The effect of down regulation of calcineurin Aα by lentiviral vector-mediated RNAi on the biological behavior of small-cell lung cancer and its bone metastasis

Bibliometric analysis of bone metastases from lung cancer research from 2004 to 2023

Background

Bone metastases of lung cancer (BMLC) severely diminish patients' quality of life due to bone-related events, and the lack of clear guidelines globally regarding medical and surgical treatment significantly reduces patient survival. While knowledge about BMLC has grown exponentially over the past two decades, a comprehensive and objective bibliometric analysis remains absent.

Methods

A comprehensive bibliometric analysis was conducted on relevant literature on BMLC extracted from the Web of Science database from 2004 to 2023 by Biblioshiny, VOSviewer, Scimago Graphica, CiteSpace, and Microsoft Office Excel Professional Plus 2016 software. 936 papers related to BMLC were extracted from the Web of Science Core Collection (WoSCC). The number of publications, countries, institutions, global collaborations, authors, journals, keywords, thematic trends, and cited references were then visualized. Finally, the research status and development direction in the last 20 years were analyzed.

Results

This study included a total of 936 papers on BMLC from 2004 to 2023. There has been a steady increase in global publications each year, peaking in 2021. China had the highest number of publications, followed by Japan and the United States. Additionally, China had the most citations with an H-index of 35, while the US followed with an H-index of 34, highlighting their significant contributions to the field. "Frontiers in Oncology" had the highest number of publications. CiteSpace analysis identified "lung cancer," "bone metastasis," and "survival" as the top high-frequency keywords, encapsulating the core research focus. Keyword clustering analysis revealed six main clusters representing the primary research directions. Burst analysis of keywords showed that "skeletal complications" had the highest burst intensity from 2005 to 2013, while recent research trends include "immunotherapy" and "denosumab," with bursts from 2021 to 2023. Trend topic analysis indicated that "non-small cell lung cancer," "immunotherapy," and "immune checkpoint inhibitors" represent the cutting-edge research directions in this field.

Conclusion

This article reveals the current status and trend of research on BMLC, which is increasing worldwide. China and the United States have contributed the most, but international cooperative research on BMLC should be strengthened. The pathogenesis, early prevention, and individualized treatment of BMLC need to be strengthened for further study, and immunotherapy is the next hotspot of lung cancer bone metastasis research.

Roles of calcium signaling in cancer metastasis to bone

Bone metastasis is a frequent complication for cancers and an important reason for the mortality in cancer patients. After surviving in bone, cancer cells can cause severe pain, life-threatening hypercalcemia, pathologic fractures, spinal cord compression, and even death. However, the underlying mechanisms of bone metastasis were not clear. The role of calcium (Ca2+) in cancer cell proliferation, migration, and invasion has been well established. Interestingly, emerging evidence indicates that Ca2+ signaling played a key role in bone metastasis, for it not only promotes cancer progression but also mediates osteoclasts and osteoblasts differentiation. Therefore, Ca2+ signaling has emerged as a novel therapeutical target for cancer bone metastasis treatments. Here, the role of Ca2+ channels and Ca2+-binding proteins including calmodulin and Ca2+-sensing receptor in bone metastasis, and the perspective of anti-cancer bone metastasis therapeutics via targeting the Ca2+ signaling pathway are summarized.

Calcineurin in development and disease

Calcineurin (CaN) is a unique calcium (Ca²⁺) and calmodulin (CaM)-dependent serine/threonine phosphatase that becomes activated in the presence of increased intracellular Ca²⁺ level. CaN then functions to dephosphorylate target substrates including various transcription factors, receptors, and channels. Once activated, the CaN signaling pathway participates in the development of multiple organs as well as the onset and progression of various diseases via regulation of different cellular processes. Here, we review current literature regarding the structural and functional properties of CaN, highlighting its crucial role in the development and pathogenesis of immune system disorders, neurodegenerative diseases, kidney disease, cardiomyopathy and cancer.

