Calmodulin (CaM), a Ca2+ binding protein, plays a critical role in cancer initiation and progression through binding and activating numerous target proteins, including Ca2+/calmodulin‐dependent protein kinase (CaMK) family proteins. However, the mechanisms underlying the effects of CaM/CaMKs on the survival capability of liver cancer cells is unclear, and this study investigates this mechanism in apicidin‐persistent HA22T cells. CaM level was upregulated, especially in the cytosol, in apicidin‐persistent HA22T cells than in parental HA22T cells and was positively associated with cell proliferation and migration capacity of apicidin‐persistent HA22T cells. Further, the expression of CaM‐activated CaMKs‐dependent signaling cascades, including CaMKK2, CaMKIV, CaMKII‐γ, and p‐CaMKII was observed in apicidin‐persistent HA22T cells, which were transiently activated by mitogen‐activated protein kinase oncogenic signaling, such as CREB, ERK1/2, and c‐fos. Furthermore, a specific CaM inhibitor trifluoperazine reduced the levels of p‐CREB, p‐ERK1/2, and c‐fos in apicidin‐persistent HA22T cells than in parental HA22T cells. Additionally, inhibition of CaM also suppressed CaM‐induced Bcl‐XL (an antiapoptotic protein) expression in apicidin‐persistent HA22T cells. Our finding emphasizes an essential role of CaM/CaMKs in augmentation of the survival capability of apicidin‐persistent liver cancer cells and suggests that CaM inhibition significantly attenuates CaM‐induced tumor growth and abrogates antiapoptotic function and also offers a promising therapeutic target for cancer treatment.

Purpose: miR-100-5p has been found upregulated in Oxaliplatin-resistant LoVo colorectal cell lines, but its function still need further study. Here, we investigated its function in cell regulation chemoresistance in chemoresistant colorectal cancer cell lines.Methods: Microarray, quantitative polymerase chain reaction (qRT-PCR) and westernblot were used to analysis the level of miR-100-5p. The downstream candidate gen target of miR-100-5p, CTDSPL in Oxaliplatin resistant (OXR)-LoVo colorectal cell lines were screened using the different types of bioinformatics based miRNA target prediction data are TargetScan (http://www.targetscan.org/), miRanda (http://www.microrna.org/ and mirTar (http://mirtar.mbc.nctu.edu.tw/human/). CTDSPL, a phosphatase-like tumor suppressor level was detected by westernblot as well with cell cycle progression chemoresistance associated colorectal cancer cell CTDSPL/p-RB/E2F1. Immunofluorescence assay and westernblot showed the cell properties were altered between parental and Oxaliplatin resistant LoVo cell lines. Bioinformatic prediction, (http://alggen.1si.upc.es/cgi-bin/promo_v3) was used to extend the investigation of miR-100-5p upstream regulation through checking dissimilarity index with margin less or equal than 15%, FOXP3, trancription factor forkhead box as upstream target. Interaction between miR-100-5p and CTDSPL regulation was confirmed using mimic miR-100-5p overexpression and knockdown upstream target sh-RNA approach.Results: hsa-miR-100-5p level was found significantly upregulated in LoVo-OXR than parental LoVo cell line, resulted in downregulation CTDSPL as a major target of miR-100-5p. The downregulated of CTDSPL/p-RB/E2F1 promotes cell proliferation and cell cycle progression in LoVo OXR compared with LoVo parental cell lines. Moreover, among various upstream targets FOXP3 is an upstream regulator of miR-100-5p. In addition, mimic miR-100-5p overexpression downregulated CTDSPL/p-RB/E2F1 signaling pathway was reverted upon miR-100-5p inhibition in CRC cell lines.Conclusion: Collectively, miR-100-5p is chemoresistance inducer through modulation of CTDSPL/p-RB/E2F1 signaling pathway in CRC cell. This phenomenon might offer a therapeutic platform for overcoming chemoresistance in cancer treatment.

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