Non-endometrioid and high-grade endometrioid endometrial cancers show DNA fragmentation factor 40 (DFF40) and B-cell lymphoma 2 protein (BCL2) underexpression, which predicts disease-free and overall survival, but not DNA fragmentation factor 45 (DFF45) underexpression

Energetic metabolic reprogramming in Jurkat DFF40-deficient cancer cells

DNA fragmentation factor 40 (DFF40), or the caspase-activated DNase (CAD), is an endonuclease specific for double-stranded DNA. Alterations in its function and expression have been linked to apoptosis resistance, a mechanism likely used by cancer cells. However, how the DFF40-related apoptosis resistance pathway occurs remains unclear. Here, we sought to determine if DFF40 expression could be linked to cell metabolism through the regulation of mitochondrial integrity and function. We demonstrated that DFF40-deficient cells are more resistant to staurosporine and tributyltin (TBT)-induced apoptosis, and express higher levels of Mcl-1 at basal state. Treatment with TBT induces higher Bcl-2 and caspase-9 mRNA transcripts in DFF40 KO Jurkat cells, as well as enhanced Bcl-2 phosphorylation. A loss of DFF40 expression induces a higher mitochondrial mass, mtDNA copy number, mitochondrial membrane potential, and glycolysis rates in resting T cells. DFF40-deficient cells exhibit the Warburg effect phenotype, where they rely significantly more on glycolysis than oxidative phosphorylation and have a higher proliferative state, demonstrated by a higher Ki-67 transcription factor expression and AKT phosphorylation. Finally, we demonstrated with cell fractioning that DFF40 can translocate to the mitochondria following apoptosis induction. Our study reveals that DFF40 may act as a regulator of mitochondria during cell death and its loss could compromise mitochondrial integrity and cause an energetic reprogramming in pathologies such as cancer.

Review of cancer cell resistance mechanisms to apoptosis and actual targeted therapies

The apoptosis pathway is a programmed cell death mechanism that is crucial for cellular and tissue homeostasis and organ development. There are three major caspase-dependent pathways of apoptosis that ultimately lead to DNA fragmentation. Cancerous cells are known to highly regulate the apoptotic pathway and its role in cancer hallmark acquisition has been discussed over the past decades. Numerous mutations in cancer cell types have been reported to be implicated in chemoresistance and treatment outcome. In this review, we summarize the mutations of the caspase-dependant apoptotic pathways that are the source of cancer development and the targeted therapies currently available or in trial.

DFF40 deficiency in cancerous T cells is implicated in chemotherapy drug sensitivity and resistance through the regulation of the apoptotic pathway

The regulation of the apoptotic pathway is one of the most studied mechanisms regarding cancer cell resistance. Many mutations have been linked to drug resistance. The DNA fragmentation factor 40 (DFF40) has been gaining interest regarding cancer cell response to chemotherapy and patient outcomes. Glioblastomas and uterine leiomyosarcomas have been shown to have a downregulation of DFF40 expression, conferring a poor patient prognosis. In concordance with these observations, in this study, we showed that DFF40 gene is also downregulated in breast, endocervical, ovarian, lung, pancreas and glioblastomas. DFF40 is the endonuclease responsible of DNA fragmentation during apoptosis. In this study, we sought to determine if a DFF40 deficiency in Jurkat T cells could impact the sensitivity to conventional chemotherapy drugs. CRISPR-cas9 generated DFF40 knockout (DFF40 KO) stable Jurkat cells and wild-type (DFF40 WT) cells were treated with different antimetabolites and topoisomerase II (TOP2) inhibitors, and cell viability was subsequently assessed. DFF40 deficient cells show chemoresistance to antimetabolites (e.g. methotrexate, 6-mercaptopurine and cytarabine) and surprisingly, they are more sensitive to TOP2 inhibitors (e.g. etoposide and teniposide). DFF40 deficient cells exposed to cytarabine present lower phosphatidylserine translocation levels to the outer cell membrane layer. Etoposide exposure in DFF40 deficient cells induces higher mortality levels and downregulation of Bcl-xL cells compared to DFF40 expressing T cells. The abolition of DFF40 expression in Jurkat cells significantly impairs histone H2AX phosphorylation following etoposide and cytarabine treatments. Our findings suggest that DFF40 is a novel key target in cancer cell resistance that potentially regulates genomic stability.

The role of the DFF40/CAD endonuclease in genomic stability

Maintenance of genomic stability in cells is primordial for cellular integrity and protection against tumor progression. Many factors such as ultraviolet light, oxidative stress, exposure to chemical reagents, particularly mutagens and radiation, can alter the integrity of the genome. Thus, human cells are equipped with many mechanisms that prevent these irreversible lesions in the genome, as DNA repair pathways, cell cycle checkpoints, and telomeric function. These mechanisms activate cellular apoptosis to maintain DNA stability. Emerging studies have proposed a new protein in the maintenance of genomic stability: the DNA fragmentation factor (DFF). The DFF40 is an endonuclease responsible of the oligonucleosomal fragmentation of the DNA during apoptosis. The lack of DFF in renal carcinoma cells induces apoptosis without oligonucleosomal fragmentation, which poses a threat to genetic information transfer between cancerous and healthy cells. In this review, we expose the link between the DFF and genomic instability as the source of disease development.

