Page 204 - Vitamin D and Cancer

Chapter 9
Molecular Biology of Vitamin D Metabolism
and Skin Cancer

Florence S.G. Cheung and Juergen K.V. Reichardt

Abstract It is well known that UV exposure is essential for subcutaneous vitamin D
synthesis, which is important in maintaining mineral and bone homeostasis. In this
chapter, we discuss findings in recent epidemiologic, in vitro and in vivo studies that
suggest vitamin D has an additional role, skin cancer prevention. With accumulating
evidence on the neoplastic effects of vitamin D, studies on vitamin D analogs have
shown promising results. Thus we are currently faced with the dilemma in seeking a
fine balance between the amount of sun exposure needed to produce sufficient vita-
min D to maintain its function in bone health and possible anticancer effects, while
avoiding excessive exposure that can increase the risk of skin cancer development.
This is further complicated by the fact that the amount of vitamin D synthesized from
UV exposure is influenced by age, culture, and existing medical conditions of the
individual. The designing of vitamin D analogs and appropriate recommendations on
sun exposure requires further understanding of the vitamin D pathway and its actions,
as well as any genetic factors that may influence the therapeutic outcome.

Keywords Skin cancer • Solar UV radiation • Vitamin D • Epidemiology • Prevention
• Vitamin D receptor • 1,25-dihydroxyvitamin D • Keratinocytes • Differentiation
• Photoprotection • Vitamin D analogs

Abbreviations

Aa Amino acids
AC Adenylyl cyclase

J.K.V. Reichardt (*)
Plunket Chair of Molecular Biology (Medicine),
Bosch Institute, The University of Sydney,
Medical Foundation Building (K25), 92–94 Parramatta Road,
Camperdown, NSW 2006, Australia
and
School of Pharmacy and Molecular Sciences, James Cook University,
Townsville, Qld 4811, Australia
e-mail: jreichardt@med.usyd.edu.au

D.L. Trump and C.S. Johnson (eds.), Vitamin D and Cancer, 191
DOI 10.1007/978-1-4419-7188-3_9, © Springer Science+Business Media, LLC 2011