Ferritins: a family of molecules for iron storage, antioxidation and more.

An overview of agents causing hypopigmentation in human skin is presented. The review is organized to put forward groups of biological and chemical agents. Their mechanisms of action cover (i) tyrosinase inhibition, maturation and enhancement of its degradation; (ii) Mitf inhibition; (iii) downregulation of MC1R activity; (iv) interference with melanosome maturation and transfer; (v) melanocyte loss, desquamation and chemical peeling. Tyrosinase inhibition is the most common approach to achieve skin hypopigmentation as this enzyme catalyses the rate-limiting step of pigmentation. Despite the large number of tyrosinase inhibitors in vitro, only a few are able to induce effects in clinical trials. The gap between in-vitro and in-vivo studies suggests that innovative strategies are needed for validating their efficacy and safety. Successful treatments need the combination of two or more agents acting on different mechanisms to achieve a synergistic effect. In addition to tyrosinase inhibition, other parameters related to cytotoxicity, solubility, cutaneous absorption, penetration and stability of the agents should be considered. The screening test system is also very important as keratinocytes play an active role in modulating melanogenesis within melanocytes. Mammalian skin or at least keratinocytes/melanocytes co-cultures should be preferred rather than pure melanocyte cultures or soluble tyrosinase.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0749.2006.00334.x

Hypopigmenting agents: an updated review on biological, chemical and clinical aspects

https://www.cell.com/molecular-cell/pdf/S1097-2765(02)00658-5.pdf

The HtrA Family of Proteases: Implications for Protein Composition and Cell Fate

Controlled proteolysis underlies a vast diversity of protective and regulatory processes that are of key importance to cell fate. The unique molecular architecture of the widely conserved high temperature requirement A (HTRA) proteases has evolved to mediate critical aspects of ATP-independent protein quality control. The simple combination of a classic Ser protease domain and a carboxy-terminal peptide-binding domain produces cellular factors of remarkable structural and functional plasticity that allow cells to rapidly respond to the presence of misfolded or mislocalized polypeptides.

HTRA proteases: regulated proteolysis in protein quality control

Mammalian iron metabolism and its control by iron regulatory proteins.

Differential gene expression of cell lines derived from a malignant melanoma or its autologous lymph node metastasis using cDNA arrays indicated down-regulation of PRSS11, a gene encoding the serine protease HtrA1, a homolog of the Escherichia coli protease HtrA, in the metastatic line. Stable PRSS11 overexpression in the metastatic cell line strongly inhibited proliferation, chemoinvasion and Nm23-H1 protein expression in vitro, as well as cell growth in vivo in nu/nu mice. A polyclonal anti-HtrA1 serum demonstrated a significantly higher expression in primary melanomas when compared to unrelated metastatic lesions in a human melanoma tissue array, and down-modulation of HtrA1 expression in autologous lymph node melanoma metastases in seven out of 11 cases examined. These results suggest that down-regulation of PRSS11 and HtrA1 expression may represent an indicator of melanoma progression.

The HtrA1 serine protease is down-regulated during human melanoma progression and represses growth of metastatic melanoma cells

Tumor suppressor genes have a pivotal role in normal cells regulating cell cycle processes negatively. Furthermore, the inhibition of cell proliferation is a crucial step in the achievement of cell differentiation. Increasing evidence suggests that the nm23 genes, initially documented as suppressors of the invasive phenotype in some cancer types, are involved in the control of normal development and differentiation. In this review, we summarize some data concerning the involvement of the nm23 genes in development and differentiation, attempting to delineate an overall view of many facets of their biological role.

nm23: unraveling its biological function in cell differentiation.

The nm23 genes codify nucleoside diphosphate kinases, which have been shown to be involved in the regulation of microtubule dynamics. We have demonstrated previously that the association between the Nm23-M1 protein and cytoskeletal beta-tubulin correlates with cell differentiation. It is known that microtubules and microtubule-associated proteins are fundamental elements regulating neuronal differentiation. In the present study, we have investigated the ability of nm23 to influence nerve growth factor-induced PC12 cell differentiation. To this end, we have altered PC12 intracellular levels of nm23-M1 by means of sense and antisense transfections. In the presence of nerve growth factor, overexpression of nm23 delays cell cycle transition, rapidly induces neurite outgrowth, and increases the expression of neurofilament and microtubule proteins. On the contrary, down-regulation of nm23 enhances cell proliferation and inhibits neuronal differentiation. These findings indicate that neuronal cell proliferation and differentiation can be modulated by nm23 expression levels.

http://cgd.aacrjournals.org/cgi/reprint/7/12/1689.pdf

nm23 influences proliferation and differentiation of PC12 cells in response to nerve growth factor

The association of the Nm23-M1 protein and beta-tubulin correlates with cell differentiation.

Purpose: Employing an in vitro model system of human melanoma progression, we previously reported ferritin light chain ( L-ferritin ) gene overexpression in the metastatic phenotype. Here, we attempted to characterize the role of ferritin in the biology of human melanoma and in the progression of this disease. Experimental Design: Starting from the LM human metastatic melanoma cell line, we engineered cell clones in which L-ferritin gene expression was down-regulated by the stable expression of a specific antisense construct. These cells were then assayed for their growth capabilities, chemoinvasive properties, and sensitivity to oxidative stress. Additionally, ferritin protein content in primary and metastatic human melanomas was determined by immunohistochemistry. Results: Artificial L-ferritin down-regulation in the LM cells strongly inhibited proliferation and chemoinvasion in vitro and cell growth in vivo . In addition, L-ferritin down-regulated cells displayed enhanced sensitivity to oxidative stress and to apoptosis. Concurrently, immunohistochemical analysis of a human melanoma tissue array revealed that ferritin expression level in metastatic lesions was significantly higher ( P Conclusions: These data suggest that high ferritin expression can enhance cell growth and improve resistance to oxidative stress in metastatic melanoma cells by interfering with their cellular antioxidant system. The potential significance of these findings deserves to be validated in a clinical setting.

https://clincancerres.aacrjournals.org/content/clincanres/11/9/3175.full.pdf

Daniela Lombardi

Papers

The HtrA1 serine protease is down-regulated during human melanoma progression and represses growth of metastatic melanoma cells

nm23: unraveling its biological function in cell differentiation.

nm23 influences proliferation and differentiation of PC12 cells in response to nerve growth factor

The association of the Nm23-M1 protein and beta-tubulin correlates with cell differentiation.

Ferritin Contributes to Melanoma Progression by Modulating Cell Growth and Sensitivity to Oxidative Stress