Dihomo-γ-linolenic acid inhibits growth of xenograft tumors in mice bearing human pancreatic cancer cells (BxPC-3) transfected with delta-5-desaturase shRNA

Abstract

We recently reported that siRNA-knockdown of delta-5-desaturase (D5D), the rate-limiting enzyme converting upstream ω − 6 dihomo-γ-linolenic acid (DGLA) to arachidonic acid, promoted formation of the anti-cancer byproduct 8-hydroxyoctanoic acid (8-HOA) from COX-2-catalyzed DGLA peroxidation, consequently suppressing pancreatic cancer cell growth, migration and invasion. In this study, we have further investigated the anti-tumor effects of D5D-knockdown and the resulting intensified COX-2-catalyzed DGLA peroxidation in subcutaneous xenograft tumors. Four-week old female nude mice (Jackson Laboratory, J:Nu-007850) were injected with human pancreatic cancer cell line BxPC-3 or its D5D knockdown counterpart (via shRNA), followed by 4-week treatments of: vehicle control, DGLA supplementation (8 mg/mouse, twice a week), gemcitabine (30 mg/kg, twice a week), and a combination of DGLA and gemcitabine. In D5D-knockdown tumors, DGLA supplementation promoted 8-HOA formation to a threshold level (> 0.3 µg/g) and resulted in significant tumor reduction (30% vs. control). The promoted 8-HOA not only induced apoptosis associated with altered expression of Bcl-2, cleaved PARP, procaspase 3 and procaspase 9, but also suppressed the tumor metastatic potential via altering MMP-2 and E-cadherin expression. DGLA supplementation resulted in similar anti-tumor effects to those of gemcitabine in our experiments, while the combined treatment led to most significant inhibitory effect on D5D-knockdown tumor growth (70% reduction vs. control). Compared to conventional COX-2 inhibition in cancer treatment, our new strategy that takes advantage of overexpressed COX-2 in cancer cells and tumors, and of abundant ω − 6 fatty acids in the daily diet, should lead us to develop a better and safer anti-pancreatic cancer therapy for patients.

Dihomo-γ-linolenic acid inhibits xenograft tumor growth in mice bearing shRNA-transfected HCA-7 cells targeting delta-5-desaturase

“…Expression of p53, procaspase 9, γH2AX and acetyl histone 3 in HCA-7/C29 and its delta-5-desaturase- KD analog upon different treatments in vitro were assessed by western blot as described elsewhere [24–30]. For their expressions in vivo , proteins from tumor tissues (~ 50–100 mg) were extracted followed by standard western blot procedures [24–30].…”

Gamma linolenic acid suppresses hypoxia-induced gastric cancer cell growth and epithelial-mesenchymal transition by inhibiting the Wnt/b-catenin signaling pathway

“…Despite the achievements in surgical resection and chemotherapy for the treatment of gastric cancer, its recurrence rate and metastasis rate are still high, and the median overall survival (OS) time of patients with metastatic disease is still very poor [3,4]. GLA is a promising bioactive molecule that has anticancer ac-tivity in many types of cancer [18,22,26,27], but its biological activity in gastric cancer is poorly understood. It has been reported that regular intake of GLA could reduce inflammation and inhibit the development of cancer [28][29][30].…”

EpCAM-Targeted 3WJ RNA Nanoparticle Harboring Delta-5-Desaturase siRNA Inhibited Lung Tumor Formation via DGLA Peroxidation

“…The concentrations of DGLA, AA, and PGE2 in A549 cells or tumor tissues were determined by LC/MS as described in the previous studies. 6 , 15 , 47 , 50 For the in vitro test, 3.0 × 10 5 A549 cells were seeded into each well of six-well plates, followed with D5D siRNA transfection or treatment of nanoparticle. For siRNA transfection, A549 cells were randomly assigned to six groups with different treatments with 100 μM DGLA for 12, 24, and 48 h. For nanoparticle treatment, A549 cells were randomly assigned to four groups with different treatments (for 48 h), including control group (treated with the 3WJ-EpCAM nanoparticle, 100 nM), DGLA group (100 μM), 3WJ-EpCAM-D5D siRNA nanoparticle group (100 nM), and DGLA + 3WJ-EpCAM-D5D siRNA nanoparticle group.…”

“…The residual was reconstituted in dichloromethane (100 μL) and analyzed by GC-MS as described in the previous studies. 6 , 15 , 47 , 50 The contents of 8-HOA were determined by using the internal standard curve of hexanoic acid (comparing the peak area with the internal standard). For in vivo study, the collected tumor tissues were crushed in a mortar after freezing in the liquid nitrogen.…”

“…For in vivo samples, collected tumor tissues were sent to Advanced Imaging & Microscopy Laboratory in North Dakota State University (NDSU) to cut into slices for fluorescence analysis as described in the previous study. 50 The tumor tissue images were captured with a Zeiss Axio Imager M2 microscope (20×/0.75). The relative intensity of D5D, MMP2, and E-cadherin in tumors was determined by using Image-Pro software (Media Cybernetics).…”