Hypoxia and Serum deprivation protected MiaPaCa-2 cells from KAI1-induced proliferation inhibition through autophagy pathway activation in solid tumors

A bioinformatics analysis, pre-clinical and clinical conception of autophagy in pancreatic cancer: Complexity and simplicity in crosstalk

Pancreatic cancer (PC) is a serious gastrointestinal tract disease for which the 5-year survival rate is less than 10%, even in developed countries such as the USA. The genomic profile alterations and dysregulated biological mechanisms commonly occur in PC. Macroautophagy/autophagy is a cell death process that is maintained at a basal level in physiological conditions, whereas its level often changes during tumorigenesis. The function of autophagy in human cancers is dual and can be oncogenic and onco-suppressor. Autophagy is a potent controller of tumorigenesis in PC. The supportive autophagy in PC escalates the growth rate of PC cells and its suppression can mediate cell death. Autophagy also determines the metastasis of PC cells, and it can control the EMT in affecting migration. Moreover, starvation and hypoxia can stimulate glycolysis, and glycolysis induction can be mediated by autophagy in enhancing tumorigenesis in PC. Furthermore, protective autophagy stimulates drug resistance and gemcitabine resistance in PC cells, and its inhibition can enhance radiosensitivity. Autophagy can degrade MHC-I to mediate immune evasion and also regulates polarization of macrophages in the tumor microenvironment. Modulation of autophagy activity is provided by silibinin, ursolic acid, chrysin and huaier in the treatment of PC. Non-coding RNAs are also controllers of autophagy in PC and its inhibition can improve therapy response in patients. Moreover, mitophagy shows dysregulation in PC, which can enhance the proliferation of PC cells. Therefore, a bioinformatics analysis demonstrates the dysregulation of autophagy-related proteins and genes in PC as biomarkers.

KAI1/CD82 gene and autotaxin-lysophosphatidic acid axis in gastrointestinal cancers

The KAI1/CD82 gene inhibits the metastasis of most tumors and is remarkably correlated with tumor invasion and prognosis. Cell metabolism dysregulation is an important cause of tumor occurrence, development, and metastasis. As one of the important characteristics of tumors, cell metabolism dysregulation is attracting increasing research attention. Phospholipids are an indispensable substance in the metabolism in various tumor cells. Phospholipid metabolites have become important cell signaling molecules. The pathological role of lysophosphatidic acid (LPA) in tumors was identified in the early 1990s. Currently, LPA inhibitors have entered clinical trials but are not yet used in clinical treatment. Autotaxin (ATX) has lysophospholipase D (lysoPLD) activity and can regulate LPA levels in vivo. The LPA receptor family and ATX/lysoPLD are abnormally expressed in various gastrointestinal tumors. According to our recent pre-experimental results, KAI1/CD82 might inhibit the migration and metastasis of cancer cells by regulating the ATX-LPA axis. However, no relevant research has been reported. Clarifying the mechanism of ATX-LPA in the inhibition of cancer metastasis by KAI1/CD82 will provide an important theoretical basis for targeted cancer therapy. In this paper, the molecular compositions of the KAI1/CD82 gene and the ATX-LPA axis, their physiological functions in tumors, and their roles in gastrointestinal cancers and target therapy are reviewed.

Effect of the Porcine STC-1 Gene on Autophagy and Mitochondrial Function as Induced by Serum Starvation

Stanniocalcin-1 (STC-1) is a glycoprotein hormone involved in calcium/phosphorus metabolism and direct inhibition of bone and muscle growth. The aim of this study was to investigate the STC-1 gene with respect to the regulatory mechanisms of porcine growth metabolic pathways involving autophagy. Western blotting was used to detect the expression of autophagy and mitochondrial function-related proteins, and flow cytometry was used to detect mitochondrial function-related. Changes in the autophagosome and mitochondrial were observed by electron microscopy. The expression of the autophagy-related proteins was detected by confocal microscopy. The results showed that Pink1, Parkin and LC3B expression was increased; SQSTM1/P62 expression was reduced. Electron microscopy revealed that the cells in the serum starvation group all produced autophagosomes. The fluorescence intensity of GFP-LC3B and GFP-Parkin increased. The Bax/Bcl-2 ratio, Pink1 and Parkin protein levels were profoundly reduced in the STC-KO. In addition, the increase in Mfn2, OPA1, DRP1 and LC3B proteins was attenuated; the increase in the apoptosis rate and amount of active oxygen was attenuated; the decrease in membrane potential; the decrease in ATP was reversed; the fluorescence intensity of GFP-LC3B and GFP-Parkin was increased. These results indicate that autophagy can be caused by serum starvation. Knocking out the porcine STC-1 gene had an obvious antiapoptotic effect on cells, the inhibition of serum starvation-induced autophagy. This is the first study to show that the porcine STC-1 gene confers self-protection in the absence of nutrients. To provide a theoretical basis for studying the effect of STC-1 on pig growth and development.

