Drug Delivery Towards Cancer

Some special characteristics like evading growth suppressors, sustaining proliferative signaling, enabling replicative immortality, activating invasion and metastasis, inducing angiogenesis, and resisting cell death have made cancer cells very challenging to destroy (Hanahan and Weinberg 2011). Cancer cells have high level of telomerase enzyme and they are mostly unresponsive to cellular growth regulators and apoptosis. These challenging factors help the cancer to maintain its DNA integrity and allow them to replicate infinitely. The capability of inducing angiogenesis promotes rapid formation of new blood vessels in the cancerous tissue and thus the cells remove their toxic waste and get sufficient nutrients for their rapid growth. It has also capability to migrate and penetrate into the other parts of the body and thus forms new, secondary tumors. Besides, cancer cell has overexpressed glucose transporter which leads to increased glucose uptake into the cancer cells. They can also perform aerobic glycolysis which acts as metabolic switch and may allow to nucleosides and amino acids anabolism for additional growth and proliferation. Moreover, as the cancer cells are derived from own host body cells, the markers for immune recognition are not well expressed in the cell surfaces which makes it less susceptible to T-lymphocyte recognition and thus allowing them to avoid elimination by the immune system (Tran et al. 2017). All of these characteristics have made cancer targeting and treatment very challenging which ultimately fueled the demand of special type of drug delivery systems.