Current progress and mechanisms of bone metastasis in lung cancer: a narrative review

Lung cancer is a kind of malignant tumor with rapid progression and poor prognosis. Distant metastasis has been the main cause of mortality among lung cancer patients. Bone is one of the most common sites. Among all lung cancer patients with bone metastasis, most of them are osteolytic metastasis. Some serious clinical consequences like bone pain, pathological fractures, spinal instability, spinal cord compression and hypercalcemia occur as well. Since the severity of bone metastasis in lung cancer, it is undoubtedly necessary to know how lung cancer spread to bone, how can we diagnose it and how can we treat it. Here, we reviewed the process, possible mechanisms, diagnosis methods and current treatment of bone metastasis in lung cancer. We divided the process of bone metastasis in lung cancer into three steps: tumor invasion, tumor cell migration and invasion in bone tissue. It may be influenced by genetic factors, microenvironment and other adhesion-related factors. Imaging examination, laboratory examination, and pathological examination are used to diagnose lung cancer metastasis to bone. Surgery, radiotherapy, targeted therapy, bisphosphonate, radiation therapy and chemotherapy are the common clinical treatment methods currently. We also found some problems remained to be solved. For example, drugs for skeletal related events mainly target on osteoclasts at present, which increase the ratio of patients in osteoporosis and fractures in the long term. In all, this review provides the direction for future research on bone metastasis in lung cancer.

The Role of Calmodulin in Tumor Cell Migration, Invasiveness, and Metastasis

Calmodulin (CaM) is the principal Ca²⁺ sensor protein in all eukaryotic cells, that upon binding to target proteins transduces signals encoded by global or subcellular-specific changes of Ca²⁺ concentration within the cell. The Ca²⁺/CaM complex as well as Ca²⁺-free CaM modulate the activity of a vast number of enzymes, channels, signaling, adaptor and structural proteins, and hence the functionality of implicated signaling pathways, which control multiple cellular functions. A basic and important cellular function controlled by CaM in various ways is cell motility. Here we discuss the role of CaM-dependent systems involved in cell migration, tumor cell invasiveness, and metastasis development. Emphasis is given to phosphorylation/dephosphorylation events catalyzed by myosin light-chain kinase, CaM-dependent kinase-II, as well as other CaM-dependent kinases, and the CaM-dependent phosphatase calcineurin. In addition, the role of the CaM-regulated small GTPases Rac1 and Cdc42 (cell division cycle protein 42) as well as CaM-binding adaptor/scaffold proteins such as Grb7 (growth factor receptor bound protein 7), IQGAP (IQ motif containing GTPase activating protein) and AKAP12 (A kinase anchoring protein 12) will be reviewed. CaM-regulated mechanisms in cancer cells responsible for their greater migratory capacity compared to non-malignant cells, invasion of adjacent normal tissues and their systemic dissemination will be discussed, including closely linked processes such as the epithelial–mesenchymal transition and the activation of metalloproteases. This review covers as well the role of CaM in establishing metastatic foci in distant organs. Finally, the use of CaM antagonists and other blocking techniques to downregulate CaM-dependent systems aimed at preventing cancer cell invasiveness and metastasis development will be outlined.

Primary mucinous adenocarcinoma of the lung: A case report and review of the literature

Mucinous adenocarcinoma is an unusual histological type of lung cancer, and its clinicopathological feature is distinctive from that of other histopathological types of lung adenocarcinoma. Mucinous adenocarcinoma has a mucus-producing function, which explains its name. The present study reports a rare case of a mucus-producing adenocarcinoma of the lung. A 60-year-old Chinese female patient was diagnosed with mucinous adenocarcinoma of the lung, which manifested as respiratory symptoms, including fever, cough and expectoration. The patient received thoracic exploratory operation and right pneumonectomy, since the above respiratory symptoms seriously affected her daily life, and other inspections could not establish the diagnosis. Histopathology revealed no mutations in epidermal growth factor receptor. The patient received adjuvant chemotherapy using taxol and cisplatin. However, metastases in the left lung were detected 7 months after the operation. Pemetrexed and cisplatin were used as the second-line treatment. The patient survived 3 years after the initial diagnosis. The present study reports a rare mucus-producing adenocarcinoma of the lung, which is of bad prognosis. Therefore, further studies on this type of cancer are urgently required.

