The role of DOK7 and its variants in colorectal cancer

The downstream of tyrosine kinase (Dok) protein family has seven members, Dok 1-7. The precise role of these proteins is not entirely clear although some authors have suggested a potential tumour suppressor role. The aims of this clinically oriented PhD were to determine the expression profile and role of DOK7 in human colorectal cancer, to determine whether DOK7 expression is associated with tumour pathology and clinical outcome data, to determine the functional role of DOK7 in colorectal cancer cells and to evaluate DOK7 coordinated cell signalling in colorectal cancer. Initial work revealed that DOK7 mRNA expression is significantly reduced in colorectal cancer tissue compared with normal colorectal tissue and is associated with overall survival in patients with colorectal cancer. DOK7 is variably expressed in colorectal cancer cell lines with high expression in HRT-18 cells and low expression in HT-115 and RKO cells. Difficulties in obtaining DOK7 knockdown and expression subsequently revealed that DOK7 has several splice variants coding for different isoforms. Further work investigating DOK7 variants 1-3 (DOK7V1-3) revealed that DOK7V1 mRNA expression is significantly reduced in colorectal cancer tissue compared with normal colorectal tissue and is associated with disease-free status and length of diseasefree survival. In contrast, DOK7V2 and DOK7V3 mRNA expression is significantly increased in colorectal cancer tissue compared with normal colorectal tissue. Functional assays using a DOK7V2 overexpression model did not show a significant difference in colorectal cancer cell growth, adhesion or invasion in RKO DOK7V2 overexpression cells compared to the control cell line. However, antibody based protein microarray revealed that DOK7V2 overexpression is associated with significant changes in the expression and phosphorylation (activation) of numerous proteins in RKO cells. Cell signalling pathways potentially implicated include PI-3K-Akt, mTOR, MAPK, Jak/STAT and angiogenesis signalling pathways. Our findings suggest that DOK7 plays an important role in colorectal carcinogenesis and that DOK7 isoforms may ply different and possibly opposing roles. Protein microarray data provides a number of potential avenues for further work to elucidate the interaction of Dok7 with other cell signalling proteins and may help identify future potential therapeutic targets

The downstream of tyrosine kinase 7 is reduced in lung cancer and is associated with poor survival of patients with lung cancer

The downstream of tyrosine kinase 7 (DOK7) is an adaptor protein mediating signalling transduction between receptors and intracellular downstream molecules. Reduced expression of DOK7 has been observed in breast cancer. The present study aimed to investigate the role played by DOK7 in lung cancer. The expression of DOK7 at both mRNA and protein levels was evaluated in human lung cancer. A reduced expression of DOK7 transcripts was seen in lung cancers compared with normal lung tissues. Kaplan-Meier analyses showed that the reduced expression of DOK7 was associated with poorer overall survival and progression-free survival of patients with lung cancer. A further western blot analysis revealed a predominant expression of DOK7 isoform 1 (DOK7V1) in normal lung tissues, which was reduced in lung cancer. Forced overexpression of DOK7V1 in lung cancer cell lines, A549 and H3122 resulted in a decrease of in vitro cell proliferation and migration, while adhesion to extracellular matrix was enhanced following the expression. In conclusion, DOK7 was reduced in lung cancer and reduced DOK7 expression was associated with poorer survival. DOK7 isoform 1 plays an inhibitory role on the proliferation and migration of lung cancer cells in which Akt pathway may be involved

MTA1 is up-regulated in colorectal cancer and is inversely correlated with lymphatic metastasis

Background: Metastasis-associated protein 1 (MTA1) plays an important role in tumourigenesis and progression of certain cancer types. In the current study, we analyzed the relationship between MTA1 expression and disease progression of colorectal cancer (CRC). Materials and Methods: CRC tissues (n=93) and adjacent normal colorectal tissues (n=70) were analyzed by quantitative real-time polymerase chain reaction. MTA1 knockdown was established in RKO and HT115 cells using MTA1 siRNA. Results: The expression of MTA1 was significantly increased in CRC tissues compared to paired normal colorectal tissues, but decreased expression of MTA1 was correlated with poor prognosis (higher lymph node involvement stage, TNM stage, local invasion and recurrence) that was associated with increased expression of VEGFC and -D and the receptor VEGFR3. Conclusion: MTA1 is up-regulated in CRC. MTA1 expression is inversely associated with lymphatic metastases and the expression of VEGFC, VEGFD and VEGFR3

Psoriasin promotes invasion, aggregation and survival of pancreatic cancer cells; association with disease progression

Psoriasin (S100A7) is an 11-kDa small calcium binding protein initially isolated from psoriatic skin lesions. It belongs to the S100 family of proteins which play an important role in a range of cell functions including proliferation, differentiation, migration and apoptosis. Aberrant Psoriasin expression has been implicated in a range of cancers and is often associated with poor prognosis. This study examined the role of Psoriasin on pancreatic cancer cell functions and the implication in progression of the disease. Expression of Psoriasin was determined in a cohort of pancreatic tissues comprised of 126 pancreatic tumours and 114 adjacent non-tumour pancreatic tissues. Knockdown and overexpression of Psoriasin in pancreatic cancer cells was performed using specifically constructed plasmids, which either had anti-Psoriasin ribozyme transgene or the full length human Psoriasin coding sequence. Psoriasin knockdown and overexpression was verified using conventional RT-PCR and qPCR. The effect of manipulating Psoriasin expression on pancreatic cancer cell functions was assessed using several in vitro cell function assays. Local invasive pancreatic cancers extended beyond the pancreas expressed higher levels of Psoriasin transcripts compared with the cancers confined to the pancreas. Primary tumours with distant metastases exhibited a reduced expression of Psoriasin. Psoriasin overexpression cell lines exhibited significantly increased growth and migration compared to control cells. In addition, Psoriasin overexpression resulted in increased pancreatic cancer cell invasion which was associated with upregulation of matrix metalloproteinase-2 (MMP-2) and MMP-9. Overexpression of Psoriasin also promoted aggregation and survival of pancreatic cancer cells when they lost anchorage. Taken together, higher expression of Psoriasin was associated with local invasion in pancreatic cancers. Psoriasin expression is associated with pancreatic cancer cell growth, migration, cell-matrix adhesion, and invasion via regulation of MMPs. As such, the proposed implications of Psoriasin in invasion, disease progression and as a potential therapeutic target warrant further investigation

