Binding between ROCK1 and DCTN2 triggers diabetes­associated centrosome amplification in colon cancer cells.

Type 2 diabetes increases the risk various types of cancer and is associated with a poor prognosis therein. There is also evidence that the disease is associated with cancer metastasis. Centrosome amplification can initiate tumorigenesis with metastasis in vivo and increase the invasiveness of cancer cells in vitro. Our previous study reported that type 2 diabetes promotes centrosome amplification via the upregulation and centrosomal translocation of Rho­associated protein kinase 1 (ROCK1), which suggests that centrosome amplification is a candidate biological link between type 2 diabetes and cancer development. In the present study, functional proteomics analysis was used to further investigate the molecular pathways underlying centrosome amplification by targeting ROCK1 binding partners. High glucose, insulin and palmitic acid were used to induce centrosome amplification, and immunofluorescent staining was employed to visualize centrosomal alterations. Combined with immunoprecipitation, mass spectrometry­based proteomics analysis was used to identify ROCK1 binding proteins, and protein complex disruption was achieved by siRNA­knockdown. In total, 1,148 ROCK1 binding proteins were identified, among which 106 proteins were exclusively associated with the treated samples, 193 were only associated with the control samples, and 849 were found in both the control and treated samples. Of the proteins with evidence of centrosomal localization, Dynactin subunit 2 (DCTN2) was confirmed to be localized to the centrosomes. Treating the cells with high glucose, insulin and palmitic acid increased the protein levels of ROCK1 and DCTN2, promoted their binding with each other, and triggered centrosome amplification. Disruption of the protein complex by knocking down ROCK1 or DCTN2 expression partially attenuated centrosome amplification, while simultaneous knockdown of both proteins completely inhibited centrosome amplification. These results suggested ROCK1­DCTN2 binding as a signal for the regulation of centrosome homeostasis, which is key for diabetes­associated centrosome amplification, and enriches our knowledge of centrosome biology. Therefore, the ROCK1­DCTN2 complex may serve as a target for inhibiting centrosome amplification both in research or future therapeutic development.

[Comparison of clinicopathological features and prognosis in familial and sporadic gastric cancer].

OBJECTIVE: To analyze the clinicopathological characteristics and prognosis of familial gastric cancer and to improve the treatment outcome. METHODS: Clinical data of 67 patients with familial gastric cancer and 820 patients with sporadic gastric cancer in the Second Affiliated Hospital of Dalian Medical University from 1995 to 2005 were retrospectively analyzed. RESULTS: Compared to sporadic gastric cancer, the percentage of familial gastric cancer patients less than 45 years old was higher (34.3% vs. 14.6%). Early gastric cancer(23.9% vs. 13.8%), diffuse gastric cancer(79.1% vs. 29.0%), and lymph node metastasis (91.0% vs. 70.9%) were more common in patients with familial cancer(P<0.05). The 5-year survival rate of familial gastric cancer patients was lower than that of patients with sporadic gastric cancer(20.5% vs. 45.1%)(P<0.05). CONCLUSIONS: Familial gastric cancer has characteristics of younger onset age, advanced disease staging, higher positive lymph node ratio and poorer prognosis. Therefore, early diagnosis should be emphasized in the management of familial gastric cancer.