Light during darkness and cancer: relationships in circadian photoreception and tumor biology

The relationship between circadian phototransduction and circadian-regulated processes is poorly understood. Melatonin, commonly a circadian phase marker, may play a direct role in a myriad of physiologic processes. The circadian rhythm for pineal melatonin secretion is regulated by the hypothalamic suprachiasmatic nucleus (SCN). Its neural source of light input is a unique subset of intrinsically photosensitive retinal ganglion cells expressing melanopsin, the primary circadian photopigment in rodents and primates. Action spectra of melatonin suppression by light have shown that light in the 446–477 nm range, distinct from the visual system’s peak sensitivity, is optimal for stimulating the human circadian system. Breast cancer is the oncological disease entity whose relationship to circadian rhythm fluctuations has perhaps been most extensively studied. Empirical data has increasingly supported the hypothesis that higher risk of breast cancer in industrialized countries is partly due to increased exposure to light at night. Studies of tumor biology implicate melatonin as a potential mediator of this effect. Yet, causality between lifestyle factors and circadian tumor biology remains elusive and likely reflects significant variability with physiologic context. Continued rigorous empirical inquiry into the physiology and clinical implications of these habitual, integrated aspects of life is highly warranted at this time

Targeted molecular therapy of anaplastic thyroid carcinoma with AEE788

Anaplastic Thyroid Carcinoma (ATC) is one of the most aggressive human malignancies with a mean survival of only 6 months. The poor prognosis of patients with ATC reflects the current lack of curative therapeutic options and the need for development of novel therapeutic strategies. In this study, we report the results of a preclinical study of AEE788, a dual inhibitor of Epidermal Growth Factor Receptor (EGFR) and Vascular Endothelial Growth Factor Receptor (VEGFR) tyrosine kinases, against ATC. AEE788 was able to inhibit the proliferation and induce apoptosis of ATC cell lines in vitro. Administration of AEE788, alone and in combination with paclitaxel, to athymic nude mice bearing s.c. ATC xenografts inhibited the growth of ATC xenografts by 44% and 69%, respectively, compared with the control group. Furthermore, tumors from mice treated with AEE788, alone and in combination with paclitaxel, showed increase in apoptosis of tumor cells by ∼6- and 8-fold, respectively, compared with the control group. The microvessel density within the ATC xenografts was decreased by >80% in the mice treated with AEE788 alone and in combination with paclitaxel compared with the control group. Lastly, immunofluorescence microscopy showed the inhibition of EGFR autophosphorylation on the tumor cells as well as the inhibition of VEGFR-2 autophosphorylation on tumor endothelium. Considering the fact that curative options seldom exist for patients with ATC, concurrent inhibition of EGFR and VEGFR tyrosine kinases seems to be a valid and promising anticancer strategy for these patients

Antivascular therapy of human follicular thyroid cancer experimental bone metastasis by blockade of Epidermal Growth Factor Receptor and Vascular Growth Factor Receptor phosphorylation

Patients suffering from bone metastases of Follicular Thyroid Carcinoma (FTC) have a poor prognosis because of the lack of effective treatment strategies. The overexpression of Epidermal Growth Factor Receptor (EGFR) associated with increased vascularity has been implicated in the pathogenesis of FTC and subsequent bone metastases. We hypothesized that inhibiting the phosphorylation of the EGFR and Vascular Endothelial Growth Factor Receptor (VEGFR) by AEE788, a dual tyrosine kinase inhibitor of EGFR and VEGFR, in combination with paclitaxel would inhibit experimental FTC bone lesions and preserve bone structure. We tested this hypothesis using the human WRO FTC cell line. In culture, AEE788 inhibited the EGF-mediated phosphorylation of EGFR, VEGFR2, mitogen-activated protein kinase and Akt in culture. AEE788, alone and in combination with paclitaxel, inhibited cell growth and induced apoptosis. When WRO cells were injected into the tibia of nude mice, tumor and endothelial cells within the lesions expressed phosphorylated EGFR, VEGFR, Akt and mitogen-activated protein kinase that were inhibited by the oral administration of AEE788. Therapy consisting of orally given AEE788 and i.p. injected paclitaxel induced a high level of apoptosis in tumor-associated endothelial cells and tumor cells with the inhibition of tumor growth in the bone and the preservation of bone structure. Collectively, these data show that blocking the phosphorylation of EGFR and VEGFR with AEE788 combined with paclitaxel can significantly inhibit experimental human FTC in the bone of nude mice

