Dissociation of gemcitabine chemosensitization by CHK1 inhibition from cell cycle checkpoint abrogation and aberrant mitotic entry

Parsels, Leslie A.; Tanska, Daria M.; Parsels, Joshua D.; Zabludoff, Sonya; Cuneo, Kyle C.; Lawrence, Theodore S.; Maybaum, Jonathan; Morgan, Meredith A.

doi:10.1080/15384101.2016.1148841

Cited by 16 publications

(14 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, with the exception of a partial effect in MiaPaCa2 cells, roscovitine prevented AZD1775-mediated gemcitabine chemosensitization. These results are consistent with previous studies suggesting CDK1/2 hyperactivity is a significant factor in gemcitabine chemosensitization by either CHK1 [30] or WEE1 inhibitors [31] in some, but not all, cell lines.…”

Section: Contribution Of Dna Replication Stress To Gemcitabine Chemossupporting

confidence: 93%

“…As we and others have shown, persistent replication stress resulting from either gemcitabine [34], CHK1 [7,22] or WEE1 inhibitor [21] is associated with a high-intensity, pan-nuclear staining pattern that has been proposed as a potential biomarker for therapeutic response to these drugs [30]. To further test this hypothesis, we next assessed the contribution of CDK2 Figure 2.…”

Section: Correlation Between High Intensity γH2ax Staining and Gemcitmentioning

confidence: 94%

“…Figure 4B). Furthermore, we previously found that depletion of Cyclin B1 with siRNA and subsequent loss of Cyclin B-CDK1 activity (as indicated by inhibition of aberrant mitotic entry) did not affect gemcitabine sensitization by the CHK inhibitor AZD7762, suggesting that inhibition of CDK2, rather than CDK1, is responsible for this effect [30]. These results, combined with the results from multiple studies documenting the effects of roscovitine on either the CHK1-mediated intra-S-phase checkpoint or CHK1 and WEE1-mediated replication stress [6,7,27,33], are consistent with the hypothesis that roscovitine-mediated CDK2 inhibition is responsible for the effects of roscovitine on gemcitabine chemosensitization.…”

Section: Contribution Of Dna Replication Stress To Gemcitabine Chemosmentioning

confidence: 99%

See 2 more Smart Citations

The contribution of DNA replication stress marked by high-intensity, pan-nuclear γH2AX staining to chemosensitization by CHK1 and WEE1 inhibitors

Parsels

Tanska

et al. 2018

Cell Cycle

Self Cite

View full text Add to dashboard Cite

Small molecule inhibitors of the checkpoint proteins CHK1 and WEE1 are currently in clinical development in combination with the antimetabolite gemcitabine. It is unclear, however, if there is a therapeutic advantage to CHK1 vs. WEE1 inhibition for chemosensitization. The goals of this study were to directly compare the relative efficacies of the CHK1 inhibitor MK8776 and the WEE1 inhibitor AZD1775 to sensitize pancreatic cancer cell lines to gemcitabine and to identify pharmacodynamic biomarkers predictive of chemosensitization. Cells treated with gemcitabine and either MK8776 or AZD1775 were first assessed for clonogenic survival. With the exception of the homologous recombination-defective Capan1 cells, which were relatively insensitive to MK8776, we found that these cell lines were similarly sensitized to gemcitabine by CHK1 or WEE1 inhibition. The abilities of either the CDK1/2 inhibitor roscovitine or exogenous nucleosides to prevent MK8776 or AZD1775-mediated chemosensitization, however, were both inhibitor-dependent and variable among cell lines. Given the importance of DNA replication stress to gemcitabine chemosensitization, we next assessed high-intensity, pan-nuclear γH2AX staining as a pharmacodynamic marker for sensitization. In contrast to total γH2AX, aberrant mitotic entry or sub-G1 DNA content, high-intensity γH2AX staining correlated with chemosensitization by either MK8776 or AZD1775 (R 0.83 - 0.53). In summary, we found that MK8776 and AZD1775 sensitize to gemcitabine with similar efficacy. Furthermore, our results suggest that the effects of CHK1 and WEE1 inhibition on gemcitabine-mediated replication stress best predict chemosensitization and support the use of high-intensity or pan-nuclear γH2AX staining as a marker for therapeutic response.

show abstract

Section: Contribution Of Dna Replication Stress To Gemcitabine Chemossupporting

confidence: 93%

Section: Correlation Between High Intensity γH2ax Staining and Gemcitmentioning

confidence: 94%

Section: Contribution Of Dna Replication Stress To Gemcitabine Chemosmentioning

confidence: 99%

See 1 more Smart Citation

The contribution of DNA replication stress marked by high-intensity, pan-nuclear γH2AX staining to chemosensitization by CHK1 and WEE1 inhibitors

