MiR-422a promotes loco-regional recurrence by targeting NT5E/CD73 in head and neck squamous cell carcinoma

At the time of diagnosis, 60% of patients with head and neck squamous cell carcinoma (HNSCC) present tumors in an advanced stage (III-IV) of disease and 80% will relapse within the first two years post-treatment, due to their frequent radio(chemo)resistance. To identify new molecular targets and companion biomarkers, we have investigated the miRNome of 75 stage III-IV oropharynx tumors without relapse (R) or with loco-regional relapse (non-responder, NR) within two years post-treatment. Interestingly, miR-422a was significantly downregulated in NR tumors, in agreement with the increase in cell proliferation and adhesion induced by miR-422a inhibition in vitro. Furthermore, we identified CD73/NT5E oncogene as target of miR-422a. Indeed, modulation of the endogenous level of miR-422a inversely influences the expression and the enzymatic activity of CD73. Moreover, knocking down CD73 mimics the effects of miR-422a upregulation. Importantly, in tumors, miR-422a and CD73 expression levels are inversely correlated, and both are predictive of relapse free survival - especially considering loco(regional) recurrence - in vitro two independent cohorts of advanced oropharynx or HNSCC (N=255) tumors. In all, we reported, for the first time, that MiR-422a and its target CD73 are involved in early loco(regional) recurrence of HNSCC tumors and are new targets for personalized medicine.

Preferential targeting of cancer stem cells in the radiosensitizing effect of ABT-737 on HNSCC

Head and neck squamous cell carcinomas (HNSCC) are common human malignancies with poor clinical outcomes. The 5-year survival rates for patients with advanced stage HNSCC have not changed appreciably in the past few decades, underscoring a dire need for improved therapeutic options. HNSCC is frequently characterized by overexpression of anti-apoptotic Bcl-2 family members. Increased levels of these anti-apoptotic proteins have been associated with radio- and chemoresistance and poor clinical outcome. The aim of this study was to evaluate combined effects of radiation and ABT-737, a BH3-mimetic molecule, in HNSCC. Although ABT-737, as a single agent, was largely ineffective at promoting HNSCC cell death, we found that combining ABT-737 and radiation induced strong synergistic apoptosis in HNSCC cell lines and delayed tumoral growth in vivo. Moreover, we demonstrated for the first time that ABT-737, alone or in combination with radiation, can efficiently eliminate cancer stem cells (CSCs). Altogether, our results indicate that therapy targeting anti-apoptotic Bcl-2 family members could be a highly effective potential adjuvant to radiotherapy capable of targeting CSCs in HNSCC and therefore overcoming cancer recurrence and metastasis.

Combining ultrasmall gadolinium-based nanoparticles with photon irradiation overcomes radioresistance of head and neck squamous cell carcinoma

Gadolinium based nanoparticles (GBNs, diameter 2.9±0.2nm), have promising biodistribution properties for theranostic use in-vivo. We aimed at demonstrating the radiosensitizing effect of these GBNs in experimental radioresistant human head and neck squamous cell carcinoma (SQ20B, FaDu and Cal33 cell lines). Combining 0.6mM GBNs with 250kV photon irradiation significantly decreased SQ20B cell survival, associated with an increase in non-reparable DNA double-strand breaks, the shortening of G2/M phase blockage, and the inhibition of cell proliferation, each contributing to the commitment of late apoptosis. Similarly, radiation resistance was overcome for SQ20B stem-like cells, as well as for FaDu and Cal33 cell lines. Using a SQ20B tumor-bearing mouse model, combination of GBNs with 10Gy irradiation significantly delayed tumor growth with an increase in late apoptosis and a decrease in cell proliferation. These results suggest that GBNs could be envisioned as adjuvant to radiotherapy for HNSCC tumors.

Impact of hyperthermic intraperitoneal chemotherapy on Hsp27 protein expression in serum of patients with peritoneal carcinomatosis

Despite the strong rationale for combining cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) in patients with peritoneal carcinomatosis, thermotolerance and chemoresistance might result from heat shock protein overexpression. The aim of the present study was thus to determine whether the heat shock protein 27 (Hsp27), a potential factor in resistance to treatment, could have a higher level in serum from patients under this combined therapy. Patients receiving CRS plus HIPEC for peritoneal carcinomatosis (group 1), patients with cancer or a history of cancer undergoing abdominal surgery (group 2), and patients without malignancies undergoing abdominal surgery (group 3) were included. Hsp27 serum levels were determined before and at different times following CRS and HIPEC using enzyme-linked immunosorbent assay. In group 1 (n = 25), the high Hsp27 levels, observed at the end of surgery compared with before (p < 0.0001), decreased during HIPEC, but remained significantly higher than before surgery (p < 0.0005). In groups 2 (n = 11) and 3 (n = 15), surgery did not significantly increase Hsp27 levels. A targeted molecular strategy, inhibiting Hsp27 expression in tumor tissue, could significantly reduce resistance to the combined CRS plus HIPEC treatment. This approach should be further assessed in a clinical phase I trial.

