The Chemopreventive Effects of Polyphenols and Coffee, Based upon a DMBA Mouse Model with microRNA and mTOR Gene Expression Biomarkers

Polyphenols are capable of decreasing cancer risk. We examined the chemopreventive effects of a green tea (Camellia sinensis) extract, polyphenol extract (a mixture of blackberry (Rubus fruticosus), blackcurrants (Ribes nigrum), and added resveratrol phytoalexin), Chinese bayberry (Myrica rubra) extract, and a coffee (Coffea arabica) extract on 7,12-dimethylbenz[a]anthracene (DMBA) carcinogen-increased miR-134, miR-132, miR-124-1, miR-9-3, and mTOR gene expressions in the liver, spleen, and kidneys of CBA/Ca mice. The elevation was quenched significantly in the organs, except for miR-132 in the liver of the Chinese bayberry extract-consuming group, and miR-132 in the kidneys of the polyphenol-fed group. In the coffee extract-consuming group, only miR-9-3 and mTOR decreased significantly in the liver; also, miR-134 decreased significantly in the spleen, and, additionally, miR-124-1 decreased significantly in the kidney. Our results are supported by literature data, particularly the DMBA generated ROS-induced inflammatory and proliferative signal transducers, such as TNF, IL1, IL6, and NF-κB; as well as oncogenes, namely RAS and MYC. The examined chemopreventive agents, besides the obvious antioxidant and anti-inflammatory effects, mainly blocked the mentioned DMBA-activated factors and the mitogen-activated protein kinase (MAPK) as well, and, at the same time, induced PTEN as well as SIRT tumor suppressor genes.

Changes in miR-124-1, miR-212, miR-132, miR-134, and miR-155 Expression Patterns after 7,12-Dimethylbenz(a)anthracene Treatment in CBA/Ca Mice

Specific gene and miRNA expression patterns are potential early biomarkers of harmful environmental carcinogen exposures. The aim of our research was to develop an assay panel by using several miRNAs for the rapid screening of potential carcinogens. The expression changes of miR-124-1, miR-212, miR-132, miR-134, and miR-155 were examined in the spleen, liver, and kidneys of CBA/Ca mice, following the 20 mg/bwkg intraperitoneal 7,12-dimethylbenz(a)anthracene (DMBA) treatment. After 24 h RNA was isolated, the miRNA expressions were analyzed by a real-time polymerase chain reaction and compared to a non-treated control. DMBA induced significant changes in the expression of miR-134, miR-132, and miR-124-1 in all examined organs in female mice. Thus, miR-134, miR-132, and miR-124-1 were found to be suitable biomarkers for the rapid screening of potential chemical carcinogens and presumably to monitor the protective effects of chemopreventive agents.

Who should talk with patients about their end-of-life care wishes? A nationwide survey of the Hungarian population

OBJECTIVE

To explore the needs and opportunities of the general population to communicate their end-of-life care wishes and to investigate what roles are assigned to healthcare providers and family members in end-of-life care discussions.

DESIGN

A cross-sectional social survey was carried out in Hungary. Descriptive analysis and analysis of variance were performed.

SETTING

Nationwide survey of the Hungarian general population.

SUBJECT

The sample (n = 1100) was designed to represent the adult population as per distribution by gender, age and geographical region.

MAIN OUTCOME MEASURES

Needs and opportunities of the general population to communicate end-of-life care wishes.

RESULTS

72% of participants found it important to discuss their end-of-life care wishes with someone. Six out of ten believed that it was also the GPs' task to talk with the patients about their end-of-life care wishes. An almost equal level of engagement was expected from healthcare providers (80%) -especially physicians (72%)- and family members (75%) in end-of-life conversations. However, only 36% of participants felt that there was someone among their healthcare providers, and 56% of them had a family member or friend with whom they could speak openly about death, dying and preparing for death.

