Maspin mediates the gemcitabine sensitivity of hormone-independent prostate cancer.

Androgen deprivation therapy has constituted the main treatment for prostate cancer; however, tumors ultimately progress to hormone-independent prostate cancer (HIPC), and suitable therapeutic strategies for HIPC are not available. Maspin, which is also known as mammary serine protease inhibitor, has been suggested to be a valuable focus for targeted cancer therapy. Specifically, maspin has been shown to be upregulated after androgen ablation therapy. Gemcitabine is used as a first-line therapy for metastatic castration-resistant prostate cancer, but its disease control rate is low. Furthermore, the role of maspin in the therapeutic efficacy of gemcitabine for HIPC remains unclear. The expression levels of maspin in PC-3 and DU145 cells were determined by real-time PCR and Western blotting. Furthermore, the expression of maspin was silenced using shRNA technology to generate maspin-KD cells. The cytotoxicity of gemcitabine to prostate cancer cells was assessed using 3-[4,5-dimethylthiazol-2-yl]-3,5-diphenyl tetrazolium bromide (MTT) assays, whereas flow cytometry analyses and annexin V-propidium iodide (PI) apoptosis assays were used to assess the ability of gemcitabine to induce apoptosis in maspin-KD and control cells. Additionally, the expression patterns of anti-apoptosis proteins (myeloid cell leukemia 1 (Mcl-1) and B cell lymphoma 2 (Bcl-2)) and pro-apoptosis proteins (Bcl-2-associated death promoter (Bad) and Bcl-2-associated X protein (Bax)) were determined by Western blotting. In this study, PC-3 cells were more resistant to gemcitabine administration than DU145 cells, which correlated with the higher expression levels of maspin observed in PC-3 cells. Furthermore, maspin knockdown enhanced gemcitabine-induced cell death, as evidenced by the increased number of apoptotic cells. Gemcitabine treatment upregulated the levels of anti-apoptosis proteins (Mcl-2 and Bcl-2) in both scrambled control and maspin-KD cells; however, the fold changes in Mcl-1 and Bcl-2 expression were larger in gemcitabine-treated scrambled control cells than in maspin-KD cells. Finally, our findings indicate for the first time that maspin may mediate the therapeutic efficacy of gemcitabine in HIPC. Our results demonstrate that maspin knockdown enhanced the sensitivity of androgen-independent prostate cancer cells to gemcitabine. Therefore, combining gemcitabine with a drug that targets maspin might constitute a valuable strategy for prostate cancer treatment.

The α7-nicotinic acetylcholine receptor mediates the sensitivity of gastric cancer cells to taxanes.

Gastric cancer is difficult to cure because most patients are diagnosed at an advanced disease stage. Systemic chemotherapy remains an important therapy for gastric cancer, but both progression-free survival and disease-free survival associated with various combination regimens are limited because of refractoriness and chemoresistance. Accumulating evidence has revealed that the homomeric α7-nicotinic acetylcholine receptor (A7-nAChR) promotes human gastric cancer by driving cancer cell proliferation, migration, and metastasis. Therefore, A7-nAChR may serve as a potential therapeutic target for gastric cancer. However, the role of A7-nAChR in taxane therapy for gastric cancer was unclear. Cells were subjected to A7-nAChR knockdown (A7-nAChR KD) using short interfering RNA (siRNA). The anti-proliferative effects of taxane were assessed via 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), terminal deoxynucleotidyl transferase-mediated nick-end labeling (TUNEL), and cell cycle distribution assays. A7-nAChR-KD cells exhibited low resistance to docetaxel and paclitaxel treatment, as measured by the MTT assay. Following paclitaxel treatment, the proportion of apoptotic cells was higher among A7-nAChR-KD cells than among scrambled control cells, as measured by cell cycle distribution and TUNEL assays. Further molecular analyses showed a reduction in the pAKT levels and a dramatic increase in the Bad levels in paclitaxel-treated A7-nAChR-KD cells but not in scrambled control cells. Following paclitaxel treatment, the level of Bax was slightly increased in both cell populations, whereas Poly (ADP-ribose) polymerase (PARP) cleavage was increased only in A7-nAChR-KD cells. These findings indicate that A7-nAChR-KD cells are more sensitive to paclitaxel treatment. We conclude that A7-nAChR may be a key biomarker for assessing the chemosensitivity of gastric cancer cells to taxane.