Antigen p57/Kip2 as a potential negative regulator of human astrocytoma growth

Immunohistochemical Expression of p27Kip1, p57Kip2, Cyclin D1, Nestin, and Ki-67 in Ependymoma

p27 and p57 are tumor suppressors that are dysregulated in many cancers. We investigated the immunohistochemical expression of p27 and p57 in ependymoma, with a secondary emphasis on cyclin D1, nestin, and Ki-67. Sixty-five patients diagnosed with ependymoma were included. Clinical and tumoral data were retrieved, and the expression of p27, p57, cyclin D1, nestin, and Ki-67 was measured. Pearson’s χ2 test was used to measure associations and the Kaplan–Meier method was used for survival analysis. p27 underexpression was significantly associated with pseudopalisading necrosis in tumors with foci of necrosis (p = 0.004). Cyclin D1 overexpression was associated with intracranial (p = 0.044), recurrent (p = 0.022) and grade 3 tumors (p = 0.016); nestin overexpression was associated with supratentorial (p = 0.025), mitotically active (p < 0.001), and grade 3 tumors (p = 0.004); Ki-67 overexpression was associated with supratentorial (p = 0.044) and grade 3 tumors (p < 0.001) and the 3 main features of anaplasia. None of the markers were intercorrelated or predictive of overall survival. In conclusion, p27 underexpression in tumors with foci of necrosis signals a pseudopalisading pattern. Cyclin D1, nestin, and Ki-67 are useful markers in ependymoma, but evidence-based cutoff values are required to standardize this interpretation.

P57-mediated autophagy promotes the efficacy of EGFR inhibitors in hepatocellular carcinoma

BACKGROUND & AIMS

Resistance to EGFR-targeted therapy is a major obstacle in hepatocellular carcinoma (HCC) treatment, but its underlying mechanism remains unclear. Autophagy plays a vital role in antitumour treatment. Our previous study suggested that p57 is associated with autophagy and cisplatin resistance. The present study aimed to investigate whether p57 can enhance the sensitivity of HCC cells to Erlotinib (Er)/Cetuximab(C-225) and further explore the potential mechanisms of Er/C-225 resistance.

METHODS

HCC cells were transfected with pIRES2-EGFP-p57 and pIRES2-EGFP-nc, accompanied by Er/C-225 treatment. Cell viability was detected by an Annexin apoptosis kit and MTT assay. Xenograft experiments were performed to study the function of p57 in the treatment of Er/C-225 in vivo. The level of autophagy was determined by analysis of the appearance of autophagic vacuoles. Western blotting was used to investigate the potential pathways involved.

RESULTS

Up-regulation of p57 decreased the level of Er/C-225-induced autophagy and enhanced the decrease in Er/C-225-induced cell viability. P57 overexpression combined with CQ treatment further enhanced the therapeutic efficiency of Er/C-225. The xenograft experiment verified that p57 up-regulation sensitizes HCC cells to Er/C-225. Moreover, a mechanistic investigation demonstrated that the up-regulation of p57 resulted in a decrease of LC3B-II and beclin-1, and an increase in p-PI3K, p-AKT and p-mTOR protein expressions.

CONCLUSIONS

Through activating the PI3K/AKT/mTOR signalling pathway, p57 can reverse Er/C-225-induced autophagy, and thereby increase the therapeutic efficiency of Er/C-225 treatment. Given these results, p57 up-regulation may be applicable as a therapeutic strategy to improve EGFR-targeted therapy in HCC.

Prognostic significance of co-expression of nm23 and p57 protein in hepatocellular carcinoma

AIM

  To investigate the unbalance of proliferation and apoptosis and the functions of cell-cycle proteins and apoptotic factor in metastasis of hepatocellular carcinoma (HCC) and their effect in prognosis.

METHODS

  Proliferation index and apoptosis index, as well as seven relatively molecular markers, namely p15, p34, p53, p57, p73, survivin and nm23, were evaluated by immunohistochemistry and TUNEL in HCC tissues and compared to adjacent non-cancerous tissues and normal liver tissues. Furthermore, the prognostic significance by follow-up and mutual relationships for each clinicopathologic factor and molecular marker were analysed.

RESULTS

  The dysregulation between proliferation and apoptosis and the abnormal expression of seven molecular markers were observed in HCC tissues. The unbalance of proliferation and apoptosis and abnormal expressions of p15, p34, p57 and nm23 were correlated with TNM stage and extrahepatic metastasis. In particular, the abnormal co-expression of nm23/p57 correlated with advanced TNM stage and bigger tumor size and was an independent prognostic factor of HCC.

CONCLUSION

  The unbalance of proliferation and apoptosis and abnormal expression of cell-cycle proteins promote metastasis of HCC. Moreover, the abnormal co-expression of nm23/p57 may be a useful molecular marker for metastasis and unfavourable prognosis for HCC.