P1-09-06: Single Nucleotide Polymorphisms in the BRMS1 and SIPA1 Metastasis Suppressor Genes as Prognostic Markers in Breast Cancer Patients

Introduction: Single nucleotide polymorphisms (SNPs) in the metastasis suppressors BRMS1 and SIPA1 may affect metastatic efficiency. BRMS1 affects apoptosis, colonization, cell adhesion, and invasive potential. Loss of BRMS1 expression has been correlated with younger age at diagnosis and reduced survival time in patients with progesterone-receptor (PR) negative, HER2−positive tumors. SIPA1 affects extracellular matrix gene expression and cell adhesion, and while SNPs have been associated with node positive, estrogen-receptor (ER)/PR negative tumors, evidence for a relationship with survival has been conflicting. Identifying SNPs that affect risk of recurrence and survival may improve the ascertainment of patients who require aggressive adjuvant therapy following a diagnosis of breast cancer. We evaluated associations between seven BRMS1 and SIPA1 SNPs and recurrence and survival in patients with primary breast cancer.

Methods: We identified 1,015 incident breast cancer patients who received surgery at Roswell Park Cancer Institute (RPCI) and participated in the DataBank and BioRepository (DBBR) resource. Participants completed an epidemiologic questionnaire and provided a blood sample prior to surgery or other treatment. Clinical and pathologic data were linked to de-identified participant data in the DBBR database. SNPs in BRMS1 (rs11537993, rs3116068, and rs1052566) and SIPA1 (rs75894763, rs746429, rs3741378, and rs2306364) were genotyped by RPCI's Genomics facility using Sequenom® iPLEX Gold and Taqman® real-time PCR assays. Cox proportional hazards regression was used to estimate hazard ratios and 95% confidence intervals.

Results: The median follow-up time was 33 months, and 49 deaths and 42 recurrences occurred. Tumors were more likely to be larger, node positive, ER/PR negative, and high grade among patients who experienced a recurrence or death. Recurrence was less likely in older patients and those with higher body mass index, although the latter association was nonsignificant (p=0.06). Patients with at least one variant allele of the BRMS1 rs3116068 genotype experienced shorter overall survival compared to patients with the homozygous common genotype (HR=2.05, 95% CI 1.15−3.63, rs3116068 AG+AA compared to GG). The remaining SNPs were not associated with overall survival, and none of the SNPs were associated with recurrence.

Conclusions: In our data, the variant allele of rs3116068 was more common among women whose breast cancer was node negative and HER2−positive, compared to those with the common rs3116068 allele. The rs3116068 variant allele is also associated with poorer survival. While our findings do not support a role for common SNPs in the SIPA1 gene in breast cancer prognosis, BRMS1 rs3116068 may be a useful prognostic biomarker. Future goals are to examine additional SNPs in BRMS1 and other metastasis-related genes in a larger, racially diverse population.

Funding: This research was supported by a gift from the Jayne and Phil Hubbell Family. The DBBR and Genomics Facility are RPCI Cancer Center Support Grant shared resources, supported by P30 CA016056-32. Ms. Roberts is a DOD Predoctoral Award recipient (BC10068) and Dr. Ambrosone is funded by the Breast Cancer Research Foundation.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-09-06.

Proliferation of dental follicle-derived cell populations in heat-stress conditions

OBJECTIVES

Isolation and purification of adult stem cells (ASC) are a great challenge. Our objectives were to determine whether ASC are more heat-tolerant than non-stem cells, and to explore if ASC could be enriched by heat-stress treatments.

MATERIALS AND METHODS

Rat dental follicle cells were cultured in a variety of media to obtain either a heterogeneous cell population (H-DFC) consisting of stem cells and non-stem cells, or a homogenous cell population (DFC) containing non-stem cells only. Real-time RT-PCR was conducted to compare expression of heat-shock proteins (HSPs) between the two populations. To study heat tolerance, H-DFC and DFC were incubated under heat-stress conditions and cell proliferation was evaluated by alamar blue reduction assay. Furthermore, cells resulting from heat-stress treatments were evaluated for differentiation capability and expression of stem cell markers.