Expression of phospholipase C isozymes in human breast cancer and their clinical significance

Phospholipase C (PLC) regulates a number of cellular behaviours including cell motility, cell transformation, differentiation and cell growth. PLC plays a regulatory role in cancer cells partly by acting as signalling intermediates for cytokines such as EGF and interleukins. The current study examined the expression of the PLC isozymes in human breast cancer and corresponding clinical relevance. Transcript levels of human PLC-α, -β1, -δ, -ε, and -γ1 in human breast cancer tissues were quantitatively determined by real-time PCR. Immunochemical staining was performed for PLC-δ. The clinical relevance was analysed with clinic pathological information. Mammary tissues widely expressed PLC-α, -β1, -δ, -ε, and -γ1. Significantly high levels of PLC -β1 and -ε were seen in breast cancer tissues in comparison with normal mammary gland tissues. PLC-γ1 however, showed marginally low levels in tumour tissues. No significant difference was seen in the expression of the PLC isozymes in tumours with lymph node metastases. Moderately and poorly differentiated breast tumours (grade 2 and grade 3) had significantly higher levels of PLC-γ1, compared with well differentiated tumours. High levels of PLC-δ were significantly correlated with a shorter disease-free survival. The altered expression of other isozymes had no correlation with the survival. It is concluded that mammary tissues differentially expressed PLC isozymes. These isozymes have certain implications in the disease development and progression, with PLC-δ showing a significant correlation with shorter disease-free survival

Reduced NOV expression correlates with disease progression in colorectal cancer and is associated with survival, invasion and chemoresistance of cancer cells

Aberrant expression of nephroblastoma overexpressed (NOV) has been evident in certain malignancies. In the current study, we aim to investigate the role played by NOV in colorectal cancer (CRC). NOV expression was determined in a cohort of 359 CRC tissues and 174 normal colorectal tissues. Its impact on CRC cells was investigated using in vitro NOV knockdown and overexpression models. NOV transcripts were reduced in the CRC tumours compared with the paired adjacent normal colorectal tissues (p < 0.01) and was associated with distant metastases. NOV knockdown resulted in increased cell proliferation and invasion of RKO cells, whilst an opposite effect was seen in the HT115 NOV over expressing cells. A positive association between Caspase-3/-8 and NOV was seen in NOV knockdown and overexpression cell lines which contributed to the survival of serum deprived CRC cells. Further investigation showed that NOV regulated proliferation, survival and invasion through the JNK pathway. NOV knockdown in RKO cells reduced the responsiveness to 5-Fluorouracil treatment, whilst overexpression in HT115 cells exhibited a contrasting effect. Taken together, NOV is reduced in CRC tumours and this is associated with disease progression. NOV inhibits the proliferation and invasion of CRC cells in vitro. Inhibition of proliferation is mediated by a regulation of Caspase-3/-8, via the JNK pathway, which has potential for predicting and preventing chemoresistance

YangZheng XiaoJi exerts anti-tumour growth effects by antagonising the effects of HGF and its receptor, cMET, in human lung cancer cells

BACKGROUND: Hepatocyte growth factor (HGF) is a cytokine that has a profound effect on cancer cells by stimulating migration and invasion and acting as an angiogenic factor. In lung cancer, the factor also plays a pivotal role and is linked to a poor outcome in patients. In particular, HGF is known to work in combination with EGF on lung cancer cells. In the present study, we investigated the effect of a traditional Chinese medicine reported in cancer therapies, namely YangZheng XiaoJi (YZXJ) on lung cancer and on HGF mediated migration and invasion of lung cancer cells. METHODS: Human lung cancer cells, SKMES1 and A549 were used in the study. An extract from the medicine was used. Cell migration was investigated using the EVOS and by ECIS. Cell–matrix adhesion and in vitro invasion were assessed. In vivo growth of lung cancer was tested using an in vivo xenograft tumour model and activation of the HGF receptor in lung tumours by an immunofluorescence method. RESULTS: Both lung cancer cells increased their migration in response to HGF and responded to YZXJ by reducing their speed of migration. YZXJ markedly reduced the migration and in vitro invasiveness induced by HGF. It worked synergistically with PHA665752 and SU11274, HGF receptor inhibitors on the lung cancer cells both on HGF receptor activation and on cell functions. A combination of HGF and EGF resulted in a greater increase in cell migration, which was similarly inhibited by YZXJ, and in combination with the HGF receptor and EGF receptor inhibitors. In vivo, YZXJ reduced the rate of tumour growth and potentiated the effects of PHA665752 on tumour growth. It was further revealed that YZXJ significantly reduced the degree of phosphorylation of the HGF receptor in lung tumours. CONCLUSION: YZXJ has a significant role in reducing the migration, invasion and in vivo tumour growth of lung cancer and acts to inhibit the migratory and invasive effects induced by HGF and indeed by HGF/EGF. This effect is likely attributed to the inhibition of the HGF receptor activation. These results indicate that YZXJ has a therapeutic role in lung cancer and that combined strategy with methods to block HGF and EGF should be considered. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12967-015-0639-1) contains supplementary material, which is available to authorized users