Randomized, Placebo-Controlled Analysis of the Knee Synovial Environment Following Platelet-Rich Plasma Treatment for Knee Osteoarthritis.

BACKGROUND: Platelet-rich-plasma (PRP) is used to treat knee osteoarthritis; however, mechanistic evidence of PRP effectiveness for pain relief is limited. OBJECTIVE: To assess molecular biomarkers and mesenchymal stem cells (MSCs) in synovial fluid during PRP treatment of the osteoarthritic knee joint. DESIGN: Single blinded, randomized, placebo controlled pilot study. SETTING: Veterans Affairs Medical Center. PARTICIPANTS: Seventeen participants with mild to moderate knee osteoarthritis were randomized in a 2:1 placebo-controlled ratio, receiving PRP or saline (placebo) intra-articular injection into the knee joint. METHODS: Knee synovial fluid was analyzed before the respective injections and again 10 days following injection. Participants were followed up to 12 months completing visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires at intervals over that period. MAIN OUTCOME MEASURES: The effects of PRP on synovial protein and MSC gene expression levels were measured by multiplex enzyme-linked immunosorbent assay and quantitative polymerase chain reaction. RESULTS: Novel biomarkers including levels of interleukin (IL)-5, IL-6, IL-10, and tumor necrosis factor-α were measured in synovial fluid 10 days after PRP treatment. Altered gene expression profiles in MSCs from patients treated with PRP were observed for matrix metalloproteinases and inflammatory markers (IL-6, IL-8, CCL2, TNF-α). A2M protease was significantly increased following PRP treatment (P = .005). WOMAC scores declined for up to 3 months from baseline levels and remained low at 6 and 12 months in the PRP group. In contrast, WOMAC scores for patients receiving the saline injection were relatively unchanged for up to 12 months. CONCLUSIONS: We report significant changes for the biomarker A2M (P = .005) as well as differences in expression of cellular markers and postulate that PRP modulates the local knee synovial environment by altering the inflammatory milieu, matrix degradation, and angiogenic growth factors. The PRP treatment group had less pain and stiffness and improved function scores.

Blueprint for cancer research: Critical gaps and opportunities.

We are experiencing a revolution in cancer. Advances in screening, targeted and immune therapies, big data, computational methodologies, and significant new knowledge of cancer biology are transforming the ways in which we prevent, detect, diagnose, treat, and survive cancer. These advances are enabling durable progress in the goal to achieve personalized cancer care. Despite these gains, more work is needed to develop better tools and strategies to limit cancer as a major health concern. One persistent gap is the inconsistent coordination among researchers and caregivers to implement evidence-based programs that rely on a fuller understanding of the molecular, cellular, and systems biology mechanisms underpinning different types of cancer. Here, the authors integrate conversations with over 90 leading cancer experts to highlight current challenges, encourage a robust and diverse national research portfolio, and capture timely opportunities to advance evidence-based approaches for all patients with cancer and for all communities.

Telomere lengths in women treated for breast cancer show associations with chemotherapy, pain symptoms, and cognitive domain measures: a longitudinal study.

