Effect of GEN1 interference on the chemosensitivity of the breast cancer MCF-7 and SKBR3 cell lines

Abstract

Chemotherapy is a notable method for the treatment of breast cancer. Numerous genes associated with the sensitivity of cancer to chemotherapy have been found. In recent years, evidence has suggested that a particular structure termed Holliday junction (HJ) plays a crucial role in cancer chemosensitivity. Targeting HJ resolvases, such as structure-specific endonuclease subunit SLX4 (Slx4) and MUS81 structure-specific endonuclease subunit (Mus81), significantly increases the chemosensitivity of tumor cells. Flap endonuclease GEN homolog 1 (GEN1) is a HJ resolvase that belongs to the Rad2/xeroderma pigmentosum complementation group G nuclease family. Whether GEN1 affects the chemosensitivity of tumor cells in a similar manner to Slx4 and Mus81 remains unknown. The aim of the present study was to determine the effect of GEN1 interference on the chemosensitivity of breast cancer cell lines. The investigation of the function of GEN1 was performed using MCF-7 and SKBR3 cells. Short hairpin RNA was used to suppress the expression of GEN1, and western blot analysis and reverse transcription-quantitative polymerase chain reaction were used to detect gene expression. In addition, a cell counting kit-8 assay was performed to detect the viability of cells and flow cytometry was performed to test apoptosis levels. Suppression of GEN1 in SKBR3 cells effectively increased the sensitivity to the chemotherapeutic drug 5-fluorouracil (5-FU), while MCF-7 cells showed no significant change in sensitivity following GEN1 suppression. However, when GEN1 was targeted in addition to Mus81, the MCF-7 cells also demonstrated a significantly increased sensitivity to 5-FU. In addition, when the level of Mus81 was low, GEN1 expression was increased under a low concentration of 5-FU. The present results suggest that GEN1 may play different roles in different breast cancer cell lines. The function of GEN1 may be affected by the level of Mus81 in the cell line. In addition, GEN1 interference may improve the sensitivity to chemotherapy induced by targeting Mus81 alone.

MitoQ Prevents Human Breast Cancer Recurrence and Lung Metastasis in Mice

“…To test the effects of combination treatments on cell numbers, MDA-MB-231 and SkBr3 cancer cells were plated in 96-well plates and treated with increasing concentrations of chemotherapeutic drug ± MitoQ for 24 h (epirubicin), 48 h (doxorubicin, 5-FU, cisplatin, paclitaxel) or 72 h (gemcitabine). Treatment times were adapted to known drug activities [27][28][29][30][31][32]. Cells were then fixed in 4% PFA and stained with crystal violet.…”

“…To assess whether the antioxidant activity of MitoQ interfered with these processes, we counted cells treated in vitro with chemotherapy ± 100 nM MitoQ. Treatment times were adapted to known drug activities [27][28][29][30][31][32]. In MDA-MB-231 cancer cells, MitoQ did not alter the cytostatic/cytotoxic effects of increasing doses of doxorubicin, epirubicin, 5-fluorouracil (5-FU), cisplatin, gemcitabine or paclitaxel (Figure 4a).…”

Human ANKLE1 is a nuclease specific for branched DNA

“…There is considerable redundancy between junction dissolution and resolution activities, and genetic interaction between the corresponding mutants have been reported. The loss of a single activity is generally well tolerated, but when cells become defective in multiple activities then they become very sensitive to DNA damage (21)(22)(23) and aberrant chromosomes are formed (23)(24)(25). It has been shown in human cells that the combinations of SLX4 and either BLM or GEN1 are synthetic lethal (26), underlining the vital importance of having a functional junction resolution activity.…”

Osterix Decreases the Chemosensitivity of Breast Cancer Cells by Upregulating GALNT14

“…The chemotherapy response in various cancer patients is frequently compromised by drug insensitivity, which eventually leads to treatment failure [33, 34]. Numerous genes associated with the drug sensitivity of chemotherapy have been identified [35]. The molecular mechanisms of drug insensitivity are associated with both genetic and epigenetic changes, including drug-induced mutations, cell cycle- and apoptosis-associated genes, histone modifications and DNA methylation [36].…”