Editing Melanin (section)

== Physical properties and technological applications ==
Evidence exists for a highly cross-linked [[heteropolymer]] bound [[covalent bond|covalently]] to matrix scaffolding [[melanoprotein]]s.<ref>{{Cite journal |vauthors=Donatien PD, Orlow SJ |date=August 1995 |title=Interaction of melanosomal proteins with melanin |journal=European Journal of Biochemistry |volume=232 |issue=1 |pages=159–64 |doi=10.1111/j.1432-1033.1995.tb20794.x |pmid=7556145}}</ref> It has been proposed that the ability of melanin to act as an [[antioxidant]] is directly proportional to its degree of polymerization or [[molecular weight]].<ref>{{Cite journal |vauthors=Sarangarajan R, Apte SP |year=2005 |title=Melanin aggregation and polymerization: possible implications in age-related macular degeneration |journal=Ophthalmic Research |volume=37 |issue=3 |pages=136–41 |doi=10.1159/000085533 |pmid=15867475 |s2cid=27499198}}</ref> Suboptimal conditions for the effective polymerization of melanin [[monomer]]s may lead to formation of pro-oxidant melanin with lower-molecular-weight, implicated in the causation and progression of [[macular degeneration]] and [[melanoma]].<ref>{{Cite journal |vauthors=Meyskens FL, Farmer PJ, Anton-Culver H |date=April 2004 |title=Etiologic pathogenesis of melanoma: a unifying hypothesis for the missing attributable risk |url=https://escholarship.org/content/qt6sz6501z/qt6sz6501z.pdf?t=nhskht |journal=Clinical Cancer Research |volume=10 |issue=8 |pages=2581–3 |doi=10.1158/1078-0432.ccr-03-0638 |pmid=15102657 |s2cid=26079375 |doi-access=free |access-date=24 August 2019 |archive-date=3 August 2020 |archive-url=https://web.archive.org/web/20200803203751/https://escholarship.org/content/qt6sz6501z/qt6sz6501z.pdf?t=nhskht |url-status=live }}</ref> [[Signal transduction|Signaling pathway]]s that [[upregulation|upregulate]] melanization in the [[retinal pigment epithelium]] (RPE) also may be implicated in the [[downregulation]] of [[rod cell|rod]] outer segment [[phagocytosis]] by the RPE. This phenomenon has been attributed in part to [[Fovea centralis|fovea]]l sparing in [[macular degeneration]].<ref>{{Cite journal |vauthors=Sarangarajan R, Apte SP |year=2005 |title=Melanization and phagocytosis: implications for age related macular degeneration |journal=Molecular Vision |volume=11 |pages=482–90 |pmid=16030499}}</ref>

=== Role in melanoma metastasis ===
Heavily pigmented melanoma cells have a [[Young's modulus]] of about 4.93 kPa, compared to non-pigmented cells, with a value of 0.98 kPa.<ref name="Sarna_2019">{{Cite journal |last1=Sarna |first1=Michal |last2=Krzykawska-Serda |first2=Martyna |last3=Jakubowska |first3=Monika |last4=Zadlo |first4=Andrzej |last5=Urbanska |first5=Krystyna |date=26 June 2019 |title=Melanin presence inhibits melanoma cell spread in mice in a unique mechanical fashion |journal=Scientific Reports |language=en |volume=9 |issue=1 |pages=9280 |bibcode=2019NatSR...9.9280S |doi=10.1038/s41598-019-45643-9 |issn=2045-2322 |pmc=6594928 |pmid=31243305 |doi-access=free}}</ref> The [[Elasticity (physics)|elasticity]] of melanoma cells is crucial to metastasis and growth; non-pigmented tumors were larger than pigmented tumors, and spread far more easily. Pigmented and non-pigmented cells are both present in melanoma [[Neoplasm|tumors]], so that they can both be [[Drug resistance|drug-resistant]] and metastatic.<ref name="Sarna_2019" />