PTPN9 induces cell apoptosis by mitigating the activation of Stat3 and acts as a tumor suppressor in colorectal cancer.

BACKGROUND: Accumulating evidence has shown that protein tyrosine phosphatases (PTPs) are involved in regulating the transduction of many signaling pathways and play important roles in modulating the progression of some cancers, but the functions of PTPs in cancers have not been well elucidated until now. Here, we aimed to identify the roles of protein tyrosine phosphatase nonreceptor type 9 (PTPN9), a cytoplasmic PTP, in the development of colorectal cancer and elucidate the regulatory mechanism involved. MATERIALS AND METHODS: Cell viability assessment, colony formation assay, caspase-3 and caspase-9 activity assay, real-time PCR, and Western blot analysis were applied. RESULTS: Our results showed that PTPN9 expression was frequently downregulated in colorectal cancer tissues compared with adjacent normal tissues. Overexpression of PTPN9 mitigated cell growth and colony formation and induced cell apoptosis in colorectal cancer. Conversely, PTPN9 knockdown promoted cell growth and survival. Moreover, PTPN9 negatively regulated the activation of Stat3 and depressed its nuclear translocation in colorectal cancer. The effects of PTPN9 knockdown on cell apoptosis were attenuated by inhibition of the Stat3 pathway. CONCLUSION: These results indicate that PTPN9 inhibits cell growth and survival by repressing the activation of Stat3 in colorectal cancer, which suggests an important underlying mechanism of regulating cell growth and provides a novel candidate therapeutic target for colorectal cancer.

Activation of CXCL12/CXCR4 renders colorectal cancer cells less sensitive to radiotherapy via up-regulating the expression of survivin.

Colorectal cancer is the most common malignancy of the gastrointestinal tract. Surgical treatment combined with radiotherapy is the main treatment course for colorectal cancer; nevertheless, radio-resistance is commonly encountered during the treatment course and seriously influences the therapeutic efficacy. We tested the hypothesis that the CXCL12/CXCR4 axis is closely related to radiotherapy sensitivity in colorectal cancer cells. Here, we found that the decrease in cell viability and the increase in cell death induced by radiotherapy were attenuated by CXCL12 treatment, and the inhibition of CXCR4 promoted colorectal cancer cells to be more sensitive to radiotherapy. We also examined the critical roles of CXCL12/CXCR4 in cell survival and found that radiotherapy induced Bax expression and facilitated the activity of caspase-3 and caspase-9, which were reversed by CXCL12 treatment. Cell apoptosis was enhanced by the inhibition of CXCR4 under radiotherapy conditions. Furthermore, treatment with CXCL12 resulted in an increased expression of survivin, and the inhibitory roles of CXCL12 in radiotherapy-induced apoptosis were mitigated by survivin knockdown. These results indicate that CXCL12/CXCR4 protects colorectal cancer cells against radiotherapy via survivin, implying an important underlying mechanism of resistance to radiotherapy during colorectal cancer therapy.

Long-term outcomes of laparoscopic splenectomy versus open splenectomy for idiopathic thrombocytopenic purpura.

The long-term outcomes of laparoscopic splenectomy (LS) versus open splenectomy (OS) in patients with idiopathic thrombocytopenic purpura (ITP) are not known. A retrospective analysis of 73 patients who underwent splenectomy (32 LS and 41 OS) for refractory ITP between April 2003 and June 2012 was conducted. LS was associated with shorter hospital stay (P = 0.01), less blood loss and blood transfusion during surgery, quicker resumption of oral diet (P < 0.0001), and earlier drain removal (P < 0.01). Conversion to OS was required in 4 patients (12.5%). Operation time was significantly longer in LS (P < 0.0001). Deep venous thrombosis (DVT) was observed in 1 patient after LS and in 4 patients after OS (P = 0.52). One patient died from intraperitoneal bleeding after OS, another patient developed pulmonary embolism. Median follow-up of 36 months was performed in LS group (29 of 32, 91%) and of 46 months in OS group (35 of 41, 85%), 25 patients (86%) in LS group and 32 (91%) in OS group reached sustained complete response (P = 0.792). Kaplan-Meier analysis showed that there was no significant difference in the relapse-free survival rate between the groups (P = 0.777). In conclusion, the long-term outcome of laparoscopic splenectomy is not different from that of open splenectomy for patients with ITP.

A core cross-linked polymeric micellar platium(IV) prodrug with enhanced anticancer efficiency.

A core cross-linked polymeric micellar cisplatin(IV) conjugate prodrug is prepared by attaching the cisplatin(IV) to mPEG-b-PLL biodegradable copolymers to form micellar nanoparticles that can disintegrate to release the active anticancer agent cisplatin(II) in a mild reducing environment. Moreover, in vitro studies show that this cisplatin(IV) conjugate prodrug displays enhanced cytotoxicity against HepG2 cancer cells compared with cisplatin(II). Further studies demonstrate that the high cellular uptake and platinum-DNA adduct of this cisplatin(IV) conjugate prodrug can induce more cancer-cell apoptosis than cisplatin(II), which is responsible for its enhanced anticancer activity.