Modulation of cell physiology under hypoxia in pancreatic cancer

In solid tumors, the development of vasculature is, to some extent, slower than the proliferation of the different types of cells that form the tissue, both cancer and stroma cells. As a consequence, the oxygen availability is compromised and the tissue evolves toward a condition of hypoxia. The presence of hypoxia is variable depending on where the cells are localized, being less extreme at the periphery of the tumor and more severe in areas located deep within the tumor mass. Surprisingly, the cells do not die. Intracellular pathways that are critical for cell fate such as endoplasmic reticulum stress, apoptosis, autophagy, and others are all involved in cellular responses to the low oxygen availability and are orchestrated by hypoxia-inducible factor. Oxidative stress and inflammation are critical conditions that develop under hypoxia. Together with changes in cellular bioenergetics, all contribute to cell survival. Moreover, cell-to-cell interaction is established within the tumor such that cancer cells and the microenvironment maintain a bidirectional communication. Additionally, the release of extracellular vesicles, or exosomes, represents short and long loops that can convey important information regarding invasion and metastasis. As a result, the tumor grows and its malignancy increases. Currently, one of the most lethal tumors is pancreatic cancer. This paper reviews the most recent advances in the knowledge of how cells grow in a pancreatic tumor by adapting to hypoxia. Unmasking the physiological processes that help the tumor increase its size and their regulation will be of major relevance for the treatment of this deadly tumor.

KAI1 reverses the epithelial-mesenchymal transition in human pancreatic cancer cells

BACKGROUND

Epithelial-mesenchymal transition (EMT) plays an important role in pancreatic cancer (PC). In the present study, we investigated the effects of KAI1 gene overexpression on the EMT of human PC cell lines, MIA PaCa-2 and PACN-1.

METHODS

Plasmids overexpressing KAI1 and pCMV were transfected into MIA PaCa-2 and PACN-1 cells, respectively. After selection of differently transfected cells by G418, KAI1 protein levels were examined by Western blotting, and transfected cells were renamed as MIA PaCa-2-K, MIA PaCa-2-p, PACN-1-K and PACN-1-p. Wound healing and Transwell migration assays were then performed comparing the two groups of cells. EMT-related markers were analyzed by Western blotting.

RESULTS

The percentage of wound closure significantly decreased in MIA PaCa-2-K cells compared with MIA PaCa-2-p and MIA PaCa-2 cells after 24, 48 and 72 h (P < 0.05). In PACN-1-K cells, the percentage of wound closure significantly decreased as well (P < 0.05). Numbers of invading MIA PaCa-2, MIA PaCa-2-p and MIA PaCa-2-K cells were determined as 48.0 ± 15.4, 50.0 ± 12.4, and 12.0 ± 3.8, respectively. The corresponding numbers of invading PACN-1, PACN-1-p and PACN-1-K cells were 29.0 ± 10.6, 31.0 ± 11.4, and 8.0 ± 4.2, respectively. KAI1 overexpression induced a significant upregulation of E-cadherin and also significant downregulation of Snail, vimentin, matrix metalloproteinase 2 (MMP2) and MMP9 (all P < 0.05) in PC cells.

CONCLUSIONS

KAI1 reversed EMT-related marker expression and inhibited migration and invasion of PC cells. Thus, KAI1 might represent a novel potential therapeutic target for PC.

