Timing of Lung Transplant Referral in Patients with Severe COVID-19 Lung Injury Supported by ECMO

Severe respiratory failure caused by COVID-19 often requires mechanical ventilation, including extracorporeal membrane oxygenation (ECMO). In rare cases, lung transplantation (LTx) may be considered as a last resort. However, uncertainties remain about patient selection and optimal timing for referral and listing. This retrospective study analyzed patients with severe COVID-19 who were supported by veno-venous ECMO and listed for LTx between July 2020 and June 2022. Out of the 20 patients in the study population, four who underwent LTx were excluded. The clinical characteristics of the remaining 16 patients were compared, including nine who recovered and seven who died while awaiting LTx. The median duration from hospitalization to listing was 85.5 days, and the median duration on the waitlist was 25.5 days. Younger age was significantly associated with a higher likelihood of recovery without LTx after a median of 59 days on ECMO, compared to those who died at a median of 99 days. In patients with severe COVID-19-induced lung damage supported by ECMO, referral to LTx should be delayed for 8-10 weeks after ECMO initiation, particularly for younger patients who have a higher probability of spontaneous recovery and may not require LTx.

Abstract CT154: B-cell infiltration in lung cancer predicts response to neoadjuvant pembrolizumab

Background Neoadjuvant immune checkpoint inhibitor treatment is a promising approach for resectable cancer, including non-small cell lung cancer (NSCLC). The characteristics of potential responders to such treatments and the molecular underlying events are not known. Methods We have conducted a phase I, investigator-initiated single-center study (MK3457-223), to examine the safety of neoadjuvant pembrolizumab for stage I-II resectable NSCLC and to determine the recommended phase II dose/schedule (RP2D/S). FFPE biopsies and surgical specimens were subjected to correlative studies. NanoString’s GeoMx Digital Spatial Profiler (DSP) analysis was conducted on pre-treatment samples and post-treatment responder samples. Protein (72 proteins) and mRNA expression data (73 genes) analysis was conducted on regions of interest (ROIs), defined as mostly CD8 positive or mostly pan-cytokeratin positive (presumed cancer cells). Pathology assessment was done on the surgical specimen to identify major pathologic response (MPR; ≤10% remaining viable cells). Statistical analysis was done to compare responders (MPR+) to non-responders (MPR-) by Mann Whitney with false discovery rate correction. Immunohistochemistry (IHC) was conducted on post-treatment samples. Results Twenty-six patients initiated treatment on the study. Two patients (8%, 95% C.I 0-18%) had adverse events that precluded surgery, 1 patient refused surgery after treatment. 7 patients (27%, 95% C.I 10-44%) achieved a major pathologic response (MPR; responders), 3 patients (12%, 95% C.I 0-24%) achieved complete pathologic response. Responders had a longer interval from treatment to surgery (43 days vs. 36 days, univariate analysis, p-value 0.043). RP2D/S was determined as 2 treatments of 200mg pembrolizumab at 3 week interval, followed by surgery at least 2 weeks later. The expression of several proteins and genes differed between responders and non-responders. Pre-treatment, CD20 protein was the most differentially expressed protein both in in CD8+ (4.7 fold, p=0.002) and in cancer cells (4.8 fold, p=0.001) ROIs, in both cases higher in the responders compared to the non-responders. Comparing pre to post-treatment expression in responding tumors, the protein found to be upregulated to the highest extent following pembrolizumab treatment was CD20 protein (6.2-fold, p=0.001), as was its encoding gene, MS4A1 (2.4-fold, p=0.006). CD20 IHC of post-treatment samples demonstrated tertiary lymphoid structures (TLS) to be more prevalent in responders compared to non-responders (3.2-fold, p<0.05). Conclusions Longer interval from treatment to surgery was associated with higher rate of MPR. Presence of tumor-infiltrating B-cells and evolvement of TLSs was strongly correlated with pathologic response to neoadjuvant pembrolizumab in early stage NSCLC.

Citation Format: Jair Bar, Iris Kamer, Oranit Zadok, Damien Urban, Marina Perelman, Ilanit Redinsky, Aliza Ackerstein, Sameh Daher, Efrat Ofek, Amir Onn, Nona Zeitlin, Alon Ben-Nun, Ran Kremer, Inbal Daniel, Yossef Glantzspiegel, Irit Gat-Viks. B-cell infiltration in lung cancer predicts response to neoadjuvant pembrolizumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT154.

Histomorphometric and microarchitectural analysis of bone in metastatic breast cancer patients

BACKGROUND

Despite widespread use of repeated doses of potent bone-targeting agents (BTA) in oncology patients, relatively little is known about their in vivo effects on bone homeostasis, bone quality, and bone architecture. Traditionally bone quality has been assessed using a trans-iliac bone biopsy with a 7 mm "Bordier" core needle. We examined the feasibility of using a 2 mm "Jamshidi™" core needle as a more practical and less invasive technique.

METHODS

Patients with metastatic breast cancer on BTAs were divided according to the extent of bone metastases. They were given 2 courses of tetracycline labeling and then underwent a posterior trans-iliac trephine biopsy and bone marrow aspirate. Samples were analyzed for the extent of tumor invasion and parameters of bone turnover and bone formation by histomorphometry.

