Serine Phosphorylation-Dependent Coregulation of Topoisomerase I by the p14ARF Tumor Suppressor

Bandyopadhyay, Keya; Lee, Casey; Haghighi, A. Pejmun; Banères, Jean-Louis; Parello, Joseph; Gjerset, Ruth A.

doi:10.1021/bi7013618

Cited by 11 publications

(41 citation statements)

References 57 publications

(77 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indirect mechanisms of phosphorylation dependent regulation of TopI has previously been reported by the Gjerset group showing that hyperphosphorylated TopI forms a complex with the p14ARF tumor suppressor and that p14ARF may play a role in modulating TopI activity and CPT sensitivity of cancer cell lines [60].…”

Section: Discussionmentioning

confidence: 85%

See 1 more Smart Citation

Decreased Camptothecin Sensitivity of the Stem-Cell-Like Fraction of Caco2 Cells Correlates with an Altered Phosphorylation Pattern of Topoisomerase I

et al. 2014

View full text Add to dashboard Cite

The CD44+ and CD44− subpopulations of the colorectal cancer cell line Caco2 were analyzed separately for their sensitivities to the antitumor drug camptothecin. CD44+ cells were less sensitive to camptothecin than CD44− cells. The relative resistance of CD44+ cells was correlated with (i) reduced activity of the nuclear enzyme topoisomerase I and (ii) insensitivity of this enzyme to camptothecin when analyzed in extracts. In contrast, topoisomerase I activity was higher in extracts from CD44− cells and the enzyme was camptothecin sensitive. Topoisomerase I from the two subpopulations were differentially phosphorylated in a manner that appeared to determine the drug sensitivity and activity of the enzyme. This finding was further supported by the fact that phosphorylation of topoisomerase I in CD44+ cell extract by protein kinase CK2 converted the enzyme to a camptothecin sensitive, more active form mimicking topoisomerase I in extracts from CD44− cells. Conversely, dephosphorylation of topoisomerase I in extracts from CD44− cells rendered the enzyme less active and camptothecin resistant. These findings add to our understanding of chemotherapy resistance in the Caco2 CD44+ cancer stem cell model.

show abstract

Section: Discussionmentioning

confidence: 85%

“…One of the well known post-translational modifications that can regulate the activity of TopI is phosphorylation [18], [58], [59], [60], [61]. We therefore investigated the phosphorylation pattern of TopI in extracts from different Caco2 cell subpopulations by 2D gel-electrophoresis.…”

Section: Resultsmentioning

confidence: 99%

Decreased Camptothecin Sensitivity of the Stem-Cell-Like Fraction of Caco2 Cells Correlates with an Altered Phosphorylation Pattern of Topoisomerase I

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Although complete absence of topo I is lethal to mammalian cells, the level of topo I can be highly variable amongst tumor specimens and cell lines (4–8) and this can lead to variable cellular responses to camptothecin and related drugs (6). Low level expression of topo I in cultured cells can be selected by long term exposure to camptothecin (9) and correlates with camptothecin resistance [reviewed in (10– 12)].…”

mentioning

confidence: 99%

Protein Kinase CK2 Is a Central Regulator of Topoisomerase I Hyperphosphorylation and Camptothecin Sensitivity in Cancer Cell Lines

Bandyopadhyay

Gjerset

2011

Biochemistry

Self Cite

View full text Add to dashboard Cite

Topoisomerase I (topo I) is required to unwind DNA during synthesis, and provides the unique target for camptothecin-derived chemotherapeutic agents, including Irinotecan and Topotecan. While these agents are highly effective anticancer agents, some tumors do not respond due to intrinsic or acquired resistance, a process that remains poorly understood. Because of treatment toxicity, there is interest in identifying cellular factors that regulate tumor sensitivity and might serve as predictive biomarkers of therapy sensitivity. Here we identify the serine kinase, protein kinase CK2, as a central regulator of topo I hyperphosphorylation and activity, and cellular sensitivity to camptothecin. In 9 cancer cell lines and 3 normal tissue-derived cell lines we observe a consistent correlation between CK2 levels and camptothecin responsiveness. Two other topo Itargeted serine kinases, protein kinase C and cyclin-dependent kinase1, do not show this correlation. Camptothecin-sensitive cancer cell lines display high CK2 activity, hyperphosphorylation of topo I, elevated topo I activity, and elevated phosphorylation-dependent complex formation between topo I and p14ARF, a topo I activator. Camptothecin-resistant cancer cell lines and normal cell lines display lower CK2 activity, lower topo I phosphorylation, lower topo I activity, and undetectable topo I/p14ARF complex formation. Experimental inhibition or activation of CK2 demonstrates that CK2 is necessary and sufficient for regulating these topo I properties and altering cellular responses to camptothecin. The results establish a cause and effect relationship between CK2 activity and camptothecin sensitivity, and suggest that CK2, topo I phosphorylation, or topo I/p14ARF complex formation could provide biomarkers of therapy responsive tumors. Figure S1), (2) Effect of CK2 activator on purified PKC, cdk1, and CK2 activities, and on endogenous PKC and cdk1 activity in H23 cells ( Figure S2), (3) Effect of CK2 activator on CK2α transcription ( Figure S3), (4) Levels of serine/threonine phosphatase activity in cell lines ( Figure S4), and (5) Topo-I phosphorylation levels in A549 and K562 cell lines ( Figure S5). The material can be accessed free of charge via the Internet at

