Expression Of Sorcin Research Articles

Sorcin can trigger pancreatic cancer-associated new-onset diabetes through the secretion of inflammatory cytokines such as serpin E1 and CCL5.

A rise in blood glucose is an early warning sign of underlying pancreatic cancer (PC) and may be an indicator of genetic events in PC progression. However, there is still a lack of mechanistic research on pancreatic cancer-associated new-onset diabetes (PCAND). In the present study, we identified a gene SRI, which possesses a SNP with the potential to distinguish PCAND and Type 2 diabetes mellitus (T2DM), by machine learning on the basis of the UK Biobank database. In vitro and in vivo, sorcin overexpression induced pancreatic β-cell dysfunction. Sorcin can form a positive feedback loop with STAT3 to increase the transcription of serpin E1 and CCL5, which may directly induce β-cell dysfunction. In 88 biopsies, the expression of sorcin was elevated in PC tissues, especially in PCAND samples. Furthermore, plasma serpin E1 levels are higher in peripheral blood samples from PCAND patients than in those from T2DM patients. In conclusion, sorcin may be the key driver in PCAND, and further study on the sorcin-STAT3-serpin E1/CCL5 signaling axis may help us better understand the pathogenesis of PCAND and identify potential biomarkers.

Lipid-coated albumin-paclitaxel nanoparticles loaded with sorcin-siRNA reverse cancer chemoresistance via restoring intracellular calcium ion homeostasis

Chemoresistance is often a cause of the failure of chemotherapy in cancer treatment. Sorcin (SRI) is a soluble resistance-related calcium-binding protein involved in chemoresistant processes and is overexpressed in many chemoresistant cancer cells, including paclitaxel (PTX)-resistant ovarian cancer. Increased SRI can reduce the concentration of calcium ions in the cytosol and mitochondria and the decrease of calcium ion concentration prevents the occurrence of apoptosis. Here we examined the SRI expression in multiple cancers using a human TissueArray and found that SRI expression was significantly higher in malignant tumor tissues. Furthermore, SRI was overexpressed, while intracellular calcium concentration was decreased, in chemoresistant cancer cells. To restore intracellular calcium homeostasis and overcome chemoresistance, we developed lipid-coated albumin-PTX nanoparticles loaded with SRI-siRNA (LANP-PTX-siSRI) for PTX and SRI-siRNA co-delivery. LANP-PTX-siSRI had dual-target roles in the regulation of SRI and the delivery of PTX into chemoresistant cells. The LANP-PTX-siSRI inhibited the expression of SRI and enhanced intracellular calcium, leading to the induction of apoptosis and the inhibition of the growth of PTX-resistant cancer cells in vitro and in vivo. In addition, the mechanism study revealed that the overexpression of SRI was associated with an impaired TGF-β signaling pathway. The administration of TGF-β1 inhibited two calcium-binding proteins SRI and S100A14. In conclusion, our data unveil that restoring intracellular calcium ion homeostasis via reducing SRI expression can reverse chemoresistance. Thus, the fabricated LANP-PTX-siSRI has a potentially therapeutical application.

348P Up-regulation of sorcin promotes glioblastoma progression via activating the PI3K/AKT/mTOR pathway

Glioblastoma (GBM) is one of the most common malignant intracranial tumors exhibiting highly aggressive and invasive features. Sorcin (SRI) is a soluble calcium (Ca2+)-binding protein, one prominent member of penta-EF-hand (PEF) protein family, and was involved in the tumorigenesis. In this study, the expression of SRI and the functional role in the progression of GBM were investigated.

