Tumor-specific promoters are DNA sequences that regulate the expression of genes specifically in tumor cells. These promoters can be used in gene therapy to drive the expression of therapeutic genes selectively in tumor cells, while minimizing expression in normal cells, thereby reducing the potential for off-target effects and toxicity.

Tumor-specific promoters can be classified into two main types: constitutive and inducible promoters. Constitutive promoters drive gene expression constantly and at a fixed rate in both normal and tumor cells, while inducible promoters are activated only under specific conditions or in response to certain stimuli, such as hypoxia or radiation, which are commonly present in tumor cells.

Examples of constitutive tumor-specific promoters include the human telomerase reverse transcriptase (hTERT) promoter, which is active in many types of cancer cells, and the human tumor necrosis factor receptor type 2 (TNFR2) promoter, which is active in various types of solid tumors.

Examples of inducible tumor-specific promoters include the hypoxia-responsive element (HRE) promoter, which is activated in response to low oxygen levels in tumor cells, and the radiation-inducible promoter, which is activated in response to ionizing radiation.

In addition to these examples, numerous other tumor-specific promoters have been identified and characterized, and their use in gene therapy is being actively investigated in preclinical and clinical studies.

Tumor-specific promoters offer an important tool for gene therapy by providing a means to selectively target and treat cancer cells while minimizing off-target effects and toxicity. However, further research is needed to optimize their use in gene therapy and to fully realize their potential as a cancer treatment strategy.