RESULTS

H-DFC expressed higher levels of HSP110, HSP70s and HSP27s than did DFC. H-DFC increased levels of proliferation at 40 °C compared to controls grown at 37 °C; no significant reduction in proliferation occurred at temperatures below 40.5 °C. In contrast, DFC showed significant reduction in proliferation under all heat-stress treatments. Heat-stressed H-DFC had increased differentiation capability and increased expression of stem cell markers.

CONCLUSION

Stem cells appear to be more tolerant to heat stress than non-stem cells. Incubation of a heterogeneous cell population in heat-stress conditions resulted in increased stem cell numbers.

Analysis and design of a modular underactuated mechanism for robotic fingers

This paper presents an analysis of the design problems and requirements for underactuated mechanisms for robotic fingers. The case of performing a grasping task is considered and a solution is proposed that consists of a series of linked underactuated mechanisms. Optimality criteria are analysed with the aim of formulating a general design algorithm based on a suitable optimization problem. An example of a four-phalanx modular finger is used to highlight the practical feasibility of the proposed modular design concepts and procedures.

First Report of Xylella fastidiosa in Peach in New Mexico

Xylella fastidiosa is a gram-negative bacterium that causes disease in a wide variety of plants such as grapes, citrus trees, oleanders, and elm and coffee trees. This bacterium is xylem limited and causes disease symptoms such as leaf scorch, stunting of plant growth, branch dieback, and fruit loss. The presence of X. fastidiosa was previously reported in New Mexico where it was found to be infecting chitalpa plants and grapevines (3). In the summer of 2010, peach (Prunus persica (L.) Batsch) trees from two locations in northern New Mexico exhibited leaf deformity and stunting, dark green venation, slight mottling, and branch dieback. Preliminary viral diagnostic screening was performed by Agdia (Elkhart, IN) on one symptomatic tree and it was negative for all viruses tested. Three trees from two different orchards tested positive for X. fastidiosa by ELISA and PCR analysis using X. fastidiosa-specific primer sets HL (1) and RST (2). Bacterial colonies were also cultured from these samples onto periwinkle wilt media. Eight colonies obtained from these three plants tested PCR positive using the X. fastidiosa-specific primers. The 16S ribosomal and 16S-23S rRNA internal transcribed spacer (ITS) region (557 nucleotides) (GenBank Accession No. HQ292776) along with the gyrase region (400 nucleotides) (GenBank Accession No. HQ292777) was amplified from the peach total DNA samples and the bacterial colonies. Sequencing analysis of these regions indicate that the X. fastidiosa found in peach is 100% similar to other X. fastidiosa multiplex isolates including isolates from peach, pecan, sycamore, and plum trees and 99% similar to the X. fastidiosa isolates previously found in New Mexico. Further analysis of the 16S ribosomal and 16S-23S rRNA ITS sequences with maximum likelihood phylogenetic analysis using Paup also groups the peach isolates into the X. fastidiosa multiplex subspecies. The gyrase sequence could not be used to differentiate the peach isolates into a subspecies grouping because of the lack of variability within the sequence. This X. fastidiosa multiplex subspecies could possibly be a threat to the New Mexico pecan industry since pecan infecting X. fastidiosa isolates belong to the same bacterial subspecies. It is not known if X. fastidiosa subspecies multiplex isolates from peach are capable of infecting pecans but they are closely genetically related. It is interesting to note that the isolates from peach are different than previously described X. fastidiosa isolates in New Mexico that were infecting chitalpa and grapes (3). X. fastidiosa has previously been described in peach; the disease is called "phony peach". The peach trees exhibited stunting and shortened internodes as reported for "phony peach". They also exhibited slight mottling and branch dieback that may be due to the environment in New Mexico or perhaps they are also exhibiting mineral deficiency symptoms in association with the X. fastidiosa disease. To our knowledge, this is the first report of X. fastidiosa in peach in New Mexico. References: (1) M. H. Francis et al. Eur. J. Plant Pathol. 115:203, 2006. (2) G. V. Minsavage et al. Phytopathology 84:456, 1994. (3) J. J. Randall et al. Appl. Environ. Microbiol. 75:5631, 2009.

