Tumorigenic

Tumorigenic refers to the property of cells, tissues, or agents to initiate and develop tumors. In cancer biology, tumorigenicity describes the capacity of transformed cells to form tumors when introduced into a suitable host, typically immunocompromised animals, or to grow as malignant masses in culture. In virology, certain viruses or viral oncogenes can confer tumorigenic potential to infected cells. The term is distinct from oncogenicity in that tumorigenicity specifically implies tumor formation in vivo or in tumor-forming assays, whereas oncogenic mutations may promote uncontrolled growth without necessarily yielding a discernible tumor in a particular model.

Tumorigenicity arises from genetic and epigenetic changes that promote cell proliferation, survival, invasion, and angiogenesis, including activation of oncogenes, loss of tumor suppressor function, and chromosomal instability. The tumor microenvironment, immune evasion, and cellular context influence whether transformed cells form detectable tumors. Experimental assessment commonly uses in vivo assays in immunodeficient mice to monitor tumor formation after implantation, and in vitro assays such as anchorage-independent growth in soft agar as a surrogate of transformation.

In regenerative medicine and stem cell research, pluripotent stem cells can be tumorigenic because residual undifferentiated cells may form teratomas after transplantation. As a result, evaluating and mitigating tumorigenicity is a key safety goal when developing therapies derived from induced pluripotent or embryonic stem cells. Approaches include directed differentiation, purification of lineage-committed cells, sensitive assays for residual pluripotent cells, and stringent quality controls.

Terminology notes: tumorigenicity is a property assessed in experimental settings and is influenced by model choice and endpoint. It is a critical consideration in cancer research, virology, and the safety evaluation of cellular therapies.