Xiaohua Rong

Overexpressed eIF4E Is Functionally Active in Surgical Margins of Head and Neck Cancer Patients via Activation of the Akt/Mammalian Target of Rapamycin Pathway

Purpose: Overexpression of eIF4E in surgical margins of head and neck cancer patients is an independent risk factor for recurrence. We hypothesize that overexpressed eIF4E is functionally active in tumor margins through activation of the Akt/mammalian target of rapamycin (mTOR) pathway Experimental Design: Western blots and/or immunohistochemistry were performed to determine whether phosphorylation of mTOR and activation of its downstream molecules eIF4E-binding protein-1 (4E-BP1) and p70 S6 kinase and the upstream modulator of mTOR, Akt, were expressed in margins overexpressing eIF4E. Results: There was a significant association between phospho-4E-BP1 and eIF4E expression of a margin or a significant difference in phospho-4E-BP1 expression between the eIF4E-positive and -negative margins (P < 0.01). A significant association between eIF4E and phospho-p70 S6 kinase as well as eIF4E and phospho-mTOR was also noted (P < 0.05). Western blot analysis indicated a highly significant difference in the phosphorylation status of 4E-BP1 between tumors and resection margins. A total of 89% of the 4E-BP1-expressing margins expressed more of the phosphorylated (β, γ, and δ) isoforms, whereas 81% of the 4E-BP1-expressing tumors expressed more of the unphosphorylated α isoform. A similar difference in Akt activation was noted between eIF4E-positive margins and tumors (P < 0.05). Conclusions: Overexpression of eIF4E is functionally active in tumor margins through activation of the Akt/mTOR signaling pathway. The greater degree of expression of downstream targets and upstream regulators of mTOR in margins compared with the tumors indicates preferential activation of the Akt/mTOR signaling pathway in margins overexpressing eIF4E. Rapamycin analogs can potentially be used as adjuvant therapy for patients with eIF4E-positive margins.

Comparison of radiosensitizing effects of the mammalian target of rapamycin inhibitor CCI-779 to cisplatin in experimental models of head and neck squamous cell carcinoma

To determine if the mammalian target of rapamycin (mTOR) inhibitor CCI-779 can sensitize head and neck squamous cell carcinoma (HNSCC) to radiotherapy (XRT) and compare the radiosensitizing effects to cisplatin with its known considerable toxicity. Radiosensitizing effects of CCI-779 were assayed on HNSCC cell lines in vitro. CCI-779 (5 mg/kg), cisplatin (1 mg/kg), and XRT (2 Gy) alone and in combination were evaluated for antitumor activity in mice bearing FaDu and SCC40 xenografts. Effects of CCI-779 on radiation-induced activation of the Akt/mTOR pathway were analyzed. Although CCI-779 did not sensitize HNSCC cells to ionizing radiation in vitro, combination of CCI-779 and XRT significantly augmented the in vivo tumor growth-inhibitory effects of XRT and CCI-779 (P < 0.05). In addition, CCI-779 + XRT suppressed tumor growth more effectively than cisplatin + XRT (P < 0.05). CCI-779 + XRT significantly improved survival compared with XRT alone in both cisplatin-sensitive FaDu (P < 0.01) and cisplatin-resistant SCC40 (P < 0.05) xenograft mice. There were no additional benefits of adding cisplatin to CCI-779 + XRT. CCI-779 significantly attenuated irradiation-induced up-regulation of the mTOR pathway, increased apoptosis and displayed potent antiangiogenic activity in FaDu xenografts that was further enhanced by its combination with XRT (P < 0.05), which may explain the mechanism of its selective radiosensitizing effects in vivo and not in vitro. Antitumor activity of XRT was enhanced when combined with CCI-779 in HNSCC xenograft model. CCI-779 + XRT showed antitumor activity superior to conventional chemoradiotherapy with cisplatin. These results pave the way for clinical trials using molecular targeted therapy with CCI-779 in combination with XRT for HNSCC treatment. [Mol Cancer Ther 2009;8(8):2255–65]

Teasing out the best molecular marker in the AKT/mTOR pathway in head and neck squamous cell cancer patients.

No reliable molecular biomarker is currently available for clinical application in the management of head and neck cancer patients. The AKT/mTOR pathway is activated in 90% to 100% of head and neck squamous cell cancer (HNSCC) and could be promising biomarkers closely linked to cancer incidence.

Curcumin inhibits carcinogen and nicotine-induced Mammalian target of rapamycin pathway activation in head and neck squamous cell carcinoma.