A novel homeostatic loop of sorcin drives paclitaxel-resistance and malignant progression via Smad4/ZEB1/miR-142-5p in human ovarian cancer

The primary chemotherapy of ovarian cancer (OC) often acquires chemoresistance. Sorcin (SRI), a soluble resistance-related calcium-binding protein, has been reported to be an oncogenic protein in cancer. However, the molecular mechanisms of SRI regulation and the role and aberrant expression of SRI in chemoresistant OC remain unclear. Here, we identified SRI as a key driver of paclitaxel (PTX)-resistance and explored its regulatory mechanism. Using transcriptome profiles, qRT-PCR, proteomics, Western blot, immunohistochemistry, and bioinformatics analyses, we found that SRI was overexpressed in PTX-resistant OC cells and the overexpression of SRI was related to the poor prognosis of patients. SRI was a key molecule required for growth, migration, and PTX-resistance in vitro and in vivo and was involved in epithelial–mesenchymal transition (EMT) and stemness. Mechanistic studies showed that miR-142-5p directly bound to the 3ʹ-UTR of SRI to suppress its expression, whereas a transcription factor zinc-finger E-box binding homeobox 1 (ZEB1) inhibited the transcription of miR-142-5p by directly binding to the E-box fragment in the miR-142 promoter region. Furthermore, ZEB1 was negatively regulated by SRI which physically interacted with Smad4 to block its translocation from the cytosol to the nucleus. Taken together, our findings unveil a novel homeostatic loop of SRI that drives the PTX-resistance and malignant progression via Smad4/ZEB1/miR-142-5p in human OC. Targeting this SRI/Smad4/ZEB1/miR-142-5p loop may reverse the PTX-resistance.

Knockdown of sorcin increases HEI-OC1 cell damage induced by cisplatin in vitro

Hearing loss caused by ototoxic drugs is a kind of acquired hearing loss. Cisplatin is one of the most commonly used drugs and its main action sites are hair cells (HCs). Sorcin is a drug-resistant calcium-binding protein belonging to the small penta-EF-hand protein family. Sorcin is highly expressed in many tissues, including bone, heart, brain, lung, and skin tissues. Single-cell RNA sequencing showed that sorcin was expressed in the outer HCs of mice, but its role remained unknown. We also found that sorcin was highly expressed in the cytoplasm of cochlear HCs and HEI-OC1 cells. After cisplatin injury, the expression of sorcin in HCs and HEI-OC1 cells decreased significantly. SiRNA transfection technology was used to knock down the expression of sorcin. The results showed that the number of apoptotic cells, the expression of cleaved caspased-3, and the expression of Bax increased while the anti-apoptotic factor Bcl-2 decreased in the siRNA-Sorcin + CIS group. The observed increase in apoptosis was related to the increase of reactive oxygen species (ROS) and the destruction of the mitochondrial membrane potential (MMP). Finally, we found that the downregulated sorcin worked by activating the P-ERK1/2 signaling pathway. Overall, this study showed that sorcin can be used as a new target to prevent the ototoxicity of platinum drugs.

Antitumor activity of triptolide in SKOV3 cells and SKOV3/DDP in vivo and in vitro.

This study was designed to investigate the antitumor activity of triptolide in ovarian cancer inoculated with SKOV3 and SKOV3/cisplatin (DDP) cells, and to assess the mechanisms. In-vivo and in-vitro experiments were designed to evaluate the effects of triptolide on the tumor growth of SKOV3 and SKOV3/DDP cells. The experiments were divided into four groups: a SKOV3 group, a SKOV3 + TP treatment group, a SKOV3/DDP group and a SKOV3/DDP + TP treatment group. The expression of Sorcin, vascular endothelial growth factor and matrix metalloproteinase-2 were detected by western blotting and immunohistochemistry. Tumor cell apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling. In-vitro experiments showed that compared with SKOV3 control group, the level of colony-stimulating factor 1 and expression of Sorcin in SKOV3/DDP was significantly higher. Interestingly, triptolide treatment could reduce colony-stimulating factor 1 level and expression of Sorcin in both SKOV3 and SKOV3/DDP cell lines. In-vivo experiments showed that tissue necrosis area in SKOV3 + TP and SKOV3/DDP + TP was larger than SKOV3 and SKOV3/DDP group, respectively. Triptolide treatment induced apoptosis in both SKOV3 and SKOV3/DDP cells. Compared with SKOV3 group, the size of tumors was large, and the expression of MMP-2, Sorcin and vascular endothelial growth factor was higher in SKOV3/DDP group. Triptolide treatment reduced the size of tumors, and the expression of MMP-2, Sorcin and vascular endothelial growth factor in SKOV3/DDP as well as in SKOV3 tumors. In conclusion, triptolide has antitumor activity in both SKOV3 and SKOV3/DDP cells likely through inducing apoptosis and regulating MMP-2, Sorcin and vascular endothelial growth factor expression.

