Hypoxia-augmented chemotherapy potentiates imaging-guided combinatorial radionuclide-sonodynamic therapy for pancreatic cancer

Abstract

Radionuclide therapy and chemotherapy are effective for pancreatic cancer, yet their efficacy is often limited by tumor hypoxia. In this study, manganese porphyrin (MnTTP) and tirapazamine (TPZ) were encapsulated in polylactic-co-glycolic acid (PLGA) spheres, which were subsequently coated with polydopamine to label the radionuclide ¹³¹I, forming a theranostic nanoplatform. The nanoplatform demonstrated excellent biocompatibility, stable labeling efficiency, and dual-modal MRI/SPECT imaging capabilities. The nanoplatform generated reactive oxygen species (ROS) under ultrasound(US) activation, in combination with the β-rays emitted by ¹³¹I, synergistically eradicate tumor cells and exacerbate hypoxia in the tumor microenvironment. Furthermore, TPZ was activated to produce toxic free radicals under hypoxic conditions, enabling a synergistic therapeutic approach that combined radionuclide therapy and sonodynamic therapy. This approach effectively inhibited tumor stem cell formation and enhanced anti-tumor efficacy. Additionally, the nanoplatform's metabolism in vivo and the therapeutic effect were monitored in real-time under MRI/SPECT dual-modality imaging. This therapeutic strategy offers a promising solution for overcoming tumor hypoxia and achieving efficient combination therapy for tumors.

Keywords: Hypoxia-activated chemotherapy; Radionuclide therapy; SPECT imaging; Sonodynamic therapy; Synergistic therapeutic.

Scheme 1

Schematic of the synthetic route of ¹³¹I-TMP@D and the synergistic diagnosis and treatment of radionuclide therapy, sonodynamic therapy, and hypoxia-activated chemotherapy

Fig. 1

Hydration particle size distribution of TMP and TMP@D(100 µg·mL^− 1) (A); TEM images of TMP@D (B); UV-visible absorption spectrum of TPZ, MnTTP, and TMP@D (C); Zeta potential of TP, MP, TMP and TMP@D (D); Intensity change curves of singlet oxygen release after ultrasound with different concentrations of TMP@D (E); Intensity change curves of singlet oxygen released from the same concentration of TMP@D (100 µg·mL^− 1) after ultrasound for different numbers of times (F); Plot of R1 (1/T1) versus concentration of TMP@D corresponding relaxivity (inset: T1 weighted MR imaging) (G); Radiochemical purity of ¹³¹I and ¹³¹I-TMP@D (H); Haemolysis of erythrocytes in different concentrations of TMP@D nanoplatforms (I)

Fig. 2

Confocal laser scanning microscopy (CLSM) (A) and intensity surface plot of CLSM for the penetration about Cy5 and lyso-tracker in BxPC-3 after ¹³¹I-TMP@D-Cy5(200 µg·mL^− 1, 50 µCi·mL^− 1) co-incubation for 1, 3, 6 h (B); fluorescence semi-quantitative analysis of Cy5 (C) and the Pearson’s correlation coefficient (D) of Fig. 2A; CLSM images of ¹³¹I-TMP@D-Cy5 after co-incubation with BxPC-3 tumor spheres for different times (E); CLSM images depicting BxPC-3 tumor spheroids subjected to various treatments after co-incubation for 4 h. Cell nuclei and ZO-1 were visualized through staining with DAPI (blue) and antibody (green) (F); DCFH-DA detection of ROS release (G) and fluorescence se mi-quantitative analysis (H) of BxPC-3 cells treated with different treatment groups; **p < 0.01

Fig. 3

Survival rates of BxPC-3 cells post-treatment in normoxic and hypoxic conditions (A) and Calcein AM/PI fluorescent imaging (B); Apoptosis assessment across different treatment groups under normoxia and hypoxia (C); DNA damage evaluation in various treatment groups under normoxic and hypoxic conditions (D) and fluorescent semi-quantitative analysis (E). **p < 0.01 (probe concentration: 200 mg·mL^− 1, incubation time: 4 h)

Fig. 4

The changes of white blood cell count (WBC), red blood cell count (RBC), hemoglobin (HGB), platelet count (PLT), alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), creatinine (CREA), and organ indices in mice 30 d post-injection of ¹³¹I-TMP@D (A); Hematoxylin and eosin (H&E) staining and high magnification images of various organs (B)

Fig. 5

T1-weighted MR imaging of tumor-bearing mice at various time points after intratumoral injection (A); SPECT images of tumor-bearing mice at different time points after intratumoral injection of ¹³¹I and ¹³¹I-TMP@D (B); Distribution of ¹³¹I-TMP@D in major organs at various time points following tail vein injection (C) and intratumoral injection (D) (n = 3)

Fig. 6

Schematic illustration of treatment BxPC-3 tumor-bearing mouse route (A); tumor volumes size change curves (B) and images (C); Tumor inhibition rate (D); CD133 protein expression in tumor tissue (E); H&E and TUNEL stained sections of tumors after treatment with different treatment groups (F). **: P < 0.01, ***: P < 0.001