Cudraflavone C Induces Tumor-Specific Apoptosis in Colorectal Cancer Cells through Inhibition of the Phosphoinositide 3-Kinase (PI3K)-AKT Pathway

Cudraflavone C (Cud C) is a naturally-occurring flavonol with reported anti-proliferative activities. However, the mechanisms by which Cud C induced cytotoxicity have yet to be fully elucidated. Here, we investigated the effects of Cud C on cell proliferation, caspase activation andapoptosis induction in colorectal cancer cells (CRC). We show that Cud C inhibits cell proliferation in KM12, Caco-2, HT29, HCC2998, HCT116 and SW48 CRC but not in the non-transformed colorectal epithelial cells, CCD CoN 841. Cud C induces tumor-selective apoptosis via mitochondrial depolarization and activation of the intrinsic caspase pathway. Gene expression profiling by microarray analyses revealed that tumor suppressor genes EGR1, HUWE1 and SMG1 were significantly up-regulated while oncogenes such as MYB1, CCNB1 and GPX2 were down-regulated following treatment with Cud C. Further analyses using Connectivity Map revealed that Cud C induced a gene signature highly similar to that of protein synthesis inhibitors and phosphoinositide 3-kinase (PI3K)-AKT inhibitors, suggesting that Cud C might inhibit PI3K-AKT signaling. A luminescent cell free PI3K lipid kinase assay revealed that Cud C significantly inhibited p110β/p85α PI3K activity, followed by p120γ, p110δ/p85α, and p110α/p85α PI3K activities. The inhibition by Cud C on p110β/p85α PI3K activity was comparable to LY-294002, a known PI3K inhibitor. Cud C also inhibited phosphorylation of AKT independent of NFκB activity in CRC cells, while ectopic expression of myristoylated AKT completely abrogated the anti-proliferative effects, and apoptosis induced by Cud C in CRC. These findings demonstrate that Cud C induces tumor-selective cytotoxicity by targeting the PI3K-AKT pathway. These findings provide novel insights into the mechanism of action of Cud C, and indicate that Cud C further development of Cud C derivatives as potential therapeutic agents is warranted.

Personalized colon cancer care in 2010

Colon cancer (CC) therapies have improved patient outcomes significantly over the last decades in both the adjuvant and metastatic settings. With the introduction of a number of novel agents, both traditional chemotherapies and biologically targeted agents, the need to identify subgroups that are likely and not likely to respond to a particular treatment regimen is paramount. This will allow patients who are likely to benefit to receive optimal care, while sparing those unlikely to benefit from unnecessary toxicity and cost. With the identification of several novel biomarkers and a variety of technologies to interrogate the genome, we already are able to rapidly study patient tumor or blood samples and normal tissues to generate a large dataset of aberrations within the cancer. How to digest this complex information to obtain accurate, reliable, and meaningful results that will allow us to provide truly personalized care for CC patients is just starting to be addressed. In this article, we briefly review the history of CC treatment, with an emphasis on current clinical standards that incorporate a "personalized medicine" approach. We then review strategies that will potentially improve our ability to individualize therapy in the future.

Akt inhibitors in clinical development for the treatment of cancer

IMPORTANCE OF THE FIELD

The evolution of targeted therapies is dependent upon identification of cellular moieties that can be pharmacologically modulated. As one such example, the serine-threonine kinase Akt was identified nearly two decades ago. Since then, its role in mediating multiple signaling cascades (ultimately leading to cell growth and proliferation) has since been identified. More recently, several agents have been developed that antagonize Akt--these agents are in various stages of clinical testing.

AREAS COVERED IN THIS REVIEW

Herein, we outline development of several promising Akt inhibitors, including perifosine, MK-2206, RX-0201, PBI-05204, GSK2141795 and others.

WHAT THE READER WILL GAIN

The reader will gain insight into the current pipeline of Akt inhibitors, and the degree to which these agents have been examined both clinically and preclinically.

TAKE HOME MESSAGE

With an emerging pipeline of agents targeting Akt, it will be critical to decipher which amongst them holds the greatest promise. Herein, we explore this drug pipeline and provide strategies for determining the future clinical application of these agents.

The evolving role of monoclonal antibodies in colorectal cancer: early presumptions and impact on clinical trial development

Targeted biologic agents have an established role in treating metastatic colorectal cancer (mCRC). Bevacizumab, a recombinant monoclonal antibody against the vascular endothelial growth factor ligand is approved by the U.S. Food and Drug Administration (FDA) for bevacizumab-naïve patients. Cetuximab, a chimeric monoclonal antibody (mAb) against the epidermal growth factor receptor (EGFR) is FDA approved as a single agent, or in combination with irinotecan, in both irinotecan-naïve and refractory patients, and has additional efficacy in combination with oxaliplatin. Panitumumab, a fully human EGFR mAb, is FDA approved as a single agent in refractory patients but has additional efficacy in combination with chemotherapy. After reaching a temporary therapeutic plateau of FDA-approved agents for the treatment of mCRC, pivotal results have developed that critically affect the care for these patients. Correlative data from randomized trials of EGFR inhibitors across disease settings have demonstrated higher response rates, specifically for patients with wild-type K-RAS tumors. The interpretation of the B-RAF mutation and other molecular markers may further define the appropriateness of anti-EGFR therapy. Recent literature revealed that the first-line use of combined anti-EGFR therapy plus bevacizumab resulted in inferior outcomes and additional toxicities. Furthermore, the role of biologic agents for locally advanced colon cancer cannot be advocated at this time. With impending changes in the health care system, the economic impact of mAbs will continue to be scrutinized. Hence, as the significance of molecular markers continues to develop, their role as it pertains to the appropriate use of biologic agents in the treatment of mCRC will continue to evolve.