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Paraneoplastic syndromes: mechanisms
1St Joseph's Hospital, Bellingham, WA, USA.
Abstract:
Neoplasms may affect distant host tissues, but they always involve normal physiologic mechanisms. Van R. Potter said that "Oncogeny is blocked ontogeny," so tumors are committed to their organ anlagen. Paraneoplastic mediators are appropriate to their blocked anlagen stages. Mediators may have autocrine, paracrine, or endocrine actions. However, their release and distribution depend on the mode of cell death, and the spatial relations to host vascularity. Invasiveness and metastasis are means of normal embryonic development, and not new cancer-specific properties. Nor do human cancers acquire new foreign genetic information; thus, they cannot express neoantigens nor be recognized by the host. However, tumors breach the blood-brain barrier and basement membrane separations of ectoderm from mesenchyme and release "forbidden" self-antigens, to which host immunocytes may respond causing cell- and antibody-mediated autoimmunity. This can damage normal host tissues by a "bystander" effect. Paraneoplastic mechanisms can also be analyzed as arising from three-way interactions between cells blocked in ontogeny, their molecular messengers, and the host tissues they target.
Insights
Cancer development involves normal physiological processes, not new genetic information. Tumors release self-antigens, potentially triggering autoimmune responses and bystander damage to host tissues.
Area of Science:
- Oncology
- Immunology
- Developmental Biology
Background:
- Neoplasms engage normal physiological mechanisms, challenging the view of cancer as entirely novel.
- The concept of "oncogeny is blocked ontogeny" suggests tumors are tied to their embryonic origins.
- Paraneoplastic phenomena arise from interactions between tumor cells, mediators, and host tissues.
Purpose of the Study:
- To re-evaluate cancer mechanisms through the lens of normal developmental processes.
- To explore the role of paraneoplastic mediators in cancer progression and host interactions.
- To understand how tumors interact with host immunity and tissues.
Main Methods:
- Conceptual analysis integrating developmental biology (ontogeny) with cancer biology (oncogeny).
- Examination of mediator release based on cell death and vascular proximity.
- Analysis of tumor interactions with host barriers and immune responses.
Main Results:
- Tumor invasiveness and metastasis mirror embryonic development, lacking cancer-specific novelty.
- Cancers do not acquire foreign genetic information, thus not expressing neoantigens.
- Tumors breaching barriers release self-antigens, inducing autoimmunity and bystander damage.
Conclusions:
- Cancer mechanisms, including mediator release and metastasis, are rooted in blocked ontogeny.
- Host immune responses to tumor-released self-antigens can cause autoimmune damage.
- Paraneoplastic effects result from a complex interplay between developmental arrest, molecular signaling, and host responses.