| Gastrointestinal cancers, including gastric cancer, liver cancer and colorectal cancer, are the top five causes in cancer incidence and death and difficult to cure, which make tumor vaccine to participate in the combined therapy and play a key role in it. The cytotoxic T lymphocytes (CTL) are the crucial point in the immunity against tumors, which have been shown to be effective in mounting an antitumor response both in vitro and in vivo. CTL responses are to efficiently deliver tumor-associated antigens (TAAs) into the major histocompatibility complex class I (MHC- I ) processing passway of the professional antigen presenting cells (APCs). Therefore, immunization generated against a universal tumor antigen such as the human telomerase reverse transcriptase (hTERT) would have a much greater impact on cancer immunotherapy.hTERT, the catalytic subunit of human telomerase, is considered to be essential for the immortality of cancer cells and highly expressed in over 85 percent of human GI cancers, but with restricted expression in normal adult tissues, making it as a broadly applicable molecule target for cancer therapy. What advantages would hTERT as a tumor vaccine target? First, the broad expression of hTERT across different types of tumors would extend to more patients with cancers. Second, tumor downregulation of hTERT, as a means of immune escape, might itself be incompatible with sustained tumor growth. Third, it was not found that tumor vaccine of hTERT has the potential lysis of rare normal telomerase positive cell types. Thus, if efficient immunity can be successfully elicited in cancer patients without the induction of severe autoimmunity, hTERT clearly becomes a prime candidate for a widely applicable GI cancer vaccine.Peptide and naked DNA vaccine have been considered of the most commonly used technologies for tumor vaccination due to their safety and practicability. However, both... |
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