Cathepsin B protein levels in endometrial cancer: Potential value as a tumour biomarker

Cysteine cathepsins: From diagnosis to targeted therapy of cancer

Cysteine cathepsins are a fascinating group of proteolytic enzymes that play diverse and crucial roles in numerous biological processes, both in health and disease. Understanding these proteases is essential for uncovering novel insights into the underlying mechanisms of a wide range of disorders, such as cancer. Cysteine cathepsins influence cancer biology by participating in processes such as extracellular matrix degradation, angiogenesis, immune evasion, and apoptosis. In this comprehensive review, we explore foundational research that illuminates the diverse and intricate roles of cysteine cathepsins as diagnostic markers and therapeutic targets for cancer. This review aims to provide valuable insights into the clinical relevance of cysteine cathepsins and explore their capacity to advance personalised and targeted medical interventions in oncology.

The Role of Cysteine Protease Cathepsins B, H, C, and X/Z in Neurodegenerative Diseases and Cancer

Papain-like cysteine proteases are composed of 11 human cysteine cathepsins, originally located in the lysosomes. They exhibit broad specificity and act as endopeptidases and/or exopeptidases. Among them, only cathepsins B, H, C, and X/Z exhibit exopeptidase activity. Recently, cysteine cathepsins have been found to be present outside the lysosomes and often participate in various pathological processes. Hence, they have been considered key signalling molecules. Their potentially hazardous proteolytic activities are tightly regulated. This review aims to discuss recent advances in understanding the structural aspects of these four cathepsins, mechanisms of their zymogen activation, regulation of their activities, and functional aspects of these enzymes in neurodegeneration and cancer. Neurodegenerative effects have been evaluated, particularly in Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, multiple sclerosis, and neuropsychiatric disorders. Cysteine cathepsins also participate in tumour progression and metastasis through the overexpression and secretion of proteases, which trigger extracellular matrix degradation. To our knowledge, this is the first review to provide an in-depth analysis regarding the roles of cysteine cathepsins B, H, C, and X in neurodegenerative diseases and cancer. Further advances in understanding the functions of cysteine cathepsins in these conditions will result in the development of novel, targeted therapeutic strategies.

BODIPY-Caged Photoactivated Inhibitors of Cathepsin B Flip the Light Switch on Cancer Cell Apoptosis

Acquired resistance to apoptotic agents is a long-standing challenge in cancer treatment. Cathepsin B (CTSB) is an enzyme which, among many essential functions, promotes apoptosis during cellular stress through regulation of intracellular proteolytic networks on the minute time scale. Recent data indicate that CTSB inhibition may be a promising method to steer cells away from apoptotic death toward necrosis, a mechanism of cell death that can overcome resistance to apoptotic agents, stimulate an immune response and promote antitumor immunity. Unfortunately, rapid and selective intracellular inactivation of CTSB has not been possible. However, here we report on the synthesis and characterization of photochemical and biological properties of BODIPY-caged inhibitors of CTSB that are cell permeable, highly selective and activated rapidly upon exposure to visible light. Intriguingly, these compounds display tunable photophysical and biological properties based on substituents bound directly to boron. Me₂BODIPY-caged compound 8 displays the dual-action capability of light-accelerated CTSB inhibition and singlet oxygen production from a singular molecular entity. The dual-action capacity of 8 leads to a rapid necrotic response in MDA-MB-231 triple negative breast cancer cells with high phototherapeutic indexes (>30) and selectivity vs noncancerous cells that neither CTSB inhibition nor photosensitization gives alone. Our work confirms that singlet oxygen production and CTSB inactivation is highly synergistic and a promising method for killing cancer cells. Furthermore, this ability to trigger intracellular inactivation of CTSB with light provides researchers with a powerful photochemical tool for probing biochemical processes on short time scales.