Competitive electroporation formulation for cell therapy

Established cell transfection via nucleofection relies on nucleofection buffers with unknown and proprietary makeup due to trade secrecy, inhibiting the possibility of using this otherwise effective method for developing cell therapy. We devised a three-step method for discovering an optimal formulation for the nucleofection of any cell line. These steps include the selection of the best nucleofection program and known buffer type, selection of the best polymer for boosting the transfection efficiency of the best buffer and the comparison with the optimal buffer from an established commercial vendor (Amaxa). Using this three-step selection system, competitive nucleofection formulations were discovered for multiple cell lines, which are equal to or surpass the efficiency of the Amaxa nucleofector solution in a variety of cells and cell lines, including primary adipose stem cells, muscle cells, tumor cells and immune cells. Through the use of scanning electron microscopy, we have revealed morphological changes, which predispose for the ability of these buffers to assist in transferring plasmid DNA into the nuclear space. Our formulation may greatly reduce the cost of electroporation study in laboratory and boosts the potential of application of electroporation-based cell therapies in clinical trials.

Photosensitization of carbon nanotubes using dye aggregates

Ordered assemblies of dye molecules, dye aggregates, possess significantly larger molar optical absorptivity than dye monomers. Yet, aggregates have not been utilized for photosensitizing nanoscale electronic devices. We find that single-walled carbon nanotubes, which are cleaned down to the atomic scale, template the growth of squaraine dye aggregates and these aggregates effectively photosensitize nanotubes. Templating of aggregates by nanotubes and functionalization of nanotubes with ordered molecular films are reported for the first time. The sensitivity achieved by aggregate-functionalized nanotube network devices is approximately an order of magnitude better than those of similar nanotube devices functionalized with dye monomers and photoactive polymers.

Is radiation therapy superior to conservative management in men with localized prostate cancer?

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Background: Radiation therapy is commonly employed for localized prostate cancer; however, there is little data regarding the comparative effectiveness of radiation therapy (RAD) vs. conservative management (CM).

Methods: We performed a population-based cohort study, using Medicare claims data linked to the Surveillance, Epidemiology, and End Results data, to evaluate outcomes in 42,039 men aged 65-85 years treated with either primary RAD or CM for T1-T2 prostate cancer diagnosed in 1992-2005. To overcome potential biases associated with unmeasured confounding variables, we used instrumental variable analysis (IVA), a pseudo-randomization technique that captures the randomness associated with geographic variations in the use of RAD, to control for overt and hidden confounders.

Results: The majority of patients (57%) had low-risk disease (Gleason score ≤7, PSA <10, and T stage ≤T2a), and RAD was commonly used (60%) with considerable geographic variations. With median age 74 years and median follow-up 119 months, higher RAD use was not associated with improved survival in low-risk patients (10-year disease-specific survival differed by −0.9%, 94.9% vs. 95.8% in the highest and lowest tertile RAD use areas respectively; 95% C.I. −.1 to 0.6%). Among high-risk patients (Gleason score >7 or PSA >20), highest tertile RAD areas showed a borderline improved (2.7%) 10-year disease-survival (83.9% vs. 81.2% in the highest and lowest tertile radiation use areas; 95% C.I. −1.1% to 7.0%). The results in the moderate-risk group were between that of the low- and high-risk group. Primary RAD did not reduce future ADT use (odds ratios 0.95 for low-risk, 1.02 for moderate-risk, and 1.07 for high-risk with corresponding P values of 0.50, 0.86, and 0.51, respectively).

Conclusions: In patients aged over 65 years old with low-risk prostate cancer, primary RAD is unlikely to improve 10-year disease-specific survival or prevent future ADT use. Weighing the potential risks and benefits of radiation therapy is critical for decision making.

No significant financial relationships to disclose.

Goserelin plus letrozole as first- or second-line hormonal treatment in premenopausal patients with advanced breast cancer

