Frequency and prognostic relevance of disseminated tumor cells in bone marrow of patients with metastatic renal cell carcinoma

Diagnostic and prognostic value of circulating tumor cells in renal cell cancer: A systematic review and meta-analysis

Renal cell carcinoma (RCC) is a type of tumor with high morbidity and recurrence rates. The application of circulating tumor cells (CTCs) in RCC remains controversial. Hence, we performed a meta-analysis to elucidate the diagnostic and prognostic value of CTCs in RCC. To obtain a precise conclusion, a systematic search was conducted in Pubmed, Cochrane Database, Embase and Web of Science up to Dec 01, 2022. We also further identified the references in relevant studies. The diagnostic accuracy variables (sensitivity, specificity) and odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to access precise of CTCs and relationship between CTCs and disease stages, respectively. Heterogeneity test, sensitivity analysis, meta-regression and publishing bias were also applied. A total of 12 studies involving 767 patients were considered to be included in the final meta-analysis. The results revealed that the overall sensitivity, specificity of CTC detection in RCC were 45% (95%CI, 32-60%) and 99% (95%CI, 97-100%), respectively. In subgroup analysis, diagnostic sensitivity of CTCs in clear cell renal cell carcinoma (ccRCC) (69%, 95%CI; 50-88%) was significantly higher than other RCC subtypes (34%, 95%CI; 21-48%) (p<0.05). Meanwhile, advanced diseases (stage III-IV) were more likely to find CTCs than localized diseases (stage I-II) (OR, 2.29; 95%CI, 1.37-3.83; p = 0.002). This systematic review and meta-analysis demonstrated that CTC detection could be considered as a promising auxiliary diagnostic and staging method for RCC, especially ccRCC subtype. Meanwhile, the presence of cytokeratin-positive CTCs is highly likely associated with increased risk of poor prognosis in RCC.

Role of Nuclear Claudin-4 in Renal Cell Carcinoma

Claudin-4 (CLDN4) is a tight junction protein to maintain the cancer microenvironment. We recently reported the role of the CLDN4 not forming tight junction in the induction of epithelial-mesenchymal transition (EMT). Herein, we investigated the role of CLDN4 in renal cell carcinoma (RCC), focusing on CLDN4. CLDN4 expression in 202 RCCs was examined by immunostaining. CLDN4 phosphorylation and subcellular localization were examined using high metastatic human RCC SN12L1 and low metastatic SN12C cell lines. In 202 RCC cases, the CLDN4 expression decreased in the cell membrane and had no correlation with clinicopathological factors. However, CLDN4 was localized in the nucleus in 5 cases (2%), all of which were pT3. Contrastingly, only 6 of 198 nuclear CLDN4-negative cases were pT3. CLDN4 was found in the nuclear fraction of a highly metastatic human RCC cell line, SN12L1, but not in the low metastatic SN12C cells. In SN12L1 cells, phosphorylation of tyrosine and serine residues was observed in cytoplasmic CLDN4, but not in membranous CLDN4. In contrast, phosphorylation of serine residues was observed in nuclear CLDN4. In SN12L1 cells, CLDN4 tyrosine phosphorylation by EphA2/Ephrin A1 resulted in the release of CLDN4 from tight junction and cytoplasmic translocation. Furthermore, protein kinase C (PKC)-ε phosphorylated the CLDN4 serine residue, resulting in nuclear import. Contrarily, in SN12C cells that showed decreased expression of EphA2/Ephrin A1 and PKCε, the activation of EphA2/EphrinA1 and PKCε induced cytoplasmic and nuclear translocation of CLDN4, respectively. Furthermore, the nuclear translocation of CLDN4 promoted the nuclear translocation of Yes-associated protein (YAP) bound to CLDN4, which induced the EMT phenotype. These findings suggest that the release of CLDN4 by impaired tight junction might be a mechanism underlying the malignant properties of RCC. These findings suggest that the release of CLDN4 by impaired tight junction might be one of the mechanisms of malignant properties of RCC.

Prognostic impact of urokinase-type plasminogen activator system components in clear cell renal cell carcinoma patients without distant metastasis

Background

Members of the urokinase-type plasminogen activator (uPA) system including uPA, its receptor uPAR and the plasminogen activator inhibitor 1 (PAI-1) play an important role in tumour invasion and progression in a variety of tumour types. Since the majority of clear cell renal cell carcinoma (ccRCC) shows distant metastasis at time of diagnosis or later, the interplay of uPA, uPAR and PAI-1 might be of importance in this process determining the patients’ outcome.

