Adhesion,growth and cytoskeletal characteristics of 8701-BC breast carcinoma cells cultured in the presence of type V collagen

Type V collagen is one of the minor components of the extracellular matrix (ECM) whose content is increased in cases of ductal infiltrating carcinomas of the breast. In order to clarify its biological role, we have investigated the effect of this molecule, both as substrate and as soluble factor, on the behaviour of a breast carcinoma cell line (8701-BC) grown in vitro. Cell-collagen adhesion was monitored for 24 h from plating in the absence or presence of serum. The influence of type V collagen on cell growth was followed during 9 days of culture, and the actin-vinculin arrangement was studied by simultaneous fluorescent immuno-staining. The results indicate that type V collagen is not a permissive substrate for neoplastic cell proliferation and dissemination in vitro.     

CXCL5, a promoter of cell proliferation, migration and invasion, is a novel serum prognostic marker in patients with colorectal cancer

PurposeSerum CXCL5 levels in patients with colorectal cancer (CRC) were assessed to evaluate correlation with clinicopathologic features and prognosis. The effects of CXCL5 on CRC cells were also investigated in vitro.MethodsBased on cytokine array analysis, CXCL5 was identified as a novel prognostic serum marker. Serum levels of CXCL5 were assessed in 250 CRC patients and 33 normal volunteers by enzyme-linked immunosorbent assay (ELISA), and their relation to clinicopathologic findings and survival investigated. CXCL5 levels in CRC cell lines were also measured by ELISA, and CXCL5 and CXCR2 expression was evaluated by immunohistochemistry. To investigate the biological role of the CXCL5/CXCR2 axis, recombinant human CXCL5 and CXCR2 neutralisation antibodies were used for proliferation, migration and invasion assays.ResultsPreoperative serum CXCL5 was significantly elevated in patients with CRC compared with healthy volunteers (p = 0.013). High serum CXCL5 was significantly associated with female sex (p = 0.0098) and liver metastasis (p = 0.0040). Univariate analysis correlated elevated CXCL5 with poor overall survival (p = 0.0002). Multivariate analysis showed that elevated CXCL5 was a significant and independent prognostic factor of survival in all CRC patients (p = 0.038). CRC cells secreted CXCL5, and administration of recombinant human CXCL5 promoted proliferation, migration and partial invasion. These effects were generally inhibited by CXCR2 neutralisation antibody.ConclusionsPreoperative serum CXCL5 could serve as a novel predictive marker for prognosis determination of CRC patients. CXCL5/CXCR2 axis might be associated with colorectal cancer progression.     

Scavenger receptor class B type I regulates cellular cholesterol metabolism and cell signaling associated with breast cancer development

Introduction

Previous studies have identified cholesterol as an important regulator of breast cancer development. High-density lipoprotein (HDL) and its cellular receptor, the scavenger receptor class B type I (SR-BI) have both been implicated in the regulation of cellular cholesterol homeostasis, but their functions in cancer remain to be established.

Methods

In the present study, we have examined the role of HDL and SR-BI in the regulation of cellular signaling pathways in breast cancer cell lines and in the development of tumor in a mouse xenograft model.

Results

Our data show that HDL is capable of stimulating migration and can activate signal transduction pathways in the two human breast cancer cell lines, MDA-MB-231 and MCF7. Furthermore, we also show that knockdown of the HDL receptor, SR-BI, attenuates HDL-induced activation of the phosphatidylinositol 3-kinase (PI3K)/protein Kinase B (Akt) pathway in both cell lines. Additional investigations show that inhibition of the PI3K pathway, but not that of the mitogen-activated protein kinase (MAPK) pathway, could lead to a reduction in cellular proliferation in the absence of SR-BI. Importantly, whereas the knockdown of SR-BI led to decreased proliferation and migration in vitro, it also led to a significant reduction in tumor growth in vivo. Most important, we also show that pharmacological inhibition of SR-BI can attenuate signaling and lead to decreased cellular proliferation in vitro. Taken together, our data indicate that both cholesteryl ester entry via HDL-SR-BI and Akt signaling play an essential role in the regulation of cellular proliferation and migration, and, eventually, tumor growth.

