Synergism between ATM and PARP1 Inhibition Involves DNA Damage and Abrogating the G2 DNA Damage Checkpoint

Mak, Joyce Pui Ying; Tang, Hoi; Poon, Randy Y. C.

doi:10.1158/1535-7163.mct-19-0474

Cited by 36 publications

(29 citation statements)

References 55 publications

(49 reference statements)

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“…In fact, PARP1 inhibitors, such as olaparib, have demonstrated high effectiveness against TNBC. However, the extensive use of PARP1 inhibitors can lead to the occurrence of resistance ( 29 ), partly due to the restoration of homologous recombination and upregulation of the ataxia-telangiectasia-mutated-and-Rad3-related kinase/checkpoint kinase 1 signaling pathway ( 30 ). Thus, it is important to identify other drugs or genes that can overcome this resistance.…”

Section: Discussionmentioning

confidence: 99%

MAPK4 silencing together with a PARP1 inhibitor as a combination therapy in triple‑negative breast cancer cells

et al. 2021

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Triple-negative breast cancer (TNBC) is the most common type of cancer among females worldwide and is associated with poor prognosis. Poly ADP-ribose polymerase-1 (PARP1) inhibitors are effective against TNBC with mutations in the breast cancer type 1 susceptibility protein (BRCA1) and/or BRCA2 genes; however, the development of resistance to PARP1 inhibitors limits their use. Thus, identifying strategies to overcome this resistance is urgently required. The aim of the present study was to investigate the potential function and mechanism of small interfering (si)RNA-MAPK4 (siMAPK4) in enhancing the efficacy of a PARP1 inhibitor and reducing the resistance. In the present study, data on the mRNA expression level of MAPK4 in normal breast tissues and TNBC tissues were obtained from The Cancer Genome Atlas database. The mRNA and protein expression levels of MAPK4 in normal breast cells and TNBC cells were analyzed using reverse transcription-quantitative PCR and western blotting, respectively. The phosphorylated (p) histone H2AX (γH2AX) protein expression was assessed via immunofluorescence. Cell Counting Kit-8, wound healing and TUNEL assays were used to determine the proliferative, migratory and apoptotic abilities of HCC1937 cells. MAPK4 was highly expressed in TNBC patient tissues and cell lines. Moreover, overexpression of MAPK4 could promote HCC1937 cell proliferation. Treatment of HCC1937 cells with the combination of siMAPK4 and a PARP1 inhibitor olaparib decreased their proliferation and migration and increased their apoptosis. The protein expression levels of the DNA repair-related proteins p-DNA-dependent protein kinase catalytic subunit (DNA-PK) and RAD51 recombinase (RAD51) were inhibited in the siMAPK4 and siMAPK4 + olaparib groups. However, the marker of a double-stranded break γH2AX showed increased protein expression in the siMAPK4 + olaparib group. As MAPK4 could phosphorylate AKT at threonine 308 (AKT T308 ), the current study restored p-AKT T308 using a constitutively active AKT plasmid (AKT-CA). p-DNA-PK and RAD51 showed high expression and γH2AX exhibited lower protein expression in the AKT-CA group. The present findings suggested that siMAPK4 can enhance the sensitivity of TNBC cells to PARP1 inhibitors.

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Section: Discussionmentioning

confidence: 99%

MAPK4 silencing together with a PARP1 inhibitor as a combination therapy in triple‑negative breast cancer cells

et al. 2021

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“…Flow cytometry analysis after propidium iodide staining was performed as previously described (Mak et al, 2020). After selection with hygromycin and/or puromycin for 2 weeks, lysates were prepared and analyzed with immunoblotting.…”

Section: Flow Cytometrymentioning

confidence: 99%

One-step multiplex toolkit for efficient generation of conditional gene silencing human cell lines

Yeung

Lau

Tang

et al. 2021

MBoC

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Loss-of-function analysis is one of the major arsenals we have for understanding gene functions in mammalian cells. For analysis of essential genes, the major challenge is to develop simple methodologies for tight and rapid inducible gene inactivation. One approach involves CRISPR-Cas9-mediated disruption of the endogenous locus in conjunction with the expression of a rescue construct, which can subsequently be turned off to produce a gene inactivation effect. Here we describe the development of a set of Sleeping Beauty transposon-based vectors for expressing auxin-inducible degron (AID)-tagged genes under the regulation of a tetracycline-controlled promoter. The dual transcriptional and degron-mediated post-translational regulation allows rapid and tight silencing of protein expression in mammalian cells. We demonstrated that both non-essential and essential genes could be targeted in human cell lines using a one-step transfection method. Moreover, multiple genes could be simultaneously or sequentially targeted, allowing inducible inactivation of multiple genes. These resources enable highly efficient generation of conditional gene silencing cell lines to facilitate functional studies of essential genes.

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“…ATM is also increasingly being recognized as a target for synthetic lethality with PARP inhibitors. The ATM inhibition combined with PARP1 depletion or inhibition caused a massive synergistic increase of DNA damage suggesting the effectiveness of combined treatments [ 334 ].…”

Section: Targeting the Chromatin Response To Dsb Dna Damagementioning

confidence: 99%

The Chromatin Response to Double-Strand DNA Breaks and Their Repair

Aleksandrov

Hristova

Stoynov

et al. 2020

Cells

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Cellular DNA is constantly being damaged by numerous internal and external mutagenic factors. Probably the most severe type of insults DNA could suffer are the double-strand DNA breaks (DSBs). They sever both DNA strands and compromise genomic stability, causing deleterious chromosomal aberrations that are implicated in numerous maladies, including cancer. Not surprisingly, cells have evolved several DSB repair pathways encompassing hundreds of different DNA repair proteins to cope with this challenge. In eukaryotic cells, DSB repair is fulfilled in the immensely complex environment of the chromatin. The chromatin is not just a passive background that accommodates the multitude of DNA repair proteins, but it is a highly dynamic and active participant in the repair process. Chromatin alterations, such as changing patterns of histone modifications shaped by numerous histone-modifying enzymes and chromatin remodeling, are pivotal for proficient DSB repair. Dynamic chromatin changes ensure accessibility to the damaged region, recruit DNA repair proteins, and regulate their association and activity, contributing to DSB repair pathway choice and coordination. Given the paramount importance of DSB repair in tumorigenesis and cancer progression, DSB repair has turned into an attractive target for the development of novel anticancer therapies, some of which have already entered the clinic.

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Synergism between ATM and PARP1 Inhibition Involves DNA Damage and Abrogating the G2 DNA Damage Checkpoint

Cited by 36 publications

References 55 publications

MAPK4 silencing together with a PARP1 inhibitor as a combination therapy in triple‑negative breast cancer cells

MAPK4 silencing together with a PARP1 inhibitor as a combination therapy in triple‑negative breast cancer cells

One-step multiplex toolkit for efficient generation of conditional gene silencing human cell lines

The Chromatin Response to Double-Strand DNA Breaks and Their Repair

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