Investigating Novel Genes Potentially Involved in Endometrial Adenocarcinoma using Next-Generation Sequencing and Bioinformatic Approaches

Endometrial cancer is one of the most common cancers in women worldwide, affecting more than 300,000 women annually. Dysregulated gene expression, especially those mediated by microRNAs, play important role in the development and progression of cancer. This study aimed to investigate differentially expressed genes in endometrial adenocarcinoma using next generation sequencing (NGS) and bioinformatics. The gene expression profiles and microRNA profiles of endometrial adenocarcinoma (cancer part) and normal endometrial tissue (non-cancer part) were assessed with NGS. We identified 56 significantly dysregulated genes, including 47 upregulated and 9 downregulated genes, in endometrial adenocarcinoma. Most of these genes were associated with defense response, response to stimulus, and immune system process, and further pathway analysis showed that human papillomavirus infection was the most significant pathway in endometrial adenocarcinoma. In addition, these genes were also associated with decreased cell death and survival as well as increased cellular movement. The analyses using Human Protein Atlas, identified 6 genes (PEG10, CLDN1, ASS1, WNT7A, GLDC, and RSAD2) significantly associated with poorer prognosis and 3 genes (SFN, PIGR, and CDKN1A) significantly associated with better prognosis. Combining with the data of microRNA profiles using microRNA target predicting tools, two significantly dysregulated microRNA-mediated gene expression changes in endometrial adenocarcinoma were identified: downregulated hsa-miR-127-5p with upregulated CSTB and upregulated hsa-miR-218-5p with downregulated HPGD. These findings may contribute important new insights into possible novel diagnostic or therapeutic strategies for endometrial adenocarcinoma.

A water-soluble nucleolin aptamer-paclitaxel conjugate for tumor-specific targeting in ovarian cancer

Paclitaxel (PTX) is among the most commonly used first-line drugs for cancer chemotherapy. However, its poor water solubility and indiscriminate distribution in normal tissues remain clinical challenges. Here we design and synthesize a highly water-soluble nucleolin aptamer-paclitaxel conjugate (NucA-PTX) that selectively delivers PTX to the tumor site. By connecting a tumor-targeting nucleolin aptamer (NucA) to the active hydroxyl group at 2' position of PTX via a cathepsin B sensitive dipeptide bond, NucA-PTX remains stable and inactive in the circulation. NucA facilitates the uptake of the conjugated PTX specifically in tumor cells. Once inside cells, the dipeptide bond linker of NucA-PTX is cleaved by cathepsin B and then the conjugated PTX is released for action. The NucA modification assists the selective accumulation of the conjugated PTX in ovarian tumor tissue rather than normal tissues, and subsequently resulting in notably improved antitumor activity and reduced toxicity.

Cathepsin B expression in colorectal cancer in a Middle East population: Potential value as a tumor biomarker for late disease stages

Cathepsin B (CTSB), is a cysteine protease belonging to the cathepsin (Clan CA) family. The diagnostic and prognostic significance of increased CTSB in the serum of cancer patients have been evaluated for some tumor types. CTSB serum and protein levels have also been reported previously in colorectal cancer (CRC) with contradictory results. The aim of the present study was to investigate CTSB expression in CRC patients and the association of CTSB expression with various tumor stages in a Middle East population. Serum CTSB levels were evaluated in 70 patients and 20 healthy control subjects using enzyme-linked immunosorbant assay (ELISA) technique. CTSB expression was determined in 100 pairs of CRC tumor and adjacent normal colonic tissue using quantitative PCR for mRNA levels. Detection of CTSB protein expression in tissues was carried out using both immunohistochemistry and western blotting techniques. ELISA analysis showed that in sera obtained from CRC patients, the CTSB concentration was significantly higher in late stage patients with lymph node metastases when compared to early stage patients with values of 2.9 and 0.33 ng/ml, respectively (P=0.001). The majority of tumors studied had detectable CTSB protein expression with significant increased positive staining in tumors cells when compared with matched normal colon subjects (P=0.006). The mRNA expression in early stage CRC compared to late stage CRC was 0.04±0.01 and 0.07±0.02, respectively. Increased mRNA expression was more frequently observed in the advanced cancer stages with lymph node metastases when compared with the control (P=0.002). Mann-Whitney test and paired t-test were used to compare serum CTSB and mRNA levels in early and late tumor stage. A subset of four paired tissue extracts were analyzed by western blotting. The result confirmed a consistent increase in the CTSB protein expression level in tumor tissues compared with that noted in the adjacent normal mucosal cells. These findings indicate that CTSB may be an important prognostic biomarker for late stage CRC and cases with lymph node metastases in the Middle Eastern population. Monitoring serum CTSB in CRC patients may predict and/or diagnose cases with lymph node metastases.