CONCLUSION

Compared to their needs, the general population had fewer opportunities to speak about death, dying and preparing for death. Training programs for healthcare providers, particularly GPs, and public awareness campaigns may support the broader application of advance care planning in Hungary.Key PointsCurrent guidelines recommend that GPs initiate advance care planning discussions. However, little is known with whom the general population wish to discuss their end-of-life care preferences and with whom there is an opportunity to do so.An almost equal level of engagement was expected from healthcare providers -especially physicians- and family members in end-of-life conversations. Most of the general population thought that participation in end-of-life discussions was also the GPs' task.The majority of participants reported that there was no one among their healthcare providers and a sizable minority felt that there was no one among their family members or friends with whom they could talk openly about death, dying, and preparing for death.The highest levels of unmet needs regarding end-of-life conversations with healthcare providers were found among those who considered it important to discuss their end-of-life care wishes.

Effective chemotherapy and targeted therapy supplemented with stereotactic radiotherapy of a patient with metastatic colon cancer following renal transplantation: a case report

Background

Previous studies have shown that patients who underwent renal transplantation were at a greater risk of developing malignancies. Due to advances in effective surgical techniques and immunosuppressive therapies, organ recipients live longer. Yet, there is insufficient information about the recommended type of therapy for colorectal cancer patients following transplantation. We describe the oncological treatment of a patient with renal transplantation, who presented with metastatic colon cancer 5 years after transplantation.

Case presentation

A 66-year-old Caucasian male patient, with hypertension, type 2 diabetes mellitus, paroxysmal atrial fibrillation, and renal failure underwent successful kidney transplantation in 2013. In April 2018, the adenocarcinoma of the sigmoid colon was found, and surgical resection was performed. The histological diagnosis was low-grade adenocarcinoma. Fluorodeoxyglucose positron emission tomography/computerized tomography scan showed a 2.5-cm metastasis in the VIIth segment of the liver and a metastatic paraaortical lymph node on the left. The clinical diagnosis was, therefore, metastatic (stage IV) sigmoid colon cancer (AJCC TNM system). The ongoing medications of the patient included immunosuppressive drugs and medication for his cardiovascular comorbidities. In July 2018, palliative cetuximab plus folinic acid–fluorouracil–irinotecan chemotherapeutic treatment was initiated, then cetuximab was substituted for panitumumab because of adverse events. In August 2018, the follow-up positron emission tomography/computerized tomography scan revealed stable disease. Because of side effects, the patient was unwilling to continue with the panitumumab plus folinic acid–fluorouracil–irinotecan treatment regimen. Therefore, the patient received 10× 5 Gy stereotactic body irradiation for his liver metastasis and mono-panitumumab therapy. By January 2019, the positron emission tomography/computerized tomography scan showed regression of the liver metastasis but a progression in the paraaortic lymph node. Therefore, 5× 8 Gy stereotactic irradiation was given to the paraaortic lesion. Meanwhile, the patient received altogether 16 cycles of panitumumab until June 2019, when complete remission was attained. In July 2019, the patient suffered a hemorrhagic stroke, probably due to his cardiovascular comorbidities, and died subsequently.

Conclusions

Since information is scarce regarding oncological treatment of patients following organ transplantation, data about their oncological treatment is essential. To our knowledge, this is the first case report to describe the successful chemotherapy and targeted therapy supplemented with stereotactic radiotherapy of a posttransplant patient with metastatic colorectal cancer.

PARP inhibitor attenuated colony formation can be restored by MAP kinase inhibitors in different irradiated cancer cell lines

Abstract Purpose: Sensitizing cancer cells to irradiation is a major challenge in clinical oncology. We aimed to define the signal transduction pathways involved in poly(ADP-ribose) polymerase (PARP) inhibitor-induced radiosensitization in various mammalian cancer lines.

MATERIALS AND METHODS

Clonogenic survival assays and Western blot examinations were performed following telecobalt irradiation of cancer cells in the presence or absence of various combinations of PARP- and selective mitogen-activated protein kinase (MAPK) inhibitors.

