TopBP1 contributes to the chemoresistance in non-small cell lung cancer through upregulation of p53

Figures & data

Table 1 Determination of doxorubicin IC₅₀ in different tumor cell lines

IC50(μg/mL)	48 hours	72 hours
NCI-H358	0.5409	0.3677
A549	0.3304	0.1263
HCC827	0.8896	0.777
NCI-H1299	3.423	1.030

Abbreviation: IC₅₀, 50% inhibitory concentration.

Figure 1 Different doxorubicin sensitivity and topoisomerase IIβ binding protein 1 (TopBP1) expression in lung cancer cells.

Notes: Lung cancer cells were incubated with different concentrations of doxorubicin for 48 or 72 hours. CCK-8 assay was applied to measure the cell viability of different lung cancer including NCI-H358 (A), A549 (B), NCI-H1299 (C), and HCC827 (D). Western blot was used to detect the protein expression of TopBP1 in four cancer cell lines (E).

Figure 2 Measurement of cell proliferation in lung cancer cells.

Notes: Lung cancer cells were incubated with or without doxorubicin (Dox) for 48 hours. EdU incorporation assay was performed to measure the proliferation of NCI-H358 (A), NCI-H1299 (B), A549 (C), and HCC827 (D) cells. *P<0.05.

Figure 3 TopBP1 was involved in the chemoresistance of tumor cells.

Notes: TopBP1 siRNA was transfected into different lung cancer cells and Western blot was applied to detect the protein levels of TopBP1 and p53 in tumor cells with or without doxorubicin treatment (A). After transfection, the chemosensitivity of NCI-H1299 cells to doxorubicin was measured using CCK-8 methods (B).
Abbreviations: TopBP1, topoisomerase IIβ binding protein 1; siRNA, small interfering RNA.

Figure 4 Measurement of cell proliferation in TopBP1 siRNA-transfected lung cancer cells.

Notes: Lung cancer cells were transfected with TopBP1 siRNA or control siRNA in the presence of doxorubicin (Dox). EdU incorporation assay was performed to measure the proliferation of NCI-H358 (A), NCI-H1299 (B), A549 (C), and HCC827 (D) cells. *P<0.05.
Abbreviations: TopBP1, topoisomerase IIβ binding protein 1; siRNA, small interfering RNA.

Figure 5 Upregulation of p53 by topoisomerase IIβ binding protein 1 (TopBP1) in NCI-H1299 cells.

Notes: Lung cancer cells were incubated with or without doxorubicin for 48 hours. Co-immunoprecipitation assay was applied to detect the expression of TopBP1 and p53 in NCI-H1299 (A), -and 827 cells (B).
Abbreviations: Ctrl, control; Dox, doxorubicin; TopBP1, topoisomerase IIβ binding protein 1.

Figure S1 Cell viability (A) and apoptosis (B) in doxorubicin (Dox)-treated non-small cell lung cancer cells before and after p53 knockdown. * represents statistical significance with P<0.05.

Abbreviations: siRNA, small interfering RNA; IC₅₀, 50% inhibitory concentration.

Figure S2 Effect of TopBP1 in non-small cell lung cancer cells.

Abbreviations: TopBP1, topoisomerase IIβ binding protein 1; siRNA, small interfering RNA.