Rho GTPase effectors and NAD metabolism in cancer immune suppression

Dbl family RhoGEFs in cancer: different roles and targeting strategies

Small Ras homologous guanosine triphosphatase (Rho GTPase) family proteins are highly associated with tumorigenesis and development. As intrinsic exchange activity regulators of Rho GTPases, Rho guanine nucleotide exchange factors (RhoGEFs) have been demonstrated to be closely involved in tumor development and received increasing attention. They mainly contain two families: the diffuse B-cell lymphoma (Dbl) family and the dedicator of cytokinesis (Dock) family. More and more emphasis has been paid to the Dbl family members for their abnormally high expression in various cancers and their correlation to poor prognosis. In this review, the common and distinctive structures of Dbl family members are discussed, and their roles in cancer are summarized with a focus on Ect2, Tiam1/2, P-Rex1/2, Vav1/2/3, Trio, KALRN, and LARG. Significantly, the strategies targeting Dbl family RhoGEFs are highlighted as novel therapeutic opportunities for cancer.

RHOJ Induces Epithelial-to-Mesenchymal Transition by IL-6/STAT3 to Promote Invasion and Metastasis in Gastric Cancer

Background: Recently, the molecular classification of gastric cancer (GC) promotes the advances of GC patients' precision therapy and prognosis prediction. According to the Asian Cancer Research Group (ACRG), GC is classified as microsatellite instable (MSI) subtype GC, microsatellite stable/epithelial-to-mesenchymal transition (MSS/EMT) subtype GC, MSS/TP53- subtype GC, and MSS/TP53+ subtype GC. Due to the easy metastasis of EMT-subtype GC, it has the worst prognosis, the highest recurrence rate, and the tendency to occur at a younger age. Therefore, it is curious and crucial for us to understand the molecular basis of EMT-subtype GC. Methods: The expression of RHOJ was detected by quantitative real-time PCR (qPCR) and immunohistochemistry (IHC) in GC cells and tissues. Western blotting and immunofluorescence (IF) were conducted to examine the effects of RHOJ on the EMT markers' expression of GC cells. The GC cells' migration and invasion were investigated by transwell assay. The tumor growth and metastasis were demonstrated correspondingly in different xenograft models. Results: Firstly, it was noticed that RHOJ was significantly upregulated in EMT-subtype GC and RHOJ has close relationships with the EMT process of GC, based on the Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA) databases. Next, transwell assay and tail vein metastasis models were conducted to verify that RHOJ mediates the EMT to regulate the invasion and metastasis of GC in vitro and in vivo. In addition, weakened tumor angiogenesis was observed after RHOJ knockdown by the angiogenesis assay of HUVEC. RNA-seq and further study unveiled that RHOJ aggravates the malignant progression of GC by inducing EMT through IL-6/STAT3 to promote invasion and metastasis. Finally, blocking the IL-6/STAT3 signaling overcame RHOJ-mediated GC cells' growth and migration. Conclusions: These results indicate that the upregulation of RHOJ contributes to EMT-subtype GC invasion and metastasis via IL-6/STAT3 signaling, and RHOJ is expected to become a promising biomarker and therapeutic target for EMT-subtype GC patients.

Circ_0000235 targets MCT4 to promote glycolysis and progression of bladder cancer by sponging miR-330-5p

Warburg effect plays a crucial role in bladder cancer (Bca) development. However, the mechanism by which glycolysis is involved in Bca remains poorly understood. CircRNAs commonly play a regulatory role in tumor progression. Our study discovered and identified a novel circRNA, hsa_circ_0000235 (circ235), and investigated its role in the glycolytic process, which further results in the progression of Bca. We applied qRT-PCR to assess its clinicopathological relevance and evaluated its proliferation, migration, and glycolytic capacity. We investigated its mechanism using RNA immunoprecipitation, dual-luciferase reporters, and fluorescence in situ hybridization. The findings demonstrated that circ235 was dramatically increased in Bca tissues and was related to a worse prognosis. In vitro studies revealed that circ235 accelerated the rate of extracellular acidification and promoted glucose uptake and lactate manufacture in Bca cells. Additionally, it strengthened the proliferative and migratory capacities. Experiments on animals revealed that downregulating circ235 dramatically reduced carcinogenesis and tumor growth. Circ235 activates monocarboxylate transporter 4 (MCT4) by sponging miR-330-5p, which promotes glycolysis and tumor growth. In conclusion, these findings suggest that circ235 may be a viable molecular marker and therapeutic target for Bca.