BACKGROUND: Survival rates for breast cancer (BC) have improved, but quality of life post-diagnosis/treatment can be adversely affected, with survivors reporting a constellation of psychoneurological symptoms (PNS) including stress, anxiety, depression, pain, fatigue, sleep disturbance, and cognitive dysfunction. METHODS: To assess a potential relationship between telomere length (TL) and the development/persistence of PNS, we longitudinally studied 70 women (ages 23-71) with early stage BC (I-IIIA) at 5 time-points: prior to treatment (baseline), the mid-point of their chemotherapy cycle, 6 months, 1 year, and 2 years following the initiation of chemotherapy. Measures quantified included assessments of each of the PNS noted above and TL [using both a multiplex qPCR assay and a chromosome-specific fluorescence in situ hybridization (FISH) assay]. RESULTS: Variables associated with qPCR mean TLs were age (p = 0.004) and race (T/S ratios higher in Blacks than Whites; p = 0.019). Significant differences (mostly decreases) in chromosome-specific TLs were identified for 32 of the 46 chromosomal arms at the mid-chemo time-point (p = 0.004 to 0.049). Unexpectedly, the sequential administration of doxorubicin [Adriamycin], cyclophosphamide [Cytoxan], and docetaxel [Taxotere] (TAC regimen) was consistently associated with higher TLs, when compared to TLs in women receiving a docetaxel [Taxotere], Carboplatin [Paraplatin], and trastuzumab [Herceptin] [TCH] chemotherapy regimen [association was shown with both the qPCR and FISH assays (p = 0.036)]. Of the PNS, pain was significantly negatively associated with TL (higher pain; shorter telomeres) for a subset of chromosomal arms (5q, 8p, 13p, 20p, 22p, Xp, Xq) (p = 0.014-0.047). Chromosomal TLs were also associated with 7 of the 8 cognitive domains evaluated, with the strongest relationship being noted for chromosome 17 and the visual memory domain (shorter telomeres; lower scores). CONCLUSIONS: We showed that race and age were significantly associated with telomere length in women treated for early stage BC and that acquired telomere alterations differed based on the woman's treatment regimen. Our study also demonstrated that pain and cognitive domain measures were significantly related to telomere values in this study cohort. Expanding upon the knowledge gained from this longitudinal study could provide insight about the biological cascade of events that contribute to PNS related to BC and/or its treatment.

Tumor cell escape from therapy-induced senescence.

H460 non-small cell lung, HCT116 colon and 4T1 breast tumor cell lines induced into senescence by exposure to either etoposide or doxorubicin were able to recover proliferative capacity both in mass culture and when enriched for the senescence-like phenotype by flow cytometry (based on ß-galactosidase staining and cell size, and a senescence-associated reporter, BTG1-RFP). Recovery was further established using both real-time microscopy and High-Speed Live-Cell Interferometry (HSLCI) and was shown to be accompanied by the attenuation of the Senescence-Associated Secretory Phenotype (SASP). Cells enriched for the senescence-like phenotype were also capable of forming tumors when implanted in both immunodeficient and immunocompetent mice. As chemotherapy-induced senescence has been identified in patient tumors, our results suggest that certain senescence-like phenotypes may not reflect a terminal state of growth arrest, as cells that recover with self-renewal capacity may ultimately contribute to disease recurrence.

Fibronectin fibrils regulate TGF-ß1-induced Epithelial-Mesenchymal Transition.

Epithelial-Mesenchymal Transition (EMT) is a dynamic process through which epithelial cells transdifferentiate from an epithelial phenotype into a mesenchymal phenotype. Previous studies have demonstrated that both mechanical signaling and soluble growth factor signaling facilitate this process. One possible point of integration for mechanical and growth factor signaling is the extracellular matrix. Here we investigate the role of the extracellular matrix (ECM) protein fibronectin (FN) in this process. We demonstrate that inhibition of FN fibrillogenesis blocks activation of the Transforming Growth Factor-Beta (TGF-ß) signaling pathway via Smad2 signaling, decreases cell migration and ultimately leads to inhibition of EMT. Results show that soluble FN, FN fibrils, or increased contractile forces are insufficient to independently induce EMT. We further demonstrate that inhibition of latent TGF-ß1 binding to FN fibrils via either a monoclonal blocking antibody against the growth factor binding domain of FN or through use of a FN deletion mutant that lacks the growth factor binding domains of FN blocks EMT progression, indicating a novel role for FN in EMT in which the assembly of FN fibrils serves to localize TGF-ß1 signaling to drive EMT.

Breast epithelial cell infiltration in enhanced electrospun silk scaffolds.

