Discovery of a novel cathepsin inhibitor with dual autophagy-inducing and metastasis-inhibiting effects on breast cancer cells

Recent discovery of natural substances with cathepsin L-inhibitory activity for cancer metastasis suppression

Cathepsin L (CTSL), a cysteine cathepsin protease of the papain superfamily, plays a crucial role in cancer progression and metastasis. Dysregulation of CTSL is frequently observed in tumor malignancies, leading to the degradation of extracellular matrix and facilitating epithelial-mesenchymal transition (EMT), a key process in malignant cancer metastasis. This review mainly provides a comprehensive information about recent findings on natural inhibitors targeting CTSL and their anticancer effects, which have emerged as potent anticancer therapeutic agents or metastasis-suppressive adjuvants. Specifically, inhibitors are categorized into small-molecule and macromolecule inhibitors, with a particular emphasis on cathepsin propeptide-type macromolecules. Additionally, the article explores the molecular mechanisms of CTSL involvement in cancer metastasis, highlighting its regulation at transcriptional, translational, post-translational, and epigenetic levels. This work underscores the importance of understanding natural CTSL inhibitors and provides researchers with practical insights to advance the relevant fields and discover novel CTSL-targeting inhibitors from natural sources.

Construction and validation of a novel lysosomal signature for hepatocellular carcinoma prognosis, diagnosis, and therapeutic decision-making

Lysosomes is a well-recognized oncogenic driver and chemoresistance across variable cancer types, and has been associated with tumor invasiveness, metastasis, and poor prognosis. However, the significance of lysosomes in hepatocellular carcinoma (HCC) is not well understood. Lysosomes-related genes (LRGs) were downloaded from Genome Enrichment Analysis (GSEA) databases. Lysosome-related risk score (LRRS), including eight LRGs, was constructed via expression difference analysis (DEGs), univariate and LASSO-penalized Cox regression algorithm based on the TCGA cohort, while the ICGC cohort was obtained for signature validation. Based on GSE149614 Single-cell RNA sequencing data, model gene expression and liver tumor niche were further analyzed. Moreover, the functional enrichments, tumor microenvironment (TME), and genomic variation landscape between LRRSlow/LRRShigh subgroup were systematically investigated. A total of 15 Lysosomes-related differentially expressed genes (DELRGs) in HCC were detected, and then 10 prognosis DELRGs were screened out. Finally, the 8 optimal DELRGs (CLN3, GBA, CTSA, BSG, APLN, SORT1, ANXA2, and LAPTM4B) were selected to construct the LRRS prognosis signature of HCC. LRRS was considered as an independent prognostic factor and was associated with advanced clinicopathological features. LRRS also proved to be a potential marker for HCC diagnosis, especially for early-stage HCC. Then, a nomogram integrating the LRRS and clinical parameters was set up displaying great prognostic predictive performance. Moreover, patients with high LRRS showed higher tumor stemness, higher heterogeneity, and higher genomic alteration status than those in the low LRRS group and enriched in metabolism-related pathways, suggesting its underlying role in the progression and development of liver cancer. Meanwhile, the LRRS can affect the proportion of immunosuppressive cell infiltration, making it a vital immunosuppressive factor in the tumor microenvironment. Additionally, HCC patients with low LRRS were more sensitive to immunotherapy, while patients in the high LRRS group responded better to chemotherapy. Upon single-cell RNA sequencing, CLN3, GBA, and LAPTM4B were found to be specially expressed in hepatocytes, where they promoted cell progression. Finally, RT-qPCR and external datasets confirmed the mRNA expression levels of model genes. This study provided a direct links between LRRS signature and clinical characteristics, tumor microenvironment, and clinical drug-response, highlighting the critical role of lysosome in the development and treatment resistance of liver cancer, providing valuable insights into the prognosis prediction and treatment response of HCC, thereby providing valuable insights into prognostic prediction, early diagnosis, and therapeutic response of HCC.

Development of certain aminoquinazoline scaffolds as potential multitarget anticancer agents with apoptotic and anti-proliferative effects: Design, synthesis and biological evaluation

