Carboxyl-Terminal Modulator Protein Positively Acts as an Oncogenic Driver in Head and Neck Squamous Cell Carcinoma via Regulating Akt phosphorylation

AKT kinases as therapeutic targets

AKT, or protein kinase B, is a central node of the PI3K signaling pathway that is pivotal for a range of normal cellular physiologies that also underlie several pathological conditions, including inflammatory and autoimmune diseases, overgrowth syndromes, and neoplastic transformation. These pathologies, notably cancer, arise if either the activity of AKT or its positive or negative upstream or downstream regulators or effectors goes unchecked, superimposed on by its intersection with a slew of other pathways. Targeting the PI3K/AKT pathway is, therefore, a prudent countermeasure. AKT inhibitors have been tested in many clinical trials, primarily in combination with other drugs. While some have recently garnered attention for their favorable profile, concern over resistance and off-target effects have continued to hinder their widespread adoption in the clinic, mandating a discussion on alternative modes of targeting. In this review, we discuss isoform-centric targeting that may be more effective and less toxic than traditional pan-AKT inhibitors and its significance for disease prevention and treatment, including immunotherapy. We also touch on the emerging mutant- or allele-selective covalent allosteric AKT inhibitors (CAAIs), as well as indirect, novel AKT-targeting approaches, and end with a briefing on the ongoing quest for more reliable biomarkers predicting sensitivity and response to AKT inhibitors, and their current state of affairs.

Overview of carboxyl‑terminal modulator protein 1 and its importance in various metabolic regulations (Review)

Acyl‑coenzyme A thioesterases (ACOTs) are crucial in mediating lipid metabolic functions, including energy expenditure, hepatic gluconeogenesis and neuronal function. The two distinct types are type I and II ACOTs, the latter of which are 'hotdog' fold superfamily members. Type II ACOTs include carboxyl‑terminal modulator protein 1 (CTMP1), also termed thioesterase superfamily member 4 (THEM4), and CTMP2, also termed THEM5. Due to their similar structural features and distinct sequence homology, CTMP1 and CTMP2 stand out from other type II ACOTs. CTMP1 was initially known as a protein kinase B (PKB) inhibitor that attenuates PKB phosphorylation. PKB is the central regulator of various cellular functions, including survival, proliferation, growth and metabolism. Therefore, by inhibiting PKB, CTMP1 can affect various cellular processes. Various other functions of CTMP1 have been revealed, including functions in cancer, brain injury, mitochondrial function and lipid metabolism. CTMP2 is a paralog of CTMP1 and was first identified as a cardiolipin remodeling factor involved in the development of fatty liver. As the functions of CTMP1 and CTMP2 were discovered separately, a review to summarize and connect these findings is essential. The current review delineates the intricate complexity of CTMP regulation across different metabolic pathways and encapsulates the principal discoveries concerning CTMP until the present day.

Roles of THEM4 in the Akt pathway: a double-edged sword

The protein kinase B (Akt) pathway can regulate the growth, proliferation, and metabolism of tumor cells and stem cells through the activation of multiple downstream target genes, thus affecting the development and treatment of a range of diseases. Thioesterase superfamily member 4 (THEM4), a member of the thioesterase superfamily, is one of the Akt kinase-binding proteins. Some studies on the mechanism of cancers and other diseases have shown that THEM4 binds to Akt to regulate its phosphorylation. Initially, THEM4 was considered an endogenous inhibitor of Akt, which can inhibit the phosphorylation of Akt in diseases such as lung cancer, pancreatic cancer, and liver cancer, but subsequently, THEM4 was shown to promote the proliferation of tumor cells by positively regulating Akt activity in breast cancer and nasopharyngeal carcinoma, which contradicts previous findings. Considering these two distinct views, this review summarizes the important roles of THEM4 in the Akt pathway, focusing on THEM4 as an Akt-binding protein and its regulatory relationship with Akt phosphorylation in various diseases, especially cancer. This work provides a better understanding of the roles of THEM4 combined with Akt in the treatment of diseases.

