Folate-Receptor Positive Circulating Tumor Cell Is a Potential Diagnostic Marker of Prostate Cancer

Therapeutic and Diagnostic Potential of Folic Acid Receptors and Glycosylphosphatidylinositol (GPI) Transamidase in Prostate Cancer

Due to the proliferation-induced high demand of cancer cells for folic acid (FA), significant overexpression of folate receptors 1 (FR1) is detected in most cancers. To our knowledge, a detailed characterization of FR1 expression and regulation regarding therapeutic and diagnostic feasibilities in prostate cancer (PCa) has not been described. In the present study, cell cultures, as well as tissue sections, were analyzed using Western blot, qRT-PCR and immunofluorescence. In addition, we utilized FA-functionalized lipoplexes to characterize the potential of FR1-targeted delivery into PCa cells. Interestingly, we detected a high level of FR1-mRNA in healthy prostate epithelial cells and healthy prostate tissue. However, we were able to show that PCa cells in vitro and PCa tissue showed a massively enhanced FR1 membrane localization where the receptor can finally gain its function. We were able to link these changes to the overexpression of GPI-transamidase (GPI-T) by image analysis. PCa cells in vitro and PCa tissue show the strongest overexpression of GPI-T and thereby induce FR1 membrane localization. Finally, we utilized FA-functionalized lipoplexes to selectively transfer pDNA into PCa cells and demonstrate the therapeutic potential of FR1. Thus, FR1 represents a very promising candidate for targeted therapeutic transfer pathways in PCa and in combination with GPI-T, may provide predictive imaging in addition to established diagnostics.

Ultrasound-mediated drug-free theranostics for treatment of prostate cancer

Lipid-shelled nanobubbles (NBs) can be visualized and activated using noninvasive ultrasound (US) stimulation, leading to significant bioeffects. Prior work demonstrates that active targeting of NBs to prostate-specific membrane antigen (PSMA) overexpressed in prostate cancer (PCa) results in enhanced cellular internalization and prolongs NB retention with persistent, cancer-cell specific acoustic activity. In this work, we hypothesized that tumor-accumulated PSMA-NBs combined with low frequency unfocused therapeutic US (TUS) will lead to selective damage and induce a specific therapeutic effect in PSMA-expressing tumors compared to PSMA-negative tumors. We observed that the internalized NBs and cellular compartments were disrupted after the PSMA-NB + TUS (targeted NB therapy or TNT) application, yet treated cells remained intact and viable. In vivo, PSMA-expressing tumors in mice receiving TNT treatment demonstrated a significantly greater extent of apoptosis (78.4 ± 9.3 %, p < 0.01) compared to controls. TNT treatment significantly inhibited the PSMA expressing tumor growth and increased median survival time by 103 %, p < 0.001). A significant reduction in tumor progression compared to untreated control was also seen in an orthotopic rabbit PCa model. Results demonstrate that cavitation of PSMA-NBs internalized via receptor-mediated endocytosis into target PCa cells using unfocused ultrasound results in significant, tumor-specific bioeffects. The effects, while not lethal to PSMA-expressing cancer cells in vitro, result in significant in vivo reduction in tumor progression in two models of PCa. While the mechanism of action of these effects is yet unclear, it is likely related to a locally-induced immune response, opening the door to future investigations in this area.

Diagnostic value of circulating tumor cells in patients with thyroid cancer: a retrospective study of 1478 patients

BACKGROUND

Circulating tumor cell (CTC) detection is one form of liquid biopsy. It is a novel technique that is beginning to be applied in the field of thyroid cancer. The present study was designed to evaluate the diagnostic value of CTCs in patients with thyroid cancer.

METHODS

A total of 1478 patients were retrospectively analyzed and divided into malignant group (n = 747) and benign group (n = 731). Peripheral blood was collected, and CTCs were enriched and quantified before surgery. The baseline data of the two groups were matched by Propensity Score Matching (PSM). Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic efficiency of different indicators for thyroid cancer. The malignant group before PSM was further divided into subgroups according to the BRAF V600E mutation and lymphatic metastasis (N stage), and the number of CTCs in different subgroups was compared.