In the present study, the effects of air-flow impedance electrospinning and air-flow rates on silk-based scaffolds for biological tissues were investigated. First, the properties of scaffolds obtained from 7% and 12% silk concentrations were defined. In addition, cell infiltration and viability of MCF-10A breast epithelial cells cultured onto these scaffolds were used to determine the biological suitability of these nanostructures. Air-flow impedance electrospun scaffolds resulted in an overall larger pore size than scaffolds electrospun on a solid mandrel, with the largest pores in 7% silk electrospun with an air pressure of 100 kPa and in 12% silk electrospun with an air pressure of 400 kPa (13.4 ± 0.67 and 26.03 ± 1.19 µm, respectively). After 14 days in culture, the deepest MCF-10A cell infiltration (36.58 ± 2.28 µm) was observed into 7% silk air-flow impedance electrospun scaffolds subjected to an air pressure of 100 kPa. In those scaffolds MCF-10A cell viability was also highest after 14 days in culture. Together, these results strongly support the use of 7% silk-based scaffolds electrospun with a 100 kPa air-flow as the most suitable microenvironment for MCF-10A infiltration and viability.

Is Senescence Reversible?

Senescence was originally identified by the finite lifespan of normal cells that is a consequence of telomere shortening with each cycle of DNA replication. Cells undergoing replicative senescence display pronounced morphological and biochemical changes such as flattening and/or enlargement, increases in p21(WAF1) and/or p16(INK4A), a senescence-associated secretory phenotype, and often senescence-associated heterochromatic foci. Senescence also occurs in tumor cells in response to various forms of chemotherapy or radiation (therapy-induced senescence), which could be the basis for prolonged or (ideally) permanent growth arrest. Alternatively, therapy-induced senescence could represent a means whereby tumor cells evade the potential toxicity of chemotherapy and radiation, allowing for the eventual re-emergence or escape from senescence that could lead to disease recurrence. This review discusses the experimental data in the literature that support the premise that senescence is potentially reversible through the inactivation of p53, p16(INK4A) and/or Rb, over-expression of Cdc2/cdk1 and survivin, the development of polyploidy, the survival of cancer stem cells and/or restoration of the nuclear landscape. If senescence is truly reversible, then the re-emergence of tumor cells from senescent arrest induced by chemotherapy or radiation could represent a barrier to the development of effective and curative cancer therapies.

Restoring SIRT6 Expression in Hutchinson-Gilford Progeria Syndrome Cells Impedes Premature Senescence and Formation of Dysmorphic Nuclei.

OBJECTIVES: Mice overexpressing SIRT6 live longer than wild-type mice while SIRT6 knockout mice exhibit similar degenerative phenotypes as individuals with Hutchinson-Gilford progeria syndrome (HGPS). Thus, we sought to test whether levels of SIRT6 are reduced in cells from individuals with HGPS and whether restored SIRT6 expression may impede premature aging phenotypes. METHODS: Levels of endogenous SIRT6 and progerin in HGPS and normal fibroblasts were assessed by Western blotting and immunofluorescence. A tetracycline-inducible system was utilized to test whether progerin causes a rapid reduction in SIRT6 protein. SIRT6 was overexpressed in HGPS cells via lentiviral infection with biological endpoints including senescence-associated ß-galactosidase (SA-ß-gal) positivity, frequency of nuclear atypia, the number of 53BP1-positive DNA damage foci and growth rates. RESULTS: Typical HGPS fibroblasts express lower levels of SIRT6 than fibroblasts from normal and atypical HGPS donors. Experimental induction of progerin did not cause a detectable reduction of SIRT6 protein. However, overexpression of SIRT6 in HGPS cells was associated with a reduced frequency of SA-ß-gal positivity, fewer misshapen nuclei, fewer DNA damage foci, and increased growth rates. CONCLUSIONS: Typical HGPS fibroblasts exhibit reduced levels of SIRT6 protein via a mechanism that remains to be elucidated. Our findings suggest that restoring SIRT6 expression in HGPS cells may partially impede senescence and the formation of dysmorphic nuclei. © 2015 S. Karger AG, Basel.

Mesenchymal stem cells in mammary adipose tissue stimulate progression of breast cancer resembling the basal-type.