A promising new option as the treatment of choice for premenopausal patients with metastatic breast cancer (MBC) could be the combination of a luteinising hormone-releasing hormone analog and an aromatase inhibitor. Very little data about the use of goserelin with anastrozole in advanced breast cancer are available, and no cohort studies on the efficacy of goserelin with letrozole in advanced premenopausal breast cancer patients have been reported. We present the single-centre, retrospective, experience of goserelin plus letrozole in a total of 52 premenopausal women with MBC. All patients received goserelin 3.6 mg by subcutaneous injection every 4 weeks along with letrozole 2.5 mg daily as first-line (n=36) and second-line (n=16) hormonal treatment. The median duration of goserelin with letrozole treatment was 11 (range, 2-61) months, and the median duration of overall follow-up was 31 (range, 3-66) months. The objective response rate (ORR) was 21.1%, with two complete response (CR) (3.8%) and nine partial response (PR) (17.3%). Stable disease (SD) lasting more than 6 months was achieved by 26 patients (50.0%). Thus, goserelin with letrozole conferred clinical benefit (CB) in 37 women (71.1%). The progression-free survival (PFS) was 10 months. CR was exclusively observed in hormone receptor-double-positive patients. Drug therapy was well tolerated; no grade 3/4 toxicities were reported. Goserelin plus letrozole appears to be an efficacious and well-tolerated regimen in women with advanced breast cancer. Further prospectively randomized studies involving more patients and longer follow-up are indicated.

TNIP1, SLC15A4, ETS1, RasGRP3 and IKZF1 are associated with clinical features of systemic lupus erythematosus in a Chinese Han population

Systemic lupus erythematosus (SLE) is an autoimmune disease with heterogeneous clinical manifestations influenced by genetic and environmental factors. Five novel susceptibility genes (TNIP1, SLC15A4, ETS1, RasGRP3 and IKZF1) for SLE have been identified in a recent genome-wide association study of a Chinese Han population. This study investigated their relationships with disease subphenotypes, including renal nephritis, photosensitivity, antinuclear antibody (ANA), age at diagnosis, malar rash, discoid rash, immunological disorder, oral ulcer, hematological disorder, neurological disorder, serositis, arthritis and vasculitis. Significant associations were found for the single nucleotide polymorphism rs10036748 of TNIP1 with photosensitivity (odds ratio (OR) = 0.87, p = 0.01) and vasculitis (OR = 1.18, p = 0.04); rs10847697 of SLC15A4 with discoid rash (OR = 1.18, p = 0.02); rs6590330 of ETS1 with SLE of age at diagnosis <20 years (OR = 1.24, p = 8.91 x 10(-5)); rs13385731 of RasGRP3 with malar rash (OR = 1.20, p = 0.01), discoid rash (OR = 0.78, p = 0.02) and ANA (OR = 0.72, p = 0.004); rs4917014 of IKZF1 with renal nephritis (OR = 1.13, p = 0.02) and malar rash (OR = 0.83, p = 0.00038), respectively. The study suggested that these susceptibility genes might not only play important roles in the development of SLE, but also contribute to the complex phenotypes of SLE.

Variants in the BRCA1/Fanconi-Anemia Repair Pathway and Taxane-Induced Neuropathy in SWOG S0221

Background: Taxane-induced peripheral neuropathy is a dose-limiting side effect that leads to suboptimal cancer treatment and diminished quality of life. The mode of taxane neurotoxicity is unclear, but may be through stabilization of microtubules and induction of spindle checkpoint, leading to cell cycle arrest at G2/M. Fanconi Anemia (FA) genes, including FANCD2, and FANCA, appear to be involved in G2/M phase checkpoint maintenance as well as spindle checkpoint in response to internal and external signals, such as taxane treatment. Thus, we hypothesized that variants in FA genes could impact severity of taxane-induced neuropathies.Methods: Using DNA extracted from blood collected from 893 breast cancer patients participating in a trial evaluating metronomic dosing of cyclophosphamide, doxorubicin and paclitaxel (S0221), we genotyped for single nucleotide polymorphisms (SNPs) that represent all of the variability across FANCA (44 SNPs) and FANCD2 (24 SNPs) in all race/ethnicity groups, as well as a panel of ancestry informative markers to control for potential population stratification, using Illumina GoldenGate platform. SNPs with minor allele frequency (MAF) less than 0.10 and those out of Hardy Weinberg Equilibrium (HWE) proportions (p&lt;0.001) were removed from analyses. Ordinal regression was used to test for allelic and haplotypic association with grade 3 or 4 toxicities relative to 0, 1, and 2 toxicities, adjusting for age, genetic admixture index and treatment arm. To adjust for multiple testing, permutation analyses were performed on both single SNP and haplotype models.Results: Eighteen SNPs in FANCD2 and 38 SNPs in FANCA passed MAF and HWE proportion requirements. For FANCD2, 4 SNPs spanning 67.5 Kb (rs7648104, rs2272125 [coding SNP], rs6786638 and rs644215), were significantly associated with taxane-induced neuropathy (p&lt;0.001) after controlling for multiple testing, with each SNP resulting in approximately a twofold increase in odds of severe taxane-induced neuropathy. Haplotype estimation showed that all 18 SNPs comprise a single haplotype. Two major (&gt;1% frequency) haplotypes were found. The frequencies of the risk haplotype in cases (patients with grade 3 or 4 neuropathy) and controls (patients with ≤ grade 2 neuropathy) were 0.25 and 0.15, respectively. Ordinal regression analyses were highly significant (p&lt;0.0005); patients with at least one copy of the risk haplotype had more than a twofold increased risk of grade 3 or 4 taxane-induced neuropathy (OR=2.2, 95% CI 1.44, 3.44). For FANCA, no SNPs or haplotypes were significantly associated with grade 3 or 4 neurotoxicity, either prior to or after correction for multiple testing.Conclusions: These results indicate that the Fanconi-Anemia pathway may be important for neurological sensitivity to taxanes, and that genotypic markers might be able to be used to identify patients at increased risk for severe taxane-induced neuropathy. Further studies will elucidate potential associations with survival outcomes.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2001.