Newly designed 4 - aminoquinazoline derivatives (5a-f, 6a, b, 7, 8, 9, 10a-c, 11a, b, 12a, b and 13a, b) have been synthesized and evaluated for their potential multitarget anticancer activities, apoptotic and anti-proliferative effects. Thereupon, in vitro cytotoxic activities of all the synthesized compounds were screened against NCI 60 human cancer cell lines (nine subpanels) at NCI, USA. Successfully, 2-morpholino-N-(quinazolin-4-yl) acetohydrazide 5e was granted an NSC code, owing to its significant potency and broad spectrum of activity against various cancer cell lines; leukemia K-562, non-small cell lung cancer NCI-H522 cells, colon cancer SW-620, melanoma LOX IMVI, MALME-3M, renal cancer RXF 393, ACHN and breast cancer MDA-MB231/ATCC (GI% = 99.6, 161, 126.03, 90.22, 174.47, 139.7, 191 and 97, respectively). Compound 5e showed the best inhibitory activity (GI₅₀ = 1.3 µM) against melanoma LOX IMVI, when tested at five doses against NCI 60 cell lines. Furthermore, compound 5e showed comparable EGFR and CDK2 inhibitory activity results (IC₅₀ = 0.093 ± 0.006 μM and 0.143 ± 0.008 μM, respectively) to those of lapatinib and ribociclib (IC₅₀ = 0.03 ± 0.002 μM and 0.067 ± 0.004 μM, respectively). Western blotting analysis of compound 5e against melanoma LOX IMVI marked out significant reduced EGFR and CDK2 protein expression percentages, up to 32.97% and 34.09%, respectively, if compared to lapatinib (31.18%) and ribociclib (29.66%). Moreover, compound 5e caused clear cell cycle arrests at S phase of renal UO-31 cells and at G1 phase of both breast cancer MCF7 and ovarian cancer IGROV1, associated with remarkable increase of DNA content of the controls. In accordance, it demonstrated promising anti- proliferative and apoptotic activities, showing a significant increase in total apoptotic percentages of renal cancer UO-31, breast cancer MCF7 and ovarian IGROV1 cancer cell lines, if compared to the control untreated cells (from 1.79% to 46.72%, 2.19% to 39.02% and 1.66 to 42.51%, respectively). Molecular modelling and dynamic simulation study results supported the main objectives of the present work.

Cysteine Cathepsins in Breast Cancer: Promising Targets for Fluorescence-Guided Surgery

The majority of breast cancer patients is treated with breast-conserving surgery (BCS) combined with adjuvant radiation therapy. Up to 40% of patients has a tumor-positive resection margin after BCS, which necessitates re-resection or additional boost radiation. Cathepsin-targeted near-infrared fluorescence imaging during BCS could be used to detect residual cancer in the surgical cavity and guide additional resection, thereby preventing tumor-positive resection margins and associated mutilating treatments. The cysteine cathepsins are a family of proteases that play a major role in normal cellular physiology and neoplastic transformation. In breast cancer, the increased enzymatic activity and aberrant localization of many of the cysteine cathepsins drive tumor progression, proliferation, invasion, and metastasis. The upregulation of cysteine cathepsins in breast cancer cells indicates their potential as a target for intraoperative fluorescence imaging. This review provides a summary of the current knowledge on the role and expression of the most important cysteine cathepsins in breast cancer to better understand their potential as a target for fluorescence-guided surgery (FGS). In addition, it gives an overview of the cathepsin-targeted fluorescent probes that have been investigated preclinically and in breast cancer patients. The current review underscores that cysteine cathepsins are highly suitable molecular targets for FGS because of favorable expression and activity patterns in virtually all breast cancer subtypes. This is confirmed by cathepsin-targeted fluorescent probes that have been shown to facilitate in vivo breast cancer visualization and tumor resection in mouse models and breast cancer patients. These findings indicate that cathepsin-targeted FGS has potential to improve treatment outcomes in breast cancer patients.

Design and synthesis of dual cathepsin L and S inhibitors and antimetastatic activity evaluation in pancreatic cancer cells

Currently, the migration and invasion of cancer cells remain the main factors of poor prognosis in the majority of cancer patients. Developing an effective antimetastatic agent is crucial for cancer therapy. Our recent research revealed that Cat L and S are expressed concurrently in metastatic pancreatic cancer cells. Asperphenamate analog ASPER-29, which exhibits dual Cat L and S inhibitory potency, showed a definite antimetastatic effect on pancreatic cancer BxPC-3 and PANC-1 cells. To further improve the antimetastatic ability of asperphenamate-type molecules, 24 derivatives were designed and synthesized by a scaffold-hopping strategy. The cathepsin inhibitory activity assay results showed that most of the derivatives exhibited dual inhibitory effects on Cat L and S. Among all derivatives, Compound B1a showed the strongest inhibitory activity, with IC50 values of 4.10 ± 0.14 μM and 1.79 ± 0.11 μM, which were 1.5-fold and 2.8-fold more potent than those of positive drugs against Cat L and S, respectively. Further wound-healing and transwell chamber assays demonstrated that B1a presented significant antimetastatic ability in vitro.

ASPER-29 suppresses the metastasis of pancreatic cancer cells by dual inhibition of cathepsin-L and cathepsin-S