RESULTS

HO3089 resulted in significant cytotoxicity when combined with irradiation. In human U251 glioblastoma and A549 lung cancer cell lines, Erk1/2 and JNK/SAPK were found to mediate this effect of HO3089 since inhibitors of these kinases ameliorated it. In murine 4T1 breast cancer cell line, p38 MAPK rather than Erk1/2 or JNK/SAPK was identified as the main mediator of HO3089's radiosensitizing effect. Besides the aforementioned changes in kinase signaling, we detected increased p53, unchanged Bax and decreased Bcl-2 expression in the A549 cell line.

CONCLUSIONS

HO3089 sensitizes cancer cells to photon irradiation via proapoptotic processes where p53 plays a crucial role. Activation of MAPK pathways is regarded the consequence of irradiation-induced DNA damage, thus their inhibition can counteract the radiosenzitizing effect of the PARP inhibitor.

The effect of a novel antagonist of growth hormone releasing hormone on cell proliferation and on the key cell signaling pathways in nine different breast cancer cell lines

Growth hormone releasing hormone (GHRH) antagonists have been developed for the treatment of various cancers. We investigated the effects of a novel GHRH antagonist, MIA-602, on nine breast cancer cell lines, differing in their expression for estrogen-, progesterone- and HER-2 receptors. We detected the presence of pituitary-type GHRH receptors (pGHRH-R) on 6 of the 9 breast cancer cell lines. The main splice variant of pGHRH-R, SV1, was found on all 9 cell lines. MTT assay showed that following treatment with MIA-602, cell viability decreased significantly in all 9 cell lines. The reduction in cell viability was greater in cells positive for both pGHRH-R and SV1, than in cells positive for only SV1, but the difference was not significant. Using Western blotting, we demonstrated that the levels of phospho-Akt, -GSK3β and -ERK1/2 decreased significantly following exposure to MIA-602 and the level of phospho-p38 increased after treatment. The reduction of the phosphorylated anti-apoptotic proteins was significantly greater in cells where both pGHRH-R and SV1 were present, than where only SV1 was expressed. In conclusion, our study shows that MIA-602 is effective against a wide range of breast cancer cells in vitro, independently of their receptor positivity, suggesting the potential use of GHRH antagonists also in the treatment of triple-negative breast cancer. The effect of MIA-602 was mediated nearly as well in tumors that expressed only the SV1 receptor compared to those in which both SV1 and pGHRH-R were present, although a difference could be detected at the level of cell signaling.

Correlation between tumor-associated proteins and response to neoadjuvant treatment in patients with advanced squamous-cell esophageal cancer

BACKGROUND

Possible predictive markers of response to neoadjuvant radiochemotherapy (NRCT) of esophageal cancer have been identified.

PATIENTS AND METHODS

Patient biopsies were obtained from both tumor and normal tissue before the NRCT of locally advanced esophageal squamous cell carcinoma. Protein solutions were separated and immunoblot analysis was performed with heat shock protein (Hsp)16.2, heme-binding protein 2 (SOUL), BCL2-associated X protein (Bax), B-cell-associated leukemia protein 2 (Bcl-2) and heat shock protein 90 (Hsp90) antibodies. Following NRCT, the patients were restaged according to the Response Evaluation Criteria In Solid Tumors (RECIST). Following resections the pathological down-staging was evaluated.

RESULTS

Clinical restaging revealed a response rate of 65%. Pathological examination revealed down-staging in 30% and 25% of the cases for the T and N categories respectively. Compared to the normal esophageal mucosa, a decreased expression of Hsp16.2, Hsp90 and SOUL proteins and an increased Bax/Bcl-2 ratio was found in the responding tumors.

CONCLUSION

Hsp16,2, Hsp90 and SOUL expression and Bax/ Bcl-2 ratio correlates to the efficacy of NRCT and predict outcome in patients with locally advanced squamous-cell esophageal cancer.