RESULTS

Twelve patients were accrued, 1 had no bone metastases, 3 had limited bone metastases (LSM) (<3 lesions) and 7 had extensive bone metastases (ESM) (>3 lesions). Most of the primary tumors were estrogen receptor (ER)/progesterone receptor (PR) positive. The procedure was well tolerated. The sample quality was sufficient to analyze bone trabecular structure and bone turnover by histomorphometry in 11 out of 12 patients. There was a good correlation between imaging data and morphometric analysis of tumor invasion. Patients with no evidence or minimal bone metastases had no evidence of tumor invasion. Most had suppressed bone turnover and no detectable bone formation when treated with BTA. In contrast, 6 out of 7 patients with extensive bone invasion by imaging and evidence of tumor cells in the marrow had intense osteoclastic activity as measured by the number of osteoclasts. Of these 7 patients with ESM, 6 were treated with BTA with 5 showing resistance to BTA as demonstrated by the high number of osteoclasts present. 3 of these 6 patients had active bone formation. Based on osteoblast activity and bone formation, 3 out of 6 patients with ESM responded to BTA compared to all 3 with LSM. Compared to untreated patients, all patients treated with BTA showed a trend towards suppression of bone formation, as measured by tetracycline labelling. There was also a trend towards a significant difference between ESM and LSM treated with BTA, highly suggestive of resistance although limited by the small sample size.

DISCUSSION

Our results indicate that trans-iliac bone biopsy using a 2 mm trephine shows excellent correlation between imaging assessment of tumor invasion and tumor burden by morphometric analysis of bone tissues. In addition, our approach provides additional mechanistic information on therapeutic response to BTA supporting the current clinical understanding that the majority of patients with extensive bone involvement eventually fail to suppress bone turnover (Petrut B, et al. 2008). This suggests that antiresorptive therapies become less effective as disease progresses.

Intercostal chest drain fixation strength: comparison of techniques and sutures

OBJECTIVE

The accidental removal of an intercostal chest drain (ICD) is common and may result in serious complications. A number of fixation techniques and suture material are in use, and the selection is often based on personal preferences and equipment availability. This study is designed to determine which of the common techniques provides the strongest ICD fixation.

METHODS

This study compared the mechanical strength of eight different ICD fixation techniques (purse string, 'Roman sandal', 'Jo'burg' (JO) technique, a suture through the tube, one and two passes through a locking plastic tie, tape fixation and a commercial disposable drainage tube holder) and two silk suture sizes using porcine cadavers and a digital push-pull dynamometer to simulate accidental removal of an ICD. A total of 14 different experimental set-ups produced 280 measurements.

RESULTS

Significant differences in ICD fixation strength were observed. A modified JO technique using a size 1 silk suture was nearly three times stronger than a purse-string fixation using a size 0 silk and 10 times stronger from a commercial, adhesive-based device (180, 70 and 22, respectively).

CONCLUSION

In situations where the mechanical strength of ICD fixation is important, using a size 1 silk and a modified JO technique may provide the strongest fixation.

The human tumor microbiome is composed of tumor type-specific intracellular bacteria

Bacteria were first detected in human tumors more than 100 years ago, but the characterization of the tumor microbiome has remained challenging because of its low biomass. We undertook a comprehensive analysis of the tumor microbiome, studying 1526 tumors and their adjacent normal tissues across seven cancer types, including breast, lung, ovary, pancreas, melanoma, bone, and brain tumors. We found that each tumor type has a distinct microbiome composition and that breast cancer has a particularly rich and diverse microbiome. The intratumor bacteria are mostly intracellular and are present in both cancer and immune cells. We also noted correlations between intratumor bacteria or their predicted functions with tumor types and subtypes, patients' smoking status, and the response to immunotherapy.

Head-to-Head Prospective Comparison of Quantitative Lung Scintigraphy and Segment Counting in Predicting Pulmonary Function in Lung Cancer Patients Undergoing Video-Assisted Thoracoscopic Lobectomy

Prediction of postoperative pulmonary function in lung cancer patients before tumor resection is essential for patient selection for surgery and is conventionally done with a nonimaging segment counting method (SC) or 2-dimensional planar lung perfusion scintigraphy (PS). The purpose of this study was to compare quantitative analysis of PS to SPECT/CT and to estimate the accuracy of SC, PS, and SPECT/CT in predicting postoperative pulmonary function in patients undergoing lobectomy. Methods: Seventy-five non-small cell lung cancer patients planned for lobectomy were prospectively enrolled (68% male; average age, 68.1 ± 8 y). All patients completed tests of preoperative forced expiratory volume capacity in 1 s (FEV1) and diffusing capacity of the lungs for carbon monoxide (DLCO), as well as ^99mTc-macroaggregated albumin PS and SPECT/CT quantification. A subgroup of 60 patients underwent video-assisted thoracoscopic lobectomy and measurement of postoperative FEV1 and DLCO. Relative uptake of the lung lobes estimated by PS and SPECT/CT was compared. Predicted postoperative FEV1 and DLCO were derived from SC, PS, and SPECT/CT. Prediction results were compared between the different methods and the true postoperative measurements in patients who underwent lobectomy. Results: Relative uptake measurements differed significantly between PS and SPECT/CT in right lung lobes, with a mean difference of -8.2 ± 3.8, 18.0 ± 5.0, and -11.5 ± 6.1 for right upper, middle, and lower lobes, respectively (P < 0.001). The differences between the methods in the left lung lobes were minor, with a mean difference of -0.4 ± 4.4 (P > 0.05) and -2.0 ± 4.0 (P < 0.001) for left upper and lower lobes, respectively. No significant difference and a strong correlation (R = 0.6-0.76, P < 0.001) were found between predicted postoperative lung function values according to SC, PS, SPECT/CT, and the actual postoperative FEV1 and DLCO. Conclusion: Although lobar quantification parameters differed significantly between PS and SPECT/CT, no significant differences were found between the predicted postoperative lung function results derived from these methods and the actual postoperative results. The additional time and effort of SPECT/CT quantification may not have an added value in patient selection for surgery. SPECT/CT may be advantageous in patients planned for right lobectomy, but further research is warranted.

