Long non-coding RNA RP11-468E2.5 curtails colorectal cancer cell proliferation and stimulates apoptosis via the JAK/STAT signaling pathway by targeting STAT5 and STAT6.

BACKGROUND: Long non-coding RNAs (lncRNAs) are tumor-associated biological molecules and have been found to be implicated in the progression of colorectal cancer (CRC). This study aims to examine the effects of lncRNA RP11-468E2.5 and its target genes (STAT5 and STAT6) on the biological activities of CRC cells via the Janus kinase-signal transducer and activator of transcription (JAK/STAT) signaling pathway. METHODS: We initially screened the GEO database for differentially expressed lncRNAs related to CRC and then made a prediction of the implicated target genes. Then we collected CRC tissues and adjacent normal tissues from 169 CRC patients. Human CRC HCT116 and SW480 cells were treated with small interference RNA (siRNA) against RP11-468E2.5, AG490 (an inhibitor of the JAK/STAT signaling pathway), or both in combination. Next, we measured the effects of RP11-468E2.5 treatment on cellular activities such as cell viability, cycle distribution and cell apoptosis, and studied interactions among RP11-468E2.5, STAT5/STAT6, and the JAK/STAT signaling pathway. Finally, an in vivo tumor formation assay was performed to observe the effect of RP11-468E2.5 on tumor growth. RESULTS: The CRC-related gene microarray data showed low expression of RP11-468E2.5 in CRC surgical specimens. However, RP11-468E2.5 was confirmed to target STAT5 and STAT6, which participate in the JAK/STAT signaling pathway. CRC tissues showed lower expression of RP11-468E2.5, higher expression of STAT5, STAT6 and of the cell cycle marker Cyclin D1 (CCND1), compared to the findings in adjacent normal tissues. The treatment of siRNA against RP11-468E2.5 increased expression of JAK2, STAT3, STAT5, STAT6, CCND1 and Bcl-2 along with the extent of STAT3, STAT5 and STAT6 phosphorylation, while lowering expression of P21 and P27. Treatment with AG490 exhibited approximately opposite effects, whereas siRNA against RP11-468E2.5 treatment stimulated CRC cell proliferation and reduced cell apoptosis, while promoting cell cycle entry; AG490 treatment reversed these results. CONCLUSIONS: Altogether, we conclude that up-regulation of RP11-468E2.5 inhibits the JAK/STAT signaling pathway by targeting STAT5 and STAT6, thereby suppressing cell proliferation and promoting cell apoptosis in CRC.

Abnormal expression of p190RhoGAP in colorectal cancer patients with poor survival.

PURPOSE: This study aims to investigate the expression and clinical significance of p190RhoGAP, a member of the RhoGAP family, in colorectal cancer (CRC). METHODS: The expression p190RhoGAP was detected by RT-PCR, western blot (WB) and immunohistochemistry (IHC) in 14 paired CRCs and matched non-cancerous mucosal tissues. The protein content of p190RhoGAP was identified in 114 CRCs by IHC. In addition, the association of the expression of p190RhoGAP with carcinogenesis, distant metastasis and prognosis was further evaluated. RESULTS: In 14 paired fresh tissues, the mRNA (P<0.0001) and protein (P = 0.003) expression levels of p190RhoGAP were significantly higher in primary CRCs than in paired non-cancerous mucosal tissues; and was consistent with WB results. The expression of p190RhoGAP increased from normal mucosa to adenoma, and became even greater in primary carcinoma (P = 0.001). The expression level of p190RhoGAP was highest in liver metastasis compared to primary carcinoma (P = 0.028). The incidence of p190RhoGAP expression-positive cases was 58.77% in 114 CRC tissues. Furthermore, the enhanced expression of p190RhoGAP was significantly associated with shorter disease-specific survival (P<0.001) and shorter disease-free survival (P<0.001). Cox regression analysis indicated that p190RhoGAP was an independent prognostic parameter for CRC. CONCLUSION: p190RhoGAP may be an independent predictive factor for the prognosis of CRC, and the abnormal expression of p190RhoGAP may play a crucial role in colorectal carcinogenesis and distant metastasis.

[Study on retrograde metastasis rule of middle-low rectal cancer].

OBJECTIVE: To investigate the resection range of mesorectum and rectum below the inferior margin of tumor for the total mesorectum excision (TME) in middle-low rectal cancer. METHODS: Sixty patients were enrolled in the study. After TME operation, serial 5 mm interval sections were made in specimens of middle-low rectal cancer. The retrograde metastasis of rectal cancer was observed by routine HE staining. RESULTS: The phenomena of retrograde metastasis in mesorectum were found in 15 cases, and the distance of retrograde metastasis was 0.5-4.0(2.47+/-1.06) cm, which was correlated with Dukes stage, lymph node metastasis and histological differentiation. The retrograde metastases in bowel were found in 11 cases, and the distance of retrograde metastasis was 0.5-4.0 (1.64+/-1.16) cm, which was correlated with histological differentiation. CONCLUSIONS: The distal mesorectum should be resected at least 4 cm when TME is carried out, and the distal bowel at least 2.5 cm. More than 5 cm mesorectum and bowel should be resected when advanced Dukes stage, extensive lymph node metastasis and poor histological differentiation occurred.