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Nimotuzumab enhances radiation sensitivity of NSCLC H292 cells in vitro by blocking epidermal growth factor receptor nuclear translocation and inhibiting radiation-induced DNA damage repair.

Teng K, Zhang Y, Hu X, Ding Y, Gong R, Liu L - Onco Targets Ther (2015)

Bottom Line: Nimotuzumab reduced the viability of H292 cells and sensitized H292 cells to ionizing radiation.H292 cells after nimotuzumab administration were arrested at the G0/G1 phase in response to radiation.Our research revealed a possible mechanism to explain the radiosensitivity in H292 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Thoracic Oncology, Cancer Center of Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China ; Department of Radiation Oncology, Hainan Cancer Hospital, Haikou, Hainan, People's Republic of China.

ABSTRACT

Background: The epidermal growth factor receptor (EGFR) signaling pathway plays a significant role in radiation resistance. There is evidence that EGFR nuclear translocation is associated with DNA double-strand breaks (DSB) repair. Nimotuzumab has shown the effect of radiosensitization in various cancer cells, but little is known about the relationship between nimotuzumab and EGFR nuclear translocation in non-small cell lung cancer (NSCLC) cell lines. In this study, we selected two NSCLC cell lines, namely, H292 (with high EGFR expression) and H1975 (with low EGFR expression) and explored the mechanisms underlying radiation sensitivity.

Methods: MTT assay, clonogenic survival assay, and flow cytometry were performed separately to test cell viability, radiation sensitivity, cell cycle distribution, and apoptosis. Protein γ-H2AX, DNA-PK/p-DNA-PK, and EGFR/p-EGFR expression were further compared both in the cytoplasm and the nucleus with the western blot.

Results: Nimotuzumab reduced the viability of H292 cells and sensitized H292 cells to ionizing radiation. The radiation sensitivity enhancement ratio (SER) was 1.304 and 1.092 for H292 and H1975 cells, respectively. H292 cells after nimotuzumab administration were arrested at the G0/G1 phase in response to radiation. Apoptosis was without statistical significance in both cell lines. γ-H2AX formation in the combination group (nimotuzumab and radiation) increased both in the cytoplasm and the nucleus along with the decreased expression of nuclear EGFR/p-EGFR and p-DNA-PK in H292 cells (P<0.05) that was more significant than that in H1975 cells.

Conclusion: Our research revealed a possible mechanism to explain the radiosensitivity in H292 cells. Nimotuzumab decreased the radiation-induced activation of DNA-PK by blocking EGFR nuclear translocation and impairing DNA DSB repair, thus enhancing radiosensitivity in H292 cells. Because these results represent early research, the matters of how γ-H2AX and DNA-PK dynamically change simultaneously with nuclear EGFR and the best time to administer nimotuzumab will require further exploration.

No MeSH data available.


Related in: MedlinePlus

Illustration of EGFR/p-EGFR expression in both cytoplasm and nucleus.Notes: Cytoplasmic p-EGFR expression was decreased in both cell lines when comparing the RT group with the RT+h-R3 group. The decrease was more significant in H292 cells, but the decrease did not reach statistical significance (B and C). Nuclear EGFR and p-EGFR was significantly decreased in H292 cells (D and F, P<0.05), and the decrease in H1975 cells was not statistically significant (E and G). (A) illustrates the brief profile of protein expression (n=3). Each bar represents the mean ± SD and *indicates significant difference (P<0.05).Abbreviations: EGFR, epidermal growth factor receptor; p-EGFR, phospho-epidermal growth factor receptor; h-R3, nimotuzumab group; RT, irradiation group.
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f3-ott-8-809: Illustration of EGFR/p-EGFR expression in both cytoplasm and nucleus.Notes: Cytoplasmic p-EGFR expression was decreased in both cell lines when comparing the RT group with the RT+h-R3 group. The decrease was more significant in H292 cells, but the decrease did not reach statistical significance (B and C). Nuclear EGFR and p-EGFR was significantly decreased in H292 cells (D and F, P<0.05), and the decrease in H1975 cells was not statistically significant (E and G). (A) illustrates the brief profile of protein expression (n=3). Each bar represents the mean ± SD and *indicates significant difference (P<0.05).Abbreviations: EGFR, epidermal growth factor receptor; p-EGFR, phospho-epidermal growth factor receptor; h-R3, nimotuzumab group; RT, irradiation group.

Mentions: EGFR expression was associated with radiation resistance. Phosphorylated EGFR expression in H292 cytoplasm was more significantly decreased than that in H1975 cells. As for the nucleus, EGFR and p-EGFR expression were suppressed in both cell lines; however, the decrease was more significant in H292 cells (P<0.05, Figure 3).


