Targeting V1A-vasopressin receptors with [Arg6, D-Trp7,9, NmePhe8]-substance P (6-11) identifies a strategy to develop novel anti-cancer therapies.
OBJECTIVE
The anti-cancer agent [Arg(6), D-Trp(7,9), N(me)Phe(8)]-substance P (6-11) (SP-G) modulates gastrin releasing peptide (GRP) and arginine vasopressin signalling in small cell lung cancer cells leading to growth arrest and apoptosis. We have shown that SP-G acts as a biased agonist at GRP receptors. This work examines the hypothesis that SP-G acts as a biased agonist at the V(1A) vasopressin receptor.


METHODS
The human V(1A) receptor was expressed in CHO-K1 cells. Extracellular regulated kinase (ERK) activation and intracellular Ca(2+) were measured using activation state-specific antibodies and Fura-2-AM respectively. The effect of SP-G on tumourigenicity was assessed by colony assay.


RESULTS
In V(1A) receptor expressing cells, SP-G caused a sustained activation of ERK via a stimulation of V(1A) receptor coupling to G(i). Inhibition of G(i) with Pertussis toxin attenuated the inhibition by SP-G of the growth of CHO-K1 cells stably expressing the V(1A) receptor. Chimeric V(1A) receptors containing the second or third intracellular loop of the V(2) receptor were capable of binding vasopressin and SP-G but had altered ability to activate phospholipase C (PLC) and ERK. The second intracellular loop of the V(1A) receptor was essential for vasopressin-stimulated PLC and ERK activation but not for SP-G-induced ERK activation.


CONCLUSIONS
This work provides mechanistic insight, for biased agonists at V(1A) receptors and highlights a potential role for such agents as anti-cancer agents.
MacKinnon
Alison C
AC
University of Edinburgh, Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK.
Tufail-Hanif
Uzma
U
Wheatley
Mark
M
Rossi
Adriano G
AG
Haslett
Christopher
C
Seckl
Michael
M
Sethi
Tariq
T
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001127:Arginine Vasopressin / Q000494:pharmacology; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D018288:Carcinoma, Small Cell; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms; D010446:Peptide Fragments / Q000494:pharmacology*; D037342:Pertussis Toxin / Q000494:pharmacology; D018004:Receptors, Bombesin / Q000819:agonists / Q000378:metabolism; D017483:Receptors, Vasopressin / Q000819:agonists* / Q000378:metabolism / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects*; D013373:Substance P / Q000031:analogs & derivatives* / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism
D000970:Antineoplastic Agents; D010446:Peptide Fragments; D018004:Receptors, Bombesin; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; C046958:substance P (6-11), Arg(6)-Trp(7,9)-Me-Phe(8)-; D013373:Substance P; D037342:Pertussis Toxin; D048049:Extracellular Signal-Regulated MAP Kinases; D010738:Type C Phospholipases; D002118:Calcium