Hormonal-receptor positive breast cancer: IL-6 augments invasion and lymph node metastasis via stimulating cathepsin B expression

Hormonal-receptor positive (HRP) breast cancer patients with positive metastatic axillary lymph nodes are characterized by poor prognosis and increased mortality rate. The mechanisms by which cancer cells invade lymph nodes have not yet been fully explored. Several studies have shown that expression of IL-6 and the proteolytic enzyme cathepsin B (CTSB) was associated with breast cancer poor prognosis. In the present study, the effect of different concentrations of recombinant human IL-6 on the invasiveness capacity of HRP breast cancer cell line MCF-7 was tested using an in vitro invasion chamber assay. The impact of IL-6 on expression and activity of CTSB was also investigated. IL-6 treatment promoted the invasiveness potential of MCF-7 cells in a dose-dependent manner. Furthermore, MCF-7 cells displayed elevated CTSB expression and activity associated with loss of E-cadherin and upregulation of vimentin protein levels upon IL-6 stimulation. To validate these results in vivo, the level of expression of IL-6 and CTSB in the carcinoma tissues of HRP-breast cancer patients with positive and negative axillary metastatic lymph nodes (pLNs and nLNs) was assessed. Western blot and immunohistochemical staining data showed that expression of IL-6 and CTSB was higher in carcinoma tissues in HRP-breast cancer with pLNs than those with nLNs patients. ELISA results showed carcinoma tissues of HRP-breast cancer with pLNs exhibited significantly elevated IL-6 protein levels by approximately 2.8-fold compared with those with nLNs patients (P < 0.05). Interestingly, a significantly positive correlation between IL-6 and CTSB expression was detected in clinical samples of HRP-breast cancer patients with pLNs (r = 0.78, P < 0.01). Collectively, this study suggests that IL-6-induced CTSB may play a role in lymph node metastasis, and that may possess future therapeutic implications for HRP-breast cancer patients with pLNs. Further studies are necessary to fully identify IL-6/CTSB axis in different molecular subtypes of breast cancer.

Silencing of Cathepsin B suppresses the proliferation and invasion of endometrial cancer

The molecular mechanism involved in the metastasis of endometrial cancer (EC) remains unclear. The lysosomal cysteine protease Cathepsin B has been implicated in the progression of various human tumors. In the present study, we assessed the expression of Cathepsin B and its functions in EC. Immunohistochemistry was used to examine Cathepsin B expression in 76 paraffin-embedded endometrial tumor tissues. Lentiviral packing short hairpin RNA (shRNA) was transfected into HEC-1A cells to build a stable Cathepsin B knockdown cell line. The cellular levels of Cathepsin B mRNA and protein were detected by real-time PCR and western immunoblotting. The functions of Cathepsin B in EC cells were measured by MTT, migration and invasion assays. In additon, tumorigenicity assays were established in nude mice to study tumor growth in vivo. The results of our study showed that Cathepsin B was overexpressed in EC tissues compared with normal endometrium and endometrial atypical hyperplasia. Depletion of Cathepsin B in vitro inhibited cell proliferation, migration and invasion. Tumor formation assays confirmed that suppression of Cathepsin B inhibited the proliferation potential of HEC-1A cells in vivo, demonstrated by lower proliferation rates. These results suggest that Cathepsin B may act as an oncogene in EC, with the potential to provide a new therapeutic target for treating endometrial malignancy.