Hypoxia and serum deprivation induces glycan alterations in triple negative breast cancer cells

Triple negative breast cancer (TNBC) is a major global public health problem. The lack of targeted therapy and the elevated mortality evidence the need for better knowledge of the tumor biology. Hypoxia and aberrant glycosylation are associated with advanced stages of malignancy, tumor progression and treatment resistance. Importantly, serum deprivation regulates the invasive phenotype and favors TNBC cell survival. However, in TNBC, the role of hypoxia and serum deprivation in the regulation of glycosylation remains largely unknown. The effects of hypoxia and serum deprivation on the expression of glycosyltransferases and glycan profile were evaluated in the MDA-MB-231 cell line. We showed that the overexpression of HIF-1α was accompanied by acquisition of epithelial-mesenchimal transition features. Significant upregulation of fucosyl- and sialyltransferases involved in the synthesis of tumor-associated carbohydrate antigens was observed together with changes in fucosylation and sialylation detected by Aleuria aurantia lectin and Sambucus nigra agglutinin lectin blots. Bioinformatic analysis further indicated a mechanism by which HIF-1α can regulate ST3GAL6 expression and the relationship within the intrinsic characteristics of TNBC tumors. In conclusion, our results showed the involvement of hypoxia and serum deprivation in glycosylation profile regulation of TNBC cells triggering breast cancer aggressive features and suggesting glycosylation as a potential diagnostic and therapeutic target.

KAI1 overexpression promotes apoptosis and inhibits proliferation, cell cycle, migration, and invasion in nasopharyngeal carcinoma cells

OBJECTIVES

The purpose of this study is to characterize the effect of KAI1 overexpression on the biological behavior of nasopharyngeal carcinoma (NPC) cells.

BACKGROUND

Nasopharyngeal carcinoma is a highly malignant tumor with a high rate of incidence in China. Currently, there are no ideal therapeutic options for patients with NPC, but a targeted therapy would have great potential for treating it. Therefore, there is an urgent need for novel therapeutic targets to provide new options for treating NPC. The KAI1 gene was originally identified as a metastasis suppressor gene for advanced human cancer. In NPC cell lines and tissues, the expression of KAI1 decreased as the metastatic potential of cells increased, but its potential as a therapeutic target has not been elucidated.

METHODS

Non-transformed nasopharyngeal epithelium cell NP69 and NPC cell line C666-1 were cultured and KAI1 expression in these cells was detected by qRT-PCR and Western blot. After the transfection of KAI1-pCDNA3.1 to NP69 and C666-1, the KAI1 expression in these cells was detected by qRT-PCR and Western blot, the proliferation was performed by MTS, the cell cycle and apoptosis were performed by flow cytometry, the migration and invasion were examined by transwell.

RESULTS

Our results showed that KAI1 was significantly upregulated in C666-1 cells compared to that in NP69 cells. In addition, KAI1 overexpression significantly inhibited the proliferation, cell cycle, migration, and invasion, and promoted apoptosis of C666-1 cells, but had no significant effect on NP69 cells.

CONCLUSION

Our findings suggest that KAI1 overexpression promotes apoptosis and inhibits proliferation, cell cycle, migration, and invasion in NPC cells. We hypothesize that KAI1 overexpression could be a potential therapeutic target for NPC.

GADD45β induction by S-adenosylmethionine inhibits hepatocellular carcinoma cell proliferation during acute ischemia-hypoxia

Growth arrest DNA damage-inducible gene 45β (GADD45β), which influences cell growth, apoptosis and cellular response to DNA damage, is downregulated in hepatocellular carcinoma (HCC). S-adenosylmethionine (SAMe) serves as an essential methyl donor in multiple metabolic pathways and is a polyamine and glutathione (GSH) precursor. In this study, we assessed the roles of GADD45β and SAMe in cell survival during acute ischemia-hypoxia (I/H). SAMe treatment induced growth of HL-7702 normal hepatic cells, but decreased the viability of HepG2 (p53 wild-type) and Hep3B (p53 null) HCC cells. Cells were exposed to I/H with or without SAMe pre-treatment. I/H exposure alone triggered HCC cell proliferation promoted by autophagy. SAMe pre-treatment restored GADD45β expression and activated HCC cell apoptosis and eliminated I/H-induced HCC cell proliferation. p53 loss blunted the response to SAMe and I/H exposure in Hep3B cells; thus, the inhibitory effect of SAMe on cell proliferation may be reduced in p53-null cells as compared to wild-type cells. These results indicate that GADD45β induction by SAMe inhibits HCC cell proliferation during I/H as a result of increased apoptosis, and that SAMe also protects normal hepatocytes from apoptotic cell death and promotes normal cell regeneration. SAMe should be considered a potential therapeutic agent for the management of HCC.