Effect of genetic polymorphisms on outcomes following nivolumab for advanced renal cell carcinoma in the SNiP-RCC trial

BACKGROUND

Anti-PD-1 antibodies are widely used for cancer treatment including advanced renal cell carcinoma (RCC). However, their therapeutic and adverse effects vary among patients. This study aimed to identify genetic markers that predict outcome after nivolumab anti-PD-1 antibody treatment for advanced RCC.

METHODS

This study was registered on the website of the University Hospital Medical Information Network (protocol ID, UMIN000037739). Patient enrollment was conducted at 23 institutions in Japan between August 19, 2019, and September 30, 2020. Patient follow-up ended on March 31, 2021. Patients were treated with nivolumab for advanced clear cell RCC. A genome-wide association study was performed in the development set, while genotyping of target regions in the validation set was undertaken. Single nucleotide polymorphisms (SNPs) in genes of interest CD274, PDCD1LG2 and PDCD1 were genotyped in the combined set. The primary endpoint was the association of SNPs with objective response following nivolumab treatment. As secondary endpoints, the associations of SNPs with radiographic progression-free survival (rPFS) and treatment-related grade  ≥ 3 adverse events (AEs) were evaluated.

RESULTS

A genome-wide association study followed by a validation study identified that SNPs in FARP1 (rs643896 and rs685736) were associated with objective response and rPFS but not AEs following nivolumab treatment. Furthermore, SNPs in PDCD1LG2 (rs822339 and rs1411262) were associated with objective response, rPFS, and AEs following nivolumab treatment. Genetic risk category determined according to the number of risk alleles in SNPs (rs643896 in FARP1 and rs4527932 in PDCD1LG2) excellently predicted objective response and rPFS in nivolumab treatment.

CONCLUSION

This study revealed that SNPs in FARP1 and PDCD1LG2 were correlated with outcome in nivolumab treatment. The use of these SNPs may be beneficial in selecting appropriate treatment for individual patients and may contribute to personalized medicine.

RhoGTPase Signalling in Cancer Progression and Dissemination

Rho GTPases are a family of small G proteins that regulate a wide array of cellular processes related to their key roles controlling the cytoskeleton. On the other hand, cancer is a multi-step disease caused by the accumulation of genetic mutations and epigenetic alterations, from the initial stages of cancer development when cells in normal tissues undergo transformation, to the acquisition of invasive and metastatic traits, responsible for a large number of cancer related deaths. In this review, we discuss the role of Rho GTPase signalling in cancer in every step of disease progression. Rho GTPases contribute to tumour initiation and progression, by regulating proliferation and apoptosis, but also metabolism, senescence and cell stemness. Rho GTPases play a major role in cell migration, and in the metastatic process. They are also involved in interactions with the tumour microenvironment and regulate inflammation, contributing to cancer progression. After years of intensive research, we highlight the importance of relevant models in the Rho GTPase field, and we reflect on the therapeutic opportunities arising for cancer patients.

Drug discovery targeting p21-activated kinase 4 (PAK4): a patent review

Introduction: The Ser/Thr protein kinase PAK4 is a downstream regulator of Cdc42, mediating cytoskeleton remodeling, and cell motility, and inhibiting apoptosis and transcriptional regulation. Nowadays, efforts in PAK4 inhibitor development are focusing on improving inhibitory selectivity, cellular potency, and in vivo pharmacokinetic properties, and identifying the feasibility of immunotherapy combination in oncology therapy.Areas covered: This review summarized the development of PAK4 inhibitors that reported on patents in the past two decades. According to their binding features, these inhibitors were classified into type I, type I 1/2, and PAMs. Their designing ideas and SAR were elucidated in this review. Moreover, synergistic therapy of PAK4 inhibitors with PD-1/PD-L1 or CAR-T were also summarized .Expert opinion: In the past years, preclinical and clinical studies of PAK4 inhibitors ended in failure due to poor selectivity, cellular activity, or pharmacokinetic issues. There are researchers questioning the reliability of PAK4 as a drug target, particularly PAK4-related therapy is concerned with the distinguishment of the non-kinase functions and catalytic functions triggered by PAK4 phosphorylation. Meanwhile, synergistic effects of PAK4 inhibitors with PD-1/PD-L1 and CAR-T immunotherapy shed light for the development of PAK4 inhibitors.