Differential lung ventilation for increased oxygenation during one lung ventilation for video assisted lung surgery

BACKGROUND

One lung ventilation (OLV) is the technique used during lung resection surgery in order to facilitate optimal surgical conditions. OLV may result in hypoxemia due to the shunt created. Several techniques are used to overcome the hypoxemia, one of which is continuous positive airway pressure (CPAP) to the non-dependent lung. Another technique is ventilating the non-dependent lung with a minimal volume, thus creating differential lung ventilation (DLV). In this study we compared the efficacy of CPAP to DLV during video assisted thoracoscopic lung resection.

PATIENTS AND METHOD

This is a prospective study of 30 adult patients undergoing elective video assisted thoracoscopic lung lobectomy. Each patient was ventilated in four modes: two lung ventilation, OLV, OLV + CPAP and OLV + DLV. Fifteen patients were ventilated with CPAP first and DLV next, and the other 15 were ventilated with DLV first and then CPAP. Five minutes separated each mode, during which the non-dependent lung was open to room air. We measured the patient's arterial blood gas during each mode of ventilation. The surgeons, who were blinded to the ventilation technique, were asked to assess the surgical conditions at each stage.

RESULTS

Oxygenation during OLV+ CPAP was significantly lower that OLV + DLV (p = 0.018). There were insignificant alterations of pH, PCO2 and HCO3 during the different ventilating modes. The surgeons' assessments of interference in the field exposure between OLV + CPAP or OLV + DLV was found to be insignificant (p = 0.073).

CONCLUSIONS

During OLV, DLV is superior to CPAP in improving patient's oxygenation, and may be used where CPAP failed.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03563612 . Registered 9 June 2018, retrospectively (due to clerical error).

Abstract P4-05-02: Conditional inactivation of the 25-hydroxyvitamin D-24-hydroxylase (Cyp24a1) in the mouse mammary epithelium alters mammary gland development

The biologically active form of vitamin D (1,25(OH)2D) regulates proliferation, differentiation, and apoptosis in diverse cell types. We have previously identified anti-proliferative activities of 1,25(OH)2D in human breast tissue, as well as 1,25(OH)2D target gene expression consistent with reports that elevated vitamin D levels may protect against cancer. In mouse studies, vitamin D signaling modulates normal mammary gland development, including ductal outgrowth and branching, and protects against tumorigenesis. Degradation of 1,25(OH)2D is initiated by the enzyme Cyp24a1 in target tissues, providing critical local control of 1,25(OH)2D bioactivity. In vitro, blockade of Cyp24a1 activity potentiates the anti-proliferative effects of 1,25(OH)2D. However, the extent to which endogenous Cyp24a1 activity within the mammary epithelium regulates local 1,25(OH)2D levels to modulate normal mammary gland development, with possible implications for cancer, has not been investigated. We generated a novel mouse model with conditional knockout of the Cyp24a1 gene specifically in the mammary epithelium (MMTV-Cre x Cyp24a1lox/lox). Ablation of Cyp24a1 activity in the mammary epithelium does not alter either gland or body weight at 4, 6 or 10 weeks of age. Preliminary analyses of mammary gland whole mounts indicate that virgin knockout mice form fewer terminal end buds compared to glands from wild-type littermates at 4 and 6 weeks of age (P&lt;0.05). Moreover, the width of the ducts proximal to the central lymph node of knockout mice was less than that of wild-type mice at 4 and 10 weeks of age (P&lt;0.05 and P&lt;0.01, respectively). In addition, the number of secondary and tertiary branching points is reduced in mammary glands from knockout mice at 6 weeks of age (P&lt;0.05 and P&lt;0.01, respectively). In summary, our findings suggest that Cyp24a1 activity within epithelial cells plays a crucial role to modulate postnatal mammary gland development, presumably by limiting the local accumulation of 1,25(OH)2D.

[ASSESSING THE SHORT AND LONG TERM EFFECT OF VIDEO-ASSISTED THORACIC SURGERY LOBECTOMY IN OCTOGENARIAN PATIENTS]

BACKGROUND

Lung cancer is a leading deadly malignancy, both in men and women, with an increasing cancer diagnosis risk with age. Although thoracic surgery techniques have evolved and now include Video Assisted Thoracic Surgery (VATS), older operable lung cancer patients are still operated on less compared to the younger population. This study aimed at investigating the postoperative morbidity, mortality, and long-term quality of life in our pool of octogenarian patients.

METHODS

Octogenarians with newly diagnosed lung cancer at a clinical operable stage undergoing VATS procedures were reviewed. All patients had a clinical evaluation of their malignant stage. Patients' long-term quality of life (QOL) and performance status were evaluated using an institutional telephone questionnaire and the Karnofsky score at least 12 months postoperatively.

RESULTS

Between January 2009 to April 2012, 22 patients underwent VATS lobectomy (median age: 82 years). In four cases (18%) the procedure was converted to open thoracotomy. Patient follow-up periods ranged from 22 to 52 months. All but one patient were released to their homes. Lung malignancy was diagnosed in 19 patients. Pathological staging ranged from IA to IIB. Three patients had a non-malignant lung lesion on final pathology. Median postoperative hospital stay was 6 days. During the first 18 months post-surgery, no mortalities were recorded in this case study. The Karnofsky performance score yielded a median of 90. A telephone questionnaire revealed that all patients were free of operation-related physical limitations. All but one patient described the surgical experience as nontraumatic.

