Inhibition of human endometrial cancer cell growth in vitro and in vivo by somatostatin analog RC-160

Decreased PTGDS Expression Predicting Poor Survival of Endometrial Cancer by Integrating Weighted Gene Co-Expression Network Analysis and Immunohistochemical Validation

Purpose

To identify key pathogenic genes and reveal the potential molecular mechanisms of endometrial cancer (EC) using bioinformatics analysis and immunohistochemistry validation.

Materials and Methods

Through weighted gene co-expression network analysis (WGCNA), a co-expression network was constructed based on the top 25% variant genes in the GSE50830 dataset downloaded from gene expression omnibus (GEO). GO and KEGG pathway enrichment analyses were performed using the DAVID online tool. Candidate genes were selected using the cytoHubba plug-in of Cytoscape, mRNA expression levels and prognostic values in EC were analyzed by Oncomine, GEPIA, and Kaplan–Meier Plotter database to determine hub genes. One hub gene was validated by immunohistochemical (IHC) staining of 116 paraffin-embedded endometrial tissues and TCGA-UCEC cohort. Genes co-expressed with this hub gene were identified by LinkedOmics. Finally, its correlation with immune infiltration was evaluated by TIMER.

Results

Three co-expression modules and five candidate genes in each module were obtained by WGCNA; four hub genes were identified (LGR5, SST, ZNF558, and PTGDS). The mRNA levels of LGR5 and SST were significantly upregulated in EC, whereas those of ZNF558 and PTGDS were significantly downregulated; the expression of all four genes was associated with EC prognosis. Further validation demonstrated that PTGDS was significantly downregulated in the EC group compared with the atypical hyperplasia and normal endometrial groups, and its low expression was an independent risk factor for worse prognosis of EC. Biological function analysis indicated that PTGDS might be involved in the adaptive immune response, leukocyte migration, as well as in the regulation of cell adhesion molecules and chemokine signaling. Additionally, PTGDS expression was positively correlated with immune infiltration status of B cells, CD4⁺ T cells and macrophages.

Conclusion

LGR5, SST, ZNF558, and PTGDS may participate in the development, progression, and prognosis of EC, in which PTGDS may be a novel biomarker and therapeutic target for EC.

Somatostatin and somatostatin analogues reduce PDGF-induced endometrial cell proliferation and motility

BACKGROUND

Endometriosis is characterized by ectopic implantation of endometrial cells, which show increased proliferation and migration. Somatostatin (SST) and its analogues inhibit normal and cancer cell growth and motility through the SST receptors, sst1-5. Cortistatin (CST), which displays high structural and functional homology with SST, binds all ssts, as well as MrgX2. Our objective was to investigate the gene expression of the SST/CST system and to determine the effect of SST and its analogues on platelet-derived growth factor (PDGF)-induced proliferation and motility in telomerase-immortalized human endometrial stromal cell (T HESC) line and in primary endometrial stromal cell (ESCs) isolated from human endometriotic tissues.

METHODS

Ectopic endometrial tissues were collected from women (n= 23) undergoing laparoscopic surgery for endometriosis (Stage III/IV). Gene expression was evaluated by real-time PCR, cell motility by wound healing assay, protein expression and β-actin rearrangement by immunofluorescence, cell proliferation by the Alamar blue assay and ERK1/2 and Akt phosphorylation by western blot.

RESULTS

Human endometriotic tissues, primary ESCs and T HESCs expressed SST, CST and ssts. SST, its analogues SOM230 and octreotide, as well as CST, counteracted PDGF-induced proliferation and migration in both ESCs and T HESCs. SST also inhibited vascular endothelial growth factor and metalloprotease-2 mRNA expression, and reduced basal and PDGF-induced ERK1/2 phosphorylation.

CONCLUSION

These results indicate that the SST/CST system is expressed in endometriotic tissues and cells. The inhibitory effects of SST and its analogues on PDGF-induced proliferation and motility suggest that these peptides may represent promising tools in the treatment of endometriosis.

Octreotide enhances the sensitivity of the SKOV3/DDP ovarian cancer cell line to cisplatin chemotherapy in vitro

The present study aimed to investigate the effects of octreotide (OCT) on the reversal of resistance of cisplatin-resistant cancer cells and on enhancement of the cisplatin sensitivity of cancer cells. The 3-(4,5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide method and flow cytometry were used to investigate the effect of cisplatin, OCT or the combination of these two compounds on the proliferation and apoptosis of SKOV3/DDP cells. Real-time, quantitative RT-PCR was used to detect the mRNA expression of SSTR2, MDR1, MRP2, GST-π and EGFR in SKOV3/DDP cells following OCT treatment. At the concentration of 2.5-20 μg/ml, OCT significantly reduced the IC(50) value (P<0.05) and promoted apoptosis (P<0.05) in the SKOV3/DDP cells in response to cisplatin. The synergistic effect of OCT and cisplatin on SKOV3/DDP cell proliferation was observed. SSTR2 was expressed on the SKOV3/DDP cell surface. OCT increased GST-π expression (P<0.05) and reduced MRP2 and EGFR expression (P<0.05) in a dose-dependent manner. However, it had no effect on the expression of MDR1 (P>0.05). It is suggested that OCT inhibits ovarian cancer proliferation and promotes apoptosis, via the cell surface expression of SSRT2, and reverses cisplatin resistance through the inhibition of MRP2 and EGFR expression.