Tumor Cell-Intrinsic Immunometabolism and Precision Nutrition in Cancer Immunotherapy

One of the greatest challenges in the cancer immunotherapy field is the need to biologically rationalize and broaden the clinical utility of immune checkpoint inhibitors (ICIs). The balance between metabolism and immune response has critical implications for overcoming the major weaknesses of ICIs, including their lack of universality and durability. The last decade has seen tremendous advances in understanding how the immune system's ability to kill tumor cells requires the conspicuous metabolic specialization of T-cells. We have learned that cancer cell-associated metabolic activities trigger shifts in the abundance of some metabolites with immunosuppressory roles in the tumor microenvironment. Yet very little is known about the tumor cell-intrinsic metabolic traits that control the immune checkpoint contexture in cancer cells. Likewise, we lack a comprehensive understanding of how systemic metabolic perturbations in response to dietary interventions can reprogram the immune checkpoint landscape of tumor cells. We here review state-of-the-art molecular- and functional-level interrogation approaches to uncover how cell-autonomous metabolic traits and diet-mediated changes in nutrient availability and utilization might delineate new cancer cell-intrinsic metabolic dependencies of tumor immunogenicity. We propose that clinical monitoring and in-depth molecular evaluation of the cancer cell-intrinsic metabolic traits involved in primary, adaptive, and acquired resistance to cancer immunotherapy can provide the basis for improvements in therapeutic responses to ICIs. Overall, these approaches might guide the use of metabolic therapeutics and dietary approaches as novel strategies to broaden the spectrum of cancer patients and indications that can be effectively treated with ICI-based cancer immunotherapy.

Use of peripheral blood transcriptomic biomarkers to distinguish high-grade cervical squamous intraepithelial lesions from low-grade lesions

It is crucial to classify cervical lesions into high-grade squamous intraepithelial lesions (HSILs) and low-grade SILs (LSILs), as LSILs are conservatively treated by observation, based on an expectation of natural regression, whereas HSILs usually require electrosurgical excision. In the present study, peripheral blood gene expression profiles were analyzed to identify transcriptomic biomarkers distinguishing HSILs from LSILs. A total of 102 blood samples were collected from women with cervical SILs (66 HSIL and 36 LSIL) for microarray hybridization. Candidate gene signatures were identified using AdaBoost algorithms, and a predictive model was constructed using logistic regression to differentiate HSILs from LSILs. To correct for possible bias as a result of the limited sample size and to verify the stability of the predictive model, a two-fold cross validation and null set analysis was conducted over 1,000 iterations. The functions of the transcriptomic biomarkers were then analyzed to elucidate the pathogenesis of cervical SIL. A total of 10 transcriptomic genes (STMN3, TRPC4AP, DYRK2, AGK, KIAA0319L, GRPEL1, ZFC3H1, LYL1, ITGB1 and ARHGAP18) were identified. The predictive model based on the 10-gene panel exhibited well-discriminated power. A cross validation process using known disease status exhibited almost the same performance as that of the predictive model, whereas null-set analysis with randomly reassigned disease status exhibited much lower predictive performance for distinguishing HSILs from LSILs. These biomarkers were involved in the 'Rho GTPase cycle', 'mitochondrial protein import', 'oncogenic MAPK signaling', 'integrin cell surface interaction' and 'signaling by BRAF and RAF fusions'. In conclusion, peripheral blood gene expression analysis is a promising method for distinguishing HSILs from LSILs. The present study proposes 10 candidate genes that could be used in the future as diagnostic biomarkers and potential therapeutic targets for cervical SILs. A simple, non-invasive blood test would be clinically useful in the diagnosis and classification of patients with cervical SILs.

