The Potential Role of Akt Phosphorylation in Human Cancers

Akt/protein kinase B (PKB) is a serine/threonine kinase which is implicated in mediating a variety of biological responses including cell growth, proliferation and survival. Akt is activated by phosphorylation on two critical residues, namely threonine 308 (Thr308) and serine 473 (Ser473). Several studies have found Akt2 to be amplified or overexpressed at the mRNA level in various tumor cell lines and in a number of human malignancies such as colon, pancreatic and breast cancers. Nevertheless, activation of Akt isoforms by phosphorylation appears to be more clinically significant than Akt2 amplification or overexpression. Many studies in the past 4–5 years have revealed a prognostic and/or predictive role of Akt phosphorylation in breast, prostate and non-small cell lung cancer. Several publications suggest a role of phosphorylated Akt also in endometrial, pancreatic, gastric, tongue and renal cancer. However, different types of assays were used in these studies. Before assessment of P-Akt can be incorporated into routine clinical practice, all aspects of the assay methodology will have to be standardized.

A retrospective analysis of cardiovascular morbidity in metastatic hormone-refractory prostate cancer patients on high doses of the selective COX-2 inhibitor celecoxib

This data were previously presented in February 2007 at the American Society of Clinical Oncology's Prostate Cancer Symposium in Orlando, FL, USA. COX-2 inhibition has shown promise in treating prostate cancer, but concerns exist regarding the risk profile associated with this class of drugs. This study analyzes the cardiovascular and cerebral vascular morbidity associated with high doses of the COX-2 inhibitor, celecoxib, in patients with metastatic hormone-refractory prostate cancer (mHRPC). We retrospectively reviewed 67 patients with mHRPC who were treated at our institution between 1999 and 2005. All charts were reviewed for cardiac risk factors and the clinical course whilst on therapy and post-treatment was analyzed. This study included 34 patients who were on protocols that involved celecoxib 400 mg b.i.d.. Treatment ranged from 21 to 355 days, with a median of 118.5 days. There were three myocardial infarctions (MIs)--two in the study group and one in the control group. One patient had a MI while on treatment, but he had a significant cardiac disease history. There were also two cerebral vascular accidents (CVAs) in each group, although none in any patient who was on-study. Although this is a small study, these findings, in the context of other published data, suggest that some patients with advanced malignancies may still benefit from therapies involving COX-2 inhibitors without clinically significant increase in risk for MI or CVA.

Inhibition of Akt pathways in the treatment of prostate cancer

Akt is a serine/threonine kinase mediating multiple intracellular pathways involved in prostate cancer (CaP) biology. Increased understanding of the molecular mechanisms of Akt activation and signaling have led to the development of an increasing number of Akt inhibitors. These biologic agents demonstrate activity against a wide range of cancers in preclinical studies. Clinical studies of Akt inhibition in CaP are in progress, including agents such as celecoxib, perifosine and genistein. How best to integrate Akt inhibitors with standard CaP therapy or select patients most likely to benefit is the subject of ongoing research.

Interfering with cell-survival signalling as a treatment strategy for prostate cancer

Authors from Australia describe how interfering with cell survival is increasingly being chosen as a method of developing a treatment strategy for hormone-resistant prostate cancer. The authors show how several developmental drug candidates have preclinical and clinical activity against cell survival proteins, and that these might be worth considering as possible clinical entities in this condition. The commonly stated argument that laparoscopy has advanced the cause of donor nephrectomy in renal transplantation is examined by authors from the UK. They present a review of the published reports and show that the evidence base is poor for drawing a conclusion as to whether laparoscopic or open nephrectomy is best.