α2δ1 may be a potential marker for cancer stem cell in laryngeal squamous cell carcinoma

Role of the Ca2+ channel α2δ-1 auxiliary subunit in proliferation and migration of human glioblastoma cells

The overexpression of α2δ-1 is related to the development and degree of malignancy of diverse types of cancer. This protein is an auxiliary subunit of voltage-gated Ca2+ (CaV) channels, whose expression favors the trafficking of the main pore-forming subunit of the channel complex (α1) to the plasma membrane, thereby generating an increase in Ca2+ entry. Interestingly, TLR-4, a protein belonging to the family of toll-like receptors that participate in the inflammatory response and the transcription factor Sp1, have been linked to the progression of glioblastoma multiforme (GBM). Therefore, this report aimed to evaluate the role of the α2δ-1 subunit in the progression of GBM and investigate whether Sp1 regulates its expression after the activation of TLR-4. To this end, the expression of α2δ-1, TLR-4, and Sp1 was assessed in the U87 human glioblastoma cell line, and proliferation and migration assays were conducted using different agonists and antagonists. The actions of α2δ-1 were also investigated using overexpression and knockdown strategies. Initial luciferase assays and Western blot analyses showed that the activation of TLR-4 favors the transcription and expression of α2δ-1, which promoted the proliferation and migration of the U87 cells. Consistent with this, overexpression of α2δ-1, Sp1, and TLR-4 increased cell proliferation and migration, while their knockdown with specific siRNAs abrogated these actions. Our data also suggest that TLR-4-mediated regulation of α2δ-1 expression occurs through the NF-kB signaling pathway. Together, these findings strongly suggest that the activation of TLR-4 increases the expression of α2δ-1 in U87 cells, favoring their proliferative and migratory potential, which might eventually provide a theoretical basis to examine novel biomarkers and molecular targets for the diagnosis and treatment of GBM.

Store-Operated Calcium Entry and Its Implications in Cancer Stem Cells

Tumors are composed by a heterogeneous population of cells. Among them, a sub-population of cells, termed cancer stem cells, exhibit stemness features, such as self-renewal capabilities, disposition to differentiate to a more proliferative state, and chemotherapy resistance, processes that are all mediated by Ca²⁺. Ca²⁺ homeostasis is vital for several physiological processes, and alterations in the patterns of expressions of the proteins and molecules that modulate it have recently become a cancer hallmark. Store-operated Ca²⁺ entry is a major mechanism for Ca²⁺ entry from the extracellular medium in non-excitable cells that leads to increases in the cytosolic Ca²⁺ concentration required for several processes, including cancer stem cell properties. Here, we focus on the participation of STIM, Orai, and TRPC proteins, the store-operated Ca²⁺ entry key components, in cancer stem cell biology and tumorigenesis.

Prognostic value of α2δ1 in hypopharyngeal carcinoma: A retrospective study

Voltage-dependent calcium channel subunit alpha-2/delta-1 (α2δ1) has been identified as a marker of cancer stem cells in multiple malignant tumor types. However, α2δ1’s role in the prognosis of hypopharyngeal squamous cell carcinoma (HSCC) was not reported. In our study, ten pairs of HSCC and peritumoral normal tissues were used for immunohistochemistry assessment. And α2δ1 expression levels of 34 more HSCC samples were also evaluated, represented by the integral optic density using Image-Pro Plus. Clinicopathological associations and prognostic value of α2δ1 were analyzed. As a result, α2δ1 expression was frequently increased in HSCC tissues. Although the correlation between patients’ clinicopathological characteristics and their α2δ1 expression levels was not significant, α2δ1 expression was significantly correlated with unfavorable overall survival (OS) (P = 0.018) and progression-free survival (PFS) (P = 0.023). Univariate and multivariate cox regression analyses suggested α2δ1’s prognostic role for both OS and PFS (P = 0.013 and 0.011, respectively). This study specifically demonstrated that α2δ1 regularly increased in HSCC compared with peritumoral tissues, and α2δ1 could act as a promising prognostic marker in HSCC patients.

Calcium Channel Subunit α2δ-1 as a Potential Biomarker Reflecting Illness Severity and Neuroinflammation in Patients with Acute Ischemic Stroke

BACKGROUND

Voltage-gated calcium channels (VGCCs) dysfunction is involved in the development of acute ischemic stroke (AIS). As a subunit of VGCC complexes, we detected the levels of α2δ-1 subunit in serum and cerebrospinal fluid (CSF) specimens from AIS patients.