Epidermal Growth Factor Receptor (EGFR) is overexpressed in anaplastic thyroid cancer and the EGFR inhibitor gefitinib inhibits the growth of anaplastic thyroid cancer

Purpose: No effective treatment options currently are available to patients with Anaplastic Thyroid Cancer (ATC), resulting in high mortality rates. Epidermal Growth Factor (EGF) has been shown to play a role in the pathogenesis of many types of cancer and its receptor (EGFR) provides an attractive target for molecular therapy. Experimental Design: The expression of EGFR was determined in ATC in vitro and in vivo and in human tissue arrays of ATC. We assessed the potential of the EGFR inhibitor gefitinib (“Iressa,” ZD1839) to inhibit EGFR activation in vitro and in vivo, inhibit ATC cellular proliferation, induce apoptosis and reduce the growth of ATC cells in vivo when administered alone and in combination with paclitaxel. Results: EGFR was overexpressed in ATC cell lines in vitro and in vivo and in human ATC specimens. Activation of EGFR by EGF was blocked by the addition of gefitinib. In vitro studies showed that gefitinib greatly inhibited cellular proliferation and induced apoptosis in ATC cell lines and slowed tumor growth in a nude mouse model of thyroid carcinoma cells injected subcutaneously. Conclusions: ATC cells consistently overexpress EGFR, rendering this receptor a potential target for molecular therapy. Gefitinib effectively blocks activation of EGFR by EGF, inhibits ATC cellular proliferation and induces apoptosis in vitro. Our in vivo results show that gefitinib has significant antitumor activity against ATC in a subcutaneous nude mouse tumor model and therefore is a potential candidate for human clinical trials

Growth inhibition of orthotopic anaplastic thyroid carcinoma xenografts in nude mice by PTK787/ZK222584 and CPT-11

Background: A preclinical evaluation of CPT‐1 (Camptosar, irinotecan) and PTK787/ZK222584, a Vascular Endothelial Growth Factor Receptor (VEGFR‐2) tyrosine kinase inhibitor, as therapeutic agents against Anaplastic Thyroid Carcinoma (ATC) was performed in vitro and in an orthotopic model of ATC in nude mice. Methods: The cytotoxic and cytostatic effects of CPT‐11 on ATC cell lines were evaluated. The antitumor effects of CPT‐11 in combination with PTK787/ZK222584 on orthotopic ATC xenografts in nude mice were also studied. Results: CPT‐11 demonstrated significant antiproliferative effects on ATC cell lines. In vivo, PTK787/ZK222584, CPT‐11 and the two agents together produced 61%, 82% and 89% decrease in tumor growth, respectively. The differences in tumor volume between CPT‐11 and CPT‐11 + PTK787/ZK222584 groups were not statistically significant. PTK787/ZK222584 inhibited the phosphorylation of VEGFR‐2 on tumor endothelium and decrease the tumor microvessel density. Conclusions: The camptothecin class of chemotherapeutic agents and antiangiogenic agents such as PTK787/ZK222584 warrant further study as novel therapeutic agents against ATC

Concurrent cetuximab and bevacizumab therapy in a murine orthotopic model of anaplastic thyroid carcinoma

