The response depends on the model and endpoint. In SEB-1 cells, 13-cis RA increased LCN2/NGAL, but ATRA also induced NGAL and the between-isomer difference was not significant. TRAIL protein induction was prominent in SEB-1 cells and minimal in normal epidermal keratinocytes. At 0.1 μM 13-cis RA, TRAIL knockdown reduced the TUNEL-positive fraction from approximately 25% in control-siRNA samples to approximately 8%. [1,2]
LCN2/NGAL induction and retinoid-isomer comparison
Cell-based study · SV40 large T antigen-immortalized human SEB-1 sebocytes [1]
13-cis RA increased LCN2 mRNA and NGAL protein relative to vehicle. ATRA also induced NGAL; the difference between isomers was not significant, limiting attribution of NGAL induction uniquely to 13-cis RA.
Literature-Reported Treatment Conditions
- Treatment concentration
- 0.1 nM, 1 nM, 10 nM, 0.1 μM or 1 μM 13-cis RA; parallel ATRA comparator
- Exposure duration
- 48 hours for qPCR; 72 hours for NGAL protein
- Method
- Addition to cell culture medium
- Vehicle
- Ethanol; vehicle-treated controls (0.01% or less in western-blot methods)
Methods and source locations
Compound reported in the paper: Isotretinoin; Compound label in the paper: 13-cis retinoic acid (13-cis RA)
Evidence concerns the reported research reagent and cellular models; it does not establish Adooq lot performance.
Results: NGAL expression in SEB-1 sebocytes; Figure 4A–B and caption; Methods: Cell culture, Quantitative real-time PCR, Western blotting
LCN2 mRNA relative to vehicle: qPCR; mean ± SEM, 5 independent samples; REST-XL, P < 0.05 — Results: NGAL expression; Figure 4A and caption
NGAL protein relative to vehicle: Western blot densitometry normalized to β-actin; mean ± SEM, minimum 3 independent blots; paired t test, P < 0.05 — Results: NGAL expression; Figure 4B and caption
Comparison with ATRA-induced NGAL protein: Parallel ATRA treatments; reported Results interpretation, not an inferred exact effect size — Results: ATRA comparison following Figure 4
LCN2 knockdown attenuates the caspase response
Cell-based study · Human SEB-1 sebocytes with LCN2 siRNA, scrambled siCONTROL or GAPDH specificity-control siRNA [1]
LCN2 knockdown reduced LCN2 mRNA and eliminated detectable NGAL protein; cleaved caspase 3 was reduced to approximately 20% of scrambled-siRNA control. The residual response does not support NGAL as the sole mediator.
Literature-Reported Treatment Conditions
- Treatment concentration
- 0.1 μM 13-cis RA
- Exposure duration
- 13-cis RA added 24 hours after nucleofection; knockdown validated at 48 and 72 hours
- Method
- Addition to cell culture medium
- Vehicle
- Ethanol; vehicle-treated controls (0.01% or less in western-blot methods)
- Co-treatment
- LCN2 siRNA; scrambled siCONTROL and GAPDH siRNA controls
- Reported limits
- Figure 7 refers to Figure 6 conditions but does not specify which of the 48/72-hour collection times applies to its caspase graph; no precise caspase collection time assigned.
Methods and source locations
Compound reported in the paper: Isotretinoin; Compound label in the paper: 13-cis retinoic acid (13-cis RA)
Evidence concerns the reported research reagent and cellular models; it does not establish Adooq lot performance.