RESULTS

After 1:1 PSM, baseline characteristics of the malignant group and benign group were matched and assigned 315 cases in each group. The number of CTCs and the TPOAb values were comparable in the two groups (p > 0.05). The TgAb values [1.890 (1.110 - 16.010) vs 1.645 (1.030 - 7.073) IU/mL, p = 0.049] were significantly higher in the malignant group than in the benign group. After PSM, ROC analyses showed that the areas under the curve (AUCs) of CTC, TgAb and ultrasound were 0.537 (sensitivity 65.6%, specificity 45.8%), 0.546 (sensitivity 40.0%, specificity 70.8%) and 0.705 (sensitivity 77.1%, specificity 63.2%), respectively. The AUCs of the combined detection of 'CTC + ultrasound' (combine 1) and the combined detection of 'CTC + TgAb + ultrasound' (combine 2) were 0.718 (sensitivity 79.3%, specificity 61.7%) and 0.724 (sensitivity 78.0%, specificity 63.3%), respectively. The AUC of ultrasound was significantly higher than CTC (p < 0.001). There was no statistically significant difference in AUC between combination 1 and ultrasound, and between combination 2 and ultrasound (p > 0.05). The number of CTCs between the N0 and N1 subgroups, and between the BRAF mutant and BRAF wild subgroups was comparable (p > 0.05).

CONCLUSIONS

As an emerging and noninvasive testing tool, the efficacy of CTCs in diagnosing thyroid cancer is limited.

Sensitivity and specificity of folate receptor α-positive circulating tumour cells in gastric cancer

PURPOSE

We aimed to investigate whether folate receptor α (FRα)-positive circulating tumour cells (CTCs) could be used as a noninvasive liquid biopsy approach in gastric cancer (GC).

METHODS

Tissue microarray and bioinformatic analyses were used to evaluate FRα expression in GC. Patients with FRα-positive CTC examinations at our institute between July 2021 and May 2022 were retrospectively evaluated. Receiver operating characteristic curves were used to evaluate the diagnostic performance of FRα-positive CTCs in GC.

RESULTS

FRα was highly expressed and associated with poor prognosis in GC based on public database. Data for 163 patients (20 with benign disease and 143 with GC) were retrospectively collected. FRα-positive CTC levels were significantly higher in the GC group than in the benign disease group (12.15 ± 1.47 FU/3 ml vs. 10.47 ± 1.63 FU/3 ml, P < 0.01). FRα-positive CTC levels were also elevated in GC patients with vessel/neuron invasion or extra-nodal tumour deposits (12.31 ± 1.47 FU/3 ml vs. 11.77 ± 1.38 FU/3 ml, P = 0.037). Areas under the curve of FRα-positive CTC levels for GC and early GC were 0.774 (P < 0.001) and 0.736 (P = 0.005). With a cut-off value of 10.95 FU/3 ml, the Youden indexes for GC and early GC were 0.502 (sensitivity = 85.2% and specificity = 65.0%) and 0.450 (sensitivity = 80.0% and specificity = 65.0%), respectively.

CONCLUSION

FRα-positive CTC detection by noninvasive liquid biopsy is a useful and effective approach for screening of patients with GC.

KEY MESSAGES

Ultrasound-mediated drug-free theranostics for treatment of prostate cancer

Rationale

Lipid-shelled nanobubbles (NBs) can be visualized and activated using noninvasive ultrasound (US) stimulation, leading to significant bioeffects. We have previously shown that active targeting of NBs to prostate-specific membrane antigen (PSMA) overexpressed in prostate cancer (PCa) enhances the cellular internalization and prolongs retention of NBs with persistent acoustic activity (~hrs.). In this work, we hypothesized that tumor-accumulated PSMA-NBs combined with low frequency therapeutic US (TUS) will lead to selective damage and induce a therapeutic effect in PSMA-expressing tumors compared to PSMA-negative tumors.