The feasibility of enzyme targeted activation for amino acid/dipeptide monoester prodrugs of floxuridine; cathepsin D as a potential targeted enzyme

The improvement of therapeutic efficacy for cancer agents has been a big challenge which includes the increase of tumor selectivity and the reduction of adverse effects at non-tumor sites. In order to achieve those goals, prodrug approaches have been extensively investigated. In this report, the potential activation enzymes for 5′-amino acid/dipeptide monoester floxuridine prodrugs in pancreatic cancer cells were selected and the feasibility of enzyme specific activation of prodrugs was evaluated. All prodrugs exhibited the range of 3.0–105.7 min of half life in Capan-2 cell homogenate with the presence and the absence of selective enzyme inhibitors. 5′-O-L--Phenylalanyl-L-tyrosyl-floxuridine exhibited longer half life only with the presence of pepstatin A. Human cathepsin B and D selectively hydrolized 5′-O-L-phenylalanyl-L-tyrosylfloxuridine and 5′-O-L-phenylalanyl-L-glycylfloxuridine compared to the other tested prodrugs. The wide range of growth inhibitory effect by floxuridine prodrugs in Capan-2 cells was observed due to the different affinities of prodrug promoieties to enyzmes. In conclusion, it is feasible to design prodrugs which are activated by specific enzymes. Cathepsin D might be a good candidate as a target enzyme for prodrug activation and 5′-O-L-phenylalanyl-L-tyrosylfloxuridine may be the best candidate among the tested floxuridine prodrugs.

DICER1 expression and outcomes in endometrioid endometrial adenocarcinoma

BACKGROUND

The objective of this study was to determine whether lower expression levels of DICER1 are associated with disease recurrence in patients with endometrioid endometrial cancer. The authors also explored DNA methylation and haploinsufficiency as potential mechanisms related to altered DICER1 expression in these tumors.

METHODS

DICER1 expression was assessed by quantitative polymerase chain reaction in a selected cohort of endometrioid endometrial tumors (N = 169). Loss of heterozygosity analyses were conducted using 2 single nucleotide polymorphisms, and combined bisulfate restriction analysis was used to assess methylation in the 5'-untranslated region of DICER1 in representative tumors. The correlations between DICER1 expression and clinicopathologic variables, including overall survival (OS) and disease-free survival (DFS), were assessed using nonparametric rank-sum tests and Cox proportional hazard models as appropriate. Survival distributions were described using the Kaplan-Meier method. A nested case-control analysis was conducted to confirm the association between transcript levels and disease recurrence.

RESULTS

Lower DICER1 expression (hazard ratio [HR], 1.36; 95% confidence interval [CI], 1.05-1.75; P = .02) and advanced disease stage (HR, 2.79; 95%CI, 1.59-4.90; P < .001) were associated with worse DFS. Three variables were associated significantly with reduced OS: age (HR, 1.04; 95%CI, 1.02-1.06; P < .0001), advanced disease stage (HR, 6.41; 95%CI, 3.57-11.52; P < .0001), and high tumor grade (HR, 2.96; 95%CI, 1.46-5.99; P = .003). Nested case-control analyses confirmed that there were lower DICER1 transcript levels in patients who had recurrent disease (P = .01). Deletion of DICER1 sequences was an infrequent event (5% of analyzed patients), and no methylation was observed in the 5' DICER1 regulatory region.

CONCLUSIONS

Lower DICER1 transcript levels were correlated with disease recurrence and worse DFS survival in patients with endometrioid endometrial cancer. The factors that influence DICER1 transcript levels in primary endometrial cancers remain unknown.