Results: LCN2 siRNA; Figures 6A–B and 7 with captions; Methods: siRNA and Western blotting
LCN2 mRNA knockdown and NGAL protein validation: qPCR at 48 hours: mean ± SEM, n = 6; REST-XL P < 0.05. Western blots: representative of 4 independent experiments — Results: LCN2 knockdown; Figure 6 and caption
Cleaved caspase 3 expression relative to scrambled-siRNA control: β-actin-normalized western blot densitometry; mean ± SEM; 5 independent blots, paired t test P < 0.05 — Results paragraph preceding Figure 7; Figure 7 and caption
TRAIL induction differs between sebocytes and keratinocytes
Cell-based study · SEB-1 sebocytes; normal human epidermal keratinocytes (NHEK); SV40-immortalized KH-SV keratinocytes [2]
13-cis RA induced TRAIL mRNA and protein in SEB-1 cells. The increase in NHEK mRNA was accompanied by barely detectable TRAIL protein; the KH-SV 24-hour protein increase was not significant.
Literature-Reported Treatment Conditions
- Treatment concentration
- 0.1 μM for qPCR; 0.1 or 1 μM for protein
- Exposure duration
- qPCR: 12, 24, 48 and 72 hours; immunoblots: 24, 48 and 72 hours
- Method
- Addition to cell culture medium
- Vehicle
- Ethanol; vehicle-treated controls
Methods and source locations
Compound reported in the paper: Isotretinoin; Compound label in the paper: 13-cis retinoic acid (13-cis RA)
Evidence concerns the reported research reagent and cellular models; it does not establish Adooq lot performance.
Results: 13-cis RA increases expression of TRAIL; Figure 1A–C and caption; Methods: Reagents, Cell Culture, QPCR, Immunoblotting
SEB-1 TRAIL mRNA relative to control: qPCR with 0.1 μM 13-cis RA; mean ± SE, n = 3 samples; REST-XL, P < 0.05 — Results first paragraph; Figure 1A and caption
TRAIL protein expression and cellular specificity: β-actin-normalized immunoblots; mean ± SE of 3 independent sample sets and immunoblots; paired t test — Results following Figure 1; Figure 1C and caption
TRAIL knockdown reduces apoptosis without reducing LCN2
Cell-based study · SEB-1 sebocytes with TNFSF10/TRAIL siRNA, siCONTROL or GAPDH-control siRNA [2]
TRAIL-specific siRNA reduced TRAIL expression and the TUNEL-positive fraction after 13-cis RA. LCN2 mRNA was not significantly reduced and NGAL protein was reported unaffected; this supports a TRAIL contribution without establishing the complete ordering of apoptotic pathways.
Literature-Reported Treatment Conditions
- Treatment concentration
- 0.1 μM 13-cis RA
- Exposure duration
- 13-cis RA added 24 hours after nucleofection; qPCR at 12/24 hours; protein at 24/48 hours; TUNEL at 24 hours
- Method
- Addition to cell culture medium
- Vehicle
- Ethanol; vehicle-treated controls
- Co-treatment
- TRAIL-specific siRNA; siCONTROL and GAPDH siRNA controls
- Reported limits
- NGAL protein result is reported as data not shown; no image-based verification or precise magnitude assigned. The TUNEL methods detail recombinant-protein experiments; siRNA timing and n are supplied by Figure 3 caption/results.
Methods and source locations
Compound reported in the paper: Isotretinoin; Compound label in the paper: 13-cis retinoic acid (13-cis RA)
Evidence concerns the reported research reagent and cellular models; it does not establish Adooq lot performance.
Results: TRAIL-specific siRNA and LCN2 expression; Figure 3A–C and caption; Methods: siRNA, QPCR, Immunoblotting, TUNEL
TRAIL expression after specific knockdown: qPCR mean ± SE of 3 independent nucleofection samples; western blot validation with GAPDH specificity controls — Results: TRAIL-specific siRNA; Figure 3A–B and caption
TUNEL-positive fraction after 13-cis RA: TUNEL; mean ± SE, n = 6 independent samples; P < 0.05; Figure 3 caption does not name a test for this panel — Results paragraph following Figure 3; Figure 3C and caption
LCN2/NGAL response to TRAIL knockdown: qPCR and immunoblot assessment in TRAIL-siRNA samples versus siCONTROL; protein data not shown — Results: TRAIL-specific siRNA has no effect on LCN2 gene expression