CONCLUSIONS

Current findings support the belief that today surgeons should not deny octogenarian patients the possibility of oncological lung surgery based solely on the patients' chronological age.

Genetic parameters of objectionable fibers and of their associations with fleece traits in Corriedale sheep

The aim of this research was to assess the variability and genetic relationships among binary traits denoting the presence or absence of objectionable fibers, namely pigmented (BINPPF), medullated (BINPMED), and kemp fibers (BINPK), and of fleece traits (fiber diameter [FD] and clean fleece weight [CFW]) in Corriedale sheep. Additionally, the total response to selection against objectionable fibers and indirect responses when selecting for fleece traits were evaluated. Fiber records from 679 animals and fleece records from 795 animals obtained from 2 experimental flocks (from 2005 to 2007) were used; the pedigree file included a total of 3,792 animals. Heritability and genetic correlations among the traits were estimated with a multivariate animal model under a Bayesian setting. Heritability estimates (posterior SD) for BINPPF, BINPMED, and BINPK were 0.35 (0.08), 0.37 (0.10), and 0.63 (0.09), respectively; for CFW and FD, estimates were 0.42 (0.09) and 0.43 (0.08), respectively. The genetic correlations between CFW and the 3 types of objectionable fibers were very low (i.e., <0.2). Thus selection for CFW is not expected to affect the number of such fibers in any direction. The same occurred for the genetic correlation between BINPK and FD. Genetic correlations between FD and BINPMED and FD and BINPPF were positive and favorable (0.50 and 0.56, respectively). Selecting for lower FD would decrease the numbers of objectionable fibers. The expected correlated responses in BINPPF, BINPMED, and BINPK when selecting for CFW were -0.03 (0.11), 0.03 (0.11), and -0.05 (0.18), respectively; when selecting for FD, the correlated responses were -0.26 (0.11), -0.26 (0.11), and -0.14 (0.16). Overall, this study reports novel information on genetic parameters for the presence of objectionable fibers and their associations with fleece traits in sheep. Our findings suggest that it could be possible to improve FD while at the same time reducing the content of BINPMED and BINPPF in wool; however, improvements in CFW are likely to have no effect on the numbers of objectionable fibers.

Lower lung cancer rates in Jewish smokers in Israel and the USA

Lung cancer rates in Israeli Jews have remained stable over the last five decades and are much lower than in most developed countries despite high historical smoking rates. We compared lung cancer risk in Jews and non-Jews in Israel and in the United States. Data were derived from a population-based, case-control study in Israel (638 cases, 496 controls) to estimate lung cancer risk associated with smoking. Data were also acquired from a case-control study in the United States with information on religious affiliation (5,093 cases, 4,735 controls). Smoking was associated with lung cancer risk in all religion/gender groups in both studies. However, major differences in risk magnitude were noted between Jews and non-Jews; ever smoking was associated with a moderately elevated risk of lung cancer in Jewish men and women in Israel (OR = 4.61, 2.90-7.31 and OR = 2.10, 1.36-3.24, respectively), and in Jewish men and women in the United States (OR = 7.63, 5.34-10.90 and OR = 8.50, 5.94-12.17) but were significantly higher in Israeli non-Jewish men (OR = 12.96, 4.83-34.76) and US non-Jewish men and women (OR = 11.33, 9.09-14.12 and OR = 12.78, 10.45-15.63). A significant interaction between smoking and religion was evident in light, moderate and heavy male and female smokers. The differences in risk level between Israeli Jews and non-Jews could not be explained by lung cancer genetic risk variants which were identified in GWAS (genes in the CHRNA5, TERT and CLPTM1L regions). Data from the two studies support the notion of a reduced risk of lung cancer in Jewish compared to non-Jewish smokers in different areas of the world.

Development of APE1 enzymatic DNA repair assays: low APE1 activity is associated with increase lung cancer risk

We developed radioactivity-based and fluorescence-based assays for the DNA repair enzyme APE1 and showed that its decreased activity is associated with increased lung cancer risk. This suggests that ‘bad DNA repair’ rather than ‘bad luck’ is involved in cancer etiology.

The key role of DNA repair in removing DNA damage and minimizing mutations makes it an attractive target for cancer risk assessment and prevention. Here we describe the development of a robust assay for apurinic/apyrimidinic (AP) endonuclease 1 (APE1; APEX1), an essential enzyme involved in the repair of oxidative DNA damage. APE1 DNA repair enzymatic activity was measured in peripheral blood mononuclear cell protein extracts using a radioactivity-based assay, and its association with lung cancer was determined using conditional logistic regression with specimens from a population-based case–control study with 96 lung cancer cases and 96 matched control subjects. The mean APE1 enzyme activity in case patients was 691 [95% confidence interval (CI) = 655–727] units/ng protein, significantly lower than in control subjects (mean = 793, 95% CI = 751–834 units/ng protein, P = 0.0006). The adjusted odds ratio for lung cancer associated with 1 SD (211 units) decrease in APE1 activity was 2.0 (95% CI = 1.3–3.1; P = 0.002). Comparison of radioactivity- and fluorescence-based assays showed that the two are equivalent, indicating no interference by the fluorescent tag. The APE1Asp148Glu SNP was associated neither with APE1 enzyme activity nor with lung cancer risk. Taken together, our results indicate that low APE1 activity is associated with lung cancer risk, consistent with the hypothesis that ‘bad DNA repair’, rather than ‘bad luck’, is involved in cancer etiology. Such assays may be useful, along with additional DNA repair biomarkers, for risk assessment of lung cancer and perhaps other cancers, and for selecting individuals to undergo early detection techniques such as low-dose CT.

