Abstract

Angiogenesis is a critical step required for sustained tumor growth and tumor progression. The stimulation of endothelial cells by cytokines secreted by tumor cells such as vascular endothelial growth factor (VEGF) induces their proliferation and migration. This is a prominent feature of high-grade gliomas. The secretion of VEGF is greatly upregulated under conditions of hypoxia because of the transcription factor hypoxiainducible factor (HIF)-1α, which controls the expression of many genes, allowing rapid adaptation of cells to their hypoxic microenvironment. Flavopiridol, a novel cyclin-dependent kinase inhibitor, has been attributed with antiangiogenic properties in some cancer cell lines by its ability to inhibit VEGF production. Here, we show that flavopiridol treatment of human U87MG and T98G glioma cell lines decreases hypoxia-mediated HIF-1α expression, VEGF secretion, and tumor cell migration. These in vitro results correlate with reduced vascularity of intracranial syngeneic GL261 gliomas from animals treated with flavopiridol. In addition, we show that flavopiridol downregulates HIF-1α expression in the presence of a proteasome inhibitor, an agent that normally results in the accumulation and overexpression of HIF-1α. The potential to downregulate HIF-1α expression with flavopiridol treatment in combination with a proteasome inhibitor makes this an extremely attractive anticancer treatment strategy for tumors with high angiogenic activity, such as gliomas.

References

Adams, J., Palombella, V.J., Sausville, E.A., Johnson, J., Destree, A., Laza rus, D.D., Maas, J., Pien, C.S., Prakash, S., and Elliott, P.J. (

1999
) Proteasome inhibitors: A novel class of potent and effective antitumor agents.
Cancer Res.
59
,
2615
-2622.

Alonso, M., Tamasdan, C., Miller, D.C., and Newcomb, E.W. (

2003
) Flavopiridol induces apoptosis in glioma cell lines independent of retinoblastoma and p53 tumor suppressor pathway alterations by a caspase-independent pathway.
Mol. Cancer Ther.
2
,
139
-150.

Blagosklonny, M.V. (

2004
) Flavopiridol, an inhibitor of transcription: Implications, problems and solutions.
Cell Cycle
3
,
1537
-1542.

Brat, D.J., Castellano-Sanchez, A.A., Hunter, S.B., Pecot, M., Cohen, C., Hammond, E.H., Devi, S.N., Kaur, B., and Van Meir, E.G. (

2004
) Pseudopalisades in glioblastoma are hypoxic, express extracellular matrix proteases, and are formed by an actively migrating cell population.
Cancer Res.
64
,
920
-927.

Brown, J.M., and Giaccia, A.J. (

1998
) The unique physiology of solid tumors: Opportunities (and problems) for cancer therapy.
Cancer Res.
58
,
1408
-1416.

Carmeliet, P., Dor, Y., Herbert, J.M., Fukumura, D., Brusselmans, K., Dew erchin, M., Neeman, M., Bono, F., Abramovitch, R., Maxwell, P., Koch, C.J., Ratcliffe, P., Moons, L., Jain, R.K., Collen, D., Keshert, E., and Kes het, E. (

1998
) Role of HIF-1α in hypoxia-mediated apoptosis, cell prolif eration and tumour angiogenesis.
Nature
394
,
485
-490.

Chan, D.A., Sutphin, P.D., Denko, N.C., and Giaccia, A.J. (

2002
) Role of prolyl hydroxylation in oncogenically stabilized hypoxia-inducible factor-1α.
J. Biol. Chem.
277
,
40112
-40117.

Chao, S.H., and Price, D.H. (

2001
) Flavopiridol inactivates P-TEFb and blocks most RNA polymerase II transcription in vivo.
J. Biol. Chem.
276
,
31793
-31799.

Dai, Y., Rahmani, M., and Grant, S. (

2003
) Proteasome inhibitors poten tiate leukemic cell apoptosis induced by the cyclin-dependent kinase inhibitor flavopiridol through a SAPK/JNK- and NF-κB-dependent pro cess.
Oncogene
22
,
7108
-7122.

Damert, A., Machein, M., Breier, G., Fujita, M.Q., Hanahan, D., Risau, W., and Plate, K.H. (

1997
) Up-regulation of vascular endothelial growth factor expression in a rat glioma is conferred by two distinct hypoxia-driven mechanisms.
Cancer Res.
57
,
3860
-3864.

de Azevedo, W.F., Jr., Canduri, F., and da Silveira, N.J. (

2002
) Structural basis for inhibition of cyclin-dependent kinase 9 by flavopiridol.
Biochem. Biophys. Res. Commun.
293
,
566
-571.