METHODS

The study included 105 patients with first-ever AIS, who were admitted within 48 hours after stroke onset. The serum and CSF levels of α2δ-1 were measured with ELISA and the severity of AIS patients was evaluated according to the National Institutes of Health Stroke Scale (NIHSS) score. The cerebral infarct volume was calculated through the Pullicino formula based on the cranial CT or MRI scan. C-reactive protein (CRP) and serum amyloid A (SAA) were measured using the latex-enhanced immunoturbidimetric assay.

RESULTS

Compared to the control subjects, the serum α2δ-1 level was significantly increased in AIS patients with large infarct volume and in severe AIS cases with high NIHSS score, which correlated positively with the inflammatory markers CRP and SAA. Furthermore, the concentration of α2δ-1 in CSF was elevated with the infarct volume, which was higher in severe AIS patients.

CONCLUSION

Our study suggests that the increased α2δ-1 levels in serum and CSF specimens may be used as a potential marker for reflecting VGCCs dysfunction, illness severity and neuroinflammation in AIS patients.

Amlodipine and Verapamil, Voltage-Gated Ca2+ Channel Inhibitors, Suppressed the Growth of Gastric Cancer Stem Cells

BACKGROUND

The membrane transporters activated in cancer stem cells (CSCs) are the target of novel cancer therapies for gastric cancer. The present study investigated ion channel expression profiles in gastric CSCs (GCSCs).

METHODS

Cells strongly expressing CD44 were separated from MKN74 cells, a human gastric cancer cell line, by fluorescence-activated cell sorting (FACS), and GCSCs were identified based on tumorsphere formation. Gene expression profiles in GCSCs were examined by a microarray analysis.

RESULTS

Among MKN74 cells, CD44 messenger RNA levels were higher in CSCs than in non-CSCs. These CSCs also exhibited resistance to cisplatin. The microarray analysis revealed that the expression of several genes related to voltage-gated Ca²⁺ channels (VGCCs), including CACNA2D1 and CACNB4, was upregulated. The cytotoxicities of the CACNA2D1 inhibitor amlodipine and the CACNB4 inhibitor verapamil were greater at lower concentrations in CSCs than in non-CSCs, and markedly reduced tumorsphere numbers. Tumor volumes were significantly smaller in a xenograft nude mouse model treated with amlodipine or verapamil in combination with cisplatin than in that treated with cisplatin alone.

CONCLUSIONS

The present results indicate that VGCCs play a role in maintaining CSCs, and demonstrated the potential of their specific inhibitors, amlodipine and verapamil, as targeted therapeutic agents against gastric cancer.

MicroRNA-107 inhibits proliferation and invasion of laryngeal squamous cell carcinoma cells by targeting CACNA2D1 in vitro

Our previous studies have confirmed that α2δ1 has the potential to function as a cancer stem cell marker, and CACNA2D1 is the coding gene of α2δ1. But it is unclear how microRNAs regulate the expression of the CACNA2D1 gene in laryngeal cancer cells. We detected the expressions of α2δ1 protein, microRNA-107, and CACNA2D1 in 40 pairs of laryngeal cancer tissues and adjacent normal tissues. Laryngeal squamous cell carcinoma cells, TU212 and TU686, were cultured and transfected in the blank control group, the agomiR negative control group, the agomiR-107 group, the antagomiR negative control group, or the antagomiR-107 group, and the dual-luciferase reporter assay was employed to assess the regulatory effect of microRNA-107 on CACNA2D1. Then, the effects of microRNA-107 on the biological function of laryngeal squamous cell carcinoma cells were detected by qRT-PCR, Western blot, MTT, cell migration/invasion assay, and cell colony-formation assay. Our data suggested that the protein level of α2δ1, encoded by CACNA2D1, in laryngeal carcinoma tissues was higher than that in adjacent normal tissues, while the expression of microRNA-107 was significantly decreased in laryngeal carcinoma tissues. The dual-luciferase reporter gene assay confirmed that microRNA-107 bound to the 3′-UTR two positions (202-209, 902-908) of CACNA2D1 mRNA. Moreover, the expression of CACNA2D1 and α2δ1 protein were significantly decreased in TU212 and TU686 cells transfected with microRNA-107 expression vectors (P < 0.05), and proliferation, clone formation, migration, and invasion of these cells were also reduced. Furthermore, after knocking down microRNA-107, exactly opposite results were obtained. Overexpression of microRNA-107 can inhibit the proliferation and invasion of laryngeal carcinoma cells in vitro.