Enzymatic MPG DNA repair assays for two different oxidative DNA lesions reveal associations with increased lung cancer risk

DNA repair is a major mechanism for minimizing mutations and reducing cancer risk. Here, we present the development of reproducible and specific enzymatic assays for methylpurine DNA glycosylase (MPG) repairing the oxidative lesions 1,N6-ethenoadenine (εA) and hypoxanthine (Hx) in peripheral blood mononuclear cells protein extracts. Association of these DNA repair activities with lung cancer was determined using conditional logistic regression with specimens from a population-based case-control study with 96 lung cancer cases and 96 matched control subjects. The mean MPG-εA in case patients was 15.8 units/μg protein (95% CI 15.3-16.3), significantly higher than in control subjects-15.1 (14.6-15.5), *P = 0.011. The adjusted odds ratio for lung cancer associated with a one SD increase in MPG-εA activity (2.48 units) was significantly bigger than 1 (OR = 1.6, 95% CI = 1.1-2.4; *P = 0.013). When activity of OGG1, a different DNA repair enzyme for oxidative damage, was included in the model, the estimated odds ratio/SD for a combined MPG-εA-OGG1 score was 2.6 (95% CI 1.6-4.2) *P = 0.0001, higher than the odds ratio for each single assay. The MPG enzyme activity assays described provide robust functional risk biomarkers, with increased MPG-εA activity being associated with increased lung cancer risk, similar to the behavior of MPG-Hx. This underscores the notion that imbalances in DNA repair, including high DNA repair, usually perceived as beneficial, can cause cancer risk. Such DNA repair risk biomarkers may be useful for risk assessment of lung cancer and perhaps other cancer types, and for early detection techniques such as low-dose CT.

[Women pioneers: first female cardiothoracic surgeons in the USA and in Israel]

At the beginning of the 1960's, three female doctors managed to break the glass ceiling and become the first female cardiothoracic surgeons in the USA. Since then, the number of certified female cardiothoracic surgeons has steadily increased. Nevertheless, females stilt only account for a minority of cardiothoracic surgeons in the USA. In Israel, three women have become specialists in cardiothoracic surgery over the last two decades, aLthough these surgeons are working as general thoracic surgery consultants, without any representative females in cardiac surgery.

Low integrated DNA repair score and lung cancer risk

DNA repair is a prime mechanism for preventing DNA damage, mutation, and cancers. Adopting a functional approach, we examined the association with lung cancer risk of an integrated DNA repair score, measured by a panel of three enzymatic DNA repair activities in peripheral blood mononuclear cells. The panel included assays for AP endonuclease 1 (APE1), 8-oxoguanine DNA glycosylase (OGG1), and methylpurine DNA glycosylase (MPG), all of which repair oxidative DNA damage as part of the base excision repair pathways. A blinded population-based case-control study was conducted with 96 patients with lung cancer and 96 control subjects matched by gender, age (±1 year), place of residence, and ethnic group (Jews/non-Jews). The three DNA repair activities were measured, and an integrated DNA repair OMA (OGG1, MPG, and APE1) score was calculated for each individual. Conditional logistic regression analysis revealed that individuals in the lowest tertile of the integrated DNA repair OMA score had an increased risk of lung cancer compared with the highest tertile, with OR = 9.7; 95% confidence interval (CI), 3.1-29.8; P < 0.001, or OR = 5.6; 95% CI, 2.1-15.1; P < 0.001 after cross-validation. These results suggest that pending validation, this DNA repair panel of risk factors may be useful for lung cancer risk assessment, assisting prevention and referral to early detection by technologies such as low-dose computed tomography scanning.

[Thoracic nocardiosis with thoracic manifestations in two immunocompetent patients]

Nocardiosis is a rare infectious disease caused by bacteria of the genus nocardia, which causes considerable morbidity and mortality. We report two unusual cases of nocardiosis in young, immunocompetent patients; the first case involved a nocardia farcinica pulmonary and chest-wall infection, while the second was an anterior mediastinal nocardia asiaticum infection mimicking a mediastinal tumor. These cases reflect the need for a broad differential diagnosis during exploration of thoracic findings, white the potentially ambiguous presentation of nocardiosis must be considered.

The Role of Pain Catastrophizing in the Prediction of Acute and Chronic Postoperative Pain

Background and Objectives:

Despite the established association between greater pain catastrophizing and enhanced postoperative pain, it is still unclear: (i) what is the relative contribution of each of the pain catastrophizing scale (PCS) dimensions in the prediction of acute and chronic postoperative pain; and (ii) whether PCS scores mediate the association between acute and chronic postoperative pain intensity.

Methods:

The current prospective, observational study was conducted at Rambam Health Care Campus, Haifa, Israel. PCS was obtained in 48 pain-free patients a day before an elective thoracotomy in response to tonic heat pain. Acute postthoracotomy pain (APTP) was assessed during rest, including general pain (Restgeneral), and incision-related pain (Restincision), and in response to provoked physical activity, including hand elevation (Provokedhand) and cough (Provokedcough). Chronic postthoracotomy pain (CPTP) was assessed after 4.5±2.3 months.

Results:

Of the PCS subscales, only rumination: (i) was correlated with Restgeneral scores (r=0.337, P=0.027); and (ii) predicted chronic postthoracotomy pain in a regression analysis (P=0.001). General PCS and its subscales mediated the correlation between Restgeneral and chronic postthoracotomy pain intensity (Ps<0.006).