Cathepsin D messenger RNA is downregulated in human lung cancer

OBJECTIVES

Lysosomal proteases cathepsins B and D (CB and CD) play a significant part in cancer progression. For many oncological diseases protein expression levels of CB and CD have been investigated and correlations with tumour characteristics revealed. Meanwhile, there is very little information concerning mRNA expression level.

METHODS

In the present work, data about mRNA levels of CB and CD in human lung cancer was obtained using reverse transcription followed by real-time polymerase chain reaction.

RESULTS

For the first time CD and CB mRNA in human lung cancer tumours was quantified. It was shown that CB and CD mRNA levels do not correlate with any tumour characteristics. However, in most analysed tumours, expression of CD mRNA was downregulated compared with adjacent normal tissue (p <0.0003).

CONCLUSIONS

The data obtained indicate CD mRNA as a potential lung cancer marker.

Controversies in the management of endometrial carcinoma

Endometrial carcinoma is the most common type of female genital tract malignancy. Although endometrial carcinoma is a low grade curable malignancy, the condition of the disease can range from excellent prognosis with high curability to aggressive disease with poor outcome. During the last 10 years many researches have provided some new valuable data of optimal treatments for endometrial carcinoma. Progression in diagnostic imaging, radiation delivery systems, and systemic therapies potentially can improve outcomes while minimizing morbidity. Firstly, total hysterectomy and bilateral salphingo-oophorectomy is the primary operative procedure. Pelvic lymhadenectomy is performed in most centers on therapeutic and prognostic grounds and to individualize adjuvant treatment. Women with endometrial carcinoma can be readily segregated intraoperatively into “low-risk” and “high-risk” groups to better identify those women who will most likely benefit from thorough lymphadenectomy. Secondly, adjuvant therapies have been proposed for women with endometrial carcinoma postoperatively. Postoperative irradiation is used to reduce pelvic and vaginal recurrences in high risk cases. Chemotherapy is emerging as an important treatment modality in advanced endometrial carcinoma. Meanwhile the availability of new hormonal and biological agents presents new opportunities for therapy.

Cathepsins B and L in peripheral blood mononuclear cells of pediatric acute myeloid leukemia: potential poor prognostic markers

The diagnostic and prognostic significance of cathepsin B (CTSB) and L (CTSL) is well documented for solid tumors. However, their significance in acute leukemias is lacking. This study was planned to investigate expression and significance of these proteases in peripheral blood mononuclear cells (PBMCs) of patients with pediatric acute myeloid leukemia (AML). CTSL and CTSB activities were assayed in PBMCs of 24 children with AML and ten healthy controls by spectrofluorimetry. The mRNA levels of these proteases and their specific endogenous inhibitor cystatin C and transcriptional upregulator vascular endothelial growth factor (VEGF) were quantitated by real-time PCR. Correlation analysis of CTSL and CTSB activities/expression with their inhibitor/upregulator and event-free survival (EFS) was done using appropriate statistical tools. CTSL and CTSB protease activity and their mRNA expression were significantly higher in AML patients compared to controls (p ≤ 0.001). A strong positive correlation was observed between VEGF expression and CTSL (r = 0.812; p ≤ 0.001). Similarly, VEGF exhibited a strong positive correlation with CTSB (r = 0.501; p = 0.013). Cystatin expression though significantly high (p ≤ 0.001) in AML was negatively correlated with CTSL (r = -0.920; p ≤ 0.001) and CTSB (r = -0.580, p ≤ 0.001) expression. AML patients with higher CTSL and CTSB activity exhibited an inferior EFS (CTSL: p = 0.045; CTSB: p = 0.002) and overall survival (OS; CTSL: p = 0.05; CTSB: p = 0.004) compared to patients with lower levels of these proteases. This is the first report demonstrating increased expression of CTSL and CTSB in AML, mechanism of their increased expression in relation to VEGF, and their association with poor EFS and OS. These results suggest a potential utility of these proteases as prognostic markers for this malignancy.