Mir-1 inhibits migration of gastric cancer cells.

Gastric cancer is the fourth most common malignancy world-wide that bears a high mortality by invasiveness and metastases. To this end, we examined the role of miR-1 in mobility and migration of gastric cancer cells. miR-1 was down-regulated and Sorcin, which supports invasion, was highly expressed in gastric cancer cell lines as compared to the control. The overexpression of miR-1 significantly inhibited the mobility and migration of gastric cancer cells, while, its knockdown exerted an oppoiste effect. In addition, while overexpression of miR-1 suppressed the expression of Sorcin, the siRNA knockdown of Sorcin significantly counteracted the effect of miR-1 inhibitor on cell invasion and migration of gastric cancer cells. A miR-1 mimic decreased while its inhibitor increased the MMP-7 and VEGF required for invasion. Taken together, the findings support the view that miR-1 controls the mobility and migration of gastric cancer cells and might be a therapeutic target for blocking gastric cancer invasion.

Level of Sorcin expression influences chemoresistance and overall survival in patients with ovarian cancer

To investigate the correlation between soluble resistance-related calcium-binding protein (Sorcin) and chemoresistance or overall survival in patients with ovarian cancer. Methods: We detected the expression of Sorcin in 27 cases of chemoresistant ovarian cancer tissue and 37 cases of sensitive ovarian cancer tissue by immunohistochemistry, and analyzed the relationship between the protein and clinicopathological features or chemoresistance of ovarian cancer. Log-rank test was used to analyze the single factor impact on overall survival, Kaplan-Meier analysis was used to describe survival curve, and Cox proportional hazard model was used for multivariate analysis. Results: The immunoreactive scores for Sorcin in chemoresistant ovarian cancer tissues were higher than those in the sensitive ovarian cancer tissues (P<0.001). The levels of Sorcin inovarian cancer tissue did not show statistical significance with different ages, tumor stages, classifications, tissue types, degrees of ascites, omentums, and tumor metastases (P>0.05). The correlation between Sorcin and overall survival in resistant and sensitive ovarian cancer groups was not statistically significant (P>0.05), while there was a negative correlation between the expression of Sorcin and the overall survival of total cases (r=-0.326, P<0.05). Log-rank test showed that the drug resistance factor had a distinct impact on overall survival (P<0.001), and the Sorcin expression had an impact on overall survival (P<0.05). However, correlation between overall survival and the ages, ascites, omentum carcinoma, pathological types, pathological grade or FIGO staging was not significant (P>0.05). Cox proportional hazard model showed that drug resistance had a significant effect on overall survival (P<0.001), with a relative risk at 8.635, and the survival curve of the ovarian cancer sensitive group was obviously superior to that of ovarian cancer drug resistance group. Conclusion: Sorcin may be associated with drug resistance in ovarian cancer. The expression of Sorcin is correlated with the overall survival. The lower the Sorcin expression, the longer the survival time. Chemoresistance may act as an important independent prognostic factor for the poor prognosis for ovarian cancer.

Sorcin: a novel potential target in therapies of cancers.

