Paracrine calcitonin in prostate cancer is linked to CD44 variant expression and invasion.
BACKGROUND
Calcitonin (CT) exerts an autocrine/paracrine influence on prostatic tumor invasion through coupling to transduction protein Gsalpha. Cell adhesion glycoprotein CD44 variant v7-v10 also faciliates invasion, but its modulation by the CT-Gsalpha system was unexplored.


METHODS
LnCaP, PC-3 and metastasis-derived PC-3M cell lines were studied, including cells modified therefrom: Gsalpha-QL, expressing mutant constitutively active Gsalpha protein, and CT+, overexpressing CT. CD44 variant expression was evaluated in vivo after orthotopic implantion into nude mice, and in vitro by real-time RT-PCR and Western blotting.


RESULTS
Both mRNA and protein levels of the CD44 variant were minimal in PC-3M tumor implants, but elevated in Gsalpha-QL. Exogenous CT stimulated invasion into Matrigel strongly in LnCaP and CT+, and less in PC-3 and Gsalpha-QL. By Western blot analysis, untreated Gsalpha-QL and CT+ cells overexpressed CD44 variant compared with LnCaP or PC-3. By quantitative RT-PCR, exogenous CT dose-dependently increased CD44 variant mRNA to seven-fold. Pharmacologic agents that stimulated or inhibited Gsalpha activity or stimulated adenylyl cyclase produced proportionate dose-dependent effects on both CD44 variant expression and Matrigel invasion.


CONCLUSIONS
This paracrine factor, acting though cyclic AMP, regulates the expression of CD44v7-10, which modulates the tumor phenotype.
Iczkowski
Kenneth A
KA
Department of Pathology, Immunology, and Laboratory Medicine of The University of Florida, Gainesville, FL 32608-1197, USA. iczkoka@pathology.ufl.edu
Omara-Opyene
A Levi
AL
Kulkarni
Trupti R
TR
Pansara
Megha
M
Shah
Girish V
GV
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002116:Calcitonin / Q000378:metabolism / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000096:biosynthesis / Q000378:metabolism; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis* / Q000235:genetics; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics
C448906:CD44v9 antigen; D018960:Hyaluronan Receptors; D020033:Protein Isoforms; D012333:RNA, Messenger; D006165:Guanylyl Imidodiphosphate; D002116:Calcitonin; D019205:GTP-Binding Protein alpha Subunits, Gs; D000262:Adenylyl Cyclases