Overexpression of C16orf74 is involved in aggressive pancreatic cancers

Clinical outcome of pancreatic ductal adenocarcinoma (PDAC) has not been improved in the last three decades due to the lack of effective molecular-targeted drugs. To identify a novel therapeutic target for PDAC, we have performed genome-wide anamysis and found that Homo sapienschromosome 16 open reading frame 74 (C16orf74) was up-regulated in the vast majority of PDAC. Overexpression of C16orf74protein detected by immunohistochemical analysis was an independent prognostic factor for patients with PDAC. The knockdown of endogenous C16orf74 expression in the PDAC cell lines KLM-1 and PK-59 by vector-based small hairpin-RNA (shRNA) drastically attenuated the growth of those cells, whereas ectopic C16orf74 overexpression in HEK293T and NIH3T3 cells promoted cell growth and invasion, respectively. More importantly, the endogenous threonine 44 (T44)-phosphorylated form of C16orf74 interacted with the protein phosphatase 3 catalytic subunit alpha (PPP3CA) via the PDIIIT sequence in the PPP3CA-binding motif within the middle portion of C16orf74 in PDAC cells. The overexpression of mutants of C16orf74 lacking the PDIIIT sequence or T44 phosphorylation resulted in the suppression of invasive activity compared with wild-type C16orf74, indicating that their interaction should be indispensable for PDAC cell invasion. These results suggest that C16orf74 plays an important role for PDAC invasion and proliferation, and is a promising target for a specific treatment for patients with PDAC.

miR-335 inhibits small cell lung cancer bone metastases via IGF-IR and RANKL pathways

Small cell lung cancer (SCLC) is a rapidly progressing, incurable cancer that frequently spreads to bone. New insights are needed to identify therapeutic targets to prevent or retard SCLC metastatic progression. Human SCLC SBC-5 cells in mouse xenograft models home to skeletal and nonskeletal sites, whereas human SCLC SBC-3 cells only pervade nonskeletal sites. Because microRNAs (miRNA) often act as tumor regulators, we investigated their role in preclinical models of SCLC. miRNA expression profiling revealed selective and reduced expression of miRNA (miR)-335 and miR-29a in SBC-5 cells, compared with SBC-3 cells. In SBC-5 cells, miR-335 expression correlated with bone osteolytic lesions, whereas miR-29a expression did not. Overexpression of miR-335 in SBC-5 cells significantly reduced cell migration, invasion, proliferation, colony formation, and osteoclast induction in vitro. Importantly, in miR-335 overexpressing SBC-5 cell xenografts (n = 10), there were minimal osteolytic lesions in the majority of mice and none in three mice. Expression of RANK ligand (RANKL) and insulin-like growth factor-I receptor (IGF-IR), key mediators of bone metastases, were elevated in SBC-5 as compared with SBC-3 cells. Mechanistically, overexpression of miR-335 in SBC-5 cells reduced RANKL and IGF-IR expression. In conclusion, loss of miR-335 promoted SCLC metastatic skeletal lesions via deregulation of IGF-IR and RANKL pathways and was associated with metastatic osteolytic skeletal lesions.

IMPLICATIONS

These preclinical findings establish a need to pursue the role of miR-335 in human SCLC with metastatic skeletal disease.

