TdIF1: a putative oncogene in NSCLC tumor progression

Abstract

TdT-interacting factor 1 (TdIF1) is a ubiquitously expressed DNA- and protein-binding protein that directly binds to terminal deoxynucleotidyl transferase (TdT) polymerase. Little is known about the functional role of TdIF1 in cancer cellular signaling, nor has it previously been identified as aberrant in any type of cancer. We report here for the first time that TdIF1 is abundantly expressed in clinical lung cancer patients and that high expression of TdIF1 is associated with poor patient prognosis. We further established that TdIF1 is highly expressed in human non-small cell lung cancer (NSCLC) cell lines compared to a normal lung cell line. shRNA-mediated gene silencing of TdIF1 resulted in the suppression of proliferation and anchorage-independent colony formation of the A549 adenocarcinoma cell line. Moreover, when these TdIF1-silenced cells were used to establish a mouse xenograft model of human NSCLC, tumor size was greatly reduced. These data suggest that TdIF1 is a potent regulator of lung tumor development. Several cell cycle-related and tumor growth signaling pathways, including the p53 and HDAC1/2 pathways, were identified as participating in the TdIF1 signaling network by in silico analysis. Microarray, transcriptome and protein-level analyses validated p53 and HDAC1/2 modulation upon TdIF1 downregulation in an NSCLC cellular model. Moreover, several other cell cycle regulators were affected at the transcript level by TdIF1 silencing, including an increase in CDKN1A/p21 transcripts. Taken together, these results indicate that TdIF1 is a bona fide tumor-promoting factor in NSCLC and a potential target for therapy.

The histone deacetylase complex MiDAC regulates a neurodevelopmental gene expression program to control neurite outgrowth

“…However, loss of MiDAC function did not affect self-renewal or pluripotency as evaluated by assessing the mRNA levels of the pluripotency factors Sox2, Pou5f1, and Nanog (Figure 1-figure supplement 3A and B), nor did it alter the percentage of alkaline phosphatase (AP)-positive colonies (Figure 1-figure supplement 3C). Furthermore, DNTTIP1 or ELMSAN1 loss in mESCs did not alter the proliferation rate or cell cycle profile ( Figure 1-figure supplement 3D and E), in contrast to the reported growth-promoting function of DNTTIP1 in oral and non-small cell lung cancer (Sawai, Kasamatsu et al, 2018, Zhang, Wang et al, 2018. Gene expression of Ccna2 and the cell cycle inhibitors Cdkn1a (p21) and Cdkn1b (p27) whose protein products were reported to interact with and/or be regulated by DNTTIP1 were also unaffected in Dnttip1 KO and Elmsan1 KO mESCs (Figure 1-figure supplement 3F) (Hein et al, 2015, Huttlin et al, 2015, Pagliuca et al, 2011, Sawai et al, 2018.…”

“…We provide evidence that MiDAC originally obtained its name from a chemoproteomic profiling study due to its increased association with certain HDAC inhibitors in protein extracts from mitotically arrested versus nonsynchronized proliferating cells that otherwise displayed comparable levels of DNTTIP1 (Bantscheff et al, 2011). Individual MiDAC subunits have been shown to interact with CCNA2 and/or the cell cycle-dependent kinase CDK2, and were reported to positively regulate the cell cycle inhibitors CDKN1A and CDKN1B and cell growth in various cancer cell lines, thus implying a potential role for MiDAC in cell cycle regulation (Gizard et al, 2005, Gizard et al, 2006, Hein et al, 2015, Huttlin et al, 2015, Pagliuca et al, 2011, Sawai et al, 2018, Zhang et al, 2018.…”

The MiDAC histone deacetylase complex is essential for embryonic development and has a unique multivalent structure

“…Consistent with a role in cell proliferation, components of the MiDAC complex have been implicated in a number of human cancers. DNTTIP1 has a critical role in oral cancer and is proposed to be oncogenic in non-small cell lung cancers 18,19 . A number of large-scale cancer genome studies have associated downregulation of MIDEAS with cutaneous melanoma; MIDEAS as a mutational hotspot and potentially a rare tumour gene [20][21][22] .…”

The histone deacetylase complex MiDAC regulates a neurodevelopmental gene expression program

“…However, loss of MiDAC function did not affect self-renewal or pluripotency as evaluated by mRNA levels of the pluripotency factors Sox2, Pou5f1, and Nanog (Figure S3A, B), nor did it alter the percentage of alkaline phosphatase (AP)-positive colonies (Figure S3C). Furthermore, DNTTIP1 or ELMSAN1 loss in mESCs did not alter the proliferation rate or cell cycle profile (Figure S3D, E), in contrast to the reported growth-promoting function of DNTTIP1 in oral and non-small cell lung cancer (Sawai, Kasamatsu et al, 2018, Zhang, Wang et al, 2018. Gene expression of Ccna2 and the cell cycle inhibitors Cdkn1a (p21) and Cdkn1b (p27) whose protein products were reported to interact with and/or be regulated by DNTTIP1 were also unaffected in Dnttip1 KO and Elmsan1 KO mESCs ( Figure S3F) (Hein et al, 2015, Huttlin et al, 2015, Pagliuca et al, 2011, Sawai et al, 2018.…”

“…More specifically, we uncover a crucial role for MiDAC in MiDAC originally obtained its name from a chemoproteomic profiling study due to its increased association with certain HDAC inhibitors in protein extracts from mitotically arrested versus nonsynchronized proliferating cells that otherwise displayed comparable levels of DNTTIP1 (Bantscheff et al, 2011). Individual MiDAC subunits have been shown to interact with CCNA2 and/or the cell cycle-dependent kinase CDK2, and were reported to positively regulate the cell cycle inhibitors CDKN1A and CDKN1B and cell growth in various cancer cell lines, thus implying a potential role for MiDAC in cell cycle regulation (Gizard et al, 2005, Gizard et al, 2006, Hein et al, 2015, Huttlin et al, 2015, Pagliuca et al, 2011, Sawai et al, 2018, Zhang et al, 2018.…”