Progress of the acyl-Coenzyme A thioester hydrolase family in cancer

In recent years, the acyl-Coenzyme A thioester hydrolase family (ACOTs) has received wide attention as a key link in lipid metabolism. This family is a class of enzymes that catalyze the hydrolysis of fatty acyl-Coenzyme A, disrupting the thioester bond present within acyl-CoA ester molecules to produce free fatty acids (FFA) and the corresponding coenzyme A (CoA). Such enzymes play a very important role in lipid metabolism through maintaining appropriate levels of intracellular FFA and fatty acyl-CoA as well as CoA. It is broadly divided into two distinct subgroups, the type-I α/β-hydrolase fold enzyme superfamily and the type-II 'hot dog' fold superfamily. There are currently four human type-I genes and eight human type-II genes. Although the two subgroups catalyze the same reaction, they are not structurally similar, do not share the same sequence homology, and differ greatly in protein executive functions. This review summarizes the classification of the acyl-CoA thioester hydrolase family, an overview of the structural sequences, and advances in digestive, respiratory, and urinary systemic tumors. In order to explore potential specific drug targets and effective interventions, to provide new strategies for tumor prevention and treatment.

Carboxyl-terminal modulator protein facilitates tumor metastasis in triple-negative breast cancer

Currently, the survival rate for breast cancer is more than 90%, but once the cancer cells metastasize to distal organs, the survival rate is dramatically reduced, to less than 30%. Triple-negative breast cancer accounts for 15-20% of all breast cancers. Triple-negative breast cancer (TNBC) is associated with poor prognostic and diagnostic outcomes due to the limiting therapeutic strategies, relative to non-TNBC breast cancers. Therefore, the development of targeted therapy for TNBC metastasis remains an urgent issue. In this study, high Carboxyl-terminal modulator protein (CTMP) is significantly associated with recurrence and disease-free survival rate in TNBC patients. Overexpression of CTMP promotes migration and invasion abilities in BT549 cells. Down-regulating of CTMP expression inhibits migration and invasion abilities in MDA-MB-231 cells. In vivo inoculation of high-CTMP cells enhances distant metastasis in mice. The metastasis incidence rate is decreased in mice injected with CTMP-downregulating MDA-MB-231 cells. Gene expression microarray analysis indicates the Akt-dependent pathway is significantly enhanced in CTMP overexpressing cells compared to the parental cells. Blocking Akt activation via Akt inhibitor treatment or co-expression of the dominant-negative form of Akt proteins successfully abolishes the CTMP mediating invasion in TNBC cells. Our findings suggest that CTMP is a potential diagnostic marker for recurrence and poor disease-free survival in TNBC patients. CTMP promotes TNBC metastasis via the Akt-activation-dependent pathway.

Claudin-1 mediates progression by regulating EMT through AMPK/TGF-β signaling in head and neck squamous cell carcinoma

Claudin-1 (CLDN1), a major component of tight junction complexes in the epithelium, maintains cellular polarity, and plays a critical role in cell-to-cell communication as well as epithelial cell homeostasis. Although the role of CLDN1 has been widely studied in cancer, its role in the progression and the exact regulatory mechanisms, remain controversial. Using next-generation sequencing, we first analyzed the expression profiles of tumor/non-tumor paired tissue in patients with head and neck squamous cell carcinoma (HNSC) from public and local cohorts and found out that CLDN1 is upregulated in tumors compared to normal tissues. Next, its correlation with lymph node metastasis and poor prognosis was validated in the retrospective cohort, which collectively suggests CLDN1 as an oncogene in HNSC. As expected, the knockdown of CLDN1 inhibited invasive phenotypes by downregulating epithelial-to-mesenchymal transition (EMT) in vitro. To ascertain the regulatory mechanism of CLDN1 in HNSC analysis of GO term enrichment, KEGG pathways, and curated gene sets were used. As a result, CLDN1 was negatively associated with AMP-activated protein kinase (AMPK) and positively associated with transforming growth factor-β (TGF-β) signaling. In vitro mechanistic assay showed that CLDN1 inhibited AMPK phosphorylation by regulating AMPK upstream phosphatases, which led to inhibition of Smad2 activity. Intriguingly, the invasive phenotype of cancer cells increased by CLDN1 overexpression was rescued by AMPK activation, indicating a role of the CLDN1/AMPK/TGF-β/EMT cascade in HNSC. Consistently in vivo, CLDN1 suppression significantly inhibited the tumor growth, with elevated AMPK expression, suggesting the novel observation of oncogenic CLDN1-AMPK signaling in HNSC.