Curcumin appears to be a safe, bioactive food compound that is a potential chemopreventive for patients at a high risk for head and neck squamous cell carcinoma (HNSCC). Identification and validation of intermediate endpoints is an important step in evaluating chemopreventive agents. AKT/MTOR pathway biomarkers are intrinsic to the carcinogenic process as well as the mechanism of intervention with curcumin. Antiproliferative effects of curcumin were assayed in 9 HNSCC and a keratinocyte cell line. Nicotine, a genotoxic alkaloid involved in tobacco addiction, forms DNA adducts and has been implicated in upper aerodigestive tract cancer promotion. The antiproliferative effects of curcumin were associated with inhibition of the AKT/MTOR pathway in presence and absence of nicotine, which also induced this pathway. Curcumin was highly effective at suppressing growth of SCC40 xenografts and its activity is associated with modulation of MTORs downstream target pS6. Curcumin at 15 mg significantly increased survival (286 ± 37 vs. 350 days) in the 4NQO carcinogenic model survival study. A major cause of lethal progression of HNSCC is local regional migration and invasion of malignant cells, and curcumin significantly inhibited cancer cell migration and invasion in vitro and in vivo where downregulation of pS6 was associated with a significant decrease in MMP-9. This is the first study to demonstrate that curcumin inhibits the adverse effects of nicotine by blocking nicotine-induced activation of the AKT/MTOR pathway in HNSCC, which retards cell migration. These studies indicate that inhibiting the AKT/MTOR pathway with curcumin may be useful as an oral chemopreventive agent. Cancer Prev Res; 3(12); 1586–95. ©2010 AACR.

Curcumin Inhibits Skin Squamous Cell Carcinoma Tumor Growth In Vivo

Objective. Squamous cell carcinoma (SCCa) has increased from 4% to 10% over 4 decades, stimulating interest in developing novel agents that slow sun-damaged skin progression. This is the first study evaluating the naturally occurring bioactive food compound curcumin on skin cancer xenografts. Low bioavailability of curcumin has slowed its transition to clinical trials. It is hypothesized that curcumin has growth-inhibitory effects through the MTOR pathway and chemopreventive potential in skin SCCa where local application could bypass bioavailability problems. Study Design. A randomized experimental animal and laboratory study. Setting. Louisiana State University Health Sciences Center, Shreveport, Louisiana. Subjects and Methods. SCID mice were pretreated with 0, 5, or 15 mg of curcumin (n = 8 per group), 3 days prior to injecting 106 SRB12-p9 skin SCCa cells in each flank, and were gavaged daily thereafter. Tumor volumes were measured and tumors were harvested on day 24 when mice were sacrificed. Immunohistochemical analysis of pS6 expression (n = 3 per group) and tumor volumes in the 3 groups were compared using 1-way analysis of variance and pairwise comparisons were determined with the Tukey t test if overall comparisons were significant. Results. Tumor volume increased 2.3 times faster in control mice compared with the group receiving 15 mg of curcumin (P = .0003). A significant difference in average tumor volumes was seen (P = .0012), especially with treatment of 15 mg of curcumin compared with control P = .0003). Curcumin inhibited S6 phosphorylation (P = .0027), suggesting inhibition of the MTOR pathway. Conclusion. Curcumin appears to inhibit skin SCCa growth and blocks tumor progression by inhibiting pS6 even when gavage is used to deliver curcumin, indicating even more significant effects in future experiments with local application.

NS 398 RADIOSENSITIZES AN HNSCC CELL LINE BY POSSIBLY INHIBITING RADIATION-INDUCED EXPRESSION OF COX-2

PURPOSE Cyclooxygenase-2 (COX-2) protein is frequently elevated in squamous cell carcinoma of the head and neck (HNSCC). The aim of this study was to determine if COX-2 inhibitors have radiosensitizing effects in HNSCC and understand the mechanism by which this occurs. MATERIALS AND METHODS The radiosensitizing effects of a selective COX-2 inhibitor, NS398, on a HNSCC cell line HEp3, were determined using clonogenic survival assay. Cells were pretreated with the dose of NS398 at which 50% growth inhibition occurred (IC(50)) and then irradiated. COX-2 protein and mRNA were then determined in the presence and absence of NS398. RESULTS NS398 significantly decreased (p < 0.0001) the calculated survival fraction (SF) for all radiation doses (0.79 to 0.41 at 2 Gy). A significant increase in COX-2 protein of 2.8 fold for 2 Gy and 3.5 fold for 6 Gy was noted 48 h after radiation. Interestingly, the upregulation of COX-2 protein with radiation was suppressed when cells were pretreated with NS398. Quantitative reverse transcriptase polymerase chain reaction showed no significant corresponding increase in COX-2 mRNA at 48 h with ionizing radiation. CONCLUSIONS The radiosensitizing effect of NS398 could be due to inhibition of radiation-induced COX-2 upregulation by this drug. NS398, known as an inhibitor of COX-2 enzyme activity, down-regulated COX-2 protein expression, which may indicate that NS398 can act upstream of COX-2, and this change appears to be post-transcriptional.

