ABSTRACT
Drug resistance remains the unresolved obstacle for gastric cancer (GC) treatment. Recently more and more studies have shown that microRNAs are involved in cancer resistance and could apply to drug resistance therapy in tumors. The relationship between miR-149 and 5-fluorouracil (5-FU) resistance in GC remains unclear. Here we detected miR-149 expression in 5-FU resistance tumor tissues and cell lines, and found that miR-149 expression is upregulated in AGS/5-FU cells compared with AGS cells. Further experiments indicated that overexpression of miR-149 can alleviate 5-FU-induced apoptosis and proliferation inhibition by targeting TREM2. It was also confirmed that TREM2 regulated 5-FU resistance through ß-catenin pathway. Generally speaking, our results indicated that miR-149 contributes to resistance of 5-FU in gastric cancer via targeting TREM2 and regulating ß-catenin pathway.
Subject(s)
Fluorouracil/pharmacology , Membrane Glycoproteins/metabolism , MicroRNAs/genetics , Receptors, Immunologic/metabolism , Stomach Neoplasms/drug therapy , Stomach Neoplasms/genetics , beta Catenin/metabolism , Animals , Antineoplastic Agents/pharmacology , Apoptosis , Cell Line, Tumor , Drug Resistance, Neoplasm/genetics , Female , Heterografts , Humans , Membrane Glycoproteins/antagonists & inhibitors , Membrane Glycoproteins/genetics , Mice , Mice, Nude , MicroRNAs/metabolism , RNA, Small Interfering/genetics , Receptors, Immunologic/antagonists & inhibitors , Receptors, Immunologic/genetics , Signal Transduction , Stomach Neoplasms/metabolism , Up-Regulation , beta Catenin/antagonists & inhibitors , beta Catenin/geneticsABSTRACT
Ursolic acid (UA) induces apoptosis in gastric cancer cells by inhibiting cyclooxygenase-2 (COX-2). Paclitaxel (PTX) is an important chemotherapy agent used to treat solid tumors. We evaluated the in vitro antitumor activity of UA in combination with PTX against gastric cancer cells and investigated the mechanisms underlying the combined effects. A cytotoxicity test and flow cytometry were utilized to study the effects of UA and PTX on proliferation and apoptosis, respectively. To further elucidate the mechanism, Western blot analysis was used to assess changes in the expression of a series of related proteins, including COX-2, proliferating cell nuclear antigen (PCNA), Bcl-2, and Bax. UA and PTX dose- and time-dependently inhibited BGC-823 and SGC-7901 gastric cancer cell proliferation. Combined delivery of UA and PTX synergistically reduced cell proliferation and induced apoptosis in these cells by lowering COX-2, PCNA, and Bcl-2 expression and by increasing Bax expression. These results indicate that the synergistic inhibition of proliferation and induction of apoptosis by UA and PTX may be induced by reducing COX-2 expression in gastric cancer cells.
ABSTRACT
The potential effect of PKC412, a small molecular multi-kinase inhibitor, in colorectal cancer (CRC) cells was evaluated here. We showed that PKC412 was cytotoxic and anti-proliferative against CRC cell lines (HT-29, HCT-116, HT-15 and DLD-1) and primary CRC cells. PKC412 provoked caspase-dependent apoptotic death, and induced G2-M arrest in the CRC cells. AKT activation was inhibited by PKC412 in CRC cells. Reversely, expression of constitutively-active AKT1 (CA-AKT1) decreased the PKC412's cytotoxicity against HT-29 cells. We propose that Bcl-2 could be a primary resistance factor of PKC412. ABT-737, a Bcl-2 inhibitor, or Bcl-2 siRNA knockdown, dramatically potentiated PKC412's lethality against CRC cells. Forced Bcl-2 over-expression, on the other hand, attenuated PKC412's cytotoxicity. Significantly, PKC412 oral administration suppressed AKT activation and inhibited HT-29 tumor growth in nude mice. Mice survival was also improved with PKC412 administration. These results indicate that PKC412 may have potential value for CRC treatment.
Subject(s)
Colorectal Neoplasms/drug therapy , Protein Kinase Inhibitors/administration & dosage , Staurosporine/analogs & derivatives , Animals , Cell Cycle/drug effects , Cell Cycle Proteins/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Colorectal Neoplasms/metabolism , Gene Expression Regulation, Neoplastic/drug effects , HCT116 Cells , HT29 Cells , Humans , Mice , Mice, Nude , Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins c-akt/metabolism , Staurosporine/administration & dosage , Staurosporine/pharmacology , Xenograft Model Antitumor AssaysABSTRACT
Gastrin, cholecystokinin2 receptor (CCK2R), and cyclooxygenase-2 (COX-2) have been implicated in the carcinogenesis and progression of gastric cancer. Our study demonstrated that antagonist or siRNA against CCK2R blocked amidated gastrin (G17)-induced activation of STAT3 and Akt in gastric cancer cell lines. G17-increased COX-2 expression and cell proliferation were effectively blocked by CCK2R antagonist and inhibitors of JAK2 and PI3K. In addition, knockdown of STAT3 expression significantly attenuated G17-induced PI3K/Akt activation, COX-2 expression, and cell proliferation. These results suggest that CCK2R-mediated COX-2 up-regulation via JAK2/STAT3/PI3K/Akt pathway is involved in the proliferative effect of G17 on human gastric cancer cells.
