Figure 4. Fibroblasts Elevate Cancer Intracellular GSH Conferring Platinum Resistance.

(A and B) Intracellular GSH level in A2780 (A) or OC8 (B) co-cultured with fibroblasts. Mean ± SD, n = 3, *p < 0.05.

(C) Intracellular GSH level in A2780 cultured in control or fibroblast medium. Mean ± SD, n = 3, *p < 0.05.

(D) Intracellular GSH level in A2780 treated with 200 μM NAC for 6 hr. GSH was measured in triplicate (mean ± SD). *p < 0.05.

(E and F) Effects of NAC on cisplatin-induced γH2AX (E) and cisplatin content (F) in A2780. Pro-caspase 9 and γH2AX were detected by western blotting (E). Platinum content in genomic DNA of A2780 was measured by ICP-MS in triplicates (mean ± SD) (F). *p < 0.05.

(G) Intracellular GSH level in A2780 treated with 6 μM BSO for 6 hr. GSH was measured in triplicates (mean ± SD). *p < 0.05.

(H and I) Platinum content in genomic DNA (H) or cisplatin-induced apoptosis (I) of A2780. A2780 were pretreated with 6 μM BSO for 6 hr. Mean ± SD, n = 3, *p < 0.05.

(J and K) Effects of GCLC knockdown on intracellular GSH level (J) and cisplatin-induced apoptosis (K) in A2780. GSH was measured and normalized with total protein. Apoptosis was determined by Annexin V staining. Mean ± SD; n = 3, *p < 0.05.

(L and M) Effect of GSH monoester on cisplatin resistance in vivo. Mice bearing A2780 ovarian cancer were treated with PBS (control) or GSH monoester for 8 hr and followed with cisplatin treatment for 24 hr. Platinum content in tumor tissue was measured by ICP-MS (L). For tumor volume monitoring, mice were treated with GSH monoester and cisplatin for three cycles (M) (mean ± SEM, n = 5 tumors/group). *p < 0.05.

See also Figure S4.