Chemopreventive and Chemotherapeutic Actions of mTOR Inhibitor in Genetically Defined Head and Neck Squamous Cell Carcinoma Mouse Model

Abstract

Purpose To assess the efficacy of Rapamycin treatment in chemoprevention and chemotherapy of tumorigenesis in a genetically-defined mouse model of head and neck squamous cell carcinoma (HNSCC). Experimental design Knockdown of Tgfbr1 and/or Pten using siRNA-mediated RNA interference was carried out in human HNSCC cell lines to analyze molecular changes in the mTOR pathway. Tgfbr1flox/flox; Ptenflox/flox; K14-CreERtam mice were treated with oral gavage of tamoxifen for the conditional deletion of Tgfbr1 and Pten in oral mucosa, resuting in HNSCC (Bian et al 2011). Tgfbr1 and Pten conditonal deletion (2cKO) mice were treated with Rapamycin before or after the onset of HNSCC, and the efficacy of this treatment was assessed by determining tumor burden, longevity, and molecular analysis of the mTOR pathway. Molecular changes observed in human HNSCC cell lines and 2cKO mice were compared to identify key alterations in the mTOR pathway. Results Knockdown of Tgfbr1 and/or Pten in human HNSCC cell lines resulted in activation of mTORC1 and increased levels of survivin. Furthermore, we observed similar changes in HNSCC of the 2cKO mouse. In the human HNSCC tissue array, a loss of Tgfbr1 expression correlated with increased survivin levels. Chemopreventive Rapamycin treatment significantly delayed the onset of the HNSCC tumors and prolonged survival in 2cKO mice. Additionally, we also found that Rapamycin had a therapeutic effect on squamous cell carcinomas in these mice. In 2cKO HNSCC tongue tumors, Rapamycin treatment induced apoptosis, inhibited cell proliferation and phosphorylation of Akt and S6, and decreased survivin expression. Conclusions These findings indicate that tumorigenesis in 2cKO HNSCC is associated with activation of the Akt/mTOR/survivin pathway, and inhibition of this pathway by Rapamycin treatment successfully ameliorates the onset and progression of tumorigenesis.

LAG-3 confers poor prognosis and its blockade reshapes antitumor response in head and neck squamous cell carcinoma

“…4A, tamoxifen was applied to Tgfbr1 ; K14-CreER tamC/¡ mice by oral gavage in five consecutive days for the conditional deletion of Tgfbr1 and Pten in head and neck epithelia, resulting in HNSCC. 29 A week later, in vivo anti-mouse LAG-3 antibody (aLAG-3 group, clone: C9B7W; 10 mg/kg) or isotype control (control group, clone: MOPC-21; 10 mg/kg) was infused by intraperitoneal injection every other day for next 10 d (Fig. 4A).…”

CTLA4 blockade reduces immature myeloid cells in head and neck squamous cell carcinoma

“…Time inducible tissue-specific Tgfbr1/Pten 2cKO mouse (K14-Cre ERtamC/¡ ; Tgfbr1 flox/flox ; Pten flox/flox ) were maintained and genotyped according to published protocols. 47 All the mice were bred in the FVBN/CD1/ 129/C57 mixed background.…”

“…The threshold for scanning of different positive cells was set according to the standard controls provided by Aperio. 47 Hierarchical clustering was performed as our previous produce. 46 …”

Inhibition of SRC family kinases reduces myeloid‐derived suppressor cells in head and neck cancer

“…22 WT mice were also treated with the same dosage of tamoxifen as blank controls. For the chemopreventive studies, one week later after the last oral gavage, Tgfbr1/Pten 2cKO mice, which were randomly divided into two groups according to body weight, were treated with PBS (10 mg/kg, i.p.…”

“…Accumulated clinical and preclinical studies have confirmed the activation of PI3K/AKT/mTOR pathway in tumorigenesis of HNSCC. 3,22 To further investigate the proliferation and tumorigenesis that are affected by dasatinib treatment, we performed Tumor Immunology and Microenvironment compared with control group, which indicated that dasatinib treatment reduced the proliferation and p-AKT pathway of HNSCC tumors (Fig. 4g).…”