The effect of GHRH antagonists on human glioblastomas and their mechanism of action

The effects of new growth hormone-releasing hormone (GHRH) antagonists JMR-132 and MIA-602 and their mechanism of action were investigated on 2 human glioblastoma cell lines, DBTRG-05 and U-87MG, in vitro and in vivo. GHRH receptors and their main splice variant, SV1 were found on both cell lines. After treatment with JMR-132 or MIA-602, the cell viability decreased significantly. A major decrease in the levels of phospho-Akt, phospho-GSK3β and phosho-ERK 1/2 was detected at 5 and 10 min following treatment with the GHRH antagonists, whereas elevated levels of phospho-p38 were observed at 24 hr. The expression of caspase-3 and poly(ADP-ribose) (PARP), as the downstream executioners of apoptosis were found to be significantly elevated after treatment. Following treatment of the glioblastoma cells with GHRH antagonists, nuclear translocation of apoptosis inducing factor (AIF) and Endonuclease G (Endo G) and the mitochondrial release of cytochrome c (cyt c) were detected, indicating that the cells were undergoing apoptosis. In cells treated with GHRH antagonists, the collapse of the mitochondrial membrane potential was shown with fluorescence microscopy and JC-1 membrane potential sensitive dye. There were no significant differences between results obtained in DBTRG-05 or U-87MG cell lines. After treatment with MIA-602 and JMR-132, the reduction rate in the growth of DBTRG-05 glioblastoma, xenografted into nude mice, was significant and tumor doubling time was also significantly extended when compared with controls. Our study demonstrates that GHRH antagonists induce apoptosis through key proapoptotic pathways and shows the efficacy of MIA-602 for experimental treatment of glioblastoma.

The inhibitory effect of a novel cytotoxic somatostatin analogue AN-162 on experimental glioblastoma

Glioblastoma multiforme is the most common and most aggressive type of high grade tumor with a poor prognosis upon discovery. Based on earlier promising results earned with AN-162, a doxorubicin molecule linked to somatostatin (SST) analogue RC-160, it was our aim to determine the effect of AN-162 on DBTRG-05 glioblastoma cell line, and to test its efficacy in experimental brain tumors. We detected the expression of mRNA for somatostatin receptor (SSTR) subtypes 2 and 3 in DBTRG-05 cells with RT-PCR. Using ligand competition assay, specific high affinity receptors for somatostatin were found. The MTT assay showed that both AN-162 and doxorubicin (DOX) significantly inhibited cell proliferation and that there was no significant difference between the effects in vitro. Nude mice were xenografted with DBTRG-05 glioblastoma tumors. AN-162 showed a significant inhibition of tumor growth compared with the control group and the groups treated with equimolar doses of doxorubicin, somatostatin analogue RC-160, or the unconjugated mixture of doxorubicin plus RC-160. The tumor doubling time in the group of animals treated with AN-162 was extended and was significantly different from doubling times in the control group and in the other treatment groups. Our study clearly demonstrates a potent inhibitory effect of AN-162 in experimental glioblastoma, thus suggesting the possibility of its utilization in patients suffering from malignant brain cancer.

A correlation of endocrine and anticancer effects of some antagonists of GHRH

GHRH receptor antagonists inhibit growth and metastasis of a large number of experimental tumors expressing the pituitary GHRH receptor (pGHRH-R) and its major splice variant SV1. In this study, using Western blot, we demonstrated that DBTRG-05 and U-87MG human glioblastoma cell lines express pGHRH-R at levels 6-15 times higher than SV1. To reveal a correlation between the anticancer activity and the endocrine potency on inhibition of GH release, we compared the antitumor effect of GHRH antagonists JV-1-63 and MZJ-7-138 on growth of DBTRG-05 human glioblastomas grafted into athymic nude mice with their inhibitory potency on GH release. JV-1-63 strongly suppressed the stimulated GH secretion induced by clonidine in rats and inhibited the exogenous GHRH-induced GH surge by 88-99% in vivo and in vitro. MZJ-7-138 decreased the stimulated GH secretion by 58% in vitro and showed only a tendency to inhibit GH secretion in vivo. The strong inhibitor of GH release JV-1-63 reduced tumor growth of DBTRG-05 glioblastomas in nude mice by 46%, while the weak GH release suppressor MZJ-7-138 did not have an effect. Exposure of DBTRG-05 cells to the GHRH antagonists in vitro caused an upregulation of mRNA expression for pGHRH-R and a downregulation of SV1 expression, with JV-1-63 having significantly greater effects than MZJ-7-138. Our results demonstrate that a positive correlation exists between the endocrine potency and the antiproliferative efficacy of GHRH antagonists in tumors strongly expressing pGHRH-R.