show abstract

“…2A, left, open triangles), over the 4-day period of the assay, consistent with previous observations. 36 In contrast, when cells were treated with 50 μM 1a and 5 nM CPT for 18 hours, followed by removal of the medium and replacement with medium containing 1a alone, [ 3 H]-thymidine incorporation decreased progressively on days 1 and 2. By day 2 post-start of treatment [ 3 H]-thymidine incorporation was less than 20% of untreated cells (Fig.…”

Section: Resultsmentioning

confidence: 93%

“…35 Treatment with 5 nM CPT alone for 18 hours has been previously shown to have minimal effects on growth of H358 cells. 36 For the combined CPT/1a treatments, the medium containing both 1a and CPT was removed from cells after 18 hours and replaced with fresh medium containing 1a only, and incubation was continued. Triplicate wells of cells were then pulsed 6 hours with [ 3 H]-thymidine at intervals 18–24 hr (Day 1), 42–48 hr (Day 2), 66–72 hr (Day 3) and 90–96 hr (Day 4) post-start of drug treatment.…”

Section: Resultsmentioning

confidence: 99%

Spermidinyl-CoA-based HAT inhibitors block DNA repair and provide cancer- specific chemo-and radiosensitization

Bandyopadhyay

Banères²,

Martin³

et al. 2009

Cell Cycle

Self Cite

View full text Add to dashboard Cite

Acetyl group turnover on specific lysine ε-amino groups of the core chromosomal histones regulates DNA accessibility function, and the acetylating and deacetylating enzymes that govern the turnover provide important targets for the development of anti-cancer drugs. Histone deacetylase (HDAC) inhibitors have been developed and evaluated extensively in clinical trials, while the development of inhibitors of histone acetyltransferase (HAT) has proceeded more slowly. Here we have examined the cellular effects of an S-substituted coenzyme A (CoA) inhibitor of histone acetylation, consisting of spermidine (Spd) linked to the S-terminus of CoA through a thioglycolic acid linkage (adduct abbreviated as Spd-CoA), as well as the effects of a truncated Spd-CoA derivative lacking the negatively charged portion of the CoA moiety. While exposure of cancer cells to Spd-CoA has little effect on cell viability, it causes a rapid inhibition of histone acetylation that correlates with a transient arrest of DNA synthesis, a transient delay in S-phase progression, and an inhibition of nucleotide excision repair and DNA double strand break repair. These effects correlate with increased cellular sensitivity to the DNA-targeted chemotherapeutic drugs, cisplatin (Platinol™) and 5-fluorouracil, to the DNA damaging drug, camptothecin, and to UV-C irradiation. The sensitization effects of Spd-CoA are not observed in normal cells due to a barrier to uptake. The truncated Spd-CoA derivative displays similar but enhanced chemosensitization effects, suggesting that further modifications of the Spd-CoA structure could further improve potency. The results demonstrate that Spd-CoA and its truncated version are efficiently and selectively internalized into cancer cells, and suggest that the resulting inhibition of acetylation-dependent DNA repair enhances cellular sensitivity to DNA damage. These and related inhibitors of histone acetylation could therefore constitute a novel class of potent therapy sensitizers applicable to a broad range of conventional cancer treatments.

show abstract

Serine Phosphorylation-Dependent Coregulation of Topoisomerase I by the p14ARF Tumor Suppressor

Cited by 11 publications

References 57 publications

Decreased Camptothecin Sensitivity of the Stem-Cell-Like Fraction of Caco2 Cells Correlates with an Altered Phosphorylation Pattern of Topoisomerase I

Decreased Camptothecin Sensitivity of the Stem-Cell-Like Fraction of Caco2 Cells Correlates with an Altered Phosphorylation Pattern of Topoisomerase I

Protein Kinase CK2 Is a Central Regulator of Topoisomerase I Hyperphosphorylation and Camptothecin Sensitivity in Cancer Cell Lines

Spermidinyl-CoA-based HAT inhibitors block DNA repair and provide cancer- specific chemo-and radiosensitization

Contact Info

Product

Resources

About