aprinocarsen and oblimersen

The currently available treatment of cancer patients is based on the use of cytotoxic drugs and/or of ionizing radiations, which have potent antitumor activity, but also cause clinically relevant side effects, since they affect cellular targets that are common to both cancer cells and normal proliferating cells. In the past 20 years, the discoveries on the molecular mechanisms of cancer development and progression have prompted the search for agents which are more selective for cancer cell molecular targets. The possibility of combining conventional cytotoxic drugs with novel agents that specifically interfere with key pathways controlling cancer cell survival, proliferation, invasion and/or metastatic spreading has generated a wide interest. This could be a promising therapeutic approach for several reasons. First, since the cellular targets for these agents and their mechanism(s) of action are different from those of cytotoxic drugs, it is possible for their combination with chemotherapy without cross-resistance. Second, alterations in the expression and/or the activity of genes that regulate mitogenic signals not only can directly cause perturbation of cell growth, but also may affect the sensitivity of cancer cells to conventional chemotherapy and radiotherapy. In this review, we will discuss the biologic bases of the combination of molecular targeted drugs with conventional medical cancer treatments and the available results of the first series of clinical trials in cancer patients.

Topics: Alkyl and Aryl Transferases; Antineoplastic Agents; Combined Modality Therapy; ErbB Receptors; Farnesyltranstransferase; Genes, bcl-2; Humans; Neoplasms; Oligodeoxyribonucleotides, Antisense; Oligonucleotides; Protein Kinase C; ras Proteins; Signal Transduction; Thionucleotides

There is a potential role for antisense oligonucleotides in the treatment of disease. The principle of antisense technology is the sequence-specific binding of an antisense oligonucleotide to target mRNA, resulting in the prevention of gene translation. The specificity of hybridisation makes antisense treatment an attractive strategy to selectively modulate the expression of genes involved in the pathogenesis of diseases. One antisense drug has been approved for local treatment of cytomegalovirus-induced retinitis, and several antisense oligonucleotides are in clinical trials, including oligonucleotides that target the mRNA of BCL2, protein-kinase-C alpha, and RAF kinase. Antisense oligonucleotides are well tolerated and might have therapeutic activity. Here, we summarise treatment ideas in this field, summarise clinical trials that are being done, discuss the potential contribution of CpG motif-mediated effects, and look at promising molecular targets to treat human cancer with antisense oligonucleotides.

Topics: Animals; Antineoplastic Agents; Clinical Trials as Topic; Drug Design; Humans; In Vitro Techniques; Isoenzymes; Neoplasms; Oligodeoxyribonucleotides, Antisense; Oligonucleotides; Oligonucleotides, Antisense; Phosphorothioate Oligonucleotides; Protein Kinase C; Protein Kinase C-alpha; Proto-Oncogene Proteins c-bcl-2; RNA, Messenger; Thionucleotides

Isis 3521 and G3139 are 20- and 18-mer phosphorothioate oligonucleotides, respectively, targeted to the protein kinase C (PKC)-alpha and bcl-2 mRNAs. Treatment of T24 bladder and PC3 prostate carcinoma cells with full-length and 3'-truncation mutants of Isis 3521 causes down-regulation of PKC-alpha protein and mRNA. However, at the level of a 15-mer and shorter, down-regulation of mRNA expression is no longer observed. Further, no diminution in cellular viability, as measured by 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide assay, in response to increasing concentrations of paclitaxel, can be observed for these shorter oligomers. These observations not only indicate that PKC-alpha protein expression can be down-regulated by both RNase H-dependent and -independent mechanisms but also that down-regulation of PKC-alpha is insufficient by itself to "chemosensitize" cells. G3139, which down-regulates bcl-2 protein and mRNA expression, also down-regulates PKC-alpha protein and mRNA expression but not that of PKC-betaI, -epsilon, or -zeta. However, the down-regulation of PKC-alpha and bcl-2 are not linked. When the carrier Eufectin 5 is employed, only bcl-2 is down-regulated in both T24 and PC3 cells at 50 nM oligonucleotide concentration. At 100 nM, both bcl-2 and PKC-alpha expression are down-regulated, and only at this concentration can "chemosensitization" to paclitaxel and carboplatin be observed. In contrast, the down-regulation of bcl-2 seems to be linked with that of RelA (p65). However, this too is also not sufficient for chemosensitization, even though it leads to the loss of expression of genes under the putative control of nuclear factor-kappaB and to detachment of the cells from plastic surfaces. These results underscore the complexity of the intracellular requirements for the initiation of chemosensitization to anti-neoplastic agents.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Cell Survival; Down-Regulation; Gene Deletion; Humans; Isoenzymes; Male; NF-kappa B; Oligodeoxyribonucleotides, Antisense; Paclitaxel; Prostatic Neoplasms; Protein Kinase C; Protein Kinase C-alpha; Proto-Oncogene Proteins c-bcl-2; Ribonuclease H; RNA, Messenger; Thionucleotides; Transcription Factor RelA; Tumor Cells, Cultured; Urinary Bladder Neoplasms