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Purpose: Circulating tumor cells (CTCs) have been proved to be responsible for tumor metastasis and resistant to anticancer therapies. This study aims to isolate and characterize circulating tumor cells from human gastric cancer patients, and investigate characteristic differences between gastric CTCs and gastric cancer cell lines. Methods: We analyzed 31 cases of gastric cancer patients using anti-CD45 antibody-conjugated magnetic microbeads negative separation, combined with fluorescence activated cell sorter CD44 positive screening. Abilities of tumor formation, metastasis, invasion, migration, irradiation and drug sensitivity of CTCs and gastric cancer cell lines were detected and compared. Results: Of all the 31 patients, CD44/CD45CTCs were isolated in 14 patients, of which 3 cases were stage IIA, 2 cases stage IIB, 2 cases stage IIIC and 7 cases stage IV. The malignant behavior was demonstrated by both clonogenetic assay and tumor xenograft in nude mice. Compared with human gastric cancer cell lines, the migration and invasion abilities of CTCs increased to 3.21-12.6-fold and 2.3-6.7-fold, respectively (all p values <0.05). In addition, the metastatic potential of CTCs is much higher in vivo than that of the control. Furthermore, CTCs were found to be relatively sensitive to FU, cisplatin and paclitaxel, but relatively resistant to irradiation, oxaliplatin, cetuximab and trastuzumab. Conclusions: CD44/CD45 gastric CTCs were isolated and found to exhibit stronger malignant behavior when compared with human gastric cancer cell lines. Furthermore, CTCs cultured in vitro have potential implications in drug sensitivity screening for the future anticancer treatments. [ABSTRACT FROM AUTHOR]

Purpose: The mammalian Janus kinase (JAK) family plays a critical role in cytokine/growth factor signalling pathways and is associated with human cancers. In this study, we explored the role of JAK1 in the non-small cell lung cancer (NSCLC) cell line A549 and its molecular crosstalk with the phosphatidyl inositol-3-kinase (PI3K)/mammalian target of the rapamycin (mTOR) pathway. Methods: One hundred and two NSCLC and 50 normal lung specimens were collected after surgical resection. JAK1 expression and phosphorylation were determined via immunohistochemical staining (IHC) assay. A stable knockdown of JAK1 was performed in A549 cells by RNA interference. Stable cell proliferation, cell cycle, apoptosis, and invasion were characterised in vitro. Tumourigenicity was analysed in vivo. The NSCLC xenograft protein expression of PI3K/mTOR pathway molecules was determined by Western blot assay. Results: JAK1 expression was higher in NSCLC tissues than in normal lung tissues ( P < 0.01). JAK1 knockdown in A549 cells significantly inhibited cell proliferation and invasion while promoting cell arrest at G0/G1 phase (all P < 0.05). The xenograft model showed that JAK1 suppression inhibited tumour growth compared with normal control ( P < 0.05). Moreover, JAK1 knockdown inhibited mTOR or P70 ribosomal protein S6 kinase (P70S6K) phosphorylation, but increased glycogen synthase kinase-3α (GSK-3α) and B-cell lymphoma-extra large (Bcl-xl) phosphorylation. Total protein expression and Akt1/2 phosphorylated status remained unchanged. Conclusion: Our study suggests that JAK1 expression and phosphorylation is abnormal in NSCLC tissues. The knockdown of JAK1 significantly inhibits tumourigenicity of the A549 cell line and demonstrates that crosstalk between the JAK1 and PI3K/mTOR pathways is involved. [ABSTRACT FROM AUTHOR]