Conclusions

These results identify SR-BI as a potential target for the treatment of breast cancer.     

Estrogen receptor alpha drives proliferation in PTEN-deficient prostate carcinoma by stimulating survival signaling,MYC expression and altering glucose sensitivity

While high doses of estrogen, in combination with androgens, can initiate prostate cancer (PCa) via activation of the estrogen receptor α (ERα), the role of ERα in PCa cells within established tumors is largely unknown. Here we show that expression of ERα is increased in high grade human PCa. Similarly, ERα is elevated in mouse models of aggressive PCa driven by MYC overexpression or deletion of PTEN. Within the prostate of PTEN-deficient mice, there is a progressive pattern of ERα expression: low in benign glands, moderate in tumors within the dorsal, lateral and ventral lobes, and high in tumors within the anterior prostate. This expression significantly correlates with the proliferation marker Ki67. Furthermore, in vitro knockdown of ERα in cells derived from PTEN-deficient tumors causes a significant and sustained decrease in proliferation. Depletion of ERα also reduces the activity of the PI3K and MAPK pathways, both downstream targets of non-genomic ERα action. Finally, ERα knockdown reduces the levels of the MYC protein and lowers the sensitivity of cellular proliferation to glucose withdrawal, which correlates with decreased expression of the glucose transporter GLUT1. Collectively, these results demonstrate that ERα orchestrates proliferation and metabolism to promote the neoplastic growth of PCa cells.     

Cholesterol-induced mammary tumorigenesis is enhanced by adiponectin deficiency: role of LDL receptor upregulation

Adiponectin is an adipokine that can suppress the proliferation of various human carcinoma cells. Although its anti-tumor activities have been suggested by many clinical investigations and animal studies, the underlying mechanisms are not fully characterized. In MMTV-polyomavirus middle T antigen (MMTV-PyVT) transgenic mice models, reduced- or complete loss-of-adiponectin expression promotes mammary tumor development. The present study demonstrated that while tumor development in control MMTV-PyVT mice is associated with a progressively decreased circulating cholesterol concentration, adiponectin deficient MMTV-PyVT mice showed significantly elevated total- and low density lipoprotein (LDL)-cholesterol levels. Cholesterol contents in tumors derived from adiponectin deficient mice were dramatically augmented. High fat high cholesterol diet further accelerated the tumor development in adiponectin deficient PyVT mice. The protein levels of LDL receptor (LDLR) were found to be upregulated in adiponectin-deficient tumor cells. In human breast carcinoma cells, treatment with LDL-cholesterol or overexpressing LDLR elevates nuclear beta-catenin activity and facilitates tumor cell proliferation. On the other hand, adiponectin decreased LDLR protein expression in breast cancer cells and inhibited LDL-cholesterol-induced tumor cell proliferation. Both in vivo and in vitro evidence demonstrated a stimulatory effect of adiponectin on autophagy process, which mediated the down-regulation of LDLR. Adiponectin-induced reduction of LDLR was blocked by treatment with a specific inhibitor of autophagy, 3-methyladenine. In conclusion, the study demonstrates that adiponectin elicits tumor suppressive effects by modulating cholesterol homeostasis and LDLR expression in breast cancer cells, which is at least in part attributed to its role in promoting autophagic flux.     