Nimotuzumab enhances radiation sensitivity of NSCLC H292 cells in vitro by blocking epidermal growth factor receptor nuclear translocation and inhibiting radiation-induced DNA damage repair.

Teng K, Zhang Y, Hu X, Ding Y, Gong R, Liu L - Onco Targets Ther (2015)

Illustration of EGFR/p-EGFR expression in both cytoplasm and nucleus.Notes: Cytoplasmic p-EGFR expression was decreased in both cell lines when comparing the RT group with the RT+h-R3 group. The decrease was more significant in H292 cells, but the decrease did not reach statistical significance (B and C). Nuclear EGFR and p-EGFR was significantly decreased in H292 cells (D and F, P<0.05), and the decrease in H1975 cells was not statistically significant (E and G). (A) illustrates the brief profile of protein expression (n=3). Each bar represents the mean ± SD and *indicates significant difference (P<0.05).Abbreviations: EGFR, epidermal growth factor receptor; p-EGFR, phospho-epidermal growth factor receptor; h-R3, nimotuzumab group; RT, irradiation group.
© Copyright Policy
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4403694&req=5

f3-ott-8-809: Illustration of EGFR/p-EGFR expression in both cytoplasm and nucleus.Notes: Cytoplasmic p-EGFR expression was decreased in both cell lines when comparing the RT group with the RT+h-R3 group. The decrease was more significant in H292 cells, but the decrease did not reach statistical significance (B and C). Nuclear EGFR and p-EGFR was significantly decreased in H292 cells (D and F, P<0.05), and the decrease in H1975 cells was not statistically significant (E and G). (A) illustrates the brief profile of protein expression (n=3). Each bar represents the mean ± SD and *indicates significant difference (P<0.05).Abbreviations: EGFR, epidermal growth factor receptor; p-EGFR, phospho-epidermal growth factor receptor; h-R3, nimotuzumab group; RT, irradiation group.
Mentions: EGFR expression was associated with radiation resistance. Phosphorylated EGFR expression in H292 cytoplasm was more significantly decreased than that in H1975 cells. As for the nucleus, EGFR and p-EGFR expression were suppressed in both cell lines; however, the decrease was more significant in H292 cells (P<0.05, Figure 3).

Bottom Line: Nimotuzumab reduced the viability of H292 cells and sensitized H292 cells to ionizing radiation.H292 cells after nimotuzumab administration were arrested at the G0/G1 phase in response to radiation.Our research revealed a possible mechanism to explain the radiosensitivity in H292 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Thoracic Oncology, Cancer Center of Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China ; Department of Radiation Oncology, Hainan Cancer Hospital, Haikou, Hainan, People's Republic of China.

ABSTRACT

Background: The epidermal growth factor receptor (EGFR) signaling pathway plays a significant role in radiation resistance. There is evidence that EGFR nuclear translocation is associated with DNA double-strand breaks (DSB) repair. Nimotuzumab has shown the effect of radiosensitization in various cancer cells, but little is known about the relationship between nimotuzumab and EGFR nuclear translocation in non-small cell lung cancer (NSCLC) cell lines. In this study, we selected two NSCLC cell lines, namely, H292 (with high EGFR expression) and H1975 (with low EGFR expression) and explored the mechanisms underlying radiation sensitivity.

Methods: MTT assay, clonogenic survival assay, and flow cytometry were performed separately to test cell viability, radiation sensitivity, cell cycle distribution, and apoptosis. Protein γ-H2AX, DNA-PK/p-DNA-PK, and EGFR/p-EGFR expression were further compared both in the cytoplasm and the nucleus with the western blot.

Results: Nimotuzumab reduced the viability of H292 cells and sensitized H292 cells to ionizing radiation. The radiation sensitivity enhancement ratio (SER) was 1.304 and 1.092 for H292 and H1975 cells, respectively. H292 cells after nimotuzumab administration were arrested at the G0/G1 phase in response to radiation. Apoptosis was without statistical significance in both cell lines. γ-H2AX formation in the combination group (nimotuzumab and radiation) increased both in the cytoplasm and the nucleus along with the decreased expression of nuclear EGFR/p-EGFR and p-DNA-PK in H292 cells (P<0.05) that was more significant than that in H1975 cells.

Conclusion: Our research revealed a possible mechanism to explain the radiosensitivity in H292 cells. Nimotuzumab decreased the radiation-induced activation of DNA-PK by blocking EGFR nuclear translocation and impairing DNA DSB repair, thus enhancing radiosensitivity in H292 cells. Because these results represent early research, the matters of how γ-H2AX and DNA-PK dynamically change simultaneously with nuclear EGFR and the best time to administer nimotuzumab will require further exploration.

No MeSH data available.


Related in: MedlinePlus