Methods

Corresponding pairs of malignant and non-malignant renal tissue specimens were obtained from 112 ccRCC patients without distant metastasis who underwent tumour nephrectomy. Tissue extracts prepared from fresh-frozen tissue samples by detergent extraction were used for the determination of antigen levels of uPA, uPAR and PAI-1 by ELISA. Antigen levels were normalised to protein concentrations and expressed as ng per mg of total protein.

Results

Antigen levels of uPA, uPAR, and PAI-1 correlated with each other in the malignant tissue specimens (r_s=0.51-0.65; all P<0.001). Antigen levels of uPA system components were significantly higher in tissue extracts of non-organ confined tumours (pT3+4) compared to organ-confined tumours (pT1+2; all P<0.05). Significantly elevated levels of uPAR and PAI-1 were also observed in high grade ccRCC. When using median antigen levels as cut-off points, all three uPA system factors were significant predictors for disease-specific survival (DSS) in univariate Cox’s regression analyses. High levels of uPA and uPAR remained independent predictors for DSS with HR=2.86 (95% CI 1.07-7.67, P=0.037) and HR=4.70 (95% CI 1.51-14.6, P=0.008), respectively, in multivariate Cox’s regression analyses. A combination of high antigen levels of uPA and/or uPAR further improved the prediction of DSS in multivariate analysis (HR=14.5, 95% CI 1.88-111.1, P=0.010). Moreover, high uPA and/or uPAR levels defined a patient subgroup of high risk for tumour-related death in ccRCC patients with organ-confined disease (pT1+2) (HR=9.83, 95% CI 1.21-79.6, P=0.032).

Conclusions

High levels of uPA and uPAR in tumour tissue extracts are associated with a significantly shorter DSS of ccRCC patients without distant metastases.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-974) contains supplementary material, which is available to authorized users.

Metastasis-Initiating Cells in Renal Cancer

Metastasis is a complex process that propagates cells from the primary or initial site of the cancer occurrence to distant parts of the body. Cancer cells break from the cancer site and circulate through the bloodstream or lymph vessels, allowing them to reach nearly all parts of the body. These circulating tumour cells (CTCs) contain specialized metastasis-initiating cells (MICs) that reside in the biological heterogeneous primary tumour. Researchers have hypothesized that metastasis of renal cell carcinoma is initiated by circulation of MICs in patients’ blood and bone marrow. Based on the cancer stem/progenitor cell concept of carcinogenesis, understanding the molecular phenotypes of metastasis-initiating cells (MICs) in renal cancer could play a vital role in developing strategies for therapeutic interventions in renal cancer. Existence of MICs among CTCs in renal carcinoma has not been proven in large scale. However, some studies have reported that specialized markers are found on the surface of circulating cells from the primary tumour. In mice, MICs have been isolated from CTCs using such markers, which have then been transplanted into xenograft model to show whether they give rise to metastasis in different organs. Considering these findings, in this review we have attempted to summarize the studies connected with MICs and their gene expression profiles that are responsible for metastasis in renal cancer.

Analyses of potential predictive markers and survival data for a response to sunitinib in patients with metastatic renal cell carcinoma

BACKGROUND

Patients with metastatic clear cell renal cell carcinoma (ccRCC) are frequently treated with tyrosine kinase inhibitors (TKI) such as sunitinib. It inhibits angiogenic pathways by mainly targeting the receptors of VEGF and PDGF. In ccRCC, angiogenesis is characterized by the inactivation of the von Hippel-Lindau gene (VHL) which in turn leads to the induction of HIF1α target genes such as CA9 and VEGF. Furthermore, the angiogenic phenotype of ccRCC is also reflected by endothelial markers (CD31, CD34) or other tumor-promoting factors like Ki67 or survivin.

METHODS

Tissue microarrays from primary tumor specimens of 42 patients with metastatic ccRCC under sunitinib therapy were immunohistochemically stained for selected markers related to angiogenesis. The prognostic and predictive potential of theses markers was assessed on the basis of the objective response rate which was evaluated according to the RECIST criteria after 3, 6, 9 months and after last report (12-54 months) of sunitinib treatment. Additionally, VHL copy number and mutation analyses were performed on DNA from cryo-preserved tumor tissues of 20 ccRCC patients.