MGr1-Ag promotes invasion and bone metastasis of small-cell lung cancer in vitro and in vivo

Bone metastasis of small-cell lung cancer (SCLC) usually occurs early in the progression of the disease. However, the molecular mechanism underlying bone metastasis is largely unknown. MGr1-Ag, a multifunction protein, has been suggested to play important roles in cell growth, differentiation and migration. In our present study, MGr1-Ag was found to be highly expressed in bone-metastatic SCLC cells (SBC-5 cell line) as compared with the expression in cells without bone-metastatic ability (SBC-3 cell line). Therefore, we hypothesized that MGr1-Ag is involved in bone metastasis of SCLC. Using a sense vector to upregulate MGr1-Ag expression in SBC-3 cells, we found that forced overexpression of MGr1-Ag enhanced cell invasion and migration in vitro and promoted bone metastases in vivo. Furthermore, specific siRNA-induced knockdown of MGr1-Ag expression in SBC-5 cells suppressed the potential of cell invasion and migration in vitro and dramatically decreased the number and sites of bone metastasis in vivo. We also found that MGr1-Ag induced SCLC cells to undergo epithelial-mesenchymal transition (EMT), as demonstrated by cell morphological changes, decreased expression of epithelial markers and increased expression of mesenchymal markers. Taken together, we conclude that MGr1-Ag promotes SCLC cell invasion and bone metastasis in vitro and in vivo, and that this is partially mediated via the EMT pathway.

Zinc finger E-box binding homeobox 1 promotes invasion and bone metastasis of small cell lung cancer in vitro and in vivo

Bone is one of the most frequent targets of small cell lung cancer (SCLC) metastasis and is closely associated with a poor prognosis, but the specific cellular gene alterations responsible for SCLC with bone metastasis are unclear. Zinc finger E-box binding homeobox 1 (ZEB1) as an E-box transcriptional repressor has been suggested that an important inducer of the epithelial-mesenchymal transition (EMT) and a promoter of tumor metastasis in colon, breast and lung cancers. However, the relationship between ZEB1 and SCLC with bone metastasis is unclear. In this study, ZEB1 was found to be highly expressed in bone-metastatic SCLC tissues and cell lines as compared with those that were non-metastatic (P < 0.05). Using a lentivirus RNA interference technique to knockdown ZEB1 expression in bone-metastatic SCLC cells (SBC-5 cell line), we found that ZEB1 siRNA could inhibit the invasive and migratory ability and decrease parathyroid hormone-related protein expression, as determined by invasion assays and enzyme-linked immunosorbent assays. Besides, ZEB1 siRNA significantly inhibited the bone metastasis of SBC-5 cells in vivo. Furthermore, overexpression of ZEB1 in SBC-3 cells, which demonstrate promoted bone-metastatic potential, dramatically promoted their invasive and migratory ability and parathyroid hormone-related protein expression as well as increased the number and sites of bone metastases in vivo compare to the control group. We also found that SBC-3 cells underwent EMT, as indicated by decreased epithelial markers and increased mesenchymal marker expression. Taken together, these results indicate that ZEB1 promoted the invasive ability and bone metastasis of SCLC cells, and that this was partially mediated via the EMT pathway.

Noninvasive monitoring of immunosuppressive drug efficacy to prevent rejection of intracerebral glial precursor allografts

The development of cell-based therapies opens up new avenues for treating a myriad of diseases of the central nervous system (CNS). While significant effort is being directed toward development of patient-specific, autologous transplantable cells, at present, the majority of cell transplantation studies performed clinically utilize allografts. In this context, the issue of graft rejection and immunoprotection is of key importance. In this study, we transplanted mouse glial-restricted progenitors into immunodeficient, immunocompetent, and immunosuppressed mice and monitored their survival noninvasively using bioluminescence imaging (BLI). With the use of serial BLI, we evaluated both the prevalence and dynamics of cell rejection. We demonstrate that allografts in immunocompetent mice were rejected at a rate of 69.2% (n = 13) indicating that graft tolerance is possible even without immunosuppression. Immunosuppression using a combination of rapamycin and FK506 or cyclosporin failed to fully protect the grafts. FK506 and rapamycin treatment resulted in a slight improvement of immunoprotection (22.2% rejected, n = 9) compared to cyclosporin A (55.6% rejected, n = 9); however, the difference was not significant. Notably, immunohistochemistry revealed leukocytes infiltrating the graft area in both rejecting and nonrejecting immunocompetent animals, but not in immunodeficient animals. The induction of an inflammatory process, even in surviving allografts, has implications for their long-term survival and functionality.