Data are accumulating to support a role for adipose-derived mesenchymal stem cells (MSCs) in breast cancer progression; however, to date most studies have relied on adipose MSCs from non-breast sources. There is a particular need to investigate the role of adipose MSCs in the pathogenesis of basal-like breast cancer, which develops at a disproportionate rate in pre-menopausal African-American women with a gain in adiposity. The aim of this study was to better understand how breast adipose MSCs (bMSCs) contribute to the progression of basal-like breast cancers by relying on isogenic HMT-3255 S3 (pre-invasive) and T4-2 (invasive) human cells that upon transplantation into nude mice resemble this tumor subtype. In vitro results suggested that bMSCs may contribute to breast cancer progression in multiple ways. bMSCs readily penetrate extracellular matrix components in part through their expression of matrix metalloproteinases 1 and 3, promote the invasion of T4-2 cells and efficiently chemoattract endothelial cells via a bFGF-independent, VEGF-A-dependent manner. As mixed xenografts, bMSCs stimulated the growth, invasion and desmoplasia of T4-2 tumors, yet these resident stem cells showed no observable effect on the progression of pre-invasive S3 cells. While bMSCs form vessel-like structures within Matrigel both in vitro and in vivo and chemoattract endothelial cells, there appeared to be no difference between T4-2/bMSC mixed xenografts and T4-2 xenografts with regard to intra- or peri-tumoral vascularity. Collectively, our data suggest that bMSCs may contribute to the progression of basal-like breast cancers by stimulating growth and invasion but not vasculogenesis or angiogenesis.

Defining essential stem cell characteristics in adipose-derived stromal cells extracted from distinct anatomical sites.

The discovery of adipose-derived stromal cells (ASCs) has created many opportunities for the development of patient-specific cell-based replacement therapies. We have isolated multiple cell strains of ASCs from various anatomical sites (abdomen, arms/legs, breast, buttocks), indicating widespread distribution of ASCs throughout the body. Unfortunately, there exists a general lack of agreement in the literature as to their "stem cell" characteristics. We find that telomerase activity and expression of its catalytic subunit in ASCs are both below the levels of detection, independent of age and culturing conditions. ASCs also undergo telomere attrition and eventually senesce, while maintaining a stable karyotype without the development of spontaneous tumor-associated abnormalities. Using a set of cell surface markers that have been promoted to identify ASCs, we find that they failed to distinguish ASCs from normal fibroblasts, as both are positive for CD29, CD73 and CD105 and negative for CD14, CD31 and CD45. All of the ASC isolates are multipotent, capable of differentiating into osteocytes, chondrocytes and adipocytes, while fibroblasts show no differentiation potential. Our ASC strains also show elevated expression of genes associated with pluripotent cells, Oct-4, SOX2 and NANOG, when compared to fibroblasts and bone marrow-derived mesenchymal stem cells (BM-MSCs), although the levels were lower than induced pluripotent stem cells (iPS). Together, our data suggest that, while the cell surface profile of ASCs does not distinguish them from normal fibroblasts, their differentiation capacity and the expression of genes closely linked to pluripotency clearly define ASCs as multipotent stem cells, regardless of tissue isolation location.

Electrospinning adipose tissue-derived extracellular matrix for adipose stem cell culture.

Basement membrane-rich extracellular matrices, particularly murine sarcoma-derived Matrigel, play important roles in regenerative medicine research, exhibiting marked cellular responses in vitro and in vivo, although with limited clinical applications. We find that a human-derived matrix from lipoaspirate fat, a tissue rich in basement membrane components, can be fabricated by electrospinning and used to support cell culture. We describe practical applications and purification of extracellular matrix (ECM) from adipose tissue (At-ECM) and its use in electrospinning scaffolds and adipose stem cell (ASC) culture. The matrix composition of this purified and electrospun At-ECM was assessed histochemically for basement membrane, connective tissue, collagen, elastic fibers/elastin, glycoprotein, and proteoglycans. Each histochemical stain was positive in fat tissue, purified At-ECM, and electrospun At-ECM, and to some extent positive in a 10:90 blend with polydioxanone (PDO). We also show that electrospun At-ECM, alone and blended with PDO, supports ASC attachment and growth, suggesting that electrospun At-ECM scaffolds support ASC cultivation. These studies show that At-ECM can be isolated and electrospun as a basement membrane-rich tissue engineering matrix capable of supporting stem cells, providing the groundwork for an array of future regenerative medicine advances.