Conclusions:

Findings may elucidate the unique role of the rumination subscale in reflecting an individual's postopertive acute and chronic pain responsiveness. The transition from acute to chronic postoperative pain seems to be facilitated by enhanced pain catastrophizing.

Association between esophageal leiomyomatosis and p53 mutation

Li-Fraumeni syndrome is a cancer predisposition syndrome associated with a variety of neoplasms, mainly soft tissue sarcoma, premenopausal breast cancer, brain tumors, adrenocortical carcinoma, and leukemia. Esophageal leiomyomatosis involves the presence of several rare benign neoplastic lesions composed of proliferating smooth muscle cells in the esophageal wall. The current case report presents a patient with recurrent diffuse leiomyomas of the esophagus and confirmed p53 mutation with clinical criteria of Li-Fraumenilike syndrome.

Collision tumor of the mediastinum: a rare entity

A collision tumor is a rare entity consisting of 2 different tumors that, because of proximity, merge together. The diagnosis of a collision tumor requires that the 2 tumors be histologically distinct. This phenomenon has been described mostly at the esophagogastric junction, where a squamous cell carcinoma of esophageal origin collides with a gastric adenocarcinoma. The present case is of 2 histologically distinct tumors with aggressive features occurring at the mediastinum.

Histomorphometric and microarchitectural analyses using the 2 mm bone marrow trephine in metastatic breast cancer patients-preliminary results

Background

Bone-targeted agents are widely used for the treatment of osteoporosis, the prevention of cancer-therapy induced bone loss, and for reducing the risk of skeletal related events in patients with metastatic disease. Despite widespread use, relatively little is known about the in vivo effect of these agents on bone homeostasis, bone quality, and bone architecture in humans. Traditionally bone quality has been assessed using a transiliac bone biopsy with a 7 mm “Bordier” core needle. We examined the possibility of using a 2 mm “Jamshidi” core needle as a more practical and less invasive method to assess bone turnover and potentially other tumor effects.

Methods

A pilot study on the feasibility of assessing bone quality and microarchitecture and tumor invasion using a 2 mm bone marrow trephine was conducted. Patients underwent a posterior trans-iliac trephine biopsy and bone marrow aspirate. Samples were analyzed for bone microarchitecture, bone density, and histomorphometry. The study plan was to accrue three patients with advanced breast cancer to assess the feasibility of the study before enrolling more patients.

Results

The procedure was well tolerated. The sample quality was excellent to analyze bone trabecular microarchitecture using both microCT and histomorphometry. Intense osteoclastic activity was observed in a patient with extensive tumor burden in bone despite intravenous bisphosphonate therapy.

Discussion

Given the success of this study for assessing bone microarchitecture, bone density, and histomorphometry assessment using a 2 mm needle the study will be expanded beyond these initial three patients for longitudinal assessment of bone-targeted therapy.

A nanomaterial-based breath test for short-term follow-up after lung tumor resection

In this case study, we demonstrate the feasibility of nanomaterial-based sensors for identifying the breath-print of early-stage lung cancer (LC) and for short-term follow-up after LC-resection. Breath samples were collected from a small patient cohort prior to and after lung resection. Gas-chromatography/mass-spectrometry showed that five volatile organic compounds were significantly reduced after LC surgery. A nanomaterial-based sensor-array distinguished between pre-surgery and post-surgery LC states, as well as between pre-surgery LC and benign states. In contrast, the same sensor-array could neither distinguish between pre-surgery and post-surgery benign states, nor between LC and benign states after surgery. This indicates that the observed pattern is associated with the presence of malignant lung tumors. The proof-of-concept presented here has initiated a large-scale clinical study for post-surgery follow-up of LC patients.

FROM THE CLINICAL EDITOR

Monitoring for tumor recurrence remains very challenging due to post-surgical and radiation therapy induced changes in target organs, which often renders standard radiological identification of recurrent malignancies inaccurate. In this paper a novel nanotechnology-based sensor array is used for identification of volatile organic compounds in exhaled air that enable identification of benign vs. malignant states.

[The learning curve of video-assisted thoracoscopic surgery (VATS) for lung lobectomy--a single Israeli center experience]

BACKGROUND

Video-assisted thoracoscopic surgery (VATS) is a method of lung lobe resection that has been implemented in medical centers worldwide since 1992. This procedure utilizes video equipment to assist in performing lobectomies without the need to open the chest wall As of 2009, VATS has been performed in the generaL thoracic surgery department of Rambam HeaLthcare Campus, Haifa. Since then, more than 200 patients were successfully operated on using this method. This study analyzed the Learning curve experienced by its surgeons and departmental staff since VATS implementation.

METHODS

Patient files for all cases which underwent VATS in the department from January 2009 to June 2010 were retrospectively evaluated. The patients were divided into three groups based on their operation date; each group included patients that were operated on during a half-year interval. Data was collected and compared between the groups in regard to the percentage of surgeries that used VATS versus procedures which involved opening the chest wall, procedure time, duration of hospital stay, conversion ratios for closed to open operations, and intra and post-operative complications. Subsequent results were then compared to those reported from other countries around the world.

RESULTS

VATS Lobectomies comprised the smallest percentage of the total Lobectomies performed in the department during the first 6 months of analysis (January 2009 - June 2009] as compared to the following year of analysis (July 2009 - June 2010), that involved a much more extensive use of VATS. The first 6 months of VATS implementation also involved fewer intra-operative complications and shorter operation times as compared to the following year. The length of stay and the number of post-operative complications were similar in each time interval analyzed.