Mitochondrial protein LETM1 and its-mediated CTMP are potential therapeutic targets for endometrial cancer

Leucine zipper/EF hand-containing transmembrane-1 (LETM1) is an important mitochondrial protein, while its function in endometrial cancer remains unknown. This study aimed to explore the function of LETM1 in endometrial cancer and reveal the underlying mechanisms involving carboxy-terminal modulator protein (CTMP). Immunohistochemistry was performed to detect the expression of LETM1 and CTMP in normal, atypical hyperplastic and endometrial cancer endometrial tissues. LETM1 and CTMP were silenced in two endometrial cancer cell lines (ISK and KLE), which were verified by western blot. Cell viability, colony number, migration and invasion were detected by cell counting kit-8, colony formation, wound healing and trans-well assays, respectively. A xenograft mouse model was established to determine the antitumor potential of LETM1/CTMP silencing in vivo . In addition, CTMP was overexpressed to evaluate its regulatory relationship with LETM1 in endometrial cancer cells. The expression of LETM1 and CTMP proteins were higher in endometrial cancer tissues than atypical hyperplastic tissues and were higher in atypical hyperplastic tissues than normal tissues. LETM1 and CTMP were also upregulated in ISK and KLE cells. Silencing of LETM1 or CTMP could decrease the viability, colony number, migration and invasion of endometrial cancer cells and the weight and volume of tumor xenografts. In addition, CTMP was downregulated by LETM1 silencing in KLE cells, and its overexpression enhanced the malignant characteristics of si-LETM1-transfected KLE cells. Silencing of LETM1 inhibits the malignant progression of endometrial cancer through downregulating CTMP.

Targeting Akt in cancer for precision therapy

Biomarkers-guided precision therapeutics has revolutionized the clinical development and administration of molecular-targeted anticancer agents. Tailored precision cancer therapy exhibits better response rate compared to unselective treatment. Protein kinases have critical roles in cell signaling, metabolism, proliferation, survival and migration. Aberrant activation of protein kinases is critical for tumor growth and progression. Hence, protein kinases are key targets for molecular targeted cancer therapy. The serine/threonine kinase Akt is frequently activated in various types of cancer. Activation of Akt promotes tumor progression and drug resistance. Since the first Akt inhibitor was reported in 2000, many Akt inhibitors have been developed and evaluated in either early or late stage of clinical trials, which take advantage of liquid biopsy and genomic or molecular profiling to realize personalized cancer therapy. Two inhibitors, capivasertib and ipatasertib, are being tested in phase III clinical trials for cancer therapy. Here, we highlight recent progress of Akt signaling pathway, review the up-to-date data from clinical studies of Akt inhibitors and discuss the potential biomarkers that may help personalized treatment of cancer with Akt inhibitors. In addition, we also discuss how Akt may confer the vulnerability of cancer cells to some kinds of anticancer agents.

Enolase-phosphatase 1 acts as an oncogenic driver in glioma

Enolase-phosphatase 1 (ENOPH1), a newly identified enzyme involved in l-methionine biosynthesis, is associated with anxiety and depression. In this study, ENOPH1 was found to play a crucial role in promoting the proliferation and migration of glioma cells. Among high-grade glioma patients, the overall survival of the group showing high ENOPH1 expression was shorter than that of the group showing low ENOPH1 expression. ENOPH1 knockdown inhibited glioma cell proliferation and migration. In parallel, ENOPH1 knockdown suppressed tumor growth capacity and prolonged survival in an orthotopic glioma model. Mechanistically, we found that ENOPH1 activates the PI3K/AKT/mTOR signaling pathway by regulating THEM4. In conclusion, ENOPH1 is an important mediator that promotes glioma cell proliferation and migration.