Elevated TRF2 in advanced breast cancers with short telomeres.

Telomere repeat binding factor 2 (TRF2) binds directly to telomeres and preserves the structural integrity of chromosome ends. In vitro models suggest that expression of TRF2 protein increases during mammary cancer progression. However, a recent study has reported that TRF2 mRNA levels tend to be lower in clinical specimens of malignant breast tissue. Here, we conduct the first large-scale investigation to assess the levels and cellular localization of the TRF2 protein in normal, pre-malignant and malignant breast tissues. Breast tissue arrays, containing normal, ductal carcinoma in situ (DCIS) and invasive carcinoma specimens, were used to assess the expression and localization of TRF2 protein. Telomere lengths were semi-quantitatively measured using a pantelomeric peptide nucleic acid probe. A mixed effects modeling approach was used to assess the relationship between TRF2 expression and telomeric signal scores across disease states or clinical staging. We demonstrate that TRF2 is exclusively nuclear with a trend toward lower expression with increased malignancy. More case-to-case variability of TRF2 immunostaining intensity was noted amongst the invasive carcinomas than the other disease groups. Invasive carcinomas also displayed variable telomere lengths while telomeres in normal mammary epithelium were generally longer. Statistical analyses revealed that increased TRF2 immunostaining intensity in invasive carcinomas is associated with shorter telomeres and shorter telomeres correlate with a higher TNM stage. All immortalized and cancer cell lines within the array displayed strong, nuclear TRF2 expression. Our data indicate that elevated expression of TRF2 is not a frequent occurrence during the transformation of breast cancer cells in vivo, but higher levels of this telomere-binding protein may be important for protecting advanced cancer cells with critically short telomeres. Our findings also reinforce the concept that serially propagated cancer cells, although tumor-derived, may not model all types of authentic tumors especially those demonstrating genetic heterogeneity.

Multipotent adipose stromal cells and breast cancer development: Think globally, act locally.

It has long been appreciated that stromal cells within the breast tumor microenvironment contribute to mammary carcinogenesis. However, to date, very little is known regarding the role of local adipose-derived stromal cells (ASCs) in the development of breast cancer. Based on pathological, epidemiological and experimental data, we postulate that breast-derived ASCs are unique mesenchymal stem-like cells that play a critical role in the development of breast cancer and discuss the global implications of this working model in terms of breast cancer prevention, early detection, and new targeted therapies.

Isolating adipose-derived mesenchymal stem cells from lipoaspirate blood and saline fraction.

Isolation of adipose-derived stem cells (ASCs) typically involves 8+ hours of intense effort, requiring specialized equipment and reagents. Here, we present an improved technique for isolating viable populations of mesenchymal stem cells from lipoaspirate saline fractions within 30 minutes. Importantly, the cells exhibit remarkable similarities to those obtained using the traditional isolation protocols, in terms of their multipotent differentiation potential and immunophenotype. Reducing the acquisition time of ASCs is critical for advancing regenerative medicine therapeutics, and our approach provides rapid and simple techniques for enhanced isolation and expansion of patient-derived mesenchymal stem cells.

Elevated expression of nuclear Hsp90 in invasive breast tumors.