CONCLUSIONS

VATS lobectomy requires surgeons and departmental staff to face a steep learning curve. Operators should invest 6-12 months usage of VATS and perform 30-60 operations in order to achieve constant results that are consistent with those reported from other medical centers worldwide.

Streptokinase fibrinolysis protocol: the advantages of a non-operative treatment for stage II pediatric empyema patients

BACKGROUND

Pediatric empyema necessitates prompt resolution and early hospital discharge with minimal morbidity. However, the most effective treatment approach is not yet established.

OBJECTIVES

To assess the efficacy of an intrapleural streptokinase washing protocol as a non-operative treatment for stage II pediatric empyema as compared to operative decortications, by the number of pediatric intensive care unit (PICU) admissions, length of PICU stay, and hospitalization duration.

METHODS

We retrospectively evaluated 75 consecutive pediatric empyema cases for the period January 2006 to December 2009. Since July 2007 we have used repeated streptokinase-based pleural washing for stage II patients whose condition did not improve with chest drainage

RESULTS

Before July 2007, 17 of 23 stage II empyema patients underwent decortication, compared to only 1 of 21 after July 2007. Non-operated children were admitted to the PICU less frequently than those who were operated (83% vs. 31%, p = 0.0006) and spent less time in the PICU (2.56 +/- 1.92 vs. 1.04 +/- 1.9 days, P= 0.0148); there was no significant statistical difference in overall hospitalization (13.33 +/- 3.69 vs.11.70 +/- 5.74 days, P= 0.301).

CONCLUSIONS

Using intrapleural streptokinase washing as a non-operative treatment for stage II pediatric empyema yielded comparable success rates to the operative approach, with less morbidity.

P4-07-02: Detection, Enrichment, Characterization and Propagation of Circulating Tumour Cells from Patients with Advanced Metastatic Breast Cancer

Background: Circulating tumour cells (CTCs) have attracted much attention lately due to their potential utility in diagnostic, therapeutic and prognostic applications. Characterization of these cells may indeed permit more targeted and individualized therapeutic approaches, as well as provide a means to monitor treatment response. Although detection of CTCs in peripheral blood (PB) is relatively easy using current methodologies, characterization of the CTC pool has proven more challenging due to their low abundance. Furthermore, in-vitro expansion of this elusive cell pool in mammosphere cultures has not yet been reported. In order to achieve a more complete characterization of CTCs and attempt to obtain live cells in sufficient quantity for in vitro expansion, we have used aphaeresis as a means to collect a large initial cell fraction from which to enrich CTCs from peripheral blood.

Methods: A cohort (n=17) of late stage breast cancer patients were first screened using 10ml PB. Peripheral blood mononuclear cells (PBMCs) were isolated using a Ficoll gradient and then enriched for CTCs by anti-CD45 negative selection using an automated system (RoboSep) based on magnetic bead separation. CTCs were detected by immunocytochemistry (ICC) for cytokeratin expression and patients classified as CTC-positive were selected for the aphaeresis procedure. Following collection of aphaeresis material (APM), PBMCs were isolated using a Ficoll gradient, enriched by automated anti-CD45 negative selection and characterized for a variety of markers by ICC, immunofluorescence and flow cytometry. CTCs were then cultured in serum-free medium as monolayers and suspensions. Recovery at the various steps of the isolation process was determined using PB from healthy subjects spiked with MCF-7 breast cancer cells and processed using the same approach.

Results: Recovery of spiked MCF-7 cells was about 40% after Ficoll and magnetic bead separation. Using this negative selection procedure 17/17 (100%) of subjects tested were positive at screening. Most patients (14/17) underwent aphaeresis and a large number (9,600 to 108,000) of enriched CTCs was recovered from APM in all patients tested, either as individual cells or as CTC clusters. Using dual immunofluorescence labelling, co-localization of the epithelial cell marker CK8 and the chemokine receptor CXCR4 was observed within CTCs. Furthermore, over 20% of CTCs were positive for both CK8 and ALDH1, indicative of a stem-like phenotype. APM-derived CTCs from all patients (14/14) could be propagated, both as attached cells and in suspension culture. They formed colonies in monolayer culture, and clusters in mammosphere culture, indicating stem cell-like properties. They replicated for at least three passages in mammosphere culture.

Conclusion: Our CTC detection and enrichment method using negative selection offers a distinct advantage over current methodologies, including collection of clusters, and the ability to grow and expand CTCs in serum-free culture conditions. Furthermore, these cells demonstrate breast cancer stem cell-like characteristics, the ability to replicate for multiple passages as mammospheres in suspensions and a metastatic signature.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-07-02.

Aberrant right subclavian artery- suggested mechanism for esophageal foreign body impaction: Case report

Aberrant right subclavian artery (ARSA) is asymptomatic in most cases. This variant anatomy can cause dysphagia in elderly patients. Impaction of foreign body in the esophagus is rarely the presenting symptom of ARSA. We present an eighty four years old patient who first presented with esophageal foreign body impaction and was diagnosed with an aberrant right subclavian artery compressing the esophagus just below the site of impaction.

We assume that the exact place of impaction was not incidental and that a relative narrowing of the esophagus caused by the vascular anomaly is responsible for this specific presentation.

