Expression of SPARC like protein 1 (SPARCL1), extracellular matrix-associated protein is down regulated in gastric adenocarcinoma

The homeoprotein HOXB2 limits triple-negative breast carcinogenesis via extracellular matrix remodeling

Homeobox genes and their encoded DNA-binding homeoproteins are master regulators of development. Consequently, these homeotic elements may regulate key steps in cancer pathogenesis. Here, using a combination of in silico analyses of large-scale patient datasets, in vitro RNAi phenotyping, and in vivo validation studies, we investigated the role of HOXB2 in different molecular subtypes of human breast cancer (BC). The gene expression signatures of HOXB2 are different across distinct BC subtypes due to various genetic alterations, but HOXB2 was specifically downregulated in the aggressive triple-negative subtype (TNBC). We found that the reduced expression of HOXB2 was correlated with the metastatic abilities (epithelial-to-mesenchymal transition) of TNBC cells. Further, we revealed that HOXB2 restrained TNBC aggressiveness by ECM organization. HOXB2 bound to the promoter regions of MATN3 and ECM2 and regulated their transcription levels. Forced expression of HOXB2 effectively prevented TNBC progression and metastasis in a mouse xenograft model. Reduction of HOXB2 and the HOXB2/MATN3/ECM2 transcriptional axis correlated with poor survival in patients with various cancers. Further, we found the long non-coding RNA HOXB-AS1 in complex with SMYD3, a lysine methyltransferase, as an epigenetic switch controlling HOXB2 expression. Overall, our results indicate a tumor-suppressive role of HOXB2 by maintaining ECM organization and delineate potential clinical utility of HOXB2 as a marker for TNBC patients.

Species-, organ- and cell-type-dependent expression of SPARCL1 in human and mouse tissues

SPARCL1 is a matricellular protein with anti-adhesive, anti-proliferative and anti-tumorigenic functions and is frequently downregulated in tumors such as colorectal carcinoma or non-small cell lung cancer. Studies have identified SPARCL1 as an angiocrine tumor suppressor secreted by tumor vessel endothelial cells, thereby exerting inhibitory activity on angiogenesis and tumor growth, in colorectal carcinoma. It is unknown whether SPARCL1 may exert these homeostatic functions in all organs and in other species. Therefore, SPARCL1 expression was comparatively analysed between humans and mice in a systematic manner. Murine Sparcl1 (mSparcl1) is most strongly expressed in the lung; expressed at an intermediate level in most organs, including the large intestine; and absent in the liver. In human tissues, SPARCL1 (hSPARCL1) was detected in all organs, with the strongest expression in the stomach, large intestine and lung, mostly consistent with the murine expression pattern. A striking difference between human and murine tissues was the absence of mSparcl1 expression in murine livers, while human livers showed moderate expression. Furthermore, mSparcl1 was predominantly associated with mural cells, whereas hSPARCL1 was detected in both mural and endothelial cells. Human SPARCL1 expression was downregulated in different carcinomas, including lung and colon cancers. In conclusion, this study revealed species-, organ- and cell-type-dependent expression of SPARCL1, suggesting that its function may not be similar between humans and mice.

5-Year Survival in Gastric Adenocarcinoma with Epithelial and Stromal Versican Expression

Background & Objective

Gastric cancer is the second most frequent cause of cancer death worldwide, despite dif- ferences in incidence around the world. The majority of gastric cancer cases concern gastric adenocarcinoma, which has a fairly high 5-year survival rate when coupled with early-stage diagnosis. Versican, a member of the aggregating chondroitin sulfate proteoglycans family, is accumulated predominantly in the tumor stroma. The aim of our study was to investigate versican expression in gastric adenocarcinoma.

Methods

In this study we investigated 80 patients with gastric adenocarcinoma who underwent gastrectomy. Each sample was obtained from paraffin-embedded resected specimens of the stomach after histopathological diagnosis. Patient follow-up was performed every 3 months after the beginning of data collection. Survival analysis was calcu- lated using the Kaplan-Meier method for univariate analysis.

