Background: The mechanism underlying cisplatin resistance in colorectal carcinoma (CRC) has not yet been elucidated. This study is aimed to illustrate the indispensable role of proline-rich acidic protein 1 (PRAP1) in cisplatin-resistant CRC. Methods: Cell viability and apoptosis were monitored using cell counting kit-8 and flow cytometry. Immunofluorescence and morphological analysis were used to determine mitotic arrest in cells. In vivo drug resistance was evaluated using a tumor xenograft assay. Results: PRAP1 was highly expressed in cisplatin-resistant CRC. PRAP1-upregulation in HCT-116 cells increased chemoresistance to cisplatin, whereas RNAi-mediated knockdown of PRAP1 sensitized cisplatin-resistant HCT-116 cells (HCT-116/DDP) to cisplatin. PRAP1-upregulation in HCT-116 cells hindered mitotic arrest and the formation of mitotic checkpoint complexes (MCC), followed by an increase in multidrug-resistant proteins such as p-glycoprotein 1 and multidrug resistance-associated protein 1, while PRAP1-knockdown in HCT-116/DDP cells partly restored colcemid-induced mitotic arrest and MCC assembly, resulting in decreased multidrug-resistant protein levels. PRAP1 downregulation-mediated sensitization to cisplatin in HCT-116/DDP cells was abolished by the inhibition of mitotic kinase activity by limiting MCC assembly. Additionally, PRAP1-upregulation increased cisplatin-resistance in CRC in vivo. Mechanistically, PRAP1 increased the expression of mitotic arrest deficient 1 (MAD1), that competitively binds to mitotic arrest deficient 2 (MAD2) in cisplatin-resistant CRC cells, leading to failed assembly of MCC and subsequent chemotherapy resistance. Conclusion: PRAP1-overexpression caused cisplatin resistance in CRC. Possibly, PRAP1 induced an increase in MAD1, which competitively interacted with MAD2 and subsequently restrained the formation of MCC, resulting in CRC cells escape from the supervision of MCC and chemotherapy resistance.

Background: Tumor deposits are one of the promising factors among the different edition of Tumor, Node, Metastasis classification. Despite improvement in the treatment of various types of metastatic disease the source and prognostic significance of tumor deposits in staging has not been deliberating the agreeable opinion. We investigated the possibility of tumor deposit as independent prognostic factor and evaluating its prognostic value in colorectal carcinoma patients. Methods: Author studied 313 colorectal cancer patients clinocopathological data and outcome who underwent radical resection. Data between 2011-2015 were retrospectively collected from Shanghai East Hospital, affiliated with Tongji University data information centre. The analysis was used to calculate 2 years disease free survival(DFS) and relation of tumor deposit with number of lymph node positive. Cox-regression analysis was performed to assess the prognostic factor. Results: Out of 313 colorectal patients included in the study, tumor deposits were detected in 17%. Tumor deposits (TDs) are relevantly associated with significant poor outcomes. The tumor deposit were significantly correlated with T-stage(P=<0.001), N-stage(P=<0.001), PLNC(P=<0.001), venous invasion(P=<0.001), TNM staging(P=<0.001), CEA(P=0.021) and CA19-9(P=0.042) of primary tumor. The Kaplan-Meier analysis revealed that disease-free survival of CRC patients with positive tumor deposit were significantly poorer that those with negative tumor deposit cohort(P=<0.001) And with multivariate analysis in different model, we found that positive tumor deposit were significantly associated with shorter DSF which is totally independent with lymph node status (P=0.001 and P=0.023 respectively). Subgroup analysis found that of 179 CRC patients with negative lymph node status, the DFS of patients with positive tumor deposit were significantly shorter that those with negative tumor deposit(P=,0.001). Of 134patients with positive lymph node status, the DFS of patients shows similar result. (P=<0.001). Conclusion: We have shown that TDs are not equal to lymph node metastasis with respect to biology and outcome. Tumor deposits are an independent adverse prognostic factor in CRC patient who have undergone radical resection.