Direct evidence of lipid translocation between adipocytes and prostate cancer cells with imaging FTIR microspectroscopy

Ehsan Gazi¹^,*, Peter Gardner, Nicholas P. Lockyer, Claire A. Hart^*, Michael D. Brown^* and Noel W. Clarke^*^,^,**

^* ProMPT Genito Urinary Cancer Research Group, Paterson Institute for Cancer Research, The University of Manchester, Manchester, UK
School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, UK
Department of Urology, Hope Hospital, NHS Trust, Manchester, UK
^** Department of Urology, Christie Hospital, NHS Trust, Manchester, UK

Published, JLR Papers in Press, May 11, 2007.

^¹ To whom correspondence should be addressed. e-mail: EGazi{at}picr.man.ac.uk

Various epidemiological studies show a positive correlationbetween high intake of dietary FAs and metastatic prostate cancer(CaP). Moreover, CaP metastasizes to the bone marrow, whichharbors a rich source of lipids stored within adipocytes. Here,we use Fourier transform infrared (FTIR) microspectroscopy tostudy adipocyte biochemistry and to demonstrate that PC-3 cellsuptake isotopically labeled FA [deuterated palmitic acid (D₃₁-PA)]from an adipocyte. Using this vibrational spectroscopic technique,we detected subcellular locations in a single adipocyte enrichedwith D₃₁-PA using the ${upsilon}$ _as+s(C-D)₂₊₃ (D₃₁-PA): ${upsilon}$ _as+s(C-H)₂₊₃ (lipidhydrocarbon) signal. In addition, larger adipocytes were foundto consist of a higher percentage of D₃₁-PA of the total lipidfound within the adipocyte. Following background subtraction,the ${upsilon}$ _as(C-D)₂₊₃ signal illuminated starved PC-3 cells coculturedwith D₃₁-PA-loaded adipocytes, indicating translocation of thelabeled FA. This study demonstrates lipid-specific translocationbetween adipocytes and tumor cells and the use of FTIR microspectroscopyto characterize various biomolecular features of a single adipocytewithout the requirement for cell isolation and lipid extraction.

Supplementary key words tumor • fatty acids • Fourier transform infrared spectroscopy • deuterated palmitic acid

Abbreviations: BMS, bone marrow stroma; CaP, prostate cancer; CPD, critical-point drying; D₃₁-PA, deuterated palmitic acid; FFA, free FA; FTIR, Fourier transform infrared; IL-6, interleukin-6; IR, infrared; MSC, mesenchymal stem cell; PF, paraformaldehyde; SR, synchrotron; TAG, triacylglyceride

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