Methods

PSMA-targeted NBs were formulated by following our previously established protocol. Cellular internalization of fluorescent PSMA-NBs was evaluated by confocal imaging using late endosome/lysosome staining pre- and post-TUS application. Two animal models were used to assess the technique. Mice with dual tumors (PSMA expressing and PSMA negative) received PSMA-NB injection via the tail vein followed by TUS 1 hr. post injection (termed, targeted NB therapy or TNT). Twenty-four hours after treatment mice were euthanized and tumor cell apoptosis evaluated via TUNEL staining. Mice with single tumors (either PSMA + or -) were used for survival studies. Tumor size was measured for 80 days after four consecutive TNT treatments (every 3 days). To test the approach in a larger model, immunosuppressed rabbits with orthotopic human PSMA expressing tumors received PSMA-NB injection via the tail vein followed by TUS 30 min after injection. Tumor progression was assessed via US imaging and at the end point apoptosis was measured via TUNEL staining.

Results

In vitro TNT studies using confocal microscopy showed that the internalized NBs and cellular compartments were disrupted after the TUS application, yet treated cells remained intact and viable. In vivo, PSMA-expressing tumors in mice receiving TNT treatment demonstrated a significantly greater extent of apoptosis (78.45 ± 9.3%, p < 0.01) compared to the other groups. TNT treatment significantly inhibited the PSMA (+) tumor growth and overall survival significantly improved (median survival time increase by 103%, p < 0.001). A significant reduction in tumor progression compared to untreated control was also seen in the rabbit model in intraprostatic (90%) and in extraprostatic lesions (94%) (p = 0.069 and 0.003, respectively).

Conclusion

We demonstrate for the first time the effect of PSMA-targeted nanobubble intracellular cavitation on cancer cell viability and tumor progression in two animal models. Data demonstrate that the targeted nanobubble therapy (TNT) approach relies primarily on mechanical disruption of intracellular vesicles and the resulting bioeffects appear to be more specific to target cancer cells expressing the PSMA receptor. The effect, while not lethal in vitro, resulted in significant tumor apoptosis in vivo in both a mouse and a rabbit model of PCa. While the mechanism of action of these effects is yet unclear, it is likely related to a locally-induced immune response, opening the door to future investigations in this area.

A Systematic Review of Circulating Tumor Cells Clinical Application in Prostate Cancer Diagnosis

Simple Summary

Cell-dependent and cell-independent information drawn from the blood stream were merged into the attractive term “liquid biopsy” and tentatively applied to most segments of cancer management: detection, risk-stratification, personalization of care and follow-up. However, the robust science behind liquid biopsies has not been widely used, thereby remaining a latent and possibly undervalued instrument. Here, we conducted a systematic review of CTCs in prostate cancer management to summarize their use in clinical practice.

Abstract

The purpose of the review is to summarize the recent data on circulating tumor cells (CTC) use in clinical practice. We performed a systematic literature search using two databases (Medline and Scopus) over the past five years and the following terms: (CTC OR “circulating tumor cells” OR “liquid biopsy”) AND prostate. The primary outcome was CTC predictive value for prostate cancer (PC) progression and survival. The secondary outcomes were the CTC predictive value for therapy response and the results of CTC detection depending on the assessment method. In metastatic PC, the CTC count showed itself to be a prognostic marker in terms of clinically important features, namely survival rates and response to treatment. CTC concentration was significantly associated with the overall survival and progression-free survival rates. A strong association between the overall survival or progression-free survival rate and CTC concentration could be observed. Variant-7 androgen receptors-positive (AR-V7-positive) patients showed a poor response to androgen receptor signaling (ARS) inhibitors, but this did not compromise their response to taxanes. In localized PC, only positive Cluster of Differentiantion 82 protein (CD82+) correlated with a higher survival rate. CTC count and AR-V7 expression showed itself to be a valuable biomarker for survival in metastatic PC and response to ARS-inhibitors. CTC diagnostic performance for localized PC or for screening and early detection is not high enough to show additional value over the other biomarkers.