Results

Out of 80 patients with gastric adenocarcinoma, 76 cases (76.3%males and 23.7% females) completed the follow-up period. Positive versican expression in tumor epithelial and stromal cells was found in 39.5% and 22.4% of tumors, respectively. Shorter survival was observed among patients whose gastric adenocarcinoma expressed epithelial or stromal versican.

Conclusion

In summary, the present study suggests that versican is likely a prognostic biomarker that predicts a poor outcome in patients with gastric adenocarcinoma. Comprehensive studies with larger sample sizes are needed.

SPARCL1 suppresses the proliferation and migration of human ovarian cancer cells via the MEK/ERK signaling

Ovarian cancer is the most lethal gynecological malignancy worldwide and is one of the five leading causes of cancer-associated mortality in women. There is an urgent requirement to obtain a greater understanding of the molecular mechanism underlying ovarian cancer progression in order to identify novel drug targets and biomarkers. Secreted protein acidic and rich in cysteine-like protein 1 (SPARCL1) has been suggested as a candidate tumor suppressor in various types of human cancers. However, the potential role of SPARCL1 for ovarian cancer has not yet been clearly established. In the present study, lower protein expression levels of SPARCL1 were detected in ovarian cancer tissues when compared with adjacent normal tissues. Overexpression of SPARCL1 significantly suppressed the proliferation and migration of cells from the ovarian cancer cell line SKOV-3, whereas knockdown of SPARCL1 significantly increased cell growth and migration. Furthermore, the results revealed that SPARCL1 overexpression significantly suppressed the activation of the mitogen-activated protein kinase kinase (MEK)/extracellular signal-related kinase (ERK) signaling pathway. Collectively, these results indicated that SPARCL1 may suppress the proliferation and migration of ovarian cancer cells by downregulating signaling via the MEK/ERK pathway.

Prognostic value of SPARCL1 in patients with colorectal cancer

Secreted protein acidic and rich in cysteine-like 1 (SPARCL1), a member of extracelluar matrix glycoprotein, has been reported to be associated with various tumor types. The present study aimed to evaluate the prognostic value of SPARCL1 in patients with colorectal cancer. Tissue microarray blocks were constructed based on 79 patients who underwent radical surgery at the Kunshan First People's Hospital between 2008 and 2010. Thirty pairs of fresh-frozen tissues were also obtained for total protein extraction. The expression of SPARCL1 protein was analyzed using immunohistochemistry and western blotting analyses, and the association between overexpressed SPARCL1 and clinicopathological factors was evaluated. Survival analysis with Kaplan Meier curves and Cox regression analysis was used to analyze the prognostic value of SPARCL1. According to western blot analyses, SPARCL1 protein expression in colorectal tumors was significantly lower compared with corresponding normal tissues. The expression of SPARCL1 was markedly decreased from differentiation I to III, and the negative rate of SPARCL1 was higher at Duke's stage C compared with B. Though without any difference between ‘positive’ and ‘negative’ in overall survival, significantly higher survival in patients with positive SPARCL1 expression at Duke's stage B was detected in the present study. These results indicated that SPARCL1 may be a potential tumor suppressor gene and associated with good prognosis.

Associations of tumor suppressor SPARCL1 with cancer progression and prognosis

SPARC-like protein 1 (SPARCL1), a member of the family of secreted proteins which is acidic and rich in cysteine, is a potential tumor suppressor gene in most types of tumor. A systemic review and bioinformatics analysis was carried out to determine the associations between SPARCL1 and tumor progression and clinical factors. Downregulation of SPARCL1, thought to be regulated by epigenetic modifications including DNA methylation, serves important functions in tumor progression and development, with its regulatory functions on cell viability, migration, invasion, cell adhesion and drug resistance. Downregulation of SPARCL1 was markedly associated with a poor overall survival rate of patients with one of ≥7 solid tumors and predicted increased mortality in patients with one of ≥4 distinct tumor types. The present review indicated that SPARCL1 may be a therapeutic target for cancer treatment and a biomarker to determine prognosis.