Abstract LB-104: Gadolinium-based nanoparticles sensitize head and neck carcinoma stem and nonstem cells to low and high LET radiation

Head and neck squamous cell carcinoma (HNSCC) is an aggressive and recurrent malignancy owing to intrinsic radioresistance and lack of induction of apoptosis. Several strategies aiming at radiosensitizing these tumors are currently being developed, one of these relying on the use of nanoparticles including high Z elements such as gadolinium (Z=64). Once delivered to the tumor, gadolinium-based nanoparticles (GBNs) should amplify the efficacy of radiotherapy through the generation of electron Auger cascades and secondary electrons.

This study aims at demonstrating the in vitro and in vivo radiosensitizing effect of sub-5 nm GBNs (composed of a core of gadolinium oxide, a shell of polysiloxane, and functionalized by diethylene triaminepentaacetic acid) in a SQ20B radioresistant HNSCC model. Owing to the crucial role of cancer stem cells in tumor initiation, disease recurrence and radioresistance, the radiosensitizing effect of GBNs was also tested in SQ20B stem-like cells.

The association of 0,6 mM GBNs with a photon or a 33.6 keV/µm carbon ion irradiation decrease significantly SQ20B cell survival. Radiosensitization goes through the increase in non-reparable DNA double-strand breaks, the shortening of G2/M phase blockage, the inhibition of cell proliferation, each contributing to the commitment into apoptosis. The combined treatment of GBNs with irradiation can also overcome the resistance of SQ20B stem-like cells.

Using an SQ20B tumor-bearing mouse model, we also demonstrate that GBNs in conjunction with photon irradiation significantly retard tumor growth compared with the radiation alone, with complete remission in some mice. Significantly, an increase in apoptosis and decrease in cell proliferation are also detected inside tumors in the combined treatment group.

These results suggest the interesting potential of GBNs in sensitizing resistant HNSCC tumors to radiotherapy and their possible contribution towards overcoming limitations of current cancer treatment.

This project was conducted under the framework of LANTHARAD (PDC019 CLARA 2010), PRRH-ETOILE and LABEX PRIMES (2012)

Citation Format: Marie-Thérèse Aloy, Imen Miladi, Emma Armandy, Claire Billotey, Olivier Tillement, François Lux, Pascal Perriat, Marc Janier, Claire Rodriguez-Lafrasse. Gadolinium-based nanoparticles sensitize head and neck carcinoma stem and nonstem cells to low and high LET radiation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-104. doi:10.1158/1538-7445.AM2013-LB-104

Internalization pathways into cancer cells of gadolinium-based radiosensitizing nanoparticles

Over the last few decades, nanoparticles have been studied in theranostic field with the objective of exhibiting a long circulation time through the body coupled to major accumulation in tumor tissues, rapid elimination, therapeutic potential and contrast properties. In this context, we developed sub-5 nm gadolinium-based nanoparticles that possess in vitro efficient radiosensitizing effects at moderate concentration when incubated with head and neck squamous cell carcinoma cells (SQ20B). Two main cellular internalization mechanisms were evidenced and quantified: passive diffusion and macropinocytosis. Whereas the amount of particles internalized by passive diffusion is not sufficient to induce in vitro a significant radiosensitizing effect, the cellular uptake by macropinocytosis leads to a successful radiotherapy in a limited range of particles incubation concentration. Macropinocytosis processes in two steps: formation of agglomerates at vicinity of the cell followed by their collect via the lamellipodia (i.e. the "arms") of the cell. The first step is strongly dependent on the physicochemical characteristics of the particles, especially their zeta potential that determines the size of the agglomerates and their distance from the cell. These results should permit to control the quantity of particles internalized in the cell cytoplasm, promising ambitious opportunities towards a particle-assisted radiotherapy using lower radiation doses.

In vitro radiosensitizing effects of ultrasmall gadolinium based particles on tumour cells

Since radiotherapy is widely used in cancer treatment, it is essential to develop strategies which lower the irradiation burden while increasing efficacy and become efficient even in radio resistant tumors. Our new strategy is relying on the development of solid hybrid nanoparticles based on rare-earth such as gadolinium. In this paper, we then evidenced that gadolinium-based particles can be designed to enter efficiently into the human glioblastoma cell line U87 in quantities that can be tuned by modifying the incubation conditions. These sub-5 nm particles consist in a core of gadolinium oxide, a shell of polysiloxane and are functionalized by diethylenetriaminepentaacetic acid (DTPA). Although photoelectric effect is maximal in the [10-100 keV] range, such particles were found to possess efficient in-vitro radiosensitizing properties at an energy of 660 keV by using the "single-cell gel electrophoresis comet assay," an assay that measures the number of DNA damage that occurs during irradiation. Even more interesting, the particles have been evidenced by MTT assays to be also efficient radiosensitizers at an energy of 6 MeV for doses comprised between 2 and 8 Gy. The properties of the gadolinium-based particles give promising opening to a particle-assisted radio-therapy by using irradiation systems already installed in the majority of hospitals.