The effect of carotid stenting on rheological parameters, free radical production and platelet aggregation

INTRODUCTION

Carotid artery stenting has become a possible treatment of significant carotid stenosis. The risk of stent occlusion and restenosis might be increased by abnormal rheological conditions amplified platelet aggregation and free radical production during the operation.

AIMS

The aim of our study was to assess the changes in hemorheological parameters, platelet aggregation, and catalase activity after endovascular treatment of carotid stenosis.

METHODS

18 patients (11 men, ages 68 +/- 9 years and 7 women, ages 62 +/- 8 years) suffering from significant carotid stenosis and treated with carotid endovascular intervention were examined. Alteration in hemorheological parameters as well as epinephrine-, ADP-, and collagen-induced platelet aggregation were evaluated. Antioxidant reserve was characterized by the determination of catalase activity. The measurements were carried out directly before and after the procedure and 1, 2, 5 days and 1 month following the intervention. Preceding the operation the patients were administered a maximum dose (300 mg) of clopidogrel.

RESULTS

Hematocrit, plasma fibrinogen concentration (PFC) and whole blood-, and plasma viscosity values (WBV and PV) significantly decreased immediately after stenting (p<0.001). By the fifth day following the intervention the PFC, WBV, PV, red blood cell (RBC) aggregation and ADP-induced platelet aggregation significantly increased (p<0.0001) compared to values measured postprocedurally. At 1 month follow-up these parameters, except whole blood viscosity, decreased significantly compared to measurements made on the 5th day. On the other hand, catalase activity showed significant elevation by the end of the first month.

CONCLUSION

Hemorheological parameters and platelet aggregation showed specific changes following carotid stenting. Abnormal changes of the rheological conditions and increasing platelet activation are the most pronounced in the first week following stenting, which may lead to early stent occlusion. Oxidative stress production returned to baseline levels only by the end of the first month.

Facilitation of mitochondrial outer and inner membrane permeabilization and cell death in oxidative stress by a novel Bcl-2 homology 3 domain protein

We identified a sequence homologous to the Bcl-2 homology 3 (BH3) domain of Bcl-2 proteins in SOUL. Tissues expressed the protein to different extents. It was predominantly located in the cytoplasm, although a fraction of SOUL was associated with the mitochondria that increased upon oxidative stress. Recombinant SOUL protein facilitated mitochondrial permeability transition and collapse of mitochondrial membrane potential (MMP) and facilitated the release of proapoptotic mitochondrial intermembrane proteins (PMIP) at low calcium and phosphate concentrations in a cyclosporine A-dependent manner in vitro in isolated mitochondria. Suppression of endogenous SOUL by diced small interfering RNA in HeLa cells increased their viability in oxidative stress. Overexpression of SOUL in NIH3T3 cells promoted hydrogen peroxide-induced cell death and stimulated the release of PMIP but did not enhance caspase-3 activation. Despite the release of PMIP, SOUL facilitated predominantly necrotic cell death, as revealed by annexin V and propidium iodide staining. This necrotic death could be the result of SOUL-facilitated collapse of MMP demonstrated by JC-1 fluorescence. Deletion of the putative BH3 domain sequence prevented all of these effects of SOUL. Suppression of cyclophilin D prevented these effects too, indicating that SOUL facilitated mitochondrial permeability transition in vivo. Overexpression of Bcl-2 and Bcl-x(L), which can counteract the mitochondria-permeabilizing effect of BH3 domain proteins, also prevented SOUL-facilitated collapse of MMP and cell death. These data indicate that SOUL can be a novel member of the BH3 domain-only proteins that cannot induce cell death alone but can facilitate both outer and inner mitochondrial membrane permeabilization and predominantly necrotic cell death in oxidative stress.