A novel genomic-clinicopathologic nomogram to improve prognosis prediction of hepatocellular carcinoma

There is a lack of precise and clinical accessible model to predict the prognosis of hepatocellular carcinoma (HCC) in clinic practice currently. Here, an inclusive nomogram was developed by integrating genomic markers and clinicopathologic factors for predicting the outcome of patients with HCC. A total of 365 samples of HCC were obtained from the Cancer Genome Atlas (TCGA) database. The LASSO analysis was carried out to identify HCC-related mRNAs, and the multivariate Cox regression analysis was used to construct a genomic-clinicopathologic nomogram. As results, 9 mRNAs were finally identified as prognostic indicators, including RGCC, CDH15, XRN2, RAB3IL1, THEM4, PIF1, MANBA, FKTN and GABARAPL1, and used to establish a 9-mRNA classifier. Additionally, an inclusive nomogram was built up by combining the 9-mRNA classifier (P < 0.001) and clinicopathologic factors including age (P = 0.006) and metastasis (P < 0.001) to predict the mortality of HCC patients. Time-dependent receiver operating characteristic, index of concordance and calibration analyses indicated favorable accuracy of the model. Decision curve analysis suggested that appropriate intervention according to the established nomogram will bring net benefit when threshold probability was above 25%. The genomic-clinicopathologic model could be a reliable tool for predicting the mortality, helping determining the individualized treatment and probably improving HCC survival.

Association between Circulating Fibroblast Growth Factor 21 and Aggressiveness in Thyroid Cancer

Fibroblast growth factor 21 (FGF21) plays important roles in regulating glucose, lipid, and energy metabolism; however, its effects in tumors remain poorly understood. To understand the role of FGF21 in regulating tumor aggressiveness in thyroid cancer, serum levels of FGF21 were measured in healthy subjects and patients with papillary thyroid cancer (PTC), and expression levels of FGF21, FGF receptors (FGFRs), and β-klotho (KLB) were investigated in human thyroid tissues. The cell viability, migrating cells, and invading cells were measured in PTC cells after treatment with recombinant FGF21. Higher serum levels of FGF21 were found in patients with thyroid cancer than in control participants, and were significantly associated with body mass index (BMI), fasting glucose levels, triglyceride levels, tumor stage, lymphovascular invasion, and recurrence. Serum FGF21 levels were positively correlated with the BMI in patients with PTC, and significantly associated with recurrence. Recombinant FGF21 led to tumor aggressiveness via activation of the FGFR signaling axis and epithelial-to-mesenchymal transition (EMT) signaling in PTC cells, and AZD4547, an FGFR tyrosine kinase inhibitor, attenuated the effects of FGF21. Hence, FGF21 may be a new biomarker for predicting tumor progression, and targeting FGFR may be a novel therapy for the treatment of obese patients with PTC.

LAMB3 is associated with disease progression and cisplatin cytotoxic sensitivity in head and neck squamous cell carcinoma

OBJECTIVES

Laminin subunit beta-3 (LAMB3) is a major component of the basement membrane zone. In our study, we investigated the role of LAMB3 in head and neck squamous cell carcinoma (HNSCC) progression and its clinical implication as a prognostic biomarker.

MATERIALS AND METHODS

A retrospective analysis of 100 patients with HNSCC who had undergone curative surgery from 1999 to 2011 was performed. We evaluated LAMB3 expression by immunohistochemistry and its associations with clinicopathological characteristics and survival. For functional in vitro analyses, cell proliferation, migration, and invasion and western blot assays were performed following LAMB3 suppression. In addition, the role of LAMB3 in cisplatin-induced cytotoxicity was clarified by measuring cell proliferation.

RESULTS

LAMB3 expression was up-regulated in HNSCC cell lines and patient tissues. High LAMB3 expression was significantly associated with positive lymph node metastasis (odds ratio: 6.316; P < 0.001) and poor prognosis in patients with HNSCC. LAMB3 suppression reduced cell migration/invasion via down-regulation of epithelial-to-mesenchymal transition-associated proteins (Vimentin and Slug). Moreover, LAMB3 suppression increased cisplatin cytotoxicity in HNSCC cells.

CONCLUSION

Our findings indicate that LAMB3 may be used as a prognostic biomarker in HNSCC and support that LAMB3 silencing could induce the sensitivity of anti-cancer drugs such as cisplatin.