Adenosine 3':5' cyclic monophosphate and myeloid leukemic cell proliferation in vitro

In order to elucidate the possible role of adenosine 3′:5′ cyclic monophosphate (cAMP) in the modulation of proliferation of human leukemic myeloblasts, we have determined cAMP levels of samples from patients with leukemia before and after in vitro suspension culture, in the presence and absence of leucocyte conditioned medium (LCM). cAMP levels correlated with the magnitude of increase of cell numbers after culture with LCM (rank-order correlation coefficient (r_s) = 0.57, P < 0.05) and with tritiated thymidine (³H TdR) incorporation during culture (r_s) = 0.68, P < 0.01). Additions of the phosphodiesterase resistant analogue 8-bromo cAMP to cultures caused modest increases of ³H TdR incorporation of 8 of 9 acute myeloid leukemia samples after 72h with LCM. Stimulation was optimal at 10^?7 M but in the absence of LCM occurred less often and required higher concentrations (10^?5 M). Inhibition was noted at concentrations of 10^?4 M and greater. Cells cultured in the presence of LCM had lower levels of cAMP (P < 0.01) particularly at points with maximal stimulation of ³H TdR incorporation (P < 0.01). These differences between paired points (with and without LCM) were small and no immediate effect of LCM upon cAMP levels, after 1 and 2-h incubations, was noted. These data suggest that cAMP promotes initiation of leukemic cell proliferation in vitro.     

Effect of B-lymphocyte- and NPC-derived EBV-1 gene expression on in vitro growth and differentiation of human epithelial cells

The effect of expression of the Epstein-Barr-virus (EBV) latent membrane protein (LMP1) derived from B-lymphocytes (B) and nasopharyngeal carcinoma (NPC) (C) on the in vitro growth and differentiation of a human keratinocyte line, Rhek-1, was analyzed in clonal growth and in in vitro differentiation assays. In contrast to the polygonal parental cells, the B-LMP1-expressing sublines were spindle-shaped while the C-LMP1-expressing cells were pleomorphic. Both B- and C-LMP1-expressing sublines showed increased proliferation as evidenced by: (1) higher colony-forming efficiency (CFE) and larger colony size at reduced serum levels; (2) an increased number of epithelial cell layers formed in the air-liquid-interface culture system and (3) increased expression of proliferative cell nuclear antigen (PCNA). At low serum concentration, the C-LMP1-expressing sublines formed larger colonies than those expressing B-LMP1. In the air-liquid-interface culture system, both B- and C-LMP1-expressing lines showed reduced epithelial differentiation resulting in reduced stratification and reduced involucrin expression similar to those of the cancer cell line, Siha. The results of the present study indicate that the expression of LMP1 in human keratinocytes is associated with morphological transformation and predisposes these cells to a more neoplastic phenotype. The structural difference between the 2 genes responsible for the functional differences and transforming ability will be pinpointed in further experiments.     

Subgroups of oligoleukemia as identified by in vitro agar culture.

Sixty-five patients with a diagnosis of oligoleukemia (myeloid leukemia with < 50% marrow leukemic infiltrate) were studied by in vitro agar culture to delineate various growth patterns and their prognostic significance. Five in vitro growth patterns were observed: (1) Category (Cat) I-A with low colony and cluster incidence, normal cluster/colony ratio and normal cellular differentiation in colonies; (2) Cat I-B with normal to high number of colonies and clusters, normal cluster/colony ratio and normal cellular differentiation in colonies; (3) Cat II with excessive clusters and a low number of colonies, high cluster/colony ratio and normal differentiation of cells in the colonies; (4) Cat III-A with excessive number of clusters only of ? 20 cells size; and (5) Cat III-B with excessive number of clusters of > 20 cell size with or without colonies consisting predominantly of blast cells. Culture patterns of Cat III-A and III-B resemble those observed in acute myeloid leukemia and therefore are called leukemic culture patterns. Patients in Cat I-A (non-leukemic culture pattern) survive longer (P = < 0.04) and progress less rapidly to acute leukemia (P = < 0.03) when compared with those in Cat III-A and III-B. Also the rate of increase in leukemic blast cell infiltrate is slower in Cat I-A than in Cat III-A and III-B. Patients with non-leukemic in vitro growth pattern are associated with a relatively benign clinical course and those in Cat III-A and III-B (leukemic growth pattern) are associated with a more aggressive leukemic disorder.     