Parsels

Tanska

et al. 2018

Cell Cycle

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is becoming increasingly clear that sensitivity to Chk1 inhibitors is a consequence of DNA damage in S phase (Koh et al, 2015;Parsels et al, 2016;Sakurikar et al, 2016;Sanjiv et al, 2016;Techer et al, 2016;Wayne et al, 2016). Our work complements these findings, by defining excess origin firing as the predominant mechanism that causes such DNA damage.…”

Section: Fitness Of Chk1-deficient Cells Is Multifactorialsupporting

confidence: 61%

Chk1 loss creates replication barriers that compromise cell survival independently of excess origin firing

et al. 2019

View full text Add to dashboard Cite

The effectiveness of checkpoint kinase 1 (Chk1) inhibitors at killing cancer cells is considered to be fully dependent on their effect on DNA replication initiation. Chk1 inhibition boosts origin firing, presumably limiting the availability of nucleotides and in turn provoking the slowdown and subsequent collapse of forks, thus decreasing cell viability. Here we show that slow fork progression in Chk1‐inhibited cells is not an indirect effect of excess new origin firing. Instead, fork slowdown results from the accumulation of replication barriers, whose bypass is impeded by CDK‐dependent phosphorylation of the specialized DNA polymerase eta (Polη). Also in contrast to the linear model, the accumulation of DNA damage in Chk1‐deficient cells depends on origin density but is largely independent of fork speed. Notwithstanding this, origin dysregulation contributes only mildly to the poor proliferation rates of Chk1‐depleted cells. Moreover, elimination of replication barriers by downregulation of helicase components, but not their bypass by Polη, improves cell survival. Our results thus shed light on the molecular basis of the sensitivity of tumors to Chk1 inhibition.

show abstract

“…Aphidicolin treatment results in S‐phase arrest through direct inhibition of DNA polymerases (Vesela et al ., ). Nocodazole is a microtubule‐disrupting drug that can block the G 2 ‐to‐M phase transition (Parsels et al ., ). When treated with roscovitine, HU and aphidicolin, the transcripts of AtRFC4 increased significantly, but AtRFC4 expression decreased when treated with mimosine.…”

Section: Resultsmentioning

confidence: 97%

Arabidopsis replication factor C4 is critical for DNA replication during the mitotic cell cycle

Qian

Chen

et al. 2018

The Plant Journal

View full text Add to dashboard Cite

Replication factor C (RFC) is a conserved eukaryotic complex consisting of RFC1/2/3/4/5. It plays important roles in DNA replication and the cell cycle in yeast and fruit fly. However, it is not very clear how RFC subunits function in higher plants, except for the Arabidopsis (At) subunits AtRFC1 and AtRFC3. In this study, we investigated the functions of AtRFC4 and found that loss of function of AtRFC4 led to an early sporophyte lethality that initiated as early as the elongated zygote stage, all defective embryos arrested at the two- to four-cell embryo proper stage, and the endosperm possessed six to eight free nuclei. Complementation of rfc4-1/+ with AtRFC4 expression driven through the embryo-specific DD45pro and ABI3pro or the endosperm-specific FIS2pro could not completely restore the defective embryo or endosperm, whereas a combination of these three promoters in rfc4-1/+ enabled the aborted ovules to develop into viable seeds. This suggests that AtRFC4 functions simultaneously in endosperm and embryo and that the proliferation of endosperm is critical for embryo maturation. Assays of DNA content in rfc4-1/+ verified that DNA replication was disrupted in endosperm and embryo, resulting in blocked mitosis. Moreover, we observed a decreased proportion of late S-phase and M-phase cells in the rfc4-1/- seedlings, suggesting that incomplete DNA replication triggered cell cycle arrest in cells of the root apical meristem. Therefore, we conclude that AtRFC4 is a crucial gene for DNA replication.

show abstract

Dissociation of gemcitabine chemosensitization by CHK1 inhibition from cell cycle checkpoint abrogation and aberrant mitotic entry

Cited by 16 publications

References 46 publications

The contribution of DNA replication stress marked by high-intensity, pan-nuclear γH2AX staining to chemosensitization by CHK1 and WEE1 inhibitors

The contribution of DNA replication stress marked by high-intensity, pan-nuclear γH2AX staining to chemosensitization by CHK1 and WEE1 inhibitors

Chk1 loss creates replication barriers that compromise cell survival independently of excess origin firing

Arabidopsis replication factor C4 is critical for DNA replication during the mitotic cell cycle

Contact Info

Product

Resources

About