Deryugina, E.I., Soroceanu, L., and Strongin, A.Y. (

2002
) Up-regulation of vascular endothelial growth factor by membrane-type 1 matrix metalloproteinase stimulates human glioma xenograft growth and angiogen esis.
Cancer Res.
62
,
580
-588.

Eberhard, A., Kahlert, S., Goede, V., Hemmerlein, B., Plate, K.H., and Augustin, H.G. (

2000
) Heterogeneity of angiogenesis and blood vessel maturation in human tumors: Implications for antiangiogenic tumor therapies.
Cancer Res.
60
,
1388
-1393.

Ellerbroek, S.M., Wu, Y.I., Overall, C.M., and Stack, M.S. (

2001
) Functional interplay between type I collagen and cell surface matrix metalloproteinase activity.
J. Biol. Chem.
276
,
24833
-24842.

Forsythe, J.A., Jiang, B.H., Iyer, N.V., Agani, F., Leung, S.W., Koos, R.D., and Semenza, G.L. (

1996
) Activation of vascular endothelial growth factor gene transcription by hypoxia-inducible factor 1.
Mol. Cell Biol.
16
,
4604
-4613.

Gojo, I., Zhang, B., and Fenton, R.G. (

2002
) The cyclin-dependent kinase inhibitor flavopiridol induces apoptosis in multiple myeloma cells through transcriptional repression and down-regulation of Mcl-1.
Clin. Cancer Res.
8
,
3527
-3538.

Guillemin, K., and Krasnow, M.A. (

1997
) The hypoxic response: Huffing and HIFing.
Cell
89
,
9
-12.

Hotary, K., Allen, E., Punturieri, A., Yana, I., and Weiss, S.J. (

2000
) Regulation of cell invasion and morphogenesis in a three-dimensional type I collagen matrix by membrane-type matrix metalloproteinases 1, 2, and 3.
J. Cell Biol.
149
,
1309
-1323.

Huang, L.E., Arany, Z., Livingston, D.M., and Bunn, H.F. (

1996
) Activation of hypoxia-inducible transcription factor depends primarily upon redox-sensitive stabilization of its α subunit.
J. Biol. Chem.
271
,
32253
-32259.

Huang, L.E., Gu, J., Schau, M., and Bunn, H.F. (

1998
) Regulation of hypoxia-inducible factor 1α is mediated by an O2-dependent degradation domain via the ubiquitin-proteasome pathway.
Proc. Natl. Acad. Sci. USA
95
,
7987
-7992.

Ishii, N., Maier, D., Merlo, A., Tada, M., Sawamura, Y., Diserens, A.C., and Van Meir, E.G. (

1999
) Frequent co-alterations of TP53, p16/CDKN2A, p14ARF, PTEN tumor suppressor genes in human glioma cell lines.
Brain Pathol.
9
,
469
-479.

Iyer, N.V., Kotch, L.E., Agani, F., Leung, S.W., Laughner, E., Wenger, R.H., Gassmann, M., Gearhart, J.D., Lawler, A.M., Yu, A.Y., and Semenza, G.L. (

1998
) Cellular and developmental control of O2 homeostasis by hypoxia-inducible factor 1α.
Genes Dev.
12
,
149
-162.

Jiang, B.H., Semenza, G.L., Bauer, C., and Marti, H.H. (

1996
) Hypoxia inducible factor 1 levels vary exponentially over a physiologically rel evant range of O2 tension.
Am. J. Physiol.
271
,
C1172
-C1180.

Jiang, B.H., Agani, F., Passaniti, A., and Semenza, G.L. (

1997
) V-SRC induces expression of hypoxia-inducible factor 1 (HIF-1) and transcription of genes encoding vascular endothelial growth factor and enolase 1: Involvement of HIF-1 in tumor progression.
Cancer Res.
57
,
5328
-5335.

Kallio, P.J., Wilson, W.J., O'Brien, S., Makino, Y., and Poellinger, L. (

1999
) Regulation of the hypoxia-inducible transcription factor 1α by the ubiq uitin-proteasome pathway.
J. Biol. Chem.
274
,
6519
-6525.