Effect of GnRH analogues and octreotide treatment on apoptosis and the cell proliferation of endometrium adenocarcinoma cell lines

OBJECTIVE

The aim of this study was to compare apoptotic and antiproliferative effects of gonadotropin-releasing hormone analogues and their combination with octeotide on endometrioid endometrial cancer cell lines.

MATERIAL AND METHOD

Women diagnosed with endometrioid adenocarcinoma at the department of Gynecology and Obstetric of Kocaeli University Medical School were included in this research. Endometrium cancer cell lines obtained from three patients were used for this study. After trypsinization in 0.5% in calcium magnesium, free phosphate buffer solution (CMFPBS) cells were seeded on glass slides in 24-well plates containing DMEM-F12 medium and 10% fetal calf serum as culture medium. Cells were incubated for 24 hours at 37ºC in 5% CO2. GnRH agonist leuprolide (Lucrin 1 μmol/L), GnRH antagonist ganirelix (Orgalutran 1 μmol/L), leuprolide with octreotide (Sandostatin 10-6 mol/L), ganirelix with octreotide and no drug were added to the wells. Apoptosis and cells proliferations were evaluated after 12, 24, 48 and 72(th) hours of incubation. The percentage of apoptotic cells was evaluated by TdT mediated biotin-dUTP nick-end labeling (TUNEL) method; cell proliferation was assessed by bromodeoxyuridine (BrdU) incorporation.

RESULTS

Apoptotic index in grade I EEC cell line among ganirelixoctreotide treated cells and leuprolide-octreotide combination therapy were respectively higher than the untreated control (p<0.001, p=0.001). The number of apoptotic cells in grade II EEC cell line among leuprolide-octreotide and leuprolide were significantly (p<0.001, p<0.001) higher than in controls. In grade III EEC cell line, the number of TUNEL positive cells among leuprolide, ganirelix and ganirelixoctreotide therapiy groups were significantly higher than in untreated control. Time dependent antiproliferative effect was obtained with leuprolide and leuprolide-octreotide in grade I EEC (p<0.001, p<0.001). Grade II EEC cell line is not influenced by hormonotherapies. However, the antiproliferative effect was obtained with ganirelix, leuprolide and leuprolide-octreotide in grade III cell line.

CONCLUSION

GnRH analogues appears to have a direct effect, enhancing the apoptotic index and decreasing the cell proliferation in endometrial adenocancer cell lines.

Role of somatostatin analogs in the clinical management of non-neuroendocrine solid tumors

The somatostatin analogs octreotide, lanreotide and RC-160 (vapreotide) are known to have direct and indirect antitumor effects. Direct effects include the arrest of tumor growth and stimulation of apoptosis, resulting in tumor shrinkage. Indirect antiproliferative effects may occur through antiangiogenesis, immunomodulatory effects and the suppression of tumor-stimulating growth factors. With a safety profile of somatostatin analogs established over 20 years of clinical use in the treatment of neuroendocrine tumors, somatostatin analogs are attractive therapeutic options for patients with non-neuroendocrine tumors. In early clinical trials of somatostatin analogs, however, some cancer patients responded well, while others showed a lack of benefit. This variability in clinical response may reflect the selective binding affinities of octreotide, lanreotide and RC-160, which bind with high affinity to just two of the five different somatostatin receptor subtypes. Treatment response may therefore depend on the specific receptor subtype(s) present in the tumor, the relative proportion of receptor(s) expressed on the tumor cell surface and the absolute quantity of each receptor subtype. Greater understanding of the role of somatostatin receptors, their binding affinities and modes of action has led to increased research into the use of somatostatin analogs, particularly octreotide, in cancer treatment as monotherapies, in combination with hormonal treatments and cytotoxic therapies, and in both adjuvant and neoadjuvant settings. A review of the literature suggests that the antitumor potential of somatostatin analogs should be investigated further and additional studies might determine how these analogs can best be used to improve the treatment of patients with non-neuroendocrine tumors.

Targeted therapy with a cytotoxic somatostatin analog, AN-238, inhibits growth of human experimental endometrial carcinomas expressing multidrug resistance protein MDR-1

BACKGROUND

Chemoresistance mediated by membrane transporters such as multidrug resistance (MDR-1) glycoprotein remains a challenge in the chemotherapy treatment of advanced or recurrent endometrial carcinoma. Targeted chemotherapy might overcome this resistance. The cytotoxic somatostatin (SST) analog, AN-238, consists of a superactive derivative of doxorubicin (DOX), 2-pyrrolino-DOX (AN-201), linked to the SST analog carrier, RC-121. This conjugate binds strongly to SST receptor subtypes (sst) 2a (sst2(a)) and 5 (sst(5)) and can be targeted to tumors that express these receptors.

