Valproic acid overcomes transforming growth factor-ß-mediated sorafenib resistance in hepatocellular carcinoma.

Sorafenib is a multi-kinase inhibitor approved for hepatocellular carcinoma, but rarely causes tumor regression in patients with chronic liver diseases. To investigate whether growth factor-mediated signaling is involved in sorafenib resistance, HepG2 and PLC/PRF/5 hepatoma cells were exposed to epidermal growth factor (EGF), hepatocyte growth factor (HGF) or transforming growth factor-ß (TGF-ß) prior to treatment with sorafenib. Furthermore, to identify an effective combination treatment with sorafenib, growth factor-sensitized cells were treated with sorafenib alone or in combination with celecoxib, lovastatin or valproic acid (VPA). Trypan blue staining and Annexin V assays showed that the cytotoxic effect of sorafenib was inhibited by 15-54% in cells sensitized to TGF-ß (P<0.05). Western blotting analysis showed that TGF-ß significantly activated extracellular signal-regulated kinase (ERK)-mediated AKT signaling, and sorafenib failed to suppress both ERK and AKT in TGF-ß-sensitized cells. The decreased anti-tumor effect of sorafenib was rescued by chemical inhibition of ERK and AKT. When TGF-ß-sensitized cells were treated with sorafenib plus VPA, the levels of phosphorylated ERK and AKT were considerably suppressed and the numbers of dead cells were increased by 3.7-5.7-fold compared with those exposed to sorafenib alone (P<0.05). Moreover, low dose sorafenib-induced cell migration was effectively suppressed by combination treatment with sorafenib and VPA. Collectively, TGF-ß/ERK/AKT signaling might play a critical role in sorafenib resistance in hepatoma cells, and combination treatment with VPA may be effective against this drug resistance.

[A case of postoperative chestwall recurrence of gastric cancer responding to a combination of radiation, hyperthermia and oral administration of TS-1].

A 77-year-old man diagnosed with advanced gastric cancer underwent total gastrectomy with combined splenectomy and resection of the pancreatic tails in 1996. He was treated with 400 mg/day of UFT for 2 years. Serum CEA level was found to be elevated on July 5, 2001. He complained of left chest pain in December 2001. A 4 cm-sized tumor was detected in the region extending from the subcutaneous region to the left chest wall containing the osteolytic change of the left sixth rib. He was diagnosed with a chest wall metastasis from gastric cancer. He underwent radiotherapy with thermotherapy and was also treated with chemotherapy. TS-1 was administered at 80-100 mg/body/day, twice daily for 3 weeks followed by a 2-week rest interval as 1 cycle. As a results, shrinkage of the tumor was confirmed on February 14, 2002. The tumor was confirmed to have disappeared on April 17, 2002, by chest CT. A complete response of the metastatic tumor was achieved. The patient maintained a complete response for more than 12 months, but died from the chest wall metastasis recurrence and weakness on August 13, 2003. The only observed adverse event, was grade 2 leukopenia.