With the current trend for early breast cancer detection, there is also a growing demand for discovering markers to assist in the patient risk stratification. Molecular chaperones play essential roles in the post-translational maturation of oncogenic client proteins and are strongly associated with carcinogenesis. To better define the role of chaperones in breast cancer, tissue arrays were immunostained for the chaperones Hsp90 and p23 and assessed in terms of reactivity, intensity and cellular localization. Cytoplasmic Hsp90 protein expression was significantly stronger in ductal carcinoma in situ and invasive breast carcinomas as compared to normal breast tissue (p < 0.0001). Importantly, invasive cores also display a significant relationship between nuclear Hsp90 expression and TNM stage (p = 0.0023) as well as estrogen receptor (ER) status (p = 0.0112). Expression of p23 was substantially stronger in normal tissue than in malignant carcinomas (p < 0.0001) with no discernable correlation with TNM stage, which differs from in vitro results. To determine the functional differences between normal and tumor cells, we assessed the bound versus free forms of Hsp90. Contrary to previous results, we find both complexed and free Hsp90 in normal, immortal and tumor cells, suggesting that the differences between normal and immortal/cancer cells in terms of functional Hsp90 levels may be related to either its overall expression level or its subcellular location. Taken together, our data suggest that blocking nuclear Hsp90 function in advanced breast cancers may be a more targeted approach to treating advanced breast cancers that are refractory to traditional therapy.

Mechanism of dominant-negative telomerase function.

Human telomerase uses its integral core components, hTR and hTERT, to maintain telomeres in many cell types. Expression of a dominant-negative mutant of the catalytic subunit of telomerase, DN-hTERT, has been shown to cause telomere shortening and ultimately cell death in a number of tumor-derived cell lines. However, the mechanism of dominant-negative hTERT function and its fate inside the cell are still unknown. In order to understand the effect of the dominant-negative on wild-type hTERT, each was fused with GFP and expressed in telomerase-positive cells. GFP-DN-hTERT expression resulted in cytoplasmic exportation and degradation via ubiquitination. Co-expression of wild-type GFP-hTERT with an untagged DN-hTERT resulted in decreased wild-type hTERT levels, export to the cytoplasm, and increased ubiquitination, suggesting that DN-hTERT complexes with wild-type hTERT to induce cytoplasmic localization. Based on the cytoplasmic degradation, we propose two new mechanisms of dominant-negative hTERT, employing the theory of interactive dimerization. First, the heterodimer of DN-hTERT with wild-type hTERT is exported to the cytoplasm for ubiquitin-mediated protein degradation, and second, the heterodimer may be degraded at a faster rate than the wild-type hTERT homodimer. Understanding mechanisms of telomerase degradation will guide future drug design to target sites on telomerase important for catalytic activity and protein stability.

Genetic inhibition of telomerase results in sensitization and recovery of breast tumor cells.

Telomerase, a ribonucleoprotein enzyme minimally composed of an RNA template (human telomerase RNA) and a catalytically active protein subunit (human telomerase reverse transcriptase), synthesizes telomeric repeats onto chromosome ends and is obligatory for continuous tumor cell proliferation. Telomerase is an attractive anticancer therapeutic target because its activity is present in >90% of human cancers, including >95% of breast carcinomas. Traditional chemotherapies lack the ability to effectively control and cure breast cancer, in part because residual cells are often resistant to DNA-damaging modalities. Although numerous telomerase inhibition strategies cause cancer cells to undergo apoptosis or senescence, there is often a lag period between the beginning of the treatment regimen and a biological effect. Thus, our goal for these studies was to show that effectively blocking telomerase genetically together with standard chemotherapeutic agents, doxorubicin/Adriamycin or Taxol, would increase the sensitization and efficacy for triggering senescence and/or apoptosis in cultures of breast cancer cells while reducing toxicity. We find that blocking telomerase in breast tumor cells substantially increases the sensitization at lower doses of Adriamycin or Taxol and that the kinetics of senescence/apoptosis is more rapid at higher concentrations. Combined with telomerase inhibition, Taxol treatment induced both apoptosis (its typical cell fate) and senescence, both at high enough levels to suggest that these two cellular responses are not mutually exclusive. Genetic inhibition of telomerase is eventually reversed due to up-regulation of endogenous telomerase activity without a net change in telomere length, suggesting that telomerase inhibition itself, not necessarily short telomeres, is important for sensitization.