Beyond Energy Metabolism: Exploiting the Additional Roles of NAMPT for Cancer Therapy

Tumor cells have increased requirements for NAD⁺. Thus, many cancers exhibit an increased reliance on NAD⁺ production pathways. This dependence may be exploited therapeutically through pharmacological targeting of NAMPT, the rate-limiting enzyme in the NAD⁺ salvage pathway. Despite promising preclinical data using NAMPT inhibitors in cancer models, early NAMPT inhibitors showed limited efficacy in several early phase clinical trials, necessitating the identification of strategies, such as drug combinations, to enhance their efficacy. While the effect of NAMPT inhibitors on impairment of energy metabolism in cancer cells has been well-described, more recent insights have uncovered a number of additional targetable cellular processes that are impacted by inhibition of NAMPT. These include sirtuin function, DNA repair machinery, redox homeostasis, molecular signaling, cellular stemness, and immune processes. This review highlights the recent findings describing the effects of NAMPT inhibitors on the non-metabolic functions of malignant cells, with a focus on how this information can be leveraged clinically. Combining NAMPT inhibitors with other therapies that target NAD⁺-dependent processes or selecting tumors with specific vulnerabilities that can be co-targeted with NAMPT inhibitors may represent opportunities to exploit the multiple functions of this enzyme for greater therapeutic benefit.

Investigation of Antigen-Specific T-Cell Receptor Clusters in Human Cancers

PURPOSE

Cancer antigen-specific T cells are key components in antitumor immune response, yet their identification in the tumor microenvironment remains challenging, as most cancer antigens are unknown. Recent advance in immunology suggests that similar T-cell receptor (TCR) sequences can be clustered to infer shared antigen specificity. This study aims to identify antigen-specific TCRs from the tumor genomics sequencing data.

EXPERIMENTAL DESIGN

We used the TRUST (Tcr Repertoire Utilities for Solid Tissue) algorithm to assemble the TCR hypervariable CDR3 regions from 9,700 bulk tumor RNA-sequencing (RNA-seq) samples, and developed a computational method, iSMART, to group similar TCRs into antigen-specific clusters. Integrative analysis on the TCR clusters with multi-omics datasets was performed to profile cancer-associated T cells and to uncover novel cancer antigens.

RESULTS

Clustered TCRs are associated with signatures of T-cell activation after antigen encounter. We further elucidated the phenotypes of clustered T cells using single-cell RNA-seq data, which revealed a novel subset of tissue-resident memory T-cell population with elevated metabolic status. An exciting application of the TCR clusters is to identify novel cancer antigens, exemplified by our identification of a candidate cancer/testis gene, HSFX1, through integrated analysis of HLA alleles and genomics data. The target was further validated using vaccination of humanized HLA-A*02:01 mice and ELISpot assay. Finally, we showed that clustered tumor-infiltrating TCRs can differentiate patients with early-stage cancer from healthy donors, using blood TCR repertoire sequencing data, suggesting potential applications in noninvasive cancer detection.

CONCLUSIONS

Our analysis on the antigen-specific TCR clusters provides a unique resource for alternative antigen discovery and biomarker identification for cancer immunotherapies.

Review: Precision medicine and driver mutations: Computational methods, functional assays and conformational principles for interpreting cancer drivers

At the root of the so-called precision medicine or precision oncology, which is our focus here, is the hypothesis that cancer treatment would be considerably better if therapies were guided by a tumor’s genomic alterations. This hypothesis has sparked major initiatives focusing on whole-genome and/or exome sequencing, creation of large databases, and developing tools for their statistical analyses—all aspiring to identify actionable alterations, and thus molecular targets, in a patient. At the center of the massive amount of collected sequence data is their interpretations that largely rest on statistical analysis and phenotypic observations. Statistics is vital, because it guides identification of cancer-driving alterations. However, statistics of mutations do not identify a change in protein conformation; therefore, it may not define sufficiently accurate actionable mutations, neglecting those that are rare. Among the many thematic overviews of precision oncology, this review innovates by further comprehensively including precision pharmacology, and within this framework, articulating its protein structural landscape and consequences to cellular signaling pathways. It provides the underlying physicochemical basis, thereby also opening the door to a broader community.