CLDN1 expression in cervical cancer cells is related to tumor invasion and metastasis.

Even though infection with human papillomaviruses (HPV) is very important, it is not the sole cause of cervical cancer. Because it is known that genetic variations that result from HPV infection are probably the most important causes of cervical cancer, we used human whole genome array comparative genomic hybridization to detect the copy number variations of genes in cervical squamous cell carcinoma. The results of the array were validated by PCR, FISH and immunohistochemistry. We find that the copy number and protein expression of claudin-1 (CLDN1) increase with the progression of cervical cancer. The strong positive staining of CLDN1 in the cervical lymph node metastasis group received a significantly higher score than the staining in the group with no lymph node metastasis of cervical cancer tissues. The overexpression of CLDN1 in SiHa cells can increase anti-apoptosis ability and promote invasive ability of these cells accompanied by a decrease in expression of the epithelial marker E-cadherin as well as an increase in the expression of the mesenchymal marker vimentin. CLDN1 induces the epithelial-mesenchymal transition (EMT) through its interaction with SNAI1. Furthermore, we demonstrate that CLDN1 overexpression has significant effects on the growth and metastasis of xenografted tumors in athymic mice. These data suggest that CLDN1 promotes invasion and metastasis in cervical cancer cells via the expression of EMT/invasion-related genes. Therefore, CLDN1 could be a potential therapeutic target for the treatment of cervical cancer.

SIX1 promotes tumor lymphangiogenesis by coordinating TGFß signals that increase expression of VEGF-C.

Lymphatic vessels are one of the major routes for the dissemination of cancer cells. Malignant tumors release growth factors such as VEGF-C to induce lymphangiogenesis, thereby promoting lymph node metastasis. Here, we report that sine oculis homeobox homolog 1 (SIX1), expressed in tumor cells, can promote tumor lymphangiogenesis and lymph node metastasis by coordinating with TGFß to increase the expression of VEGF-C. Lymphangiogenesis and lymph node metastasis in cervical cancer were closely correlated with higher expression of SIX1 in tumor cells. By enhancing VEGF-C expression in tumor cells, SIX1 could augment the promoting effect of tumor cells on the migration and tube formation of lymphatic endothelial cells (LEC) in vitro and lymphangiogenesis in vivo. SIX1 enhanced TGFß-induced activation of SMAD2/3 and coordinated with the SMAD pathway to modulate VEGF-C expression. Together, SIX1 and TGFß induced much higher expression of VEGF-C in tumor cells than each of them alone. Despite its effect in promoting VEGF-C expression, TGFß could inhibit lymphangiogenesis by directly inhibiting tube formation by LECs. However, the increased production of VEGF-C not only directly promoted migration and tube formation of LECs but also thwarted the inhibitory effect of TGFß on LECs. That is, tumor cells that expressed high levels of SIX1 could promote lymphangiogenesis and counteract the negative effects of TGFß on lymphangiogenesis by increasing the expression of VEGF-C. These findings provide new insights into tumor lymphangiogenesis and the various roles of TGFß signaling in tumor regulation. Our results also suggest that SIX1/TGFß might be a potential therapeutic target for preventing lymph node metastasis of tumor.

Amplification and overexpression of TP63 and MYC as biomarkers for transition of cervical intraepithelial neoplasia to cervical cancer.

OBJECTIVE: Biopsy confirmed that cervical intraepithelial neoplasia (CIN) may naturally regress or progress. Currently, the risk assessment for CIN progression to cervical cancer is still not satisfactory in clinical practice. We investigated copy number and protein expression of TP63 and MYC and explored the possibility to use them as progression biomarkers. METHODS: Copy numbers of TP63 and MYC, as well as human papilloma virus (HPV) integration status, were determined by fluorescence in situ hybridization in 39 patients with CIN and 66 patients with cervical cancer. Corresponding protein expressions were analyzed by immunohistochemistry. Receiver operating characteristic curves were used to measure the diagnostic test performance for the detection of cervical cancer from CIN. Sensitivity and specificity values of biomarkers were calculated. RESULTS: The average copy number and expression of TP63 and MYC, as well as the HPV integration rate, increased in the progression of CIN to cervical cancer. Receiver operating characteristic analysis for detection of cervical cancer resulted in area under the curve (AUC) values of TP63 copy number (AUC, 0.96; 95% confidence interval [CI], 0.91-1.00), MYC copy number (AUC, 0.92; 95% CI, 0.85-0.96), TP63 expression (AUC, 0.73; 95% CI, 0.61-0.85), and HPV-16 integration (AUC, 0.73; 95% CI, 0.60-0.85). MYC expression was not able to statistically distinguish cancer from CIN (P = 0.393). The combinations increased the specificity slightly but not sensitivity. Among them, TP63 amplification showed the best diagnostic performance. CONCLUSIONS: Amplification and overexpression of TP63 and MYC, and HPV integration rate, are associated with the transition of CIN to cervical cancer. Future studies on these biomarkers will help to assess the risk of CIN progression.