Soluble resistance-related calcium-binding protein (sorcin) is a member of the penta-EF-hand protein family. Sorcin is widely distributed in normal human tissues, such as the brain, heart, lymphocytes, kidneys, breast and skin. Findings suggest that sorcin is associated with the regulation of calcium homeostasis, cell cycle and vesicle trafficking. It has been reported that many types of non-neoplastic diseases such as diabetes, viral infection, infertility, and nervous system diseases were affected by the expression of sorcin. One of the main issues is the role of sorcin in neoplastic diseases. Research proved that sorcin can be found to overexpress in cells of several cancers, particularly in the case of multidrug-resistant cancers. Additionally, the researchers proposed that the expression of sorcin was significantly associated with the foundation of multidrug resistance (MDR). All the findings mentioned above emphasized the importance of studying sorcin. This review mainly includes the following aspects: functions of sorcin, role in non-neoplastic and neoplastic diseases, and research related to drugs. To sum up, sorcin is a potential novel target to be studied to deal with MDR.

Sorcin is involved during embryo implantation via activating VEGF/PI3K/Akt pathway in mice.

Our earlier studies have demonstrated the cyclic variation and also the altered expression of sorcin in endometrium during early-to-mid-secretory phase transition in women with unexplained infertility. The current study was undertaken to establish the functional role of sorcin in endometrial receptivity in mice. Results indicated that sorcin was highly expressed during the window of implantation in mice and functional blockage of sorcin caused significant reduction in number of implanted blastocyst. The receptivity markers (i.e.Integrin β3, HBEGF, IGFBP1, WNT4 and Cyclin E)) were found to be downregulated in sorcin knocked down uterine horn on day 5 as compared to untreated horn. The reduced attachment and expansion of BeWo spheroids on RL95-2 endometrial cells with sorcin knock down, in in vitro model of endometrium-trophoblast interaction further supported these findings. Uterine sorcin expression pattern during estrous cycle and in delayed implantation mice model suggested the upregulation of sorcin by estrogen. The functional blockade of sorcin induced the intracellular Ca+2 levels in endometrial epithelial cells (EECs), which indicated that altered Ca+2 homeostasis might be responsible for implantation failure. Sorcin silencing led to significant reduction in the expression of angiogenic factor VEGF and its downstream effector molecules i.e. PI3K, Akt and NOS. The migratory and invasive properties of HUVECs were abrogated by anti-VEGF or by adding culture media from sorcin blocked EECs, which indicated that sorcin might mediate angiogenesis during implantation. Taken together, sorcin is involved in the regulation of Ca+2-mediated angiogenesis via VEGF/PI3K/Akt pathway in endometrial cells and plays a crucial role in preparing the endometrium for implantation.

Targeting P‐glycoprotein and SORCIN: Dihydromyricetin strengthens anti‐proliferative efficiency of adriamycin via MAPK/ERK and Ca2+‐mediated apoptosis pathways in MCF‐7/ADR and K562/ADR

Recently, a new target Ca2+ -binding protein SORCIN was reported to participate in multidrug resistance (MDR) in cancer. Here we aim to investigate whether dihydromyricetin (DMY), a dihydroflavonol compound with anti-inflamatory, anti-oxidant, anti-bacterial and anti-tumor actions, reverses MDR in MCF-7/ADR and K562/ADR and to elucidate its potential molecular mechanism. DMY enhanced cytotoxicity of adriamycin (ADR) by downregulating MDR1 mRNA and P-gp expression through MAPK/ERK pathway and also inhibiting the function of P-gp significantly. Meanwhile, DMY decreased mRNA and protein expression of SORCIN, which resulted in elevating intracellular free Ca2+ . Finally, we investigated co-administration ADR with DMY remarkably increased ADR-induced apoptosis. Further study showed DMY elevated ROS levels and caspase-12 protein expression, which signal apoptosis in endoplasmic reticulum. At the same time, proteins related to mitochondrial apoptosis were also changed such as Bcl-2, Bax, caspase-3, caspase-9, and PARP. Finally, nude mice model also demonstrated that DMY strengthened anti-tumor activity of ADR in vivo. In conclusion, DMY reverses MDR by downregulating P-gp, SORCIN expression and increasing free Ca2+ , as well as, inducing apoptosis in MCF-7/ADR and K562/ADR. These fundamental findings provide evidence for further clinical research in application of DMY as an assistant agent in the treatment of cancer.