Pharmacodynamic evaluation of temsirolimus in patients with newly diagnosed advanced-stage head and neck squamous cell carcinoma

Activation of the mammalian target of rapamycin (mTOR) pathway in surgical margins of head and neck squamous cell carcinoma (HNSCC) is a predictor of recurrence and patients with minimal residual disease may benefit from adjuvant therapy with temsirolimus, an mTOR inhibitor.

Anti-lymphangiogenic properties of mTOR inhibitors in head and neck squamous cell carcinoma experimental models

BackgroundTumor dissemination to cervical lymph nodes via lymphatics represents the first step in the metastasis of head and neck squamous cell carcinoma (HNSCC) and is the most significant predictor of tumor recurrence decreasing survival by 50%. The lymphatic suppressing properties of mTOR inhibitors are not yet well understood.MethodsLymphatic inhibiting effects of rapamycin were evaluated in vitro using two lymphatic endothelial cell (LEC) lines. An orthotopic mouse model of HNSCC (OSC-19 cells) was used to evaluate anti-lymphangiogenic effects of rapamycin in vivo. The incidence of cervical lymph node metastases, numbers of tumor-free lymphatic vessels and those invaded by tumor cells in mouse lingual tissue, and expression of pro-lymphangiogenic markers were assessed.ResultsRapamycin significantly decreased lymphatic vascular density (p = 0.027), reduced the fraction of lymphatic vessels invaded by tumor cells in tongue tissue (p = 0.013) and decreased metastasis-positive lymph nodes (p = 0.04). Rapamycin also significantly attenuated the extent of metastatic tumor cell spread within lymph nodes (p < 0.0001). We found that rapamycin significantly reduced LEC proliferation and was correlated with decreased VEGFR-3 expression in both LEC, and in some HNSCC cell lines.ConclusionsThe results of this study demonstrate anti-lymphangiogenic properties of mTOR inhibitors in HNSCC. mTOR inhibitors suppress autocrine and paracrine growth stimulation of tumor and lymphatic endothelial cells by impairing VEGF-C/VEGFR-3 axis and release of soluble VEGFR-2. In a murine HNSCC orthotopic model rapamycin significantly suppressed lymphovascular invasion, decreased cervical lymph node metastasis and delayed the spread of metastatic tumor cells within the lymph nodes.

Topical Curcumin-Based Cream Is Equivalent to Dietary Curcumin in a Skin Cancer Model

Skin squamous cell carcinoma (SCC), the most common cancer in the USA, is a growing problem with the use of tanning booths causing sun-damaged skin. Antiproliferative effects of curcumin were demonstrated in an aggressive skin cancer cell line SRB12-p9 (P < 0.05 compared to control). Topical formulation was as effective as oral curcumin at suppressing tumor growth in a mouse skin cancer model. Curcumin at 15 mg administered by oral, topical, or combined formulation significantly reduced tumor growth compared to control (P = 0.004). Inhibition of pAKT, pS6, p-4EBP1, pSTAT3, and pERK1/2 was noted in SRB12-p9 cells post-curcumin treatment compared to control (P < 0.05). Inhibition of pSTAT3 and pERK1/2 was also noted in curcumin-treated groups in vivo. IHC analysis revealed human tumor specimens that expressed significantly more activated pERK (P = 0.006) and pS6 (P < 0.0001) than normal skin samples. This is the first study to compare topical curcumin to oral curcumin. Our data supports the use of curcumin as a chemopreventive for skin SCC where condemned skin is a significant problem. Prevention strategies offer the best hope of future health care costs in a disease that is increasing in incidence due to increased sun exposure.

Efficacy and comparative effectiveness of sirolimus as an anticancer drug

To evaluate antitumor efficacy of the generic mammalian target of rapamycin (mTOR) inhibitor sirolimus in preclinical animal models of head and neck squamous cell carcinoma (HNSCC) and compare its effects with those of the patented analogue temsirolimus.