Erufosine increases RhoB expression in oral squamous carcinoma cells independent of its tumor suppressive mode of action - a short report.
OBJECTIVE
Recently, we found that erufosine (erucylphospho-N,N,N trimethylpropylammonium) can induce up-regulation of RhoB expression in oral squamous carcinoma (OSCC) cells, thereby hinting at a tumor suppressive role. Therefore, we aimed to evaluate the role of RhoB in the tumor suppressive mode of action of erufosine on OSCC cells.


METHODS
Anti-proliferative effects of erufosine were determined in HN-5 and FaDu OSCC-derived cells using a MTT assay. RhoB up-regulation was detected using microarray and qRT-PCR-based expression assays at IC25, IC50and IC75concentrations of erufosine. The results obtained were verified by Western blotting. In addition, siRNA-mediated RhoB knockdown was carried out and combined with erufosine treatment, after which cell cycle, colony formation and migration assays were performed to evaluate its combined effects.


RESULTS
We found that after erufosine treatment of HN-5 and FaDu cells for 24, 48 and 72 h the IC50values ranged from 43 to 37 μM and 27- to 15 μM, respectively. Microarray and qRT-PCR-based expression analyses revealed RhoB up-regulation up to 9-fold and 20-fold, respectively. Using Western blotting, an increase in RhoB protein expression was observed, as well as a decrease in pAkt (Ser473and Thr308) expression and an increase in PARP cleavage. Combined siRNA-mediated RhoB knockdown and erufosine treatment resulted in slightly reduced RhoB and pAkt levels compared to erufosine treatment alone. Subsequent cell cycle analyses revealed an increased apoptotic induction, but a reduced G2 cell cycle arrest, of the combination. At the functional level, synergistic effects were observed using cell migration and colony formation assays.


CONCLUSIONS
Our data show that erufosine can cause up-regulation of RhoB expression in OSCC cells. Combining erufosine treatment with siRNA-mediated RhoB knockdown did, however, not reveal a role of RhoB in its tumor suppressive mode of action.
Toxicology and Chemotherapy Unit, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 581, 69120, Heidelberg, Germany.
Shariq S
SS
Ansari
Toxicology and Chemotherapy Unit, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 581, 69120, Heidelberg, Germany.
Nurullah
N
Akgün
Toxicology and Chemotherapy Unit, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 581, 69120, Heidelberg, Germany. m.berger@dkfz.de.
Martin R
MR
Berger
D000970:Antineoplastic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D055785:Gene Knockdown Techniques; D006801:Humans; D009062:Mouth Neoplasms / Q000378:metabolism* / Q000473:pathology; D020411:Oligonucleotide Array Sequence Analysis; D010755:Organophosphates / Q000494:pharmacology*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D015854:Up-Regulation; D020743:rhoB GTP-Binding Protein / Q000096:biosynthesis*
D000970:Antineoplastic Agents; D010755:Organophosphates; D000644:Quaternary Ammonium Compounds; C472787:erucylphospho-N,N,N-trimethylpropylammonium; D020743:rhoB GTP-Binding Protein
Akt signaling; Alkylphosphocholine; Apoptosis induction; Cell cycle analysis; Colony formation and migration assays; Head and neck cancer