LPS mediated injury to oligodendrocytes is mediated by the activation of nNOS: relevance to human demyelinating disease

Loss of oligodendrocytes and the destruction of myelin form the core features of inflammatory demyelinating disease. Although many of the inflammatory and cellular mediators of tissue injury are known, recent studies have suggested an important role for nitric oxide NO and other reactive nitrogen species in oligodendrocyte injury. The human transformed oligodendrocyte cell line, MO3.13 cells, express Toll like receptor genes (TLR) genes and are activated by lipopolysaccharide (LPS). We determined the activation and consequences of neuronal nitric oxide synthase (nNOS) following stimulation with LPS in the MO3.13 cell line. Our studies show that MO3.13 cells induce nNOS following stimulation with LPS. Most importantly, these studies show a susceptibility of MO3.13 cells to NO mediated cell death by the activation of nNOS but not of inducible NOS (iNOS). MO3.13 cells show increased susceptibility to peroxynitrite mediated cellular injury to mitochondrial proteins and decreased cell survival in the presence of LPS. Our studies suggest that the presence and activation of nNOS in oligodendrocytes can directly mediate oligodendrocyte (OC) injury and reduce cell viability.

Stress echocardiography: risk stratification, prognosis, patient outcomes and cost-effectiveness

The utilization of stress echocardiography has undergone considerable expansion and evolution over the past three decades. Although stress echocardiography was first conceived as a noninvasive diagnostic tool for determining the presence or absence of coronary artery disease (CAD), its prognostic value is now well established. Thus, identification of patients at risk for future cardiac events has become a primary objective in the noninvasive evaluation of patients with chest pain syndromes and among patients with known CAD. In particular, the ability of stress echocardiography to identify patients at low (<1%), intermediate (1-5%) or high (>5%) risk for future cardiac events is essential to patient management decisions. Moreover, previous studies have conclusively demonstrated the incremental prognostic value of stress echocardiography over clinical and treadmill exercise data, in predicting future cardiac events. This review addresses the current role and summarizes current literature with respect to the use of stress echocardiography in determining patient risk for cardiac events and the cost-effective integration of such information into patient management decisions.

Outcomes of conservatively managed localized prostate cancer

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Background: The natural history of screen-detected prostate cancer has not been well described. Methods: Cancer-specific and overall mortality, assessed through competing risk analyses, were determined for 14,516 men aged 65 years or older diagnosed between 1992–2002 and did not receive surgery or radiation within 6 months of cancer diagnosis. The population-based cohort was identified from US cancer registries, which had 98% completeness in case ascertainment. Results: Compared to earlier era studies, survival has improved considerably for conservatively managed patients diagnosed in the contemporary prostate specific antigen (PSA) era ( Table ). Conclusions: Men diagnosed with prostate cancer in the PSA era have survival outcomes significantly better than those in the past. Patients and healthcare providers may need to reassess some treatment options in light of these data.

[Table: see text]

No significant financial relationships to disclose.

