Cancer is characterized by uncontrolled division of cells and the ability of these cells to invade other tissues leading to the formation of tumor mass, vascularization, and metastasis. Chemotherapy is one of the major approaches to treat cancer by delivering a cytotoxic agent to the cancer cells. The main problem with the conventional chemotherapy is the inability to deliver the correct amount of drug directly to cancer cells without affecting normal cells. There is an urgent need for the development of novel tumor-targeted therapies that could effectively and specifically target tumor cells with lower toxicity to normal tissues. Discovery of several protein/peptide receptors and tumor-related peptides and proteins is expected to create a “new wave”of more effective and selective anticancer drugs in the future. Peptides are typically relatively short (12 to 100 amino acids), are positively charged, are amphiphilic and have been isolated from single-cell microorganisms, insects and other invertebrates, plants, amphibians, birds, fish, and mammals, including humans. Peptides possess many advantages, such as small size, ease of synthesis and modification, tumor-penetrating ability, and good biocompatibility. Therefore, based on the technologies of bioinformatics, crystal structural analysis and computer-aided design (CAD), novel peptides have been designed, synthesized, and successfully used. Peptides are capable of interacting with membranes adhesion receptors like integrins. This receptors bind to specific extra cellular matrix protein and ligands on cell surface and plays important role in the cell-cell and cell-matrix communications which are important for cell response and behavior. Furthermore, peptide could induce apoptosis in tumor cells via increase of ROS production in mitochondria of tumor cells. Reactive oxygen species (ROS) are highly reactive ions and free radicals (chemicals containing atoms with an unpaired electron in its outer orbit) involving oxygen molecules. Reactive oxygen species have a really short life and are very unstable. Because of these characteristics, ROS react with other molecules to achieve stability. ROS production has been involved in drug toxicities, inflammation, aging, fibrosis, carcinogenesis, lipid peroxidation of cellular membranes and also implicated in several specific diseases such as atherosclerosis, degenerative neurologic disease,reperfusion injury and oxygen toxicity. Peptide-induced apoptosis results when VDAC destabilization increases ROS generation and promotes ion influx and ultimate mitochondrial membrane rupture, causing the release of the proapototic protein group which led to apoptosis. Apoptosis is an intrinsic cell-suicide program that multicellular organisms have developed to control cell proliferation, in response to DNA damage in the course of development or following cellular stress. During apoptosis, the nucleus and cytoplasm shrink, condense and then fragment, releasing small membrane-bound apoptotic bodies, which are phagocytosed by macrophages or adjacent cells.

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