Development of prediction models for lymph node metastasis in endometrioid endometrial carcinoma

BACKGROUND

In endometrioid endometrial cancer (EEC), current clinical algorithms do not accurately predict patients with lymph node metastasis (LNM), leading to both under- and over-treatment. We aimed to develop models that integrate protein data with clinical information to identify patients requiring more aggressive surgery, including lymphadenectomy.

METHODS

Protein expression profiles were generated for 399 patients using reverse-phase protein array. Three generalised linear models were built on proteins and clinical information (model 1), also with magnetic resonance imaging included (model 2), and on proteins only (model 3), using a training set, and tested in independent sets. Gene expression data from the tumours were used for confirmatory testing.

RESULTS

LNM was predicted with area under the curve 0.72-0.89 and cyclin D1; fibronectin and grade were identified as important markers. High levels of fibronectin and cyclin D1 were associated with poor survival (p = 0.018), and with markers of tumour aggressiveness. Upregulation of both FN1 and CCND1 messenger RNA was related to cancer invasion and mesenchymal phenotype.

CONCLUSIONS

We demonstrate that data-driven prediction models, adding protein markers to clinical information, have potential to significantly improve preoperative identification of patients with LNM in EEC.

DNA fragmentation factor 40 expression in T cells confers sensibility to tributyltin-induced apoptosis

DNA fragmentation factor 40 (DFF40), an endonuclease, mediates the final and irreversible step of apoptosis by conducting oligonucleosomal DNA fragmentation. New emerging studies have proposed a role of DFF40 in genomic stability, besides its nuclease activity. Overexpression of DFF40 in tumoral cells increases their sensitivity to chemotherapeutic drugs. In this study, we sought to determine if DFF40 expression influences the toxicity of tributyltin (TBT), a well-known immunotoxic and apoptosis-inducing compound. The strategy used was to knockout DFF40 expression by CRISPR-cas9 method in Jurkat T cells and to determine the toxicity of TBT in DFF40 KO cells and DFF40 WT Jurkat cells. DFF40 KO Jurkat cells show an increase of cell viability following a 24-h TBT exposure (p < 0.05). There is a resistance to TBT-induced apoptosis determined by annexin V/PI am labeling (p < 0.05). Interestingly, the basal level of ROS rises in DFF40 KO Jurkat cells, but ROS production levels after TBT exposure remains at the same basal level. Other apoptosis or DNA damage makers (procaspase-3, caspase-6, and PARP cleavage) are significantly delayed and decreased. DFF40 deficient cells do not present histone H2AX phosphorylation, whereas wild-type cells present a phosphorylation following a 6-h exposure to TBT (p < 0.001). The re-expression of DFF40 in DFF40 KO cells restores the cytotoxic effects of TBT. Overall, these data suggest a role of DFF40 in cells sensitivity to TBT and possibly in DNA stability.

High Expression of Galectin-1, VEGF and Increased Microvessel Density Are Associated with MELF Pattern in Stage I-III Endometrioid Endometrial Adenocarcinoma

Background

In this study, we investigate the expression of markers of angiogenesis and microvessel density (MVD) in cases of microcystic, elongated and fragmented (MELF) pattern, with its prognostic role in the survival of endometrioid endometrial adenocarcinomas (EA) patients.

Methods

In this study, 100 cases of EA, 49 cases with MELF pattern and 51 without, were immunohistochemically stained for galectin-1, vascular endothelial growth factor (VEGF), and MVD. Morphometry and statistical (univariate and multivariate) analyses were performed to assess overall survival (OS) and disease-free survival.

Results

The expression of VEGF (p<.001) and galectin-1 (p<.001), as well as MVD area (p<.001) and number of vessels/mm² (p<.050), were significantly higher in the +MELF pattern group compared to the –MELF group. A low negative correlation between MELF-pattern and the number of days of survival (p<.001, r=–0.47) was also found. A low positive correlation of MELF-pattern with galectin-1 expression (p<.001, r=0.39), area of vessels/mm² (p<.001, r=0.36), outcome of EA (p<.001, r=0.42) and VEGF expression (p<.001, r=0.39) suggests potential pathological relevance of these factors in the prognosis of EA. A univariate survival analysis indicated a role for all parameters of survival. Multivariate Cox proportional hazard regression analysis revealed that only area of vessels/mm² (hazard ratio [HR], 1.018; 95% confidence interval [CI], 1.002 to 1.033), galectin-1 (HR, 1.049; 95% CI, 1.025 to 1.074) and VEGF (HR, 1.049; 95% CI, 1.022 to 1.077) play key roles in OS.

Conclusions

This study reports an increase in MVD, VEGF and galectin-1 expression in EA with MELF pattern and suggests that MELF pattern, along with the angiogenic profile, may be a prognostic factor in EA.