Transcriptional control of DNA repair networks by CDK7 regulates sensitivity to radiation in Myc-driven Medulloblastoma

Veo, Bethany; Danis, Etienne; Pierce, Angela; Wang, Dong; Fosmire, Susan; Sullivan, Kelly D.; Joshi, Molishree; Khanal, Santosh; Dahl, Nathan; Karam, Sana D.; Serkova, Natalie J.; Venkataraman, Sujatha; Vibhakar, Rajeev

doi:10.1101/2020.04.30.069237

Cited by 6 publications

(15 citation statements)

References 61 publications

(65 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Interestingly, our results show that CDK7 knockout also slightly increased cell apoptosis without chemotherapy (Fig. 2D and F); this may be related to the role of CDK7 in transcriptional control of DDR networks [39,40].…”

Section: Knockout Of Cdk7 Combined With Gemcitabine and Paclitaxel Ch...mentioning

confidence: 55%

“…1D), whose loss of function via specific sgRNAs led to lethality in the presence of gemcitabine and paclitaxel (Supplementary Table S4). Interestingly, CDK7 is involved in a wide spectrum of biological processes, including cell cycle regulation and DNA damage response [39]. The majority of CDK7-targeting sgRNA standardized read counts were considerably lower following treatment with gemcitabine and paclitaxel compared to non-treated cells (Fig.…”

Section: Crispr-cas9 Screening Identifies Genes Whose Deficiency Sens...mentioning

confidence: 99%

“…Following this, we investigated the mechanism through which CDK7 deficiency results in chemosensitivity. CDK7 is required for RNAPII-mediated transcription and also functions as an integral component of the transcription factor TFIIH, which is involved in transcription initiation and DDR [32,39]. We performed Western blot analysis of apoptosis and DDR-associated proteins in TB32047 and MIA PaCa-2 KO cell lines treated with vehicle or GEM and PTX.…”

Section: Knockout Of Cdk7 Combined With Gemcitabine and Paclitaxel Ch...mentioning

confidence: 99%

See 2 more Smart Citations

CDK7 inhibition augments response to multidrug chemotherapy in pancreatic cancer

Zeng

Lan

Ren

et al. 2022

J Exp Clin Cancer Res

View full text Add to dashboard Cite

Background Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with a dismal prognosis. Although combined treatment with gemcitabine and albumin-bound paclitaxel has improved the prognosis of PDAC, both intrinsic and acquired chemoresistance remain as severe hurtles towards improved prognosis. Thus, new therapeutic targets and innovative strategies are urgently needed. Methods In this study, we used the KPC mouse model-derived PDAC cell line TB32047 to perform kinome-wide CRISPR-Cas9 loss-of-function screening. Next-generation sequencing and MAGeCK-VISPR analysis were performed to identify candidate genes. We then conducted cell viability, clonogenic, and apoptosis assays and evaluated the synergistic therapeutic effects of cyclin-dependent kinase 7 (CDK7) depletion or inhibition with gemcitabine (GEM) and paclitaxel (PTX) in a murine orthotopic pancreatic cancer model. For mechanistic studies, we performed genome enrichment analysis (GSEA) and Western blotting to identify and verify the pathways that render PDAC sensitive to GEM/PTX therapy. Results We identified several cell cycle checkpoint kinases and DNA damage-related kinases as targets for overcoming chemoresistance. Among them, CDK7 ranked highly in both screenings. We demonstrated that both gene knockout and pharmacological inhibition of CDK7 by THZ1 result in cell cycle arrest, apoptosis induction, and DNA damage at least predominantly through the STAT3-MCL1-CHK1 axis. Furthermore, THZ1 synergized with GEM and PTX in vitro and in vivo, resulting in enhanced antitumor effects. Conclusions Our findings support the application of CRISPR-Cas9 screening in identifying novel therapeutic targets and suggest new strategies for overcoming chemoresistance in pancreatic cancer.

show abstract

Section: Knockout Of Cdk7 Combined With Gemcitabine and Paclitaxel Ch...mentioning

confidence: 55%

Section: Crispr-cas9 Screening Identifies Genes Whose Deficiency Sens...mentioning

confidence: 99%

Section: Knockout Of Cdk7 Combined With Gemcitabine and Paclitaxel Ch...mentioning

confidence: 99%

See 1 more Smart Citation

CDK7 inhibition augments response to multidrug chemotherapy in pancreatic cancer

Zeng

Lan

Ren

et al. 2022

J Exp Clin Cancer Res

View full text Add to dashboard Cite

show abstract

“…CDK7 has dual roles in regulation of transcription and cell division 42 . Two recent reports demonstrated that inhibition of CDK7 preferentially represses expression of genes in the DNA damage repair pathway and sensitized cancer cells to PARP inhibitor‐induced DNA damage 43 and ionizing irradiation 44 . However, our preliminary data with the same inhibitor of CDK7, THZ1, showed that inhibition of CDK7 catalytic activity did not resensitize DU145‐DxR to docetaxel (data not shown).…”

Section: Discussionmentioning

confidence: 65%

DNA‐PKc inhibition overcomes taxane resistance by promoting taxane‐induced DNA damage in prostate cancer cells