Preliminary study of TIP47 as a possible new biomarker of cervical dysplasia and invasive carcinoma

The aim of this study was to find a possible clinical use of the tail-interacting protein of 47 kDa (TIP47) and further document its expression in smear cytology, different cervical dysplasias, invasive cervical cancer and metastasis.

PATIENTS AND METHODS

A new polyclonal anti-TIP47 antibody was developed and used on smears and histological cervix sections of sixty women with different cytological pathologies. Serum TIP47 level of patients with cervical intraepithelial neoplasia (CIN) or carcinoma in stage IIb, IIIa, and IIIb was monitored during treatment.

RESULTS

TIP47 was expressed weakly in the dysplasias, stronger in invasive tumors and in lymph node metastasis. In patients with cervical carcinoma, the serum TIP47 level was found to be elevated; it decreased after therapy and elevated again in relapse.

CONCLUSION

According to our results, TIP47 could be a good clinical marker for the early detection in blood of the recurrence of cervical carcinoma.

Correlation between the progressive cytoplasmic expression of a novel small heat shock protein (Hsp16.2) and malignancy in brain tumors

Background

Small heat shock proteins are molecular chaperones that protect proteins against stress-induced aggregation. They have also been found to have anti-apoptotic activity and to play a part in the development of tumors. Recently, we identified a new small heat shock protein, Hsp16.2 which displayed increased expression in neuroectodermal tumors. Our aim was to investigate the expression of Hsp16.2 in different types of brain tumors and to correlate its expression with the histological grade of the tumor.

Methods

Immunohistochemistry with a polyclonal antibody to Hsp16.2 was carried out on formalin-fixed, paraffin-wax-embedded sections using the streptavidin-biotin method. 91 samples were examined and their histological grade was defined. According to the intensity of Hsp16.2 immunoreactivity, low (+), moderate (++), high (+++) or none (-) scores were given.

Immunoblotting was carried out on 30 samples of brain tumors using SDS-polyacrylamide gel electrophoresis and Western-blotting.

Results

Low grade (grades 1–2) brain tumors displayed low cytoplasmic Hsp16.2 immunoreactivity, grade 3 tumors showed moderate cytoplasmic staining, while high grade (grade 4) tumors exhibited intensive cytoplasmic Hsp16.2 staining. Immunoblotting supported the above mentioned results. Normal brain tissue acted as a negative control for the experiment, since the cytoplasm did not stain for Hsp16.2. There was a positive correlation between the level of Hsp16.2 expression and the level of anaplasia in different malignant tissue samples.

Conclusion

Hsp16.2 expression was directly correlated with the histological grade of brain tumors, therefore Hsp16.2 may have relevance as becoming a possible tumor marker.

[The effect of carotid stenting on rheological parameters, free radical production and platelet aggregation]

INTRODUCTION

Carotid artery stenting has become a possible treatment of significant carotid stenosis. The risk of stent occlusion and restenosis might be increased by abnormal rheological conditions amplified platelet aggregation and free radical production during the operation.

AIMS

The aim of this study was to assess the changes of the rheologic parameters, platelet aggregation, and oxidative stress after endovascular treatment of carotid stenosis.