RESULTS

Immunostaining of HIF-1α, CA9, Ki67, CD31, pVEGFR1, VEGFR1 and -2, pPDGFRα and -β was significantly associated with the sunitinib response after 6 and 9 months as well as last report under therapy. Furthermore, HIF-1α, CA9, CD34, VEGFR1 and -3 and PDGRFα showed significant associations with progression-free survival (PFS) and overall survival (OS). In multivariate Cox proportional hazards regression analyses high CA9 membrane staining and a response after 9 months were independent prognostic factors for longer OS. Frequently observed copy number loss and mutation of VHL gene lead to altered expression of VHL, HIF-1α, CA9, and VEGF.

CONCLUSIONS

Immunoexpression of HIF-1α, CA9, Ki67, CD31, pVEGFR1, VEGFR1 and -2, pPDGFRα and -β in the primary tumors of metastatic ccRCC patients might support the prediction of a good response to sunitinib treatment.

Circulating and disseminated tumor cells in the management of advanced prostate cancer

Management of prostate cancer is recognized as one of the most important medical problems. Latest findings concerning the role of circulating (CTC) and disseminated tumor cells (DTC) have provided new insights into the biology of metastasis with important implications for the clinical management of prostate cancer patients. Most of the established methods of circulating/disseminated tumor cell enrichment use density-gradient centrifugation and immunomagnetic procedures. Reverse transcriptase polymerase chain reaction is another used detection technique. Novel methods, the CTC-chip and the epithelial immunospot assay already showed promising results. For localized and metastatic prostate cancer, significant correlations between spreading tumor cells and well-established indicators of disease activity have been demonstrated. Careful randomized prospective trials will be required to justify the routine use of CTCs/DTCs for therapy decision making.

Detection of circulating tumor cells in peripheral blood of patients with renal cell carcinoma correlates with prognosis

PURPOSE

The aim of this study was to evaluate the clinical relevance of the presence of disseminated tumor cells in peripheral blood (so-called circulating tumor cells) for renal cell carcinoma patients.

METHODS

Two hundred thirty-three peripheral blood samples from 154 renal cell carcinoma patients were investigated for the presence of disseminated tumor cells by autoMACS technique and immunocytochemical staining of cytokeratin. The frequency of circulating tumor cells was analyzed statistically for correlation with relevant clinical data.

RESULTS

Two kinds of tumor cells were detected: those with expression of cytokeratin 8/18 (CK+) and cells without a detectable cytokeratin expression, which we called large blue-stained cells with a tumorlike morphology. After following the CD45 autoMACS depletion protocol, we identified circulating tumor cells in 96 (41%) of 233 peripheral blood samples, which originated from 81 (53%) of 154 renal cell carcinoma patients. A significant correlation between the detection of circulating tumor cells and positive lymph node status (P < 0.001; chi(2) test) and the presence of synchronous metastases at the time of primary tumor resection (P = 0.014; chi(2) test) was found. In a multivariate Cox's regression hazard model, presence of CK+ circulating tumor cells was significantly correlated with poor overall survival for renal cell carcinoma patients (relative risk, 2.3; P = 0.048).

CONCLUSIONS

The presence of circulating tumor cells correlated to lymph node status and presence of synchronous metastases in renal cell carcinoma. It is important to evaluate CK+ and blue-stained tumor cells together to determine the role of circulating tumor cells in tumor behavior and disease progression. Detection of CK+ circulating tumor cells in peripheral blood is a significant and independent prognostic factor for renal cell carcinoma.

Prognostic relevance of disseminated tumour cells in bone marrow of patients with transitional cell carcinoma

OBJECTIVE

This prospective study is the first immunocytochemical investigation of the frequency and prognostic value of CK+ tumour cells in the bone marrow of patients with transitional cell carcinoma (TCC).

METHODS

Bone marrow aspirates from 228 TCC patients were taken preoperatively. Cytospins were made and stained by immunocytochemistry using the monoclonal antibodies CK2 and A45-B/B3. 27 patients with no evidence of any malignant disease served as control group.

RESULTS

CK+ tumour cells were detected in 28% (63/228) of the TCC patients. No CK+ cells (0/27) were detected in the control group. In multivariate analysis the detection of > or =3 CK+ cells in bone marrow was an independent prognostic factor (hazard ratio=2.7, p<0.05) in patients with T2-4 tumour classification.

CONCLUSION

Disseminated CK+ cells play a role in the biology of tumour spread of TCC, and their immunocytochemical detection can be useful in assessing the prognosis of TCC patients with an invasive tumour.