Abstract:

Objective

To overcome cisplatin resistance in lung cancer cells，a novel metal-organic framework （MOF） nanocarrier delivery system with chemo-photodynamic combined efficacy was developed.

Methods

MOFs were synthesized using the Tetrakis（4-hydroxyphenyl） porphyrin （THPP） and loaded with cisplatin through ultrasonic emulsification method to form a drug-loaded nanosystem （Cisplatin@MOFs），which were activated under the near-infrared irradiation.The physicochemical properties were characterized though the particle size，Zeta potential，and the singlet oxygen detection experiments.The particle size and surface zeta potential were measured by the dynamic light scattering （DLS） and the shape of samples was visualized by transmission electron microscopy （TEM）.The singlet oxygen release was detected by the ROS indicator.The cisplatin release from Cisplatin@ MOF nanoparticles were assessed by the dialysis diffusion method.In vitro cytotoxicity was observed by using a CCK8 （cell counting kit-8） assay.The combined anti-tumor effect was investigated through the measurement of cell proliferation and cell migration.The proliferation was observed by Ki67 fluorescence staining and the cell migaration was assessed by the wound-healing experiment.Western Blot analysis was employed to explore the underlying regulatory mechanisms.

Results

Transmission electron microscopy （TEM） characterization showed that the Cisplatin@MOF exhibited a polygonal spherical structure with a particle size of（431.33±21.47）nm.The dynamic light scattering （DLS） measurements indicated an average size of approximately 458 nm for Cisplatin@ MOF，with a polydispersity index （PDI） of 0.482.The Zeta potential values were（3.20±0.23）mV for MOF and（6.63±0.81） mV for Cisplatin@ MOF，respectively.Under near-infrared irradiation，the MOF nanoparticles could release the singlet oxygen.The ROS generation ability of the MOFs was detected by the indicater （DPBF） and the results demonstrated the photodynamic protential.The loading capacity of cisplatin in the Cisplatin@ MOF nanodrug delivery system was （41.73±2.66）%.Release tests showed that Cisplatin@MOF could release cisplatin under acidic conditions by a dialysis method.Then we used the confocal laser scanning microscopy （CLSM） to examine the cellular internalization of MOF nanoparticles.In vitro we conducted a cell viability assay （CCK8） to evaluate MOF's cytotoxicity in cisplatin-resistant lung cancer cells （A549-DDP）.The results showed that compared to control and no-laser groups，a significant reduce in cell viability was observed in cells treated under light irradiation.Cisplatin@MOF under light irradiation exhibited the strongest damage on the cisplatin-resistant lung cancer cells.We used fluorescence immunostaining analysis of Ki67 marker to assess the cell proliferation.The results revealed that the lower Ki67 expression in the cells treated under light irradiation compared to the control and dark groups.Cisplatin@MOF under light irradiation showed the lowest Ki67 expression of cell proliferation.It was conducted that the cell scratch test to examine the impact of MOFs on cell migration.The results revealted that the cells receiving the later treatment demonstrated weak cell migration compared to the control and dark groups.Cisplatin@MOF under light irradiation exhibited the weakest cell migration compared to other rtreatmens.Thse results confrm a significant chemophotothermal combined antitumor effect on cisplatin-resistance tumor cells.Futhernore，we used the Western Blot assays to ascess the protein levels of Bcl-2/Bax signaling pathway.Cells treated with light irradiation inhibited significantly lower levels of Bcl-2 expresion compared to control and nolaser groups.And the protein levels of Bax were significantly increased in the cells from the laser groups compared to the control and dark groups.These results suggested Bcl-2/Bax signaling pathway's potential as the ksy mechanism for combined antitumor effects.

Conclusion

In summary，we developed a multifunctional MOFs-based drug delivery system that combines chemotherapy and PDT for a novel strategy.This system effectively overcomes cisplatin resistance and demonstrates combined therapeutic efficacy through chemophotodynamic therapy.These findings suggest it could potentially serve as a more efficient targeted therapy for lung cancer.

Key words: Bronchogenic carcinoma, Metal organic framework, Nano transport system, Chemophotodynamic combined therapy, Cisplatin resistance