METHODS

18 patients (11 men, ages 68 +/- 9 years and 7 women, ages 62 +/- 8 years) suffering from significant carotid stenosis and treated with carotid endovascular intervention were examined. Alteration in hemorrheological parameters as well as epinephrine-, ADP-, and collagen-induced platelet aggregation were evaluated. Oxidative stress was characterized by the determination of catalase activity. The measurements were carried out directly before and after the procedure and 1, 2, 5 days and 1 month following the intervention. Preceding the operation the patients were administered a maximum dose (300 mg) of clopidogrel.

RESULTS

The hematocrit, the plasma fibrinogen concentration (Pfc) and whole blood-, and plasma viscosity (Wbv and Pv) decreased significantly immediately after stenting ( p < 0.001). By the fifth day following the intervention the Pfc, Wdv, Pv, red blood cell (Rbc) aggregation and ADP-induced platelet aggregation increased significantly ( p < 0.0001) compared to values measured after the procedure. At 1 month follow-up these parameters, excepting Wbv, decreased significantly compared to measurements made on the 5th day. On the other hand, catalase activity showed significant elevation by the end of the first month.

CONCLUSION

Hemorrheological parameters and platelet aggregation showed specific changes following carotid stenting. Abnormal changes of the rheological conditions and increasing platelet activation are the most pronounced in the first week following stenting, which may lead to the stent's early occlusion. Oxidative stress production returned to baseline levels only by the end of the first month.

Inhibition of cell death by a novel 16.2 kD heat shock protein predominantly via Hsp90 mediated lipid rafts stabilization and Akt activation pathway

AlphaB-crystallin homology, heat stress induction and chaperone activity suggested that a previously encloned gene product is a novel small heat shock protein (Hsp16.2). Suppression of Hsp16.2 by siRNA sensitized cells to hydrogen peroxide or taxol induced cell-death. Over-expressing of Hsp16.2 protected cells against stress stimuli by inhibiting cytochrome c release from the mitochondria, nuclear translocation of AIF and endonuclease G, and caspase 3 activation. Recombinant Hsp16.2 protected mitochondrial membrane potential against calcium induced collapse in vitro indicating that Hsp16.2 stabilizes mitochondrial membrane systems. Hsp16.2 formed self-aggregates and bound to Hsp90. Inhibition of Hsp90 by geldanamycin diminished the cytoprotective effect of Hsp16.2 indicating that this effect was Hsp90-mediated. Hsp16.2 over-expression increased lipid rafts formation as demonstrated by increased cell surface labeling with fluorescent cholera toxin B, and increased Akt phosphorylation. The inhibition of PI-3-kinase-Akt pathway by LY-294002 or wortmannin significantly decreased the protective effect of the Hsp16.2. These data indicate that the over-expression of Hsp16.2 inhibits cell death via the stabilization of mitochondrial membrane system, activation of Hsp90, stabilization of lipid rafts and by the activation of PI-3-kinase-Akt cytoprotective pathway.

Preventing apoptotic cell death by a novel small heat shock protein

NCBI database analysis indicated that the human C1orf41 protein (small heat shock-like protein-Hsp16.2) has sequence similarity with small heat shock proteins (sHsps). Since sHsps have chaperone function, and so prevent aggregation of denatured proteins, we determined whether Hsp16.2 could prevent the heat-induced aggregation of denatured proteins. Under our experimental conditions, recombinant Hsp16.2 prevented aggregation of aldolase and glyceraldehyde-3-phosphate dehydrogenase, and protected Escherichia coli cells from heat stress indicating its chaperone function. Hsp16.2 also formed oligomeric complexes in aqueous solution. Hsp16.2 was found to be expressed at different levels in cell lines and tissues, and was mainly localized to the nucleus and the cytosol, but to a smaller extent, it could be also found in mitochondria. Hsp16.2 could be modified covalently by poly(ADP ribosylation) and acetylation. Hsp16.2 over-expression prevented etoposide-induced cell death as well as the release of mitochondrial cytochrome c and caspase activation. These data suggest that Hsp16.2 can prevent the destabilization of mitochondrial membrane systems and could represent a suitable target for modulating cell death pathways.