Expanding Sca-1+ mammary stem cell in the presence of oestrogen and growth hormone

Background

Sca-1 is controversial as a mammary stem cell marker in the literature, which may be due to the different isolation protocols and culture media used in different laboratories. The object of our study is to establish the Medium to promote the proliferation of mammary stem cell and explore the possibility of Sca-1 as mammary stem cell marker.

Methods

We used BM medium supplemented with different concentration of 17 MaECM medium which promoted the proliferation of mouse mammary epithelial cells and inhibited the growth of fibroblasts. Flow cytometry was used to isolate Sca-1⁺ and Sca-1^? cell populations from cultured mammary epithelial cells. Mammary fat pad transplantation and Mammosphere-forming assay were done to confirm the stem cell potential of Sca-1⁺ cells. Differentiating culture was used to detect the differentiation potential of Sca-1⁺ cells. Real-time PCR was carried out to analyse the expression of mammary stem cell-related genes in Sca-1+ cells.

Results

We first selected the medium suitable for mammary stem cell growth. Stem cell medium BM was used to culture mammary organoids, which generated many fibroblasts. We established MaECM medium supplemented with oestrogen and growth hormone (GH), in which oestrogen promoted mammary epithelial cell proliferation and inhibited fibroblast growth, and GH obviously enhanced the effect of oestrogen on mammary epithelial cell proliferation. Flow cytometry showed that 50% of cells were Sca-1⁺ under the culture of MaECM medium. We confirmed that Sca-1⁺ cells regenerated mammary outgrowths when transplanted in vivo, formed mammospheres in vitro and differentiated into luminal epithelial cells with milk-secreting function and myoepithelial cells under Matrigel culture. Furthermore, gene expression analysis by Real-time PCR revealed that Sca-1⁺ cells expressed markedly higher levels of mammary stem cell-related genes in comparison to Sca-1^? cells.

Conclusion

Our research demonstrates that Sca-1⁺ mammary stem cells can be more easily isolated when cultured in the presence of oestrogen and GH.     

Conditional reprogramming culture conditions facilitate growth of lower-grade glioma models

BackgroundThe conditional reprogramming cell culture method was developed to facilitate growth of senescence-prone normal and neoplastic epithelial cells, and involves co-culture with irradiated fibroblasts and the addition of a small molecule Rho kinase (ROCK) inhibitor. The aim of this study was to determine whether this approach would facilitate the culture of compact low-grade gliomas.MethodsWe attempted to culture 4 pilocytic astrocytomas, 2 gangliogliomas, 2 myxopapillary ependymomas, 2 anaplastic gliomas, 2 difficult-to-classify low-grade neuroepithelial tumors, a desmoplastic infantile ganglioglioma, and an anaplastic pleomorphic xanthoastrocytoma using a modified conditional reprogramming cell culture approach.ResultsConditional reprogramming resulted in robust increases in growth for a majority of these tumors, with fibroblast conditioned media and ROCK inhibition both required. Switching cultures to standard serum containing media, or serum-free neurosphere conditions, with or without ROCK inhibition, resulted in decreased proliferation and induction of senescence markers. Rho kinase inhibition and conditioned media both promoted Akt and Erk1/2 activation. Several cultures, including one derived from a NF1-associated pilocytic astrocytoma (JHH-NF1-PA1) and one from a BRAF p.V600E mutant anaplastic pleomorphic xanthoastrocytoma (JHH-PXA1), exhibited growth sufficient for preclinical testing in vitro. In addition, JHH-NF1-PA1 cells survived and migrated in larval zebrafish orthotopic xenografts, while JHH-PXA1 formed orthotopic xenografts in mice histopathologically similar to the tumor from which it was derived.ConclusionsThese studies highlight the potential for the conditional reprogramming cell culture method to promote the growth of glial and glioneuronal tumors in vitro, in some cases enabling the establishment of long-term culture and in vivo models.     