Sorcin induces gastric cancer cell migration and invasion contributing to STAT3 activation.

Gastric cancer (GC) is a globally occurring malignancy that is characterized by a high mortality rate due to a high tendency to metastasize and poor prognoses. Sorcin, as known as SRI, a soluble resistance-related calcium-binding protein, plays a significant role in multidrug resistance. Sorcin is related to the migration and invasion of cancer cells. However, the mechanism remains unclear. Here, we used immunohistochemistry to confirm that the expression of sorcin in cancer tissues is higher than that in the adjacent normal tissues. The wound healing and transwell results indicate that sorcin can induce migration and invasion of GC cells. To explore the role of sorcin in GC metastasis, isobaric tags for relative and absolutely quantitation (iTRAQ) were used to examine cells with and without sorcin knockdown to identify the differentially expressed proteins (DEPs). The results were evaluated via RT-PCR and western blot to confirm the ITRAQ data. Inhibition of sorcin expression can down- regulate the expression of CTSZ, MMP2, MMP9 and p-STAT3 followed by suppression of tumor growth and metastasis. Together, we concluded that sorcin has a oncogenic activity via inducing tumor growth and metastasis, leading to development of therapeutic treatments for GC.

Alteration in endometrial proteins during early- and mid-secretory phases of the cycle in women with unexplained infertility.

BackgroundCompromised receptivity of the endometrium is a major cause of unexplained infertility, implantation failure and subclinical pregnancy loss. In order to investigate the changes in endometrial protein profile as a cause of unexplained infertility, the current study was undertaken to analyze the differentially expressed proteins of endometrium from early-secretory (LH+2) to mid-secretory phase (LH+7), in women with unexplained infertility.Methods2-D gel electrophoresis was performed to analyze the proteomic changes between early- (n = 8) and mid-secretory (n = 8) phase endometrium of women with unexplained infertility. The differentially expressed protein spots were identified by LC-MS analysis and validated by immunoblotting and immuno-histochemical analysis in early- (n = 4) and mid-secretory (n = 4) phase endometrium of infertile women. Validated proteins were also analyzed in early- (n = 4) and mid-secretory (n = 4) phase endometrium of fertile women.ResultsNine proteins were found to be differentially expressed between early- and mid- secretory phases of endometrium of infertile women. The expression of Ras-related protein Rap-1b, Protein disulfide isomerase A3, Apolipoprotein-A1 (Apo-A1), Cofilin-1 and RAN GTP-binding nuclear protein (Ran) were found to be significantly increased, whereas, Tubulin polymerization promoting protein family member 3, Superoxide dismutase [Cu-Zn], Sorcin, and Proteasome subunit alpha type-5 were significantly decreased in mid- secretory phase endometrium of infertile women as compared to early-secretory phase endometrium of infertile women. Validation of 4 proteins viz. Sorcin, Cofilin-1, Apo-A1 and Ran were performed in separate endometrial biopsy samples from infertile women. The up-regulated expression of Sorcin and down-regulated expression of Cofilin-1 and Apolipoprotein-A1, were observed in mid-secretory phase as compared to early-secretory phase in case of fertile women.ConclusionsDe-regulation of the expression of Sorcin, Cofilin-1, Apo-A1 and Ran, during early- to mid-secretory phase may have physiological significance and it may be one of the causes for altered differentiation and/or maturation of endometrium, in women with unexplained infertility.