Pancreatic cancer will be the second leading cause of cancer-related mortality worldwide due to its high rate of metastasis. Cathepsins (CATs) are effectors of invasive growth in various cancers. Currently, targeting CATs represents an attractive strategy for the treatment of highly metastatic cancers with high CATs activity, such as pancreatic cancer. To develop a stronger antimetastatic agent, ASPER-29, a novel inhibitor of CATs designed by using the asperphenamate derivative BBP as a lead compound, was synthesized, and its therapeutic potential in pancreatic cancer metastasis was investigated in this study. Molecular docking and enzyme inhibition assays proved that ASPER-29 can inhibit the activity of CAT-L and CAT-S by binding with these enzymes in classical action modes. Furthermore, ASPER-29 significantly inhibited the activity of CAT-L and CAT-S but had no effect on their expression in PANC-1 and BxPC-3 cells. The in vitro antimetastatic activities of ASPER-29 were examined by wound healing and Transwell chamber assays. We found that ASPER-29 inhibited the migration and invasion of PANC-1 and BxPC-3 cells in a concentration-dependent manner. Moreover, the in vivo antimetastatic effects of ASPER-29 were confirmed in a mouse xenotransplantation model. H&E staining and immunohistochemistry assays of Ki67 and CEACAM6 proved that ASPER-29 treatment significantly blocked the metastasis of pancreatic cancer cells to lung and liver tissues. Additionally, the activity of both CAT-L and CAT-S was markedly inhibited in the lung and liver tissues of ASPER-29-administered mice compared with the mice in the model group, suggesting that the metastasis-blocking effect of ASPER-29 should be mediated via inhibition of the activity of CAT-L and CAT-S in pancreatic cancer cells. Together, our results demonstrated that ASPER-29, as a novel inhibitor of CAT-L and CAT-S, possessed the evident ability to block the metastasis of pancreatic cancer cells.

Discovery of a novel and selective cathepsin L inhibitor with anti-metastatic ability in vitro and in vivo against breast cancer cells

Asperphenamate is a natural product that has attracted considerable interest from researchers worldwide. In the last decade, aiming to increase the biological activity and improve druggability, modifications of the A-ring moiety in asperphenamate have been performed. Our laboratory has also recently reported functional derivatizations of the A ring and studied its effect on the inhibition of cysteine cathepsin L. However, the functional significance of the B-ring fragment toward cathepsin L has not been evaluated thus far. In this paper, forty-four derivatives of the B-ring substituted with different N-phenylsulfonyl groups were designed and synthesized. Among them, the paratrifluromethyl analog B-2a and the 2, 4-difluoro-5-chloro derivative B-11b showed more potent inhibitory activity against cathepsin L than the control compound, ABR, which displayed the strongest inhibitory effect on cathepsin L and S among all reported asperphenamate derivatives. In particular, compound B-2a showed more pronounced selectivity against cathepsin L than the other derivatives. Molecular docking revealed that the N-phenylsulfonylamide moiety was vital for the interactions between B-2a and cathepsin L. Moreover, B-2a displayed no toxicity against normal cells. Therefore, compound B-2a was selected for further studies. Wound-healing assays, Transwell chamber assays and breast cancer lung metastasis mouse models demonstrated that B-2a exhibited antimetastatic ability in vitro and in vivo.

Mass Spectrometry Guided Discovery and Design of Novel Asperphenamate Analogs From Penicillium astrolabium Reveals an Extraordinary NRPS Flexibility

Asperphenamate is a small peptide natural product that has gained much interest due to its antitumor activity. In the recent years numerous bioactive synthetic asperphenamate analogs have been reported, whereas only a handful of natural analogs either of microbial or plant origin has been discovered. Herein we describe a UHPLC-HRMS/MS and amino acid supplement approach for discovery and design of novel asperphenamate analogs. Chemical analysis of Penicillium astrolabium, a prolific producer of asperphenamate, revealed three previously described and two novel asperphenamate analogs produced in significant amounts, suggesting a potential for biosynthesis of further asperphenamate analogs by varying the amino acid availability. Subsequent growth on proteogenic and non-proteogenic amino acid enriched media, revealed a series of novel asperphenamate analogs, including single or double amino acid exchange, as well as benzoic acid exchange for nicotinic acid, with the latter observed from a natural source for the first time. In total, 22 new asperphenamate analogs were characterized by HRMS/MS, with one additionally confirmed by isolation and NMR structure elucidation. This study indicates an extraordinary nonribosomal peptide synthetase (NRPS) flexibility based on substrate availability, and therefore the potential for manipulating and designing novel peptide natural products in filamentous fungi.

A novel cathepsin L inhibitor prevents the progression of idiopathic pulmonary fibrosis

In previous work, the target of asperphenamate as a natural product was successfully determined as cathepsin by the natural product consensus pharmacophore strategy. In order to develop accurate SAR (structure-activity relationship) of asperphenamate-type cathepsin inhibitor, we chose several novel analogs with heterocyclic moiety to perform further study. The molecular simulation showed that 4-pyridyl derivative 3 with the greatest cathepsin inhibitory activity presented new interaction modes with protein utilizing its B-ring moiety. And then molecular dynamics (MD) simulation further revealed that 3 and cathepsin kept stable interaction in the binding site, which validated the molecular docking results. In view that cathepsins play an important role in fibrosis and some cathepsin inhibitors display the therapeutic ability for fibrosis, we investigated the anti-fibrotic effect of 3in vitro and in vivo. The results indicated that 3 displayed the strongest inhibitory effect on the formation of α-SMA and collagen I as the protein markers of fibrosis among all tested derivatives. Further in vivo assay confirmed that 3 indeed showed significant inhibitory ability against pulmonary fibrosis by the method of H&E and Masson staining as well as immunohistochemical staining for characteristic α-SMA proteins.