Role of Proprotein Convertases in Prostate Cancer Progression

Better understanding of the distinct and redundant functions of the proprotein convertase (PC) enzyme family within pathophysiological states has a great importance for potential therapeutic strategies. In this study, we investigated the functional redundancy of PCs in prostate cancer in the commonly used androgen-sensitive LNCaP and the androgen-independent DU145 human cell lines. Using a lentiviral-based shRNA delivery system, we examined in vitro and in vivo cell proliferation characteristics of knockdown cell lines for the endogenous PCs furin, PACE4, and PC7 in both cell lines. Of the three PCs, only PACE4 was essential to maintain a high-proliferative status, as determined in vitro using XTT proliferation assays and in vivo using tumor xenografts in nude mice. Furin knockdowns in both cell lines had no effects on cell proliferation or tumor xenograft growth. Paradoxically, PC7 knockdowns reduced in vitro cellular proliferation but had no effect in vivo. Because PCs act within secretion pathways, we showed that conditioned media derived from PACE4 knockdown cells had very poor cell growth-stimulating effects in vitro. Immunohistochemistry of PACE4 knockdown tumors revealed reduced Ki67 and higher p27^KIP levels (proliferation and cell cycle arrest markers, respectively). Interestingly, we determined that the epidermal growth factor receptor signaling pathway was activated in PC7 knockdown tumors only, providing some explanations of the paradoxical effects of PC7 silencing in prostate cancer cell lines. We conclude that PACE4 has a distinct role in maintaining proliferation and tumor progression in prostate cancer and this positions PACE4 as a relevant therapeutic target for this disease.     

Annexin A3 is a mammary marker and a potential neoplastic breast cell therapeutic target

Breast cancers are the most common cancer-affecting women; critically the identification of novel biomarkers for improving early detection, stratification and differentiation from benign tumours is important for the reduction of morbidity and mortality.To identify and functionally characterise potential biomarkers, we used mass spectrometry (MS) to analyse serum samples representing control, benign breast disease (BBD) and invasive breast cancer (IDC) patients. Complementary and multidimensional proteomic approaches were used to identify and validate novel serum markers.Annexin A3 (ANX A3) was found to be differentially expressed amongst different breast pathologies. The diagnostic value of serum ANX A3 was subsequently validated by ELISA in an independent serum set representing the three groups. Here, ANX A3 was significantly upregulated in the benign disease group sera compared with other groups (P < 0.0005).In addition, paired breast tissue immunostaining confirmed that ANX A3 was abundantly expressed in benign and to a lesser extent malignant neoplastic epithelium. Finally, we illustrated ANX A3 expression in cell culture lysates and conditioned media from neoplastic breast cell lines, and its role in neoplastic breast cell migration in vitro.This study confirms the novel role of ANX A3 as a mammary biomarker, regulator and therapeutic target.     

Circulating microRNA-1290 as a novel diagnostic and prognostic biomarker in human colorectal cancer

BackgroundCirculating microRNAs (miRNAs) are attracting major interest as potential non-invasive biomarkers for colorectal cancer (CRC). This study aimed to identify a novel serum miRNA biomarker for the early detection and/or evaluating prognosis of CRC patients.Patients and methodsComprehensive miRNA array analysis was carried out using serum samples from patients with colorectal neoplasia and healthy controls. Next, to verify whether the candidate miRNA possessed a secretory potential, we screened miRNA expression levels in culture medium from 2 CRC cell lines, followed by serum analysis from 12 stage IV CRC, 12 adenoma, and 12 control subjects. Thereafter, we validated expression of candidate miRNAs in 179 primary CRC tissues, as well as serum samples from an independent cohort of 211 CRCs, 56 adenomas, and 57 control subjects.ResultsThrough microarray analysis, we identified significantly higher levels of miRNA-1290 (miR-1290) in serum from patients with colorectal adenomas and cancers. We verified miR-1290 overexpression in serum of CRC patients in a training cohort. In the validation cohort, serum miR-1290 levels were significantly up-regulated in patients with colorectal adenomas (P < 0.0001) and cancers (P < 0.0001). Serum miR-1290 levels could robustly distinguish adenoma [area under the curve (AUC) = 0.718] and CRC patients (AUC = 0.830) from normal subjects. High miR-1290 expression in serum and tissue was significantly associated with tumor aggressiveness and poor prognosis. Moreover, serum miR-1290 levels were an independent prognostic factor [hazard ratio (HR) = 4.51; 95% confidence interval (CI) = 1.23–23.69; P = 0.0096] and an independent predictor for tumor recurrence (hazard ratio = 3.92; 95% confidence interval = 1.11–25.14; P = 0.032) in CRC.ConclusionsSerum miR-1290 is a novel biomarker for early detection, recurrence, and prognosis in CRC.     