Kerr, J.S., Wexler, R.S., Mousa, S.A., Robinson, C.S., Wexler, E.J., Mohamed, S., Voss, M.E., Devenny, J.J., Czerniak, P.M., Gudzelak, A., Jr., and Slee, A.M. (

1999
) Novel small molecule alpha v integrin antagonists: Com parative anti-cancer efficacy with known angiogenesis inhibitors.
Anticancer Res.
19
,
959
-968.

Kitagawa, H., Tani, E., Ikemoto, H., Ozaki, I., Nakano, A., and Omura, S. (

1999
) Proteasome inhibitors induce mitochondria-independent apop tosis in human glioma cells.
FEBS Lett.
443
,
181
-186.

Koshikawa, N., Giannelli, G., Cirulli, V., Miyazaki, K., and Quaranta, V. (

2000
) Role of cell surface metalloprotease MT1-MMP in epithelial cell migration over laminin-5.
J. Cell Biol.
148
,
615
-624.

Krishnamachary, B., Berg-Dixon, S., Kelly, B., Agani, F., Feldser, D., Ferreira, G., Iyer, N., LaRusch, J., Pak, B., Taghavi, P., and Semenza, G.L. (

2003
) Regulation of colon carcinoma cell invasion by hypoxia-inducible factor 1.
Cancer Res.
63
,
1138
-1143.

Li, Y., Bhuiyan, M., Alhasan, S., Senderowicz, A.M., and Sarkar, F.H. (

2000
) Induction of apoptosis and inhibition of c-erbB-2 in breast cancer cells by flavopiridol.
Clin. Cancer Res.
6
,
223
-229.

Maxwell, P.H., Dachs, G.U., Gleadle, J.M., Nicholls, L.G., Harris, A.L., Stratford, I.J., Hankinson, O., Pugh, C.W., and Ratcliffe, P.J. (

1997
) Hypoxia-inducible factor-1 modulates gene expression in solid tumors and influences both angiogenesis and tumor growth.
Proc. Natl. Acad. Sci. USA
94
,
8104
-8109.

Melillo, G., Sausville, E.A., Cloud, K., Lahusen, T., Varesio, L., and Senderow icz, A.M. (

1999
) Flavopiridol, a protein kinase inhibitor, down-regulates hypoxic induction of vascular endothelial growth factor expression in human monocytes.
Cancer Res.
59
,
5433
-5437.

Munaut, C., Noel, A., Hougrand, O., Foidart, J.M., Boniver, J., and Deprez, M. (

2003
) Vascular endothelial growth factor expression correlates with matrix metalloproteinases MT1-MMP, MMP-2 and MMP-9 in human glioblastomas.
Int. J. Cancer
106
,
848
-855.

Nawrocki, S.T., Sweeney-Gotsch, B., Takamori, R., and McConkey, D.J. (

2004
) The proteasome inhibitor bortezomib enhances the activity of docetaxel in orthotopic human pancreatic tumor xenografts.
Mol. Cancer Ther.
3
,
59
-70.

Newcomb, E.W. (

2004
) Flavopiridol: Pleiotropic biological effects enhance its anti-cancer activity.
Anti-cancer Drugs
15
,
411
-419.

Newcomb, E.W., Tamasdan, C., Entzminger, Y., Arena, E., Schnee, T., Kim, M., Crisan, D., Lukyanov, Y., Miller, D.C., and Zagzag, D. (

2004
) Fla vopiridol inhibits the growth of GL261 gliomas in vivo: Implications for malignant glioma therapy.
Cell Cycle
3
,
230
-234.

Orlowski, R.Z., and Baldwin, A.S., Jr. (

2002
) NF-κB as a therapeutic target in cancer.
Trends Mol. Med.
8
,
385
-389.

Rapella, A., Negrioli, A., Melillo, G., Pastorino, S., Varesio, L., and Bosco, M.C. (

2002
) Flavopiridol inhibits vascular endothelial growth factor production induced by hypoxia or picolinic acid in human neuroblastoma.
Int. J. Cancer
99
,
658
-664.

Rapisarda, A., Uranchimeg, B., Scudiero, D.A., Selby, M., Sausville, E.A., Shoemaker, R.H., and Melillo, G. (

2002
) Identification of small mol ecule inhibitors of hypoxia-inducible factor 1 transcriptional activation pathway.
Cancer Res.
62
,
4316
-4324.

Ravi, R., Mookerjee, B., Bhujwalla, Z.M., Sutter, C.H., Artemov, D., Zeng, Q., Dillehay, L.E., Madan, A., Semenza, G.L., and Bedi, A. (

2000
) Regulation of tumor angiogenesis by p53-induced degradation of hypoxia inducible factor 1α.
Genes Dev.
14
,
34
-44.

