Diltiazem enhances the apoptotic effects of proteasome inhibitors to induce prostate cancer cell death.

Diltiazem is a calcium channel blocker used to treat cardiovascular ailments. In addition, reports suggest that diltiazem induces cell death, which could make it a drug of choice for the treatment of cancer associated with hypertension. The goal of this research was to determine whether diltiazem is capable of inducing apoptosis in prostate cancer cells, either alone or in combination with the proteasome inhibitors, lactacystin and bortezomib (Velcade).

Novel role of androgens in mitochondrial fission and apoptosis.

Androgen and androgen receptors (AR) play critical roles in the proliferation of prostate cancer through transcriptional regulation of target genes. Here, we found that androgens upregulated the expression of dynamin-related protein 1 (Drp1), which is involved in the induction of mitochondrial fission, a common event in mitosis and apoptosis. Clinical tissue samples and various prostate cancer cell lines revealed a positive correlation between Drp1 and AR levels.

Specific mitochondrial calcium overload induces mitochondrial fission in prostate cancer cells.

Mitochondria are structurally complex organelles that undergo fragmentation or fission in apoptotic cells. Mitochondrial fission requires the cytoplasmic dynamin-related protein, Drp1, which translocates to the mitochondria during apoptosis and interacts with the mitochondrial protein, Fis1. Finely tuned changes in cellular calcium modulate a variety of intracellular functions; in resting cells, the level of mitochondrial calcium is low, while it is higher during apoptosis.

Prostaglandin E2 promotes lung cancer cell migration via EP4-betaArrestin1-c-Src signalsome.

Many human cancers express elevated levels of cyclooxygenase-2 (COX-2), an enzyme responsible for the biosynthesis of prostaglandins. Available clinical data establish the protective effect of COX-2 inhibition on human cancer progression. However, despite these encouraging outcomes, the appearance of unwanted side effects remains a major hurdle for the general application of COX-2 inhibitors as effective cancer drugs.

Identification of betaArrestin2 as a corepressor of androgen receptor signaling in prostate cancer.

Androgen receptor (AR) signaling regulates the development and homeostasis of male reproductive organs, including the prostate. Deregulation of AR and AR coregulators, expression, or activity is involved in the initiation of prostate cancer and contributes to the transition of the disease to hormone-refractory stage. The ubiquitous betaArrestin proteins are now recognized as bona fide adapters and signal transducers with target effectors found in both the cytosol and nucleus.

Therapeutic advantage of combining calcium channel blockers and TRAIL in prostate cancer.

Disruption of intracellular calcium initiates multiple cell-damaging processes, such as apoptosis. In normal cells, the levels of Ca(2+) are low in the mitochondria, whereas in apoptotic cells, Ca(2+) increases. Mitochondria uptake Ca(2+) via an inner membrane channel called the uniporter and extrude it into the cytoplasm through a Na(+)/Ca(2+) exchanger.

SAHA-sensitized prostate cancer cells to TNFalpha-related apoptosis-inducing ligand (TRAIL): mechanisms leading to synergistic apoptosis.

Treatment of cancer cells with histone deacetylase inhibitors (HDACi) such as suberolylanilide hydroxamic acid (SAHA) activates genes that promote apoptosis. To enhance proapoptotic efficiency, SAHA has been used in combination with radiation, kinase inhibitors and cytotoxic drugs. Although several prostate cells respond to TNFalpha-Related Apoptosis-Inducing Ligand (TRAIL), LNCaP are resistant.

Sensitization of TRAIL-resistant cells by inhibition of heat shock protein 90 with low-dose geldanamycin.

Due to its specificity and effectiveness, tumor necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL) is being tested for cancer therapy. Inhibition of the function of heat shock protein 90 (HSP90) is under clinical trials for cancer therapy. However, some cancer cells are resistant to TRAIL, and at the dose required for inducing apoptosis, geldanamycin, a drug that inhibits HSP90 function, has shown adverse effects.

Combination of proteasomal inhibitors lactacystin and MG132 induced synergistic apoptosis in prostate cancer cells.

The proteasome inhibitor Velcade (bortezomib/PS-341) has been shown to block the targeted proteolytic degradation of short-lived proteins that are involved in cell maintenance, growth, division, and death, advocating the use of proteasomal inhibitors as therapeutic agents. Although many studies focused on the use of one proteasomal inhibitor for therapy, we hypothesized that the combination of proteasome inhibitors Lactacystin (AG Scientific, Inc., San Diego CA) and MG132 (Biomol International, Plymouth Meeting, PA) may be more effective in inducing apoptosis.