Goserelin can inhibit ovarian cancer proliferation and simultaneously protect ovarian function from cisplatin: an in vitro and in vivo study

Abstract

This study investigates whether goserelin can inhibit ovarian cancer proliferation and protect ovarian function from cisplatin (CDDP). We evaluated proliferation and AKT phosphorylation in goserelin-treated ES-2 and SKOV3-ip ovarian cancer cells. Anti-Müllerian hormone (AMH) in human granulosa cells (hGCs) cotreated with goserelin and CDDP was measured by ELISA. Tumour volumes, Ki-67 expression, estrus, follicles, ovarian volumes, and serum AMH were compared in nude mice bearing transplanted tumours treated with goserelin and/or CDDP. Our results showed that goserelin inhibited cellular proliferation and AKT phosphorylation in vitro, and inhibited tumour growth and Ki-67 expression in vivo. Goserelin and CDDP cotreatment decreased the estrus cycles of the nude mice and prolonged estrus duration. Goserelin abrogated the CDDP-induced down-regulation of primary and preantral follicle percentage and ovarian volume. Goserelin increased AMH secretion in vitro and in vivo. In conclusion, goserelin inhibited ovarian cancer proliferation and simultaneously protected ovarian function from CDDP.     

Cytotoxic activity of guinea-pig lymph-node cells stimulated in vitro

Guinea-pig lymph-node cells (LNC) cultured for 5 days in medium containing fetal calf serum (FCS) were cytotoxic to various target cells. LNC cultured in medium supplemented with fresh, autologous guinea-pig serum (GPS) instead of FCS were not detectably cytotoxic unless agents that stimulate lymphocyte proliferation were added to the culture medium. The stimulating agents we studied were 2-mercaptoethanol (2-ME), syngeneic tumor cells, allogeneic peritoneal exudate cells (PEC) and the T-cell mitogens concanavalin A (Con A) and phytohemagglutinin (PHA). LNC cultured in the presence of these agents were cytotoxic to normal syngeneic fibroblasts and to syngeneic, allogeneic or xenogeneic tumor cells but not to PHA-induced lymphoblasts. Potentiation of cytotoxicity in vitro was accompanied by a marked proliferation of the cultured LNC; the combination of several stimulatory agents had an additive effect on the generation of cytotoxicity in culture.     

A BRCA1 Mutation Is Not Associated with Increased Indicators of Oxidative Stress

BackgroundSeveral functions have been attributed to the BRCA1 protein. A recent study suggests that BRCA1 is involved in the cellular antioxidant response by inducing the expression of genes involved in the antioxidant defense system and thus conferring resistance to oxidative stress. It is possible that individuals with a BRCA1 mutation might be susceptible to the effects of oxidative stress. The aim of this study was to evaluate whether women with a BRCA1 mutation exhibit increased indicators of oxidative stress.Patients and MethodsWe measured 3 markers of oxidative stress in vivo, the amounts of serum malondialdehyde and protein thiols, and 8-oxo-2′-deoxyguanosine (8-oxodG) levels in 25 unaffected BRCA1 mutation carriers and 25 noncarrier control subjects.ResultsThere was no significant difference in serum malondialdehyde levels (P = .41), serum thiol levels (P = .85), or the number of 8-oxodG lesions (P = .49) in BRCA1 mutation carriers versus noncarriers.ConclusionThe results of this study suggest that the presence of a heterozygous BRCA1 mutation is not associated with increased levels of indicators of oxidative stress in serum or lymphocytes. Future studies are warranted to evaluate whether strategies aimed at minimizing oxidative stress might aid in the prevention of hereditary breast cancer.     

