Phosphorylated c-Src in the nucleus is associated with improved patient outcome in ER-positive breast cancer

Elevated c-Src protein expression has been shown in breast cancer and <i>in vitro</i> evidence suggests a role in endocrine resistance. To investigate whether c-Src is involved in endocrine resistance, we examined the expression of both total and activated c-Src in human breast cancer specimens from a cohort of oestrogen receptor (ER)-positive tamoxifen-treated breast cancer patients. Tissue microarray technology was employed to analyse 262 tumour specimens taken before tamoxifen treatment. Immunohistochemistry using total c-Src and activated c-Src antibodies was performed. Kaplan–Meier survival curves were constructed and log-rank test were performed. High level of nuclear activated Src was significantly associated with improved overall survival (<i>P</i>=0.047) and lower recurrence rates on tamoxifen (<i>P</i>=0.02). Improved patient outcome was only seen with activated Src in the nucleus. Nuclear activated Src expression was significantly associated with node-negative disease and a lower NPI (<i>P</i><0.05). On subgroup analysis, only ER-positive/progesterone receptor (PgR)-positive tumours were associated with improved survival (<i>P</i>=0.004). This shows that c-Src activity is increased in breast cancer and that activated Src within the nucleus of ER-positive tumours predicts an improved outcome. In ER/PgR-positive disease, activated Src kinase does not appear to be involved in <i>de novo</i> endocrine resistance. Further study is required in ER-negative breast cancer as this may represent a cohort in which it is associated with poor outcome

p70S6K is regulated by Focal Adhesion Kinase and is required for Src-selective autophagy

AbstractHere we report that focal adhesion kinase (FAK) is required for optimal signalling to the Akt-p70S6K-S6 pathway in squamous cell carcinoma (SCC) cells. Specifically, in SCCs that are genetically deficient for FAK, there is reduced phosphorylation of Akt, p70S6K and S6, and signalling to Akt-p70S6K-S6 is more sensitive to inhibition by multiple agents that suppress the pathway. By contrast, mTOR is unaffected. Indeed, pharmacological agents that inhibit the Akt-p70S6K-S6 pathway, and PDK1 that lies upstream of Akt, also impair the autophagic targeting of activated c-Src (p-Src) in FAK deficient cells. This is associated with loss of a complex between p-Src and the autophagy protein LC3, a biochemical surrogate of impaired Src-selective autophagy. In keeping with a vital role for p70S6K, inhibition by a selective inhibitor and specific siRNA also impaired Src-selective autophagy. Finally, components of the PDK1-Akt-p70S6K signalling pathway were co-located with p-Src at autophagosomes, and Src and p70S6K co-exist in the same biochemical complex. We therefore deduce that the FAK-regulated signalling module PDK1-Akt-p70S6K that controls Src's intracellular trafficking operates at Src-containing autophagosomes

The relationship between tumour site, clinicopathological characteristics and cancer-specific survival in patients undergoing surgery for colorectal cancer

<b>Aim:</b>  It is recognised that colorectal cancer may arise from different genomic instability pathways. There is evidence to suggest that colon and rectal cancers exhibit different clinicopathological features. We examined the relationship between tumour site, clinicopathological characteristics and cancer-specific survival in patients undergoing potentially curative resection for colorectal cancer.<p></p> <b>Method:</b>  411 patients who underwent surgery. Clinicopathological data including components of the Peterson index, Klintrup scores, haemoglobin and the modified Glasgow Prognostic Score (mGPS) were studied.<p></p> <b>Results:</b>  There were 134 (33%) right sided, 125 (30%) left sided and 152 (37%) rectal tumours. Emergency presentation (P<0.001), anaemia (P<0.001), higher mGPS (P<0.001), advanced T stage (P<0.001), poor differentiation (P<0.001) and older age (P<0.05) were more commonly observed in right sided cancer. The mean follow-up was 94 months (minimum 36 months) and 114 patients died of cancer. There was no difference between tumour site and survival (P=0.427). On multivariate analysis older age (P=0.015), lymph node ratio (P<0.001), mGPS (P=0.028), Peterson Index (P<0.001) and Klintrup score (P=0.008) were independently related to cancer-specific survival. Klintrup score was only associated with poor cancer-specific survival in rectal cancer (P=0.009).<p></p> <b>Conclusion:</b>  The study suggests that colorectal cancer is a group of heterogeneous tumours with different clinicopathological features. Despite this, there was no difference between tumour site and survival. The prognostic role of clinicopathological factors in tumours arising from different genomic instability pathways requires further study

Cell growth, global phosphotyrosine elevation, and c-Met phosphorylation through Src family kinases in colorectal cancer cells

The heterogeneity of cancer cell signaling is a significant obstacle for the effective development and clinical use of molecularly targeted therapies. As a contribution to a better understanding of the diversity of signaling activities in colorectal cancers (CRCs), we have analyzed the activity of Src family kinases (SFKs), which are implicated in human cancer development, in 64 CRC cell lines. A striking diversity of SFK activity was observed within this panel. Importantly, all CRC lines tested depend on SFK activity for their growth. In addition, SFK activity levels strongly correlated with global levels of tyrosine-phosphorylated (pTyr) proteins in CRC lines. SFK inhibition substantially reduced these pTyr levels, suggesting that SFKs may function as signal integration points and master controllers for the pTyr protein status in CRC lines. The majority of analyzed CRC lines with high-SFK activity express activated c-Met (pYpY1234/1235), a receptor tyrosine kinase contributing to the regulation of cell proliferation, migration, and invasion. Inhibition of SFKs reduced c-Met phosphorylation in most cases, indicating a reversed signal flow from SFK to c-Met. We conclude that SFK activity is important for the growth of CRC lines, although only low activity levels are required. If this also is true for CRC patients, tumors with low-SFK activity may be particularly sensitive to SFK inhibitors, and such patients should be targeted in clinical trials testing SFK inhibitors