Knock-down of the TIM/TIPIN complex promotes apoptosis in melanoma cells

Abhijit Chakraborty, Faisal Aziz, Eunmiri Roh, Le Thi My Le, Raja Dey, Tianshun Zhang, Moeez G. Rathore, Aalekhya Sharma Biswas, Ann M. Bode, Zigang Dong

Research output: Contribution to journalArticlepeer-review

Abstract

The Timeless (TIM) and it's interacting partner TIPIN protein complex is well known for its role in replication checkpoints and normal DNA replication processes. Recent studies revealed the involvement of TIM and TIPIN in human malignancies; however, no evidence is available regarding the expression of the TIM/TIPIN protein complex or its potential role in melanoma. Therefore, we investigated the role of this complex in melanoma. To assess the role of the TIM/TIPIN complex in melanoma, we analyzed TIM/ TIPIN expression data from the publicly accessible TCGA online database, Western blot analysis, and RT-qPCR in a panel of melanoma cell lines. Lentivirus-mediated TIM/ TIPIN knockdown in A375 melanoma cells was used to examine proliferation, colony formation, and apoptosis. A xenograft tumor formation assay was also performed. The TIM/TIPIN complex is frequently overexpressed in melanoma cells compared to normal melanocytes. We also discovered that the overexpression of TIM and TIPIN was significantly associated with poorer prognosis of melanoma patients. Furthermore, we observed that shRNA-mediated knockdown of TIM and TIPIN reduced cell viability and proliferation due to the induction of apoptosis and increased levels of γH2AX, a marker of DNA damage. In a xenograft tumor nude mouse model, shRNA-knockdown of TIM/TIPIN significantly reduced tumor growth. Our results suggest that the TIM/TIPIN complex plays an important role in tumorigenesis of melanoma, which might reveal novel approaches for the development of new melanoma therapies. Our studies also provide a beginning structural basis for understanding the assembly of the TIM/TIPIN complex. Further mechanistic investigations are needed to determine the complex's potential as a biomarker of melanoma susceptibility. Targeting TIM/TIPIN might be a potential therapeutic strategy against melanoma.

Original languageEnglish (US)
Pages (from-to)1846-1861
Number of pages16
JournalOncotarget
Volume11
Issue number20
DOIs
StatePublished - May 19 2020

Bibliographical note

Funding Information:
This work was supported by the Hormel Foundation (Z. Dong). The funding body played no role in study design, data collection, data analysis, interpretation, writing of the report. The authors thank Todd Schuster and Josh Monts for supporting experiments and Tara Adams for supporting animal experiments.

Keywords

  • Apoptosis
  • Cryo-EM
  • TIMELESS
  • TIPIN
  • Xenograft

PubMed: MeSH publication types

  • Journal Article

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