Abstract
Retinoids modulate the growth and differentiation of cancer cells presumably by activating gene transcription via the nuclear retinoic acid receptor (RAR) alpha, beta, and gamma and retinoid X receptor (RXR) alpha, beta, and gamma.
We analyzed the effects of 38 RAR-selective and RXR-selective retinoids on the proliferation of 10 human head and neck squamous cell carcinoma (HNSCC) cell lines. All of these cell lines expressed constitutively all of the receptor subtypes except RARbeta, which was detected in only two of them.
Most of the RAR-selective retinoids inhibited the growth of HNSCC cells to varying degrees, whereas the RXR-selective retinoids showed very weak or no inhibitory effects. Three RAR antagonists suppressed growth inhibition by RAR-selective agonists, as well as by RAR/RXR panagonists such as 9-cis-retinoic acid. Combinations of RXR-selective and RAR-selective retinoids exhibited additive growth-inhibitory effects. Furthermore, we found that CD437, the most potent growth-inhibitory retinoid induced apoptosis and up-regulated the expression of several apoptosis-related genes in HNSCC cells.
These results indicate that:
(a) retinoid receptors are involved in the growth-inhibitory effects of retinoids;
(b) RXR-RAR heterodimers rather than RXR-RXR homodimer are the major mediators of growth inhibition by retinoids in HNSCC cells;
(c) induction of apoptosis can account for one mechanism by which retinoids such as CD437 inhibit the growth of HNSCC cells.
Finally, these studies identified several synthetic retinoids, which are much more effective than the natural RAs and can be good candidates for chemoprevention and therapy of head and neck cancers.
See also:
- Official Web Site: The Di Bella Method;
- Solution of retinoids in vitamin E in the Di Bella Method biological multitherapy;
- Somatostatin in oncology, the overlooked evidences - In vitro, review and in vivo publications;
- Publication, 2018 Jul: Over-Expression of GH/GHR in Breast Cancer and Oncosuppressor Role of Somatostatin as a Physiological Inhibitor (from Di Bella's Foundation);
- Publication, 2019 Aug: The Entrapment of Somatostatin in a Lipid Formulation: Retarded Release and Free Radical Reactivity (from Di Bella's Foundation);
- Publication, 2019 Sep: Effects of Somatostatin and Vitamin C on the Fatty Acid Profile of Breast Cancer Cell Membranes (from Di Bella's Foundation);
- Publication, 2019 Sep: Effects of somatostatin, curcumin, and quercetin on the fatty acid profile of breast cancer cell membranes (from Di Bella's Foundation);
- Publication, 2020 Sep: Two neuroendocrine G protein-coupled receptor molecules, somatostatin and melatonin: Physiology of signal transduction and therapeutic perspectives (from Di Bella's Foundation);
- The Di Bella Method (A Fixed Part - Bromocriptine and/or Cabergoline);
- The Di Bella Method (A Fixed Part - Dihydrotachysterol, Alfacalcidol, synthetic Vitamin D3);
- Vitamin D (analogues and/or derivatives) and cancer - In vitro, review and in vivo publications;
- Neuroblastoma: Complete objective response to biological treatment;
- Oesophageal squamocellular carcinoma: a complete and objective response;
- Complete objective response to biological therapy of plurifocal breast carcinoma;