 33342 for 1 h at 37 • C. Slides were washed, covered with ProLong Gold Antifade Reagent (Invitrogen Life-Technologies), and a LSM 700 laser scanning confocal microscope (Carl Zeiss, Oberkochen, Germany) was used to acquire images of regions of interest.…”