cucurbitacin-i and Squamous-Cell-Carcinoma-of-Head-and-Neck

Oral squamous cell carcinoma (OSCC) is the most common head and neck malignancy worldwide, with a high mortality. The prognosis of OSCC remains unsatisfactory; the dysregulated immune system plays an important role in the pathogenesis of OSCC. Myeloid-derived suppressor cells (MDSCs) have been identified as immune-suppressive cells in multiple tumor types. The aim of this study was to clarify the underlying immunoregulatory mechanism of MDSC in patients with OSCC.. Flow cytometry was used to analyze the phenotype of MDSC among peripheral blood mononuclear cells (PBMCs) from patients with OSCC and healthy control subjects. The correlation between MDSC frequency and the disease index of patients with OSCC was evaluated. T cell proliferation experiment was used to evaluate the immunosuppressive function of MDSC.. Patients with OSCC exhibited significantly higher levels of PMN-MDSCs than did healthy controls. In the co-culture assay, T cell proliferation and IFN-γ production were abrogated by the addition of PMN-MDSCs in a dose-dependent manner. The levels of reactive oxygen species were higher for PMN-MDSCs derived from patients with OSCC than for those from normal individuals. p-STAT3 levels, a key activator of MDSCs, was higher in OSCC-related PMN-MDSCs than in those from healthy controls. Both of these effects were reversed by NAC (an ROS inhibitor) and JSI-124 (a p-STAT3 inhibitor). Finally, PMN-MDSC levels were positively related to histological differentiation, nodal metastasis, and recurrence.. PMN-MDSCs were elevated in OSCC patients, with strong immune-suppressive effects via p-STAT3/reactive oxygen species, providing a new direction for therapeutic strategies.

Topics: Acetylcysteine; Adult; Aged; Case-Control Studies; Cell Proliferation; Cell Separation; Cells, Cultured; Coculture Techniques; Female; Flow Cytometry; Healthy Volunteers; Humans; Lymphocyte Activation; Male; Middle Aged; Mouth Neoplasms; Myeloid-Derived Suppressor Cells; Primary Cell Culture; Reactive Oxygen Species; Squamous Cell Carcinoma of Head and Neck; STAT3 Transcription Factor; T-Lymphocytes; Triterpenes; Young Adult

Head and neck squamous cell carcinoma (HNSCC) is a prevalent cancer worldwide. Signal transducers and activators of transcription 3 (STAT3) signaling is reported to promote tumor malignancy and recurrence in HNSCC. Cucurbitacins, triterpenoid derivatives, are strong STAT3 inhibitors with anticancer properties. Recent studies have shown aldehyde dehydrogenase 1 (ALDH1) to be a marker of cancer stem cells (CSC) in HNSCC. The aim of this study was to investigate the therapeutic effect of cucurbitacin I in HNSCC-derived CSCs. Using immunohistochemical analysis, we firstly showed that CD44, ALDH1, and phosphorylated STAT3 (p-STAT3) were higher in high-grade HNSCCs, and that triple positivity for CD44/ALDH1/p-STAT3 indicated a worse prognosis for HNSCC patients. Secondly, CD44(+)ALDH1(+) cells isolated from seven HNSCC patients showed greater tumorigenicity, radioresistance, and high expression of stemness (Bmi-1/Oct-4/Nanog) and epithelial-mesenchymal-transitional (Snail/Twist) genes as p-STAT3 level increased. Furthermore, we found that cucurbitacin I (JSI-124) can effectively inhibit the expression of p-STAT3 and capacities for tumorigenicity, sphere formation, and radioresistance in HNSCC-CD44(+)ALDH1(+). Notably, 150 nmol/L cucurbitacin I effectively blocked STAT3 signaling and downstream survivin and Bcl-2 expression, and it induced apoptosis in HNSCC-CD44(+)ALDH1(+). Moreover, microarray data indicated that 100 nmol/L cucurbitacin I facilitated CD44(+)ALDH1(+) cells to differentiate into CD44⁻ALDH1⁻ and enhanced the radiosensitivity of HNSCC-CD44(+)ALDH1(+). Xenotransplant experiments revealed that cucurbitacin I combined with radiotherapy significantly suppressed tumorigenesis and lung metastasis and further improved the survival rate in HNSCC-CD44(+)ALDH1(+)-transplanted immunocompromised mice. Taken together, our data show that cucurbitacin I, STAT3 inhibitor, reduces radioresistant, distant-metastatic, and CSC-like properties of HNSCC-CD44(+)ALDH1(+) cells. The potential of cucurbitacin I as a radiosensitizer should be verified in future anti-CSC therapy.

Topics: Aldehyde Dehydrogenase; Aldehyde Dehydrogenase 1 Family; Animals; Apoptosis; Carcinoma; Carcinoma, Squamous Cell; Down-Regulation; Gamma Rays; Head and Neck Neoplasms; Humans; Hyaluronan Receptors; Isoenzymes; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasms, Squamous Cell; Neoplastic Stem Cells; Radiation Tolerance; Radiation-Sensitizing Agents; Retinal Dehydrogenase; Squamous Cell Carcinoma of Head and Neck; Triterpenes; Tumor Cells, Cultured; Xenograft Model Antitumor Assays