A phase I dose-escalation study of the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of SCH 727965, a novel cyclin-dependent kinase inhibitor, administered weekly in subjects with advanced malignancies

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Background: SCH 727965 is a potent and selective inhibitor of the cyclin-dependent kinases CDK1,2,5 and 9 with IC50's of < 5nM. SCH 727965 induces apoptosis in a broad array of tumor cell lines, causes tumor growth inhibition or regression in various xenograft models, and has a greater therapeutic index than flavopiridol in an in vivo screening model. SCH 727965 was advanced into clinical trials. Methods: SCH 727965 was administered by 2-hour IV infusion on days 1, 8 and 15 of a 28-day cycle. Doses were escalated with an accelerated titration algorithm to define the maximally administered dose (MAD) and the recommended phase 2 dose (RPTD). PD assessments included an ex vivo PHA lymphocyte stimulation assay, skin biopsies for IHC measurement of retinoblastoma protein phosphorylation, and functional imaging using FDG-PET/CT scans. PK and PD data were obtained during Cycle 1. Results: 43 subjects have been treated at doses ranging from 0.33 to 14 mg/m2. The most common treatment-emergent adverse events were nausea, anemia, and fatigue. The MAD was 14 mg/m2 defined by a DLT of grade 3 hypotension in one subject and transient grade 4 hyperuricemia in another subject. The RPTD was 12 mg/m2. Grade 3 or 4 treatment related adverse events were uncommon. Grade 3 or 4 neutropenia was seen in only 3 subjects. SCH 727965 inhibition of lymphocyte proliferation was dose-dependent, indicating a PD effect, and was sustained up to 8 hours post-dose at the RPTD. Drug exposure was dose-proportional. SCH 727965 was rapidly eliminated with a terminal half-life of 1.5 to 3 hours. No objective responses by RECIST criteria have yet been observed although PET SUV signal decreases as large as >30% have been observed in some subjects. Conclusions: SCH 727965 is safe and well tolerated at the recommended phase 2 dose of 12 mg/m2. The AE profile of weekly dosing differed from that seen in an every -21 day dosing schedule, and plasma concentrations at the RPTD or lower doses were above those required for in vivo efficacy in xenograft tumor models. PD activity was verified in an ex vivo lymphocyte proliferation assay, and preliminary changes on PET/CT suggest drug related modulation of tumor metabolic activity.

[Table: see text]

Analysis of six synthetic adulterants in herbal weight-reducing dietary supplements by LC electrospray ionization-MS

A liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method was developed for the simultaneous determination of six synthetic adulterants, namely fenfluramine, phenolphthalein, N-di-desmethyl sibutramine, N-mono-desmethyl sibutramine, sibutramine, and orlistat. The method was applied to the analysis of herbal weight-reducing dietary supplements. Chromatographic separation of the analytes on a C(8) reversed-phase column was achieved using a gradient elution of solvent A: acetonitrile and solvent B: aqueous 20 mM ammonium formate solution. Sildenafil was utilized as an internal standard for quantification. The MS detector was operated in positive electrospray ionization mode. Selected-ion monitoring (SIM) was carried out for m/z 232, 319, 252, 266, 280, 496, and 475 for fenfluramine, phenolphthalein, N-di-desmethyl sibutramine, N-mono-desmethyl sibutramine, sibutramine, orlistat, and sildenafil, respectively. The method was validated for accuracy, precision, linearity, and selectivity. The limits of detection for the six synthetic adulterants ranged from 0.0018 to 0.73 microg g(-1). The proposed method was used for a small survey of 22 dietary supplements of which eleven samples were adulterated with phenolphthalein, N-mono-desmethyl sibutramine, and sibutramine at levels from 0.212 to 96.2 mg g(-1).

Differentiation of stem cells in the dental follicle

The dental follicle (DF) differentiates into the periodontal ligament. In addition, it may be the precursor of other cells of the periodontium, including osteoblasts and cementoblasts. We hypothesized that stem cells may be present in the DF and be capable of differentiating into cells of the periodontium. Stem cells were identified in the DF of the rat first mandibular molar by Hoechst staining, alkaline phosphatase staining, and expression of side-population stem cell markers. These cells were shown to be able to differentiate into osteoblasts/cementoblasts, adipocytes, and neurons. Treating the DF cell population with doxorubicin, followed by incubation in an adipogenesis medium, suggested that the adipocytes originated from stem cells. Thus, a possibly puripotent stem cell population is present in the rat DF.