Evaluation of diagnostic accuracy of serum calcium channel α2δ1 subunit in hepatocellular carcinoma-related cirrhosis

Background

Hepatocellular carcinoma (HCC) is one of the commonest malignancies worldwide that carries a bad prognosis particularly in Egypt due to the high prevalence of HCV burden. Late diagnosis of HCC especially in cirrhosis suffering-liver is one of the causes that worsen HCC outcome. Identification of molecular pathways of HCC will open the gate for early diagnosis and effective management. Oscillation of calcium controlled by the α2δ1 subunit has been proposed as one of the mechanisms in tumor-initiating cell properties of HCC. In this study, we aim to evaluate the serum α2δ1 subunit level as a biological marker for HCC. A total of 90 participants were enrolled, 40 patients with HCC, 40 patients with cirrhosis, and 10 healthy volunteers; serum level of α2δ1 was assessed in all participants with ELISA

Results

The mean serum levels of α2δ1 were significantly higher in HCC group (19.53 ± 6.87 ng/dL) than cirrhotic (6.24 ± 2.64 ng/dL) and control groups (0.67 ± 0.48 ng/dL) (P = 0.001). There was no significance between α2δ1 and etiology of liver disease as viral (HCV, HBV) or non-viral (P = 0.14).

Conclusion

α2δ1 subunit may serve as a potential non-invasive marker with excellent sensitivity for diagnosis of HCC regardless of the etiology of liver disease.

The Cancer Stem Cell in Hepatocellular Carcinoma

The recognition of intra-tumoral cellular heterogeneity has given way to the concept of the cancer stem cell (CSC). According to this concept, CSCs are able to self-renew and differentiate into all of the cancer cell lineages present within the tumor, placing the CSC at the top of a hierarchical tree. The observation that these cells—in contrast to bulk tumor cells—are able to exclusively initiate new tumors, initiate metastatic spread and resist chemotherapy implies that CSCs are solely responsible for tumor recurrence and should be therapeutically targeted. Toward this end, dissecting and understanding the biology of CSCs should translate into new clinical therapeutic approaches. In this article, we review the CSC concept in cancer, with a special focus on hepatocellular carcinoma.

Ion Channel Dysregulation in Head and Neck Cancers: Perspectives for Clinical Application

Head and neck cancers are a highly complex and heterogeneous group of malignancies that involve very diverse anatomical structures and distinct aetiological factors, treatments and clinical outcomes. Among them, head and neck squamous cell carcinomas (HNSCC) are predominant and the sixth most common cancer worldwide with still low survival rates. Omic technologies have unravelled the intricacies of tumour biology, harbouring a large diversity of genetic and molecular changes to drive the carcinogenesis process. Nonetheless, this remarkable heterogeneity of molecular alterations opens up an immense opportunity to discover novel biomarkers and develop molecular-targeted therapies. Increasing evidence demonstrates that dysregulation of ion channel expression and/or function is frequently and commonly observed in a variety of cancers from different origin. As a consequence, the concept of ion channels as potential membrane therapeutic targets and/or biomarkers for cancer diagnosis and prognosis has attracted growing attention. This chapter intends to comprehensively and critically review the current state-of-art ion channel dysregulation specifically focusing on head and neck cancers and to formulate the major challenges and research needs to translate this knowledge into clinical application. Based on current reported data, various voltage-gated potassium (K_v) channels (i.e. K_v3.4, K_v10.1 and K_v11.1) have been found frequently aberrantly expressed in HNSCC as well as precancerous lesions and are highlighted as clinically and biologically relevant features in both early stages of tumourigenesis and late stages of disease progression. More importantly, they also emerge as promising candidates as cancer risk markers, tumour markers and potential anti-proliferative and anti-metastatic targets for therapeutic interventions; however, the oncogenic properties seem to be independent of their ion-conducting function.