Quantitative reverse transcriptase polymerase chain reaction analysis for KiSS-1 and orphan G-protein-coupled receptor (hOT7T175) gene expression in hepatocellular carcinoma

Differential expression of G-protein coupled receptor 56 in human esophageal squamous cell carcinoma

Herein, we describe the identification of GPCR56, an orphan G-protein coupled receptor, to be differentially expressed in esophageal squamous cell carcinoma. Although, GPCRs have been demonstrated to be altered in various human cancers, much is still unknown about GPCR56 expression in tumors. To evaluate the expression of these genes in esophageal tissues, we performed semi-quantitative Reverse-Transcription Polymerase Chain Reaction in ESCCs, dysplasia and matched normal esophageal epithelium. Increased transcript levels of GPCR56 were detected in 48% of ESCCs, while the adjacent non-malignant esophageal tissue did not show the expression of this transcript. Interestingly, most of the dysplastic tissues analyzed also exhibited increased expression of GPCR56 suggesting that alteration in GPCR56 expression is an early event in esophageal tumorigenesis. In depth analysis of GPCR56 in different stages of development and progression of esophageal tumorigenesis is warranted to explore its utility as potential early diagnostic marker and its function in esophageal cancer.

Metastasis suppressor gene Raf kinase inhibitor protein (RKIP) is a novel prognostic marker in prostate cancer

BACKGROUND

Diminished expression of Raf kinase inhibitor protein (RKIP), an inhibitor of the Raf signaling cascade, promotes prostate cancer (PCa) metastasis in a murine model, suggesting that it is a metastasis suppressor gene. However, the prognostic significance of RKIP expression and its association with metastasis in PCa patients is unknown.

METHODS

To investigate RKIP protein expression is a prognostic marker in PCa we performed immunohistochemical staining for RKIP expression in tissue microarrays consisting of 758 non-neoplastic prostate tissues, primary tumors and metastases from 134 PCa patients. The Cox proportional-hazards model was used to adjust for covariates including Gleason score, tumor volume, tumor weight, clinical stage, digital rectal exam findings, serum PSA level and surgical margins.

RESULTS

RKIP expression was low in approximately 5%, 48%, and 89% of non-neoplastic prostate, primary tumors and metastases, respectively. Low RKIP expression in primary tumors was a strong positive predictive factor for PCa recurrence based on PSA levels. In patients whose primary tumors expressed high RKIP levels, the 7-year PSA recurrence rate was <10%; whereas in patients with tumors with low RKIP expression the recurrence rate was 50% (P<0.001). Multivariate analysis revealed RKIP was an independent prognostic factor (P<0.001).

CONCLUSION

In contrast to increased expression of pro-tumorigenic genes, these results demonstrate decreased protein expression of a gene, for example, RKIP, can serve as a prognostic marker in PCa patients.

KiSS1 suppresses metastasis in human ovarian cancer via inhibition of protein kinase C alpha

Metastasis is a vital target for cancer treatment, since the majority of cancer patients die from metastatic, rather than the primary disease. KiSS1 has been identified as a metastasis suppressor gene in melanoma and breast carcinomas. We show here that KiSS1 is also a metastasis suppressor in human ovarian cancer. Overexpression of KiSS1 in ovarian cancer cells inhibits cell migration induced by serum or lysophosphatidic acid (LPA), and colonization in soft agar, but not cell proliferation, representing the characteristics of a metastasis suppressor gene. Furthermore, using an experimental metastatic mouse model, we show that expression of KiSS1 in SKOV3 ovarian cancer cells suppresses >50% metastatic colonization in mice (P < 0.0001). We find that activating protein kinase C (PKC) reverses about 80% of the inhibited cell migration induced by KiSS1, while down-regulation of PKCalpha with shRNA restores KiSS1 effect, providing evidence that inhibiting PKCalpha may be an important mechanism of the effect of KiSS1. These results suggest that KiSS1 is a metastasis suppressor of ovarian cancer and may be a potential molecular target for the treatment.

The KISS1 metastasis suppressor: mechanistic insights and clinical utility

Melanoma is a highly metastatic cancer that accounts for the majority of skin cancer deaths. Unfortunately, very few improvements have been made during the last 20 years in the management of melanoma metastases, which is the major cause of melanoma deaths. Therefore, identification of molecular targets that can be exploited in the clinic to treat metastatic disease is desperately needed. The KISS1 metastasis suppressor gene has emerged as a promising molecular target for the management of metastatic disease. This review compiles data regarding the molecular and biochemical properties of KISS1 and its cognate receptor, focusing on the properties believed to be most pertinent to the use of KISS1 in the clinical setting. In addition, clinical data that supports KISS1 as having a dual role as a prognostic indicator and a therapeutic target for the management of metastatic disease will be highlighted.

KiSS-1 Expression in Human Breast Cancer

The KiSS-1 gene encodes a 145 amino acid residue peptide that is further processed to a final peptide, metastin, a ligand to a G-coupled orphan receptor (OT7T175/AXOR12). KiSS-1 has been identified as a putative human metastasis suppressor gene in melanomas and in breast cancer cell lines. This study aimed to determine the expression and distribution of KiSS-1 and its receptor in human breast cancer tissues and to identify a possible link between expression levels and patient prognosis. Frozen sections from breast cancer primary tumours (matched tumour 124 and background 33) were immuno-stained with KiSS-1 antibody. RNA was reverse transcribed and analyzed by Q-PCR (standardized using beta-actin, and normalized with cytokeratin-19 levels). Levels of expression of KiSS-1 were higher in tumour compared to background tissues (3,124+/-1,262 vs 2,397+/-1,181) and significantly increased in node positive tumours compared to node negative (3,637+/-1,719 vs 2,653+/-1,994, P = 0.02). KiSS-1 expression was also increased with increasing grade and TNM status. There were no such trends with the KiSS-1 receptor. Expression of KiSS-1 was higher in patients who had died from breast cancer than those who had remained healthy (4,631+/-3,024 vs 2,280+/-1,403) whereas expression of the receptor was reduced (480+/-162 vs 195+/-134). Immunohistochemical staining showed increased expression of KiSS-1 in tumour sections. Insertion of the KiSS-1 gene into the human breast cancer cell line MDA-MB-231, resulted in cells that were significantly more motile and invasive in behaviour, with reduced adhesion to matrix, using respective assays. In conclusion, KiSS-1 expression is increased in human breast cancer, particularly in patients with aggressive tumours and with mortality. Over-expression of KiSS-1 in breast cancer cells result in more aggressive phenotype. Together, it suggests that KiSS-1 plays a role beyond the initial metastasis repressor in this cancer type.