Salceda, S., and Caro, J. (

1997
) Hypoxia-inducible factor 1α (HIF-1α) protein is rapidly degraded by the ubiquitin-proteasome system under normoxic conditions. Its stabilization by hypoxia depends on redox-induced changes.
J. Biol. Chem.
272
,
22642
-22647.

Semenza, G.L. (

1999
) Regulation of mammalian O2 homeostasis by hypoxia-inducible factor 1.
Annu. Rev. Cell Dev. Biol.
15
,
551
-578.

Senderowicz, A.M. (

2003
) Small-molecule cyclin-dependent kinase modu lators.
Oncogene
22
,
6609
-6620.

Shannon, A.M., Bouchier-Hayes, D.J., Condron, C.M., and Toomey, D. (

2003
) Tumour hypoxia, chemotherapeutic resistance and hypoxia-related therapies.
Cancer Treat. Rev.
29
,
297
-307.

Shweiki, D., Itin, A., Soffer, D., and Keshet, E. (

1992
) Vascular endothe lial growth factor induced by hypoxia may mediate hypoxia-initiated angiogenesis.
Nature
359
,
843
-845.

Takada, Y., and Aggarwal, B.B. (

2004
) Flavopiridol inhibits NF-κB activation induced by various carcinogens and inflammatory agents through inhibition of IκBα kinase and p65 phosphorylation: Abrogation of cyclin D1, cyclooxygenase-2, and matrix metalloprotease-9.
J. Biol. Chem.
279
,
4750
-4759.

Tergaonkar, V., Bottero, V., Ikawa, M., Li, Q., and Verma, I.M. (

2003
) IκB kinase-independent IκBα degradation pathway: Functional NF-κB activity and implications for cancer therapy.
Mol. Cell Biol.
23
,
8070
-8083.

Unruh, A., Ressel, A., Mohamed, H.G., Johnson, R.S., Nadrowitz, R., Rich ter, E., Katschinski, D.M., and Wenger, R.H. (

2003
) The hypoxia-induc ible factor-1 α is a negative factor for tumor therapy.
Oncogene
22
,
3213
-3220.

Voorhees, P.M., Dees, E.C., O'Neil, B., and Orlowski, R.Z. (

2003
) The proteasome as a target for cancer therapy.
Clin. Cancer Res.
9
,
6316
-6325.

Wang, G.L., Jiang, B.H., Rue, E.A., and Semenza, G.L. (

1995
) Hypoxia inducible factor 1 is a basic-helix-loop-helix-PAS heterodimer regulated by cellular O2 tension.
Proc. Natl. Acad. Sci. USA
92
,
5510
-5514.

Zagzag, D., Zhong, H., Scalzitti, J.M., Laughner, E., Simons, J.W., and Semenza, G.L. (

2000
) Expression of hypoxia-inducible factor 1α in brain tumors: Association with angiogenesis, invasion, and progression.
Cancer
88
,
2606
-2618.

Zagzag, D., Shiff, B., Jallo, G.I., Greco, M.A., Blanco, C., Cohen, H., Hukin, J., Allen, J.C., and Friedlander, D.R. (

2002
) Tenascin-C promotes microvascular cell migration and phosphorylation of focal adhesion kinase.
Cancer Res.
62
,
2660
-2668.

Zagzag, D., Nomura, M., Friedlander, D.R., Blanco, C.Y., Gagner, J.P., Nomura, N., and Newcomb, E.W. (

2003
) Geldanamycin inhibits migration of glioma cells in vitro: A potential role for hypoxia-inducible factor (HIF-1α) in glioma cell invasion.
J. Cell Physiol.
196
,
394
-402.

Zundel, W., Schindler, C., Haas-Kogan, D., Koong, A., Kaper, F., Chen, E., Gottschalk, A.R., Ryan, H.E., Johnson, R.S., Jefferson, A.B., Stokoe, D., and Giaccia, A.J. (

2000
) Loss of PTEN facilitates HIF-1-mediated gene expression.
Genes Dev.
14
,
391
-396.

Author notes

Department of Pathology (E.W.N., M.A.A., T.S., L.L., Y.L., M.F., D.C.M., D.Z.);Division of Neuropathology and Department of Neurosurgery (D.C.M., D.Z.);New York University Cancer Institute (E.W.N., D.C.M., D.Z.), New York University School of Medicine, New York, NY 10016, USA