Increased expression of sorcin is associated with multidrug resistance in leukemia cells via up-regulation of MDR1 expression through cAMP response element-binding protein

Sorcin, a 22kDa Ca2+ binding protein, was first identified in a vincristine-resistant Chinese hamster lung cell line, and was later demonstrated to be involved in the development of multidrug-resistance (MDR) phenotypes in a variety of human cancer cell lines. However, the exact role of sorcin in MDR cells is yet to be fully elucidated. Here we explored the role of sorcin in the development of MDR in leukemia cells, and revealed that the expression level of sorcin was directly correlated to the expression of MDR1/P-glycoprotein (P-gp). In addition, it was shown that sorcin induced the expression of MDR1/P-gp through a cAMP response element (CRE) between −716 and −709bp of the mdr1/p-gp gene. Furthermore, overexpression of sorcin increased the phosphorylation of CREB1 and the binding of CREB1 to the CRE sequence of mdr1/p-gp promoter, and induced the expression of MDR1/P-gp. These findings suggested that sorcin induces MDR1/P-gp expression markedly through activation of the CREB pathway and is associated with the MDR phenotype. The new findings may be helpful for understanding the mechanisms of MDR in human cancer cells, prompting its further investigation as a molecular target to overcome MDR.

Mechanisms of Intracellular Calcium Homeostasis in Developing and Mature Bovine Corpora Lutea1

Although calcium (Ca(2+)) is accepted as an intracellular mediator of prostaglandin F2 alpha (PGF2alpha) actions on luteal cells, studies defining mechanisms of Ca(2+) homeostasis in bovine corpora lutea (CL) are lacking. The increase in intracellular Ca(2+) concentration ([Ca(2+)]i) induced by PGF2alpha in steroidogenic cells from mature CL is greater than in those isolated from developing CL. Our hypothesis is that differences in signal transduction associated with developing and mature CL contribute to the increased efficacy of PGF2alpha to induce a Ca(2+) signal capable of inducing regression in mature CL. To test this hypothesis, major genes participating in Ca(2+) homeostasis in the bovine CL were identified, and expression of mRNA, protein, or activity, in the case of phospholipase Cbeta (PLCbeta), in developing and mature bovine CL was compared. In addition, we examined the contribution of external and internal Ca(2+) to the PGF2alpha stimulated rise in [Ca(2+)]i in LLCs isolated from developing and mature bovine CL. Three differences were identified in mechanisms of calcium homeostasis between developing and mature CL, which could account for the lesser increase in [Ca(2+)]i in response to PGF2alpha in developing than in mature CL. First, there were lower concentrations of inositol 1,4,5-trisphosphate (IP3) after similar PGF2alpha challenge, indicating reduced phospholipase C beta (PLCbeta) activity, in developing than mature CL. Second, there was an increased expression of sorcin (SRI) in developing than in mature CL. This cytoplasmic Ca(2+) binding protein modulates the endoplasmic reticulum (ER) Ca(2+) release channel, ryanodine receptor (RyR), to be in the closed configuration. Third, there was greater expression of ATP2A2 or SERCA, which causes calcium reuptake into the ER, in developing than in mature CL. Developmental differences in expression detected in whole CL were confirmed by Western blots using protein samples from steroidogenic cells isolated from developing and mature CL. Localization of these genes in steroidogenic luteal cells was confirmed by immunohistochemistry. Therefore, it is concluded that the cellular mechanisms that allow PGF2alpha to induce a calcium signal of greater magnitude in mature than in developing CL involve 1) greater PLCbeta activity with enhanced generation of IP3, 2) an enhanced Ca(2+) release from the ER via unrestrained RYR2 due to a decrease in SRI expression, and 3) a reduction in calcium reuptake to the ER due to lower expression of ATP2A2. Accordingly, the increase in [Ca(2+)]i induced by PGF2alpha in mature large steroidogenic cells had less dependency from extracellular calcium than in those isolated from immature CL.