Japanese medaka: a new vertebrate model for studying telomere and telomerase biology.

A good understanding of telomeres and telomerase biology is crucial for unraveling mechanisms related to aging and cancer. However, in vivo vertebrate studies of telomere biogenesis and telomerase function have been limited by the development of appropriate animal model systems. The present study aims to demonstrate evolutionary conservation of telomerase in vertebrate species, supporting the potential application of fish as vertebrate model for studying telomeres and telomerase function. Comparison of genomic and protein information among vertebrate TERTs (TElomerase Reverse Transcriptase), the Japanese medaka Oryzias latipes shares the highest similarity to that of the human than the other small size fish species studied (including pufferfish and zebrafish). The ubiquitous expression of TERT mRNA, the high constitutive level of telomerase activity, and the humanized telomere lengths further substantiate that Japanese medaka is an ideal vertebrate model for the study of telomere and telomerase-related mechanisms in vivo. Moreover, medaka exhibits fast, invariable growth and is able to provide a variety of useful developmental and reproductive endpoints for lifelong and multi-generational experiments. Our earlier and present findings support the use of medaka for studying organismal aging, tissue regeneration and carcinogenesis.

Overexpression of telomerase-associated chaperone proteins in prostatic intraepithelial neoplasia and carcinomas.

Over 90% of prostate cancers express telomerase activity. In an experimental model, hsp90 and p23, which are necessary for telomerase assembly and function, dramatically increase during tumorigenic conversion. We immunohistochemically analyzed 60 prostate carcinomas, 50 prostatic intraepithelial neoplasias (PIN) and 25 benign prostatic tissues to determine whether hsp90/p23 expression correlates with advancing stage and whether chaperone distribution overlaps with hTERT, the catalytic component of telomerase. Strong expression of hsp90/p23 was detected in approximately 95% of PIN and carcinomas without relationship to Gleason score. While hsp90/p23 immunostaining was predominantly diffuse and cytoplasmic, nuclear immunoreactivity was observed in several moderate-to-high grade carcinomas, and those carcinomas with nuclear chaperone staining exhibited detectable hTERT. Our data suggest enhanced chaperone-mediated telomerase assembly as a mechanism for increased activity in advanced prostate carcinomas, stable association between chaperones and telomerase in vivo, and utility for chaperone immunostaining to identify focal PIN in the context of widespread hyperplasia.

Accelerated senescence: an emerging role in tumor cell response to chemotherapy and radiation.

Treatment of malignancies with chemotherapeutic drugs and/or radiotherapy is designed to eliminate the disease by depriving the tumor cell of its reproductive potential. Frequently, the desired effect of cell killing is achieved through the promotion of apoptosis; however, accumulating evidence suggests that apoptosis may not be the exclusive or even primary mechanism whereby tumor cells lose their self-renewal capacity after radiation or drug treatment, particularly in the case of solid tumors. While failure to undergo apoptosis in response to chemotherapeutic drugs or radiation may represent a mechanism of drug and radiation resistance, particularly in the case of leukemias and lymphomas, it is gradually being recognized that in the case of solid tumors, loss of reproductive capacity can occur through alternative pathways including reproductive cell death or mitotic catastrophe, through autophagic cell death, and as described below, through a terminally arrested state similar to replicative senescence. Studies building upon the phenomenon of replicative senescence in normal cells approaching the limit of their reproductive potential have identified a comparable senescence-like arrest as a component of the tumor cell response to chemotherapeutic drugs and radiation. This response, which has been termed "premature senescence", "senescence-like growth arrest", "stress-induced premature senescence", and "accelerated senescence", can also result from supraphysiological mitogenic signaling, sub-optimal culture conditions, and ectopic expression of oncogenes. Here, we will use the term "accelerated senescence" in our consideration of the morphological, biochemical, and molecular aspects of treatment-induced senescence, its relationship to classical replicative senescence, its prevalence in clinical specimens and the implications of accelerated senescence for the outcome of cancer therapy.