METHODS

The presence of sst2(a) and sst(5) was determined in 3 human endometrial carcinoma cell lines (HEC-1A, RL-95-2, and AN3CA). Nude mice bearing xenografts of these cancers were treated with AN-238 and its radical, AN-201. The antitumor effects and toxicity were compared. The authors studied the effects of AN-238 and AN-201 on the expression levels of MDR-1, multidrug resistance related protein (MRP-1), and breast carcinoma resistance protein (BCRP) by real-time polymerase chain reaction.

RESULTS

The authors demonstrated the presence of mRNA and receptor protein for sst(2a) and sst(5) on HEC-1A, RL-95-2, and AN3CA tumors. AN-238 significantly (P < 0.05) inhibited the growth of these tumors, whereas AN-201 had no effect. Blockade of SST receptors nullified the effects of AN-238. In all 3 endometrial carcinoma lines, AN-238 caused a weaker induction of MDR-1 than AN-201. No major induction of MRP-1 and BCRP occurred after treatment with AN-238 or AN-201.

CONCLUSIONS

Targeted chemotherapy with the cytotoxic SST analog, AN-238, inhibited powerfully the growth of endometrial carcinoma, which express SST receptors, regardless of their expression level of MDR-1.

Global gene expression in neuroendocrine tumors from patients with the MEN1 syndrome

Background

Multiple Endocrine Neoplasia type 1 (MEN1, OMIM 131100) is an autosomal dominant disorder characterized by endocrine tumors of the parathyroids, pancreatic islets and pituitary. The disease is caused by the functional loss of the tumor suppressor protein menin, coded by the MEN1 gene. The protein sequence has no significant homology to known consensus motifs. In vitro studies have shown menin binding to JunD, Pem, Smad3, NF-kappaB, nm23H1, and RPA2 proteins. However, none of these binding studies have led to a convincing theory of how loss-of-menin leads to neoplasia.

Results

Global gene expression studies on eight neuroendocrine tumors from MEN1 patients and 4 normal islet controls was performed utilizing Affymetrix U95Av2 chips. Overall hierarchical clustering placed all tumors in one group separate from the group of normal islets. Within the group of tumors, those of the same type were mostly clustered together. The clustering analysis also revealed 19 apoptosis-related genes that were under-expressed in the group of tumors. There were 193 genes that were increased/decreased by at least 2-fold in the tumors relative to the normal islets and that had a t-test significance value of p < = 0.005. Forty-five of these genes were increased and 148 were decreased in the tumors relative to the controls. One hundred and four of the genes could be classified as being involved in cell growth, cell death, or signal transduction. The results from 11 genes were selected for validation by quantitative RT-PCR. The average correlation coefficient was 0.655 (range 0.235–0.964).

Conclusion

This is the first analysis of global gene expression in MEN1-associated neuroendocrine tumors. Many genes were identified which were differentially expressed in neuroendocrine tumors arising in patients with the MEN1 syndrome, as compared with normal human islet cells. The expression of a group of apoptosis-related genes was significantly suppressed, suggesting that these genes may play crucial roles in tumorigenesis in this syndrome. We identified a number of genes which are attractive candidates for further investigation into the mechanisms by which menin loss causes tumors in pancreatic islets. Of particular interest are: FGF9 which may stimulate the growth of prostate cancer, brain cancer and endometrium; and IER3 (IEX-1), PHLDA2 (TSS3), IAPP (amylin), and SST, all of which may play roles in apoptosis.

Frequent expression of immunoreactive somatostatin receptors in cervical and endometrial cancer

OBJECTIVE

A variety of human cancers has been shown to express somatostatin receptors which can be utilized for in vivo tumor targeting. Although the somatostatin receptor status of mammary and ovarian cancer has been studied in detail, somatostatin receptors have not been examined in other gynecological malignancies such as cervical or endometrial carcinoma.

METHODS

We have previously developed a panel of somatostatin receptor subtype-specific antibodies that effectively stain formalin-fixed, paraffin-embedded human tumor tissue. In the present study, we have used these antibodies to determine the somatostatin receptor status of 21 randomly selected cervical carcinomas and 28 randomly selected endometrial carcinomas.

RESULTS

In cervical carcinoma, the incidence of somatostatin receptor expression was sst2A (12/21, approximately 57%) > sst3 (9/21, approximately 43%) > sst1 (8/21, approximately 38%) > sst4 (0/21, 0%) = sst5 (0/21, 0%). In endometrial carcinoma, the incidence of somatostatin receptor expression was sst3 (12/28, approximately 43%) > sst2A (11/28, approximately 39%) > sst1 (9/28, approximately 32%) > sst4 (1/28, approximately 4%) = sst5 (1/28, approximately 4%). Somatostatin receptor-like immunoreactivity was in most cases located at the plasma membrane and completely blocked with antigenic peptide. The expression of somatostatin receptor subtypes was independent of patient age, diagnosis, tumor stage, and histological grade.

CONCLUSION

Our findings reveal a previously unappreciated high incidence of sst1, sst2A, and sst3 somatostatin receptors in human cervical and endometrial cancers and suggest that a subgroup of receptor-positive uterine carcinomas may be a potential target for diagnostic and therapeutic intervention with stable somatostatin analogs.