Cross-talk between Dopachrome Tautomerase and Caveolin-1 Is Melanoma Cell Phenotype-specific and Potentially Involved in Tumor Progression

Abstract

L-Dopachrome tautomerase (L-DCT), also called tyrosinaserelated protein-2 (TRP-2), is a melanoma antigen overexpressed in most chemo-/radiotherapeutic stress-resistant tumor clones, and caveolin-1 (CAV1) is a main regulator of numerous signaling processes. A structural and functional relationship between DCT and CAV1 is first presented here in two human amelanotic melanoma cell lines, derived from vertical growth phase (MelJuSo) and metastatic (SKMel28) melanomas. DCT co-localizes at the plasma membrane with CAV1 and Cavin-1, another molecular marker for caveolae in both cell phenotypes. Our novel structural model proposed for the DCT-CAV1 complex, in addition to co-immunoprecipitation and mass spectrometry data, indicates a possible direct interaction between DCT and CAV1. The CAV1 control on DCT gene expression, DCT posttranslational processing, and subcellular distribution is cell phenotype-dependent. DCT is a modulator of CAV1 stability and supramolecular assembly in both cell phenotypes. During autocrine stimulation, the expressions of DCT and CAV1 are oppositely regulated; DCT increases while CAV1 decreases. Sub-confluent MelJuSo clones DCT high /CAV1 low are proliferating and acquire fibroblast-like morphology, forming massive, confluent clusters as demonstrated by immunofluorescent staining and TissueFAXS quantitative image cytometry analysis. CAV1 down-regulation directly contributes to the expansion of MelJuSo DCT high subtype. CAV1 involved in the perpetuation of cell phenotype-overexpressing anti-stress DCT molecule supports the concept that CAV1 functions as a tumor suppressor in early stages of melanoma. DCT is a regulator of the CAV1-associated structures and is possibly a new molecular player in CAV1-mediated processes in melanoma.Cutaneous malignant melanoma remains the deadliest form of skin cancer worldwide (1). The skin melanocytes, normally located at the epidermis-dermis junction, start an uncontrolled proliferation process (radial growth phase, RGP), followed by dermis invasion (vertical growth phase, VGP).3 In a more advanced stage, melanoma cells migrate from this primary site to distant organs (liver, lung), populating them (metastasis) and eventually causing death (2). The mechanisms that specifically operate in tumor cell phenotypes determining the switch from the non-metastatic to metastatic stage are not entirely elucidated.Tyrosinase-related protein-2 (TRP-2 or Tyrp2) is a member of the tyrosinase-related protein family, together with tyrosinase (TYR) and tyrosinase-related protein-1 (TRP-1). Tyrosinase-related proteins are expressed by both melanocytes and melanoma forming the enzymatic cluster responsible for pigment production (3).TRP-2, also named dopachrome tautomerase (DCT), functions downstream of TYR by converting dopachrome into 5,6-dihydroxyindole-2-carboxylic acid (DHICA), the precursor of eumelanins with a potent hydroxyl radical-scavenging activity (4). In the absence of DCT, dopachrome is spontaneously converted into 5,6-dihydroxyindole, a more toxic intermediate than...

Genomic GLO1 deletion modulates TXNIP expression, glucose metabolism, and redox homeostasis while accelerating human A375 malignant melanoma tumor growth

“…6 b], NanoString™ analysis revealed additional, heretofore unrecognized expression changes [downregulation: TGFBI (5.9-fold), CTSK (4.7-fold), ANGPTL4 (4.7-fold), FLT1 (3.8-fold), CAV1 (3.2-fold), MGP (3.1-fold), KDR (3.1-fold), TLR4 (3.0-fold), NR4A1 (2.9-fold), THBS1 (2.8-fold); upregulation: SERPINF1 ( PEDF ; 4.7-fold); ( Fig. 6 b)], all with established roles in melanoma invasion and metastasis, and therefore potentially involved in attenuation of EMT in response to GLO1 deletion [ [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] ].

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“…6 ) [ 26 ]. Strikingly, a large number of genes shown here for the first time to be responsive to GLO1 expression status (including TXNIP , ANGPTL4 , CAV1 , CTSK , FLT1 , KDR , NRP1 , NR4A1 , SERPINF1 , TGFBI , THSB1 , TLR4 ) have previously been associated with EMT in melanomagenesis [ [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , 65 ]. For example, concerted upregulation of VEGF-receptor expression ( FLT1 , KDR , NRP1 ) together with trombospondin-1 ( THSB1 ) has been associated with melanoma progression [ 56 ].…”

Interleukin-8 in Melanoma Pathogenesis, Prognosis and Therapy—An Integrated View into Other Neoplasms and Chemokine Networks

“…This is an example of cross-talk in melanoma molecularity. Our group has also identified such a reciprocal modulating mechanism in melanoma cells between caveolin-1, a major regulator of signaling platforms and dopachrometautomerase, a melanoma antigen with multiple functions, including melanoma resistance to therapeutical and environmental stress [ 178 ]. Importantly, this IL-8 mediated pathway has not been described, so far, to our knowledge, in other neoplasms.…”

Mass Spectrometry for Cancer Biomarkers

“…Using multienzyme digestion and different fragmentation techniques [57] available on the hybrid ion trap-Orbitrap platform, Chiritoiu et al reported the occupancy of all N-glycosylation sites of tyrosinase in a melanoma cell line [58], an enzyme shown to be correlated with patient clinical evolution in melanoma [59,60]. Moreover, recent evidence suggests that even other members of the tyrosinaserelated protein family could be also linked to melanoma progression [61,62].…”