MAD2γ, a novel MAD2 isoform, reduces mitotic arrest and is associated with resistance in testicular germ cell tumors

Abstract

Background: Prolonged mitotic arrest in response to anti-cancer chemotherapeutics, such as DNA-damaging agents, induces apoptosis, mitotic catastrophe, and senescence. Disruptions in mitotic checkpoints contribute resistance to DNA-damaging agents in cancer. MAD2 has been associated with checkpoint failure and chemotherapy response. In this study, a novel splice variant of MAD2, designated MAD2γ, was identified, and its association with the DNA damage response was investigated.Methods: Endogenous expression of MAD2γ and full-length MAD2 (MAD2α) was measured using RT-PCR in cancer cell lines, normal foreskin fibroblasts, and tumor samples collected from patients with testicular germ cell tumors (TGCTs). A plasmid expressing MAD2γ was transfected into HCT116 cells, and its intracellular localization and checkpoint function were evaluated according to immunofluorescence and mitotic index.Results: MAD2γ was expressed in several cancer cell lines and non-cancerous fibroblasts. Ectopically expressed MAD2γ localized to the nucleus and reduced the mitotic index, suggesting checkpoint impairment. In patients with TGCTs, the overexpression of endogenous MAD2γ, but not MAD2α, was associated with resistance to cisplatin-based chemotherapy. Likewise, cisplatin induced the overexpression of endogenous MAD2γ, but not MAD2α, in HCT116 cells.Conclusions: Overexpression of MAD2γ may play a role in checkpoint disruption and is associated with resistance to cisplatin-based chemotherapy in TGCTs.

Regulatory networks in mechanotransduction reveal key genes in promoting cancer cell stemness and proliferation

“…These TFs involved in the regulation of WNT/TGF-β/ PI3K-AKT pathways and affected the expression of downstream cancer-related genes such as CCT3. CCT3, then affected the selection of TRCs [42], and was significantly upregulated after increasing CCT3, consistent with the report that CCT3 affects mitotic process [27]. CCT3 overexpression and silencing affect a large number of stemness genes (Fig.…”

Deletions in metastatic colorectal cancer with chromothripsis

“…50% showed MAD2L1 deletion. Overexpression of MAD2L1 is reported in platinum resistant testicular germ cell tumors [9].…”

“…Frequently deleted genes in study population (n = 10) Gene Description, importance of gene COSMIC 1. Genes involved in cell proliferation/drug resistance COL11A1 COL11A1 is overexpressed in recurrent non-small cell lung cancer and promotes cell proliferation, migration, invasion and drug resistance [7] 1174/41930 MAD2L1 Possible resistance to chemotherapy [9] 70/32840 ADAM29 The expression of ADAM29 and its mutations in different domains significantly influenced proliferation, migration and invasion of breast cancer and colorectal cancer cells [11] 510/33364 GPM6A Identification of GPM6A and GPM6B as potential new human lymphoid leukemia-associated oncogenes [12] 167/32746 EPHA7 Downregulation or loss of EphA7 mRNA expression was detected in prostate carcinomas [13] 616/34447 ADK Adenosine kinase gene expression was significantly higher in cancer than in normal-appearing tissue, in line with our previous measurements of adenosine kinase enzyme activities in colorectal tumor samples [14] 81/32840…”

Non-Coding RNAs and Splicing Activity in Testicular Germ Cell Tumors

“…MAD2α was present in both the nucleus and the cytoplasm, while MAD2γ mainly localized to the nucleus and reduced mitotic arrest. Interestingly, in TGCTs patients, the overexpression of endogenous MAD2γ, but not MAD2α, was associated with resistance to cisplatin-based chemotherapy [ 108 , 109 ]. Since Nek2 interacts with MAD2 [ 110 ] and SAC has emerged as a promising target for cancer therapy [ 111 ], modulation of NEK2 activity and/or MAD2 AS could be exploited therapeutically in TGCTs patients displaying resistance to cisplatin-based chemotherapy.…”