Chao

Goodman

2021

The Prostate

View full text Add to dashboard Cite

Background Overcoming taxane resistance remains a major clinical challenge in metastatic castrate‐resistant prostate cancer (mCRPC). Loss of DNA repair proteins is associated with resistance to anti‐microtubule agents. We propose that alterations in DNA damage response (DDR) pathway contribute to taxane resistance, and identification of these alterations may provide a potential therapeutic target to resensitize docetaxel‐refractory mCRPC to taxane‐based therapy. Methods Alterations in DDR gene expression in our prostate cancer cell line model of docetaxel‐resistance (DU145‐DxR) derived from DU‐145 cells were determined by DDR pathway‐specific polymerase chain reaction array and immunoblotting. The PRKDC gene encoding DNA‐PKc (DNA‐dependent protein kinase catalytic unit), was noted to be overexpressed and evaluated for its role in docetaxel resistance. Cell viability and clonogenic survival of docetaxel‐treated DU145‐DxR cells were assessed after pharmacologic inhibition of DNA‐PKc with three different inhibitors—NU7441, LTURM34, and M3814. Response to second‐line cytotoxic agents, cabazitaxel and etoposide upon DNA‐PKc inhibition was also tested. The impact of DNA‐PKc upregulation on DNA damage repair was evaluated by comet assay and analysis of double‐strand breaks marker, γH2AX and Rad51. Lastly, DNA‐PKc inhibitor's effect on MDR1 activity was assessed by rhodamine 123 efflux assay. Results DDR pathway‐specific gene profiling revealed significant upregulation of PRKDC and CDK7, and downregulation of MSH3 in DU145‐DxR cells. Compared to parental DU145, DU145‐DxR cells sustained significantly less DNA damage when exposed to etoposide and docetaxel. Pharmacologic inhibition of DNA‐PKc, a component of NHEJ repair machinery, with all three inhibitors, significantly resensitized DU145‐DxR cells to docetaxel. Furthermore, DNA‐PKc inhibition also resensitized DU145‐DxR to cabazitaxel and etoposide, which demonstrated cross‐resistance. Inhibition of DNA‐PKc led to increased DNA damage in etoposide‐ and docetaxel‐treated DU145‐DxR cells. Finally, DNA‐PKc inhibition did not affect MDR1 activity, indicating that DNA‐PKc inhibitors resensitized taxane‐resistant cells via an MDR1‐independent mechanism. Conclusion This study supports a role of DDR genes, particularly, DNA‐PKc in promoting resistance to taxanes in mCRPC. Targeting prostatic DNA‐PKc may provide a novel strategy to restore taxane sensitivity in taxane‐refractory mCRPC.

show abstract

“…There is a growing body of evidence suggesting that other cyclin-dependent kinases including CDK7, CDK8, CDK9, and CDK12 may also be important for modulating the sensitivity of cancer cells to the effects of ionizing radiation (41)(42)(43). In contrast to CDK4/6 inhibitor-mediated radiosensitization in breast cancer that is primarily mediated through suppression of HR, inhibition of other CDK proteins leads to increased apoptosis, senescence, and/or inhibition of RNA Polymerase II function that leads to radiosenstization (41)(42)(43).…”

Section: Discussionmentioning

confidence: 99%

RB expression confers sensitivity to CDK4/6 inhibitor–mediated radiosensitization across breast cancer subtypes

Pesch¹,

Hirsh²,

Michmerhuizen³

et al. 2022

JCI Insight

View full text Add to dashboard Cite

Standard radiation (RT) therapy does not reliably provide locoregional control for women with multi-node positive and triple-negative (TNBC) breast cancers. We hypothesized that CDK4/6 inhibition (CDK4/6i) would increase the radiosensitivity not only of estrogen receptor positive (ER+) cells, but also TNBC that express retinoblastoma (RB) protein. We found that CDK4/6i radiosensitized RB wild-type TNBC (n=4, rER 1.49 -2.22), but failed to radiosensitize RB-null TNBC (n=3, rER: 0.84 -1.00). RB expression predicted response to CDK4/6i + RT (R 2 =0.84), and radiosensitization was lost in ER+/TNBC cells (rER: 0.88 -1.13) after RB1 knockdown in isogenic and non-isogenic models. CDK4/6i suppressed homologous recombination (HR) in RB wild-type cells, but not in RB-null cells or isogenic models of RB1 loss; HR competency was rescued with RB re-expression. Radiosensitization was independent of non-homologous end joining and the known effects of CDK4/6i on cell cycle arrest. Mechanistically, RB and RAD51 interact in vitro to promote HR repair. CDK4/6i produced RB-dependent radiosensitization in TNBC xenografts, but not in isogenic RB1-null xenografts. Our data provide the preclinical rationale for a clinical trial expanding the use of CDK4/6i + RT to difficult to control RBintact breast cancers (including TNBC) and nominate RB status as a predictive biomarker of therapeutic efficacy.

show abstract

Transcriptional control of DNA repair networks by CDK7 regulates sensitivity to radiation in Myc-driven Medulloblastoma

Cited by 6 publications

References 61 publications

CDK7 inhibition augments response to multidrug chemotherapy in pancreatic cancer

CDK7 inhibition augments response to multidrug chemotherapy in pancreatic cancer

DNA‐PKc inhibition overcomes taxane resistance by promoting taxane‐induced DNA damage in prostate cancer cells

RB expression confers sensitivity to CDK4/6 inhibitor–mediated radiosensitization across breast cancer subtypes

Contact Info

Product

Resources

About