Modulation of oxidative stress and subsequent induction of apoptosis and endoplasmic reticulum stress allows citral to decrease cancer cell proliferation.
The monoterpenoid, citral, when delivered through PEG-b-PCL nanoparticles inhibits in vivo growth of 4T1 breast tumors. Here, we show that citral inhibits proliferation of multiple human cancer cell lines. In p53 expressing ECC-1 and OVCAR-3 but not in p53-deficient SKOV-3 cells, citral induces G1/S cell cycle arrest and apoptosis as determined by Annexin V staining and increased cleaved caspase3 and Bax and decreased Bcl-2. In SKOV-3 cells, citral induces the ER stress markers CHOP, GADD45, EDEM, ATF4, Hsp90, ATG5, and phospho-eIF2α. The molecular chaperone 4-phenylbutyric acid attenuates citral activity in SKOV-3 but not in ECC-1 and OVCAR-3 cells. In p53-expressing cells, citral increases phosphorylation of serine-15 of p53. Activation of p53 increases Bax, PUMA, and NOXA expression. Inhibition of p53 by pifithrin-α, attenuates citral-mediated apoptosis. Citral increases intracellular oxygen radicals and this leads to activation of p53. Inhibition of glutathione synthesis by L-buthionine sulfoxamine increases potency of citral. Pretreatment with N-acetylcysteine decreases phosphorylation of p53 in citral-treated ECC-1 and OVCAR-3. These results define a p53-dependent, and in the absence of p53, ER stress-dependent mode of action of citral. This study indicates that citral in PEG-b-PCL nanoparticle formulation should be considered for treatment of breast and other tumors.
Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI-53792-6188, USA.
Arvinder
A
Kapur
Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI-53792-6188, USA.
Mildred
M
Felder
Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI-53792-6188, USA.
Lucas
L
Fass
Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI-53792-6188, USA.
Justanjot
J
Kaur
Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI-53792-6188, USA.
Austin
A
Czarnecki
Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI-53792-6188, USA.
Kavya
K
Rathi
School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705-2222, USA.
San
S
Zeng
Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH 44704, USA.
Kathryn Kalady
KK
Osowski
Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH 44704, USA.
Colin
C
Howell
School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705-2222, USA.
May P
MP
Xiong
Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH 44704, USA.
Rebecca J
RJ
Whelan
Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI-53792-6188, USA.
Manish S
MS
Patankar
D000080462:Acyclic Monoterpenes; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007783:Lactones / Q000008:administration & dosage / Q000737:chemistry; D039821:Monoterpenes / Q000008:administration & dosage; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry; D018384:Oxidative Stress / Q000187:drug effects; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
D000080462:Acyclic Monoterpenes; D007783:Lactones; D039821:Monoterpenes; D017382:Reactive Oxygen Species; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C521904:poly(ethylene glycol)-block-poly(epsilon-caprolactone); D011092:Polyethylene Glycols; C007076:citral