The phosphoinositide 3-kinase/mammalian target of rapamycin inhibitor NVP-BEZ235 is effective in inhibiting regrowth of tumour cells after cytotoxic therapy

PurposeRegrowth of tumour cells between cycles of chemotherapy is a significant clinical problem. Treatment strategies where antiproliferative agents are used to inhibit tumour regrowth between chemotherapy cycles are attractive, but such strategies are difficult to test using conventional monolayer culture systems.MethodsWe used the in vitro tumour spheroid model to study regrowth of 3-D colon carcinoma tissue after cytotoxic therapy. Colon carcinoma cells with wild-type or mutant phosphatidyl inositol 3-kinase catalytic subunit (PI3KCA) or KRAS alleles were allowed to form multicellular spheroids and the effects of different pharmacological compounds were studied after sectioning and staining for relevant markers of cell proliferation and apoptosis.ResultsStudies using colon cancer cells with gene disruptions suggested that the phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) pathway was essential for proliferation in 3-D culture. The dual PI3K-mTOR inhibitor NVP-BEZ235, currently in clinical trials, was found to inhibit phosphorylation of the mTOR target 4EBP1 in 3-D cultured cells. The ability of NVP-BEZ235 to inhibit tumour cell proliferation and to induce apoptosis was markedly more pronounced in 3-D cultures compared to monolayer cultures. It was subsequently found that NVP-BEZ235 was effective in inhibiting regrowth of 3-D cultured cells after treatment with two cytotoxic inhibitors of the ubiquitin–proteasome system (UPS), methyl-13-hydroxy-15-oxokaurenoate (MHOK) and bortezomib (Velcade®).ConclusionsThe dual PI3K-mTOR inhibitor NVP-BEZ235 was found to reduce cell proliferation and to induce apoptosis in 3-D cultured colon carcinoma cells, NVP-BEZ235 is a promising candidate for use in sequential treatment modalities together with cytotoxic drugs to reduce the cell mass of solid tumours.     

Loss of p53 Induces Tumorigenesis in p21-Deficient Mesenchymal Stem Cells

There is growing evidence about the role of mesenchymal stem cells (MSCs) as cancer stem cells in many sarcomas. Nevertheless, little is still known about the cellular and molecular mechanisms underlying MSCs transformation. We aimed at investigating the role of p53 and p21, two important regulators of the cell cycle progression and apoptosis normally involved in protection against tumorigenesis. Mesenchymal stem cells from wild-type, p21^-/-p53^+/+, and p21^-/-p53^+/- mice were cultured in vitro and analyzed for the appearance of tumoral transformation properties after low, medium, and high number of passages both in vitro and in vivo. Wild-type or p21^-/-p53^+/+ MSCs did not show any sign of tumoral transformation. Indeed, after short-term in vitro culture, wild-type MSCs became senescent, and p21^-/-p53^+/+ MSCs showed an elevated spontaneous apoptosis rate. Conversely, MSCs carrying a mutation in one allele of the p53 gene (p21^-/-p53^+/- MSCs) completely lost p53 expression after in vitro long-term culture. Loss of p53 was accompanied by a significant increase in the growth rate, gain of karyotypic instability, loss of p16 expression, and lack of senescence response. Finally, these cells were able to form fibrosarcomas partially differentiated into different mesenchymal lineages when injected in immunodeficient mice both after subcutaneous and intrafemoral injection. These findings show that MSCs are very sensitive to mutations in genes involved in cell cycle control and that these deficiencies can be at the origin of some mesodermic tumors.