Tegillarca granosa extract Haishengsu (HSS) suppresses expression of mdr1, BCR/ABL and sorcin in drug-resistant K562/ADM tumors in mice

To evaluate the effect of Haishengsu (HSS), a protein extract from Tegillarca granosa, on multidrug-resistance genes mdr1, BCR/ABL and sorcin in transplanted tumors. Mice were inoculated subcutaneously with a drug resistant leukemia cell line K562/ADM. Tumor-bearing animals were divided into control, adriamycin, HSS and combination therapy (adriamycin plus HSS) groups. Flow cytometry was used to detect apoptosis of tumor cells, and RT-PCR was used to evaluate the expression of mdr1, BCR/ABL and sorcin. The apoptosis rate in the high (71.8%), medium (72.3%) and low doses HSS group (72.4%) was higher than in control (1.2%, p<0.01), adriamycin (34.4%, p<0.05) or combination therapy group (46.4%, p<0.05). The mean optical density of mdr1, BCR/ABL and sorcin in HSS groups was lower than in control, adriamycin and combination therapy group (p<0.01). The optical density of the three genes in high HSS group was lower than in medium and low HSS group (p<0.01). Haishengsu promotes apoptosis of drug-resistant K562/ADM tumors in mice in a dose-dependent manner. The pro-apoptotic effect of Haishengsu may be related to a reduced expression of multidrug-resistance genes mdr1, BCR/ABL and sorcin.

Resistance to paclitxel in breast carcinoma cells requires a quality control of mitochondrial antiapoptotic proteins by TRAP1

TRAP1 is a mitochondrial antiapoptotic protein up-regulated in several human malignancies. However, recent evidences suggest that TRAP1 is also localized in the endoplasmic reticulum (ER) where it is involved in ER stress protection and protein quality control of tumor cells. Based on the mechanistic link between ER stress, protection from apoptosis and drug resistance, we questioned whether these novel roles of TRAP1 are relevant for its antiapoptotic function. Here, we show for the first time that: i) TRAP1 expression is increased in about 50% of human breast carcinomas (BC), and ii) the ER stress protecting activity of TRAP1 is conserved in human tumors since TRAP1 is co-upregulated with the ER stress marker, BiP/Grp78. Notably, ER-associated TRAP1 modulates mitochondrial apoptosis by exerting a quality control on 18 kDa Sorcin, a TRAP1 mitochondrial client protein involved in TRAP1 cytoprotective pathway. Furthermore, this TRAP1 function is relevant in favoring resistance to paclitaxel, a microtubule stabilizing/ER stress inducer agent widely used in BC therapy. Indeed, the transfection of a TRAP1 deletion mutant, whose localization is restricted to the ER, in shTRAP1 cells enhances the expression of mitochondrial Sorcin and protects from apoptosis induced by ER stress agents and paclitaxel. Furthermore, BC cells adapted to paclitaxel or ER stress inducers share common resistance mechanisms: both cell models exhibit cross-resistance to single agents and the inhibition of TRAP1 by siRNAs or gamitrinib, a mitochondria-directed HSP90 family inhibitor, in paclitaxel-resistant cells rescues the sensitivity to paclitaxel. These results support the hypothesis that ER-associated TRAP1 is responsible for an extramitochondrial control of apoptosis and, therefore, an interference of ER stress adaptation through TRAP1 inhibition outside of mitochondria may be considered a further compartment-specific molecular approach to rescue drug-resistance.

Diabetes-related defects in sarcoplasmic Ca2+ release are prevented by inactivation of Gα11 and Gαq in murine cardiomyocytes

