Targeting protein-trafficking pathways alters melanoma treatment sensitivity.
Protein-trafficking pathways are targeted here in human melanoma cells using methods independent of oncogene mutational status, and the ability to up-regulate and down-regulate tumor treatment sensitivity is demonstrated. Sensitivity of melanoma cells to cis-diaminedichloroplatinum II (cDDP, cis-platin), carboplatin, dacarbazine, or temozolomide together with velaparib, an inhibitor of poly (ADP ribose) polymerase 1, is increased by up to 10-fold by targeting genes that regulate both protein trafficking and the formation of melanosomes, intracellular organelles unique to melanocytes and melanoma cells. Melanoma cells depleted of either of the protein-trafficking regulators vacuolar protein sorting 33A protein (VPS33A) or cappuccino protein (CNO) have increased nuclear localization of cDDP, increased nuclear DNA damage by platination, and increased apoptosis, resulting in increased treatment sensitivity. Depleted cells also exhibit a decreased proportion of intracellular, mature melanosomes compared with undepleted cells. Modulation of protein trafficking via cell-surface signaling by binding the melanocortin 1 receptor with the antagonist agouti-signaling protein decreased the proportion of mature melanosomes formed and increased cDDP sensitivity, whereas receptor binding with the agonist melanocyte-stimulating hormone resulted in an increased proportion of mature melanosomes formed and in decreased sensitivity (i.e., increased resistance) to cDDP. Mutation of the protein-trafficking gene Hps6, known to impair the formation of mature melanosomes, also increased cDDP sensitivity. Together, these results indicate that targeting protein-trafficking molecules markedly increases melanoma treatment sensitivity and influences the degree of melanosomes available for sequestration of therapeutic agents.
Department of Dermatology, University of California, San Francisco, CA 94115, USA.
Zhi-ming
ZM
Huang
Milka
M
Chinen
Philip J
PJ
Chang
Tong
T
Xie
Lily
L
Zhong
Stephanie
S
Demetriou
Mira P
MP
Patel
Rebecca
R
Scherzer
Elena V
EV
Sviderskaya
Dorothy C
DC
Bennett
Glenn L
GL
Millhauser
Dennis H
DH
Oh
James E
JE
Cleaver
Maria L
ML
Wei
D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000494:pharmacology*; D016190:Carboplatin / Q000494:pharmacology; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D004260:DNA Repair; D003606:Dacarbazine / Q000031:analogs & derivatives / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D008545:Melanoma / Q000188:drug therapy*; D020460:Melanosomes / Q000187:drug effects*; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D021381:Protein Transport / Q000235:genetics; D034622:RNA Interference; D044102:Receptor, Melanocortin, Type 1 / Q000378:metabolism; D000077204:Temozolomide; D015854:Up-Regulation / Q000187:drug effects; D033921:Vesicular Transport Proteins / Q000172:deficiency* / Q000235:genetics
D000970:Antineoplastic Agents; C475463:BLOC1S4 protein, human; C493901:HPS6 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D044102:Receptor, Melanocortin, Type 1; C424440:VPS33A protein, human; D033921:Vesicular Transport Proteins; D003606:Dacarbazine; D016190:Carboplatin; D002945:Cisplatin; D000077204:Temozolomide