Carboxyl-Terminal Modulator Protein Ameliorates Pathological Cardiac Hypertrophy by Suppressing the Protein Kinase B Signaling Pathway

Background

Carboxyl‐terminal modulator protein (CTMP) has been implicated in cancer, brain injury, and obesity. However, the role of CTMP in pathological cardiac hypertrophy has not been identified.

Methods and Results

In this study, decreased expression of CTMP was observed in both human failing hearts and murine hypertrophied hearts. To further explore the potential involvement of CTMP in pathological cardiac hypertrophy, cardiac‐specific CTMP knockout and overexpression mice were generated. In vivo experiments revealed that CTMP deficiency exacerbated the cardiac hypertrophy, fibrosis, and function induced by pressure overload, whereas CTMP overexpression alleviated the response to hypertrophic stimuli. Consistent with the in vivo results, adenovirus‐mediated gain‐of‐function or loss‐of‐function experiments showed that CTMP also exerted a protective effect against hypertrophic responses to angiotensin II in vitro. Mechanistically, CTMP ameliorated pathological cardiac hypertrophy through the blockade of the protein kinase B signaling pathway. Moreover, inhibition of protein kinase B activation with LY294002 rescued the deteriorated effect in aortic banding–treated cardiac‐specific CTMP knockout mice.

Conclusions

Taken together, these findings imply, for the first time, that increasing the cardiac expression of CTMP may be a novel therapeutic strategy for pathological cardiac hypertrophy.

AKT1 restricts the invasive capacity of head and neck carcinoma cells harboring a constitutively active PI3 kinase activity

Background

In mammals, the AKT/PKB protein kinase family comprises three members (AKT1–3). PI3-Kinase (PI3K), a key oncogene involved in a wide variety of cancers, drives AKT activity. Constitutive activation of the PI3K/AKT pathway has been associated with tumorigenic properties including uncontrolled cell proliferation and survival, angiogenesis, promotion of cellular motility, invasiveness and metastasis. However, AKT1 activity has also been recently shown to repress the invasive properties of breast cancer cells in specific contexts.

Methods

This study used both pharmacological and shRNA approaches to inhibit AKT function, microscopy to characterize the cellular morphology, 3D spheroid models to assess migratory and invasive cellular capacities and a phenotypic screening approach based on electrical properties of the cells.

Results

Here we demonstrate that the alternative action of AKT1 on invasive properties of breast cancers can be extended to head and neck carcinomas, which exhibit constitutive activation of the PI3K/AKT pathway. Indeed, inhibition of AKT1 function by shRNA or a specific pharmacological inhibitor resulted in cellular spreading and an invasive phenotype. A phenotypic screening approach based on cellular electrical properties corroborated microscopic observations and provides a foundation for future high-throughput screening studies. This technique further showed that the inhibition of AKT1 signaling is phenocopied by blocking the mTORC1 pathway with rapamycin.

Conclusion

Our study suggests that the repressive action of PI3K/AKT1 on cellular invasive properties may be a mechanism common to several cancers. Current and future studies involving AKT inhibitors must therefore consider this property to prevent metastases and consequently to improve survival.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4169-0) contains supplementary material, which is available to authorized users.

Deactivating Fatty Acids: Acyl-CoA Thioesterase-Mediated Control of Lipid Metabolism

The cellular uptake of free fatty acids (FFA) is followed by esterification to coenzyme A (CoA), generating fatty acyl-CoAs that are substrates for oxidation or incorporation into complex lipids. Acyl-CoA thioesterases (ACOTs) constitute a family of enzymes that hydrolyze fatty acyl-CoAs to form FFA and CoA. Although biochemically and biophysically well characterized, the metabolic functions of these enzymes remain incompletely understood. Existing evidence suggests regulatory roles in controlling rates of peroxisomal and mitochondrial fatty acyl-CoA oxidation, as well as in the subcellular trafficking of fatty acids. Emerging data implicate ACOTs in the pathogenesis of metabolic diseases, suggesting that better understanding their pathobiology could reveal unique targets in the management of obesity, diabetes, and nonalcoholic fatty liver disease.