Neurohumoral stimulation of Gq-coupled receptors has been proposed as a central mechanism in the pathogenesis of diabetic heart disease. The resulting contractile dysfunction is closely related to abnormal intracellular Ca(2+) handling with functional defects of the sarcoplasmic reticulum (SR). The present study was therefore designed to determine the role of G(q)-protein signaling via G(alpha)(11) and G(alpha)(q) in diabetes for the induction of functional and structural changes in the Ca(2+) release complex of the SR. An experimental type 1-diabetes was induced in wild type, G(alpha)(11) knockout, and G(alpha)(11/q)-knockout mice by injection of streptozotocin. Cardiac morphology and function was assessed in vivo by echocardiography. SR Ca(2+) leak was tested in vitro based on a (45)Ca(2+) assay and protein densities as well as gene expression of ryanodine receptor (RyR2), FKBP12.6, sorcin, and annexin A7 were analyzed by immunoblot and RT-PCR. In wild type animals 8 weeks of diabetes resulted in cardiac hypertrophy and SR Ca(2+) leak was increased. In addition, diabetic wild type animals showed reduced protein levels of FKBP12.6 and annexin A7. In G(alpha)(11)- and G(alpha)(11/q)-knockout animals, however, SR Ca(2+) release and cardiac phenotype remained unchanged upon induction of diabetes. Densities of the proteins that we presently analyzed were also unaltered in G(alpha)(11)-knockout mice. G(alpha)(11/q)-knockout animals even showed increased expression of sorcin and annexin A7. Thus, based on the present study we suggest a signaling pathway via the G(q)-proteins, G(alpha)(11) and G(alpha)(q), that could link increased neurohumoral stimulation in diabetes with defective RyR2 channel function by regulating protein expression of FKBP12.6, annexin A7, and sorcin.

Comparative proteomic profiling identified sorcin being associated with gemcitabine resistance in non-small cell lung cancer

Although gemcitabine-based chemotherapy is one of the more effective chemotherapy regimens against NSCLC, there are still many patients who do not benefit from this therapy. The mechanism of initial or acquired resistance to gemcitabine chemotherapy remains unknown. In this study, we investigated the protein profiling in gemcitabine-resistant and gemcitabine-sensitive NSCLC cell lines by a proteomic technology in order to identify novel gemcitabine resistance associated biomarkers for NSCLC patients. The proteomic profiling of NSCLC cell line H460 and its gemcitabine-resistant subline H460/GEM were compared by an isotope-coded affinity tag technology and tandem mass spectrometry. We further validated the expression of sorcin, a gemcitabine-resistance-related protein identified by proteomics, in 62 NSCLC specimens by immunohistochemistry. Fourteen gemcitabine resistance-related proteins were identified including nine up-regulated proteins and five down-regulated proteins. Immunohistochemical results demonstrated that sorcin staining was seen in 66.1% of NSCLC tumors, and sorcin overexpression was associated with gemcitabine resistance and a poor prognosis in NSCLC patients. In conclusion, sorcin might play an important role in the resistance to gemcitabine, and it could also be a novel candidate biomarker for predicting the response of NSCLC patients to gemcitabine treatment.

Upregulation of soluble resistance-related calcium-binding protein (sorcin) in gastric cancer

The aim of this paper was to identify novel proteins involved in the development of gastric cancer (GC). Isobaric tags for relative and absolute quantification (iTRAQ) analysis was adopted to separate the differentially expressed proteins between normal gastric epithelial cell line GES-1 and GC cell line SGC7901. Western blotting was utilized to validate the increased expression of sorcin in SGC7901; immunohistochemistry was performed to investigate its relationship with clinicopathological features of GC. Twelve differential proteins were identified. Seven proteins were found to be significantly upregulated (≥two-fold), while five proteins were markedly downregulated (≤0.5-fold), in SGC7901 cells. Sorcin was detected by this proteomic approach with a 5.4-fold upregulation in SGC7901. Western blotting and immunohistochemistry confirmed the overexpression of sorcin in GC. Immunohistochemistry showed us that sorcin was overexpressed in 55 samples of GC tissue (55/85, 64.71%) and was related closely to the depth of invasion, TNM stage, and lymph node metastasis of GC (P<0.05). The development of GC is regulated by multiple genes. Sorcin will be a novel molecular biomarker for the diagnosis, treatment, and prognosis of GC.