Mortality association of enhanced CD44v6 expression is not mediated through occult lymphatic spread in stage II colorectal cancer

Systematic assessment of the prognostic impact of membranous CD44v6 protein expression in colorectal cancer

AIMS

To assess systematically the membranous expression of CD44v6 in colorectal cancer by immunohistochemistry to determine its prognostic impact, the differential expression between primary and metastatic tumours and expression differences between the tumour centre and invasive front.

METHODS AND RESULTS

Immunohistochemistry was performed for CD44v6 on two tissue microarrays. The first included 1279 colorectal tumours with full clinicopathological data. The second consisted of 50 matched primary and metastatic tumours sampled from the tumour centre and the invasive margin. A scoring system was tested by multiple observers. Receiver-operating characteristic curve analysis was used for cut-off point determination. Loss of membranous CD44v6 was associated with pT stage (P = 0.016; sensitivity 85.8%, specificity 20.1%), lymph node metastasis (P = 0.015; sensitivity 52.8%, specificity 55%), an infiltrating tumour margin (P < 0.001; sensitivity 71.4%, specificity 40%) and adverse prognosis (P = 0.011; hazard ratio 0.79, 95% confidence interval 0.7, 0.9), but was not an independent prognostic factor on multivariable analysis. Loss of expression occurred at the invasive front in both primary and metastatic lesions (P < 0.001).

CONCLUSIONS

This study outlines an approach to help standardize the immunohistochemical evaluation of CD44v6 and similar markers in colorectal cancer and highlights a significant role for loss of membranous CD44v6 expression in colorectal cancer progression and prognosis.

Simultaneous detection of CD44v6 expression and DNA content in rectal cancer and its clinical significance

AIM

To explore CD44v6 expression and DNA content and the ir significance in the progress of rectal cancer.

METHODS

In 40 cases of rectal cancer and 10 cases of normal intestinal tissues, CD44v6 expression and DNA content were detected simultaneously by flow cytometry.

RESULTS

The CD44v6 expression and DNA content in rectal cancer were significantly higher than those in normal tissue (70% vs 0%, 1.11±0.6 vs 0.9±0.65, P <0.01). The positive expression of CD44v6 was closely related to the depth of invasion (0% vs 50% vs 80% vs 100%, P <0.05) lymphnode metastasis (93.3% vs 56.0%, P <0.05) and Dukes stage (56.0% vs 93.3%, P <0.05). The DNA aneuploidy in cancer was also related to lymph node metastasis (100% vs 68%, P <0.05) and Duke's stage (68% vs 100%, P <0.05). The expression of CD44v6 did not show any correlation with DNA ploidy of tumor cells (85.7% vs 68.7%, P >0.05).

CONCLUSION

The abnormal expression of CD44v6 and DNA aneuploidy plays an important role in the development, invasion and metastasis of rectal cancer. The detection of CD44v6 and DNA content simultaneously may serve as a useful indicator to predict progress of tumor and lymph node metastasis.

RHO-GTPases and cancer

The RAS oncogenes were identified almost 20 years ago. Since then, we have learnt that they are members of a large family of small GTPases that bind GTP and hydrolyse it to GDP. This is then exchanged for GTP and the cycle is repeated. The switching between these two states regulates a wide range of cellular processes. A branch of the RAS family--the RHO proteins--is also involved in cancer, but what is the role of these proteins and would they make good therapeutic targets?