Objective: To evaluate the therapeutic efficacy of bevacizumab and cetuximab, alone and in combination, in an orthotopic model of Anaplastic Thyroid Carcinoma (ATC) in athymic nude mice. Study Design and Setting: This was a randomized, controlled in vivo study. Materials and Methods: The ATC cell line, ARO, was used to establish orthotopic xenografts of ATC in athymic nude mice. Mice were randomized to therapy for 4 weeks in one of four treatment groups: placebo, cetuximab, bevacizumab or the combination of cetuximab and bevacizumab. A second study compared the antitumor efficacy of the cetuximab-bevacizumab combination with doxorubicin. In both studies, tumor volumes on completion were measured and compared. Immunohistochemical analysis was performed with antiCD31 and antiproliferating cell nuclear antigen (PCNA) antibodies to assess the in vivo mechanisms of action of these agents. Results: Cetuximab decreased the production of vascular endothelial growth factor by ATC cell lines in vitro. Mean tumor volumes for the control, bevacizumab, cetuximab and combination groups at the end of the in vivo study were 291, 213, 94 and 42 mm³, respectively. The differences in mean tumor volume for the control versus treatment groups were statistically significant. Immunohistochemical analysis showed decreased microvessel density and PCNA positivity in the treatment groups. In the doxorubicin comparison study, mean tumor volumes for control, doxorubicin and combination antibody treatment groups were 175, 162, and 22 mm³, respectively. Conclusions: Cetuximab and bevacizumab alone and in combination inhibit tumor growth and angiogenesis in an in vivo model of ATC. Also, this therapy was superior to doxorubicin therapy

The Akt inhibitor KP372-1 inhibits proliferation and induces apoptosis and anoikis in squamous cell carcinoma of the head and neck

Therapies that target signaling pathways critical to the pathogenesis and progression of squamous cell carcinoma of the head and neck (HNSCC) are needed. One such target, phosphatidylinositol 3-kinase, and its downstream target serine/threonine kinase, Akt, are up-regulated in HNSCC. Targeted therapy could consist of inhibitors of these kinases or, alternatively, of inhibitors of the pathways that they regulate. To explore the effect of Akt inhibition on the growth and survival of HNSCC tumors, we evaluated the effect of a novel Akt inhibitor, KP372-1, on the growth, survival, and sensitivity to anoikis of HNSCC cell lines in culture. Using Western blotting of head and neck cancer cell lines and squamous mucosa and carcinoma specimens, we found that Akt was highly phosphorylated in head and neck cancer cell lines and human head and neck squamous carcinoma specimens. Treatment of HNSCC cell lines with KP372-1 blocked the activation of Akt, inhibited head and neck cancer cell proliferation, and induced apoptosis and anoikis in several HNSCC cell lines. Furthermore, KP372-1 decreased the phosphorylation of the S6 ribosomal (Ser240/244) protein, which is a downstream target of Akt. Taken together, these findings indicate that KP372-1 may be a useful therapeutic agent for HNSCC and should be further evaluated in preclinical models of HNSCC

Integrin-linked kinase is a potential therapeutic target for anaplastic thyroid cancer

We investigated integrin-linked kinase (ILK), a focal adhesion serine-threonine protein kinase, as a new molecular target for treating anaplastic thyroid cancer. ILK mediates cell growth and survival signals and is overexpressed in a number of cancers. Therefore, we hypothesized that inhibition of ILK leads to growth arrest and apoptosis of thyroid cancer cells. According to Western blotting, the level of ILK protein was highly expressed in one papillary (NPA187) and four of five (Hth74, DRO, ARO, KAT4, and K4) anaplastic thyroid cancer cell lines. Immunohistochemical analysis of a human tissue microarray revealed that ILK was highly expressed in anaplastic thyroid cancer but not in normal human thyroid tissue. Treating thyroid cancer cell lines with a new ILK inhibitor, QLT0267, inhibited epidermal growth factor–induced phosphorylation of AKT, inhibited cell growth, and induced apoptosis in the NPA187, DRO, and K4 cell lines. QLT0267 also inhibited the kinase activity of immunoprecipitated ILK in four of five cell lines. Tumor volumes in mice treated with QLT0267 were significantly reduced compared with those in untreated mice. In immunohistochemical studies, QLT0267 suppressed phosphorylated p-AKT and angiogenesis (i.e., reduced mean vascular density) and induced apoptosis in both tumor cells and tumor-associated endothelial cells of the thyroid DRO xenografts. In summary, we found that ILK expression and activity were elevated in human anaplastic thyroid cancer and ILK inhibition led to growth arrest and apoptosis in vitro and in vivo. Our results provide preliminary evidence that ILK is a potential therapeutic target for treating anaplastic thyroid cancer