A cell-targeted chemotherapeutic nanomedicine strategy for oral squamous cell carcinoma therapy

Abstract

Background: Oral squamous cell carcinoma (OSCC) or cancers of oral cavity is one of the most common cancers worldwide with high rate of mortality and morbidity. At present, chemotherapy is one of the most effective treatments; however it often fails to meet the requirements in the clinical therapy. In the present study, we have successfully formulated ligand-decorated cancer-targeted CDDP-loaded PLGA-PEG/NR7 nanoparticles and demonstrated the feasibility of using NR7 peptide for targeted delivery, rapid intracellular uptake, and enhanced cytotoxic effect in receptor-overexpressed OSCC cancer cells.

Results: Nanosized particles were formed and sustained release patterns were observed for PLGA/NR7 nanoparticles. Significantly higher cellular uptake was observed in HN6 OSCC cancer cells and superior anticancer effects are observed from the optimized targeted nanoparticles. Furthermore, Live/Dead assay showed a higher extent of red fluorescence was observed for the cells exposed with PLGA/NR7 than compared with non-targeted PLGA NP. The presence of the NR7-targeting moiety on the surface of PLGA carriers could allow the specific receptor-mediated internalization, enhanced cellular uptake, and higher cell killing potency. Especially, PLGA/NR7 NP exhibited a superior apoptosis effect in HN6 cancer cells with around ~45 % (early and late apoptotic stage) and ~59 % after 24 and 48 h incubation, respectively. It is apparent that the actively targeted micelles will deliver more anticancer agent to cancer cell than non-targeted one.

Conclusion: Altogether, our results show the feasibility and promise of a cell-targeted anticancer nanomedicine strategy that can be effective for the treatment of oral squamous cell carcinoma. The present work might be of great importance to the further exploration of the potential application of PLGA/NR7 in the clinically relevant animal models.

Fig. 1

Schematic illustration of synthesis of PLGA-PEG and PLGA-PEG-NR7. The self-assembly of cisplatin (CDDP) with PLGA-PEG-NR7 block copolymer into a polymeric micelles is presented

Fig. 2

a Particle size distribution of CDDP-loaded PLGA-PEG-NR7 nanoparticles. b TEM image of PD/IFS

Fig. 3

The release profile of CDDP from PLGA NP and PLGA/NR7. The release study was performed in phosphate buffered saline at 37 °C. The study was carried out for 96 h

Fig. 4

a Intracellular uptake of PLGA NP and PLGA/NR7 NP in HN6 squamous cell carcinoma. Rhodamine B was used as a fluorescent dye. The uptake is shown as a percentage of total amounts of NP (dye) incubated with the cancer cells. b Representative confocal microscopy images of targeted and non-targeted NP in HN6 cancer cells. The cells are stained with Lysotracker lysosomal stain and DAPI was used to stain the nucleus. **p < 0.01 and *p < 005 is the statistical difference between the cellular uptake of two formulations

Fig. 5

a Cytotoxicity assay of blank nanoparticles in HN6 cancer cells. b Cytotoxicity analysis of free CDDP, PLGA NP, and PLGA/NR7 NP in HN6 cancer cells. Different amounts of formulations were added from 0.001 to 100 µg/ml to each well and incubated for 24 and 48 h. Survival rate of HN6 cell was determined by MTT assay. Data were obtained from three independent triplicate experiments and were presented as mean ± S.D. **p < 0.01 is the statistical difference between the cytotoxicity of PLGA/NR7 and CDDP

Fig. 6

The cytotoxicity potential of free CDDP, PLGA NP, and PLGA/NR7 NP were evaluated by Live/Dead assay. Cells were stained with a live/dead cell viability assay (Invitrogen). This assay uses two fluorescent probes, calcein AM and ethidium homodimer-1

Fig. 7

Annexin V-FITC FACS apoptosis analysis of HN6 cancer cells after treatment with free CDDP, PLGA NP, and PLGA/NR7 NP for 24 and 48h, respectively. a indicates PI positive cells (necrosis), b represents late apoptosis (PI and Annexin positive cells), c represents healthy cells (PI and Annexin negative cells), d early apoptosis (Annexin positive cells)