Medullated fibres and fleece characteristics in Corriedale hoggets from two flocks in Uruguay

The incidence of medullation in 549 Corriedale hoggets from two experimental flocks, its association with other characteristics of the fleece, and the sire effect were evaluated. The investigation was carried out during 2005–06 in hoggets from the Faculty of Agriculture and Faculty of Veterinary Science experimental flocks. Fleeces were weighed and samples were taken at shearing by picking 104 staples from fleeces to measure medullation. A mid-side wool sample was taken to determine wool characteristics (fleece weight, wool yield, mean fibre diameter, staple strength and length). A Dark Fibre Detector was used to identify total medullated fibres and fibre type: medullated fibres (med) and kemp, which were confirmed by light microscope. Mean total medullated fibres, med and kemp content per 10 g of clean wool were 4.2 ± 11.2; 2.0 ± 8.9 and 2.3 ± 4.9, and median values were 0.9, 0.0 and 0.7, respectively, in 549 fleeces. A high variability between samples and a higher proportion of hoggets with kemp fibres than those with med were observed. There were significant differences between sire families for total medullated fibre content/10 g, med fibre content/10 g and kemp fibre content/10 g, but there were no significant effects between flocks, years or interaction between them. Phenotypic correlations between medullated fibre content and wool characteristics were generally low (less than 0.19). In conclusion, medullated fibre content was highly variable between samples and was not strongly correlated with other fleece characteristics. Medullation varied between sire groups, suggesting genetic variation, which could be exploited to improve wool quality.

Pleural fluid analysis of lung cancer vs benign inflammatory disease patients

BACKGROUND

Correct diagnosis of pleural effusion (PE) as either benign or malignant is crucial, although conventional cytological evaluation is of limited diagnostic accuracy, with relatively low sensitivity rates.

METHODS

We identified biological markers accurately detected in a simple PE examination. We analysed data from 19 patients diagnosed with lung cancer (nine adeno-Ca, five non-small-cell Ca (not specified), four squamous-cell Ca, one large-cell Ca) and 22 patients with benign inflammatory pathologies: secondary to trauma, pneumonia or TB.

RESULTS

Pleural effusion concentrations of seven analysed biological markers were significantly lower in lung cancer patients than in benign inflammatory patients, especially in matrix metalloproteinase (MMP)-9, MMP-3 and CycD1 (lower by 65% (P<0.000003), 40% (P<0.0007) and 34% (P<0.0001), respectively), and in Ki67, ImAnOx, carbonyls and p27. High rates of sensitivity and specificity values were found for MMP-9, MMP-3 and CycD1: 80 and 100%; 87 and 73%; and 87 and 82%, respectively.

CONCLUSION

Although our results are of significant merit in both the clinical and pathogenetic aspects of lung cancer, further research aimed at defining the best combination for marker analysis is warranted. The relative simplicity in analysing these markers in any routine hospital laboratory may result in its acceptance as a new diagnostic tool.

[Surgical management of esophageal pathology: 6 years of experience in a single surgical department]

BACKGROUND

Esophageal diseases vary in relation to geographic and behavioral factors. Whether benign or malignant, these diseases interfere with food swallowing. Surgical treatment is variable and aims at restoring the alimentary tract continuity. In this research the authors retrospectively studied esophageal pathologies and their surgical treatment in their department over a 6 year period.

PATIENTS AND METHODS

The records of all patients who underwent surgery for esophageal pathology in a single surgical department at a referral center between January 2002 and December 2007 were reviewed. Data that was collected included patient age, gender, type of pathology, staging, type and length of surgery, length of hospital stay, post-operative morbidity and mortality.

RESULTS

During the study period, 186 patients were operated for esophageal pathology, 154 (83%) had malignant disease and 32 (17%) had benign disease. The distribution of malignancy types was: adenocarcinoma 57%, squamous cell carcinoma 27%, signet ring cell carcinoma 8%, and other 8%. Median length of post-operative hospital stay was 27 days. Thirty two percent of the patients experienced complications, including anastomotic leak (10%), respiratory (9.5%) or cardiac (2%) complications, and infection (7.5%), while 3% required re-operation. Postoperative mortality rate in the hospital was 6.5%.

CONCLUSIONS

The majority of patients undergoing esophageal surgery suffer malignancy, mainly adenocarcinoma. The surgery is extensive and is followed by a long recovery period, during which the patient is subject to a variety of complications. Mortality rate is significant yet comparable to centers around the world with high volume of esophageal operations.

Heparanase is overexpressed in lung cancer and correlates inversely with patient survival

BACKGROUND

Heparanase is an endo-beta-D-glucuronidase that is capable of cleaving heparan sulfate (HS) side chains at a limited number of sites, yielding HS fragments of still appreciable size (approximately 5-7 kDa). Heparanase activity has been detected frequently in several cell types and tissues. Heparanase activity correlates with the metastatic potential of tumor-derived cells, a correlation that has been attributed to enhanced cell dissemination as a consequence of HS cleavage and remodeling of the extracellular matrix barrier.

METHODS

In this study, the authors examined heparanase expression in 114 patients with lung cancer by means of immunohistochemistry and correlated clinical-pathologic data with heparanase immunostaining and cellular localization.

RESULTS

Heparanase was overexpressed in 75% of the study patients. Heparanase expression was correlated with lung cancer lymph node status and metastasis classification (P = .04 and P = .01, respectively) and was correlated inversely with patient survival (P = .007). It is noteworthy that this adverse effect depended largely on the cellular localization of heparanase. Thus, whereas cytoplasmic staining of heparanase is associated with a poor prognosis, nuclear heparanase predicts a favorable outcome for patients with lung cancer.

CONCLUSIONS

The current findings suggest that heparanase expression and cellular localization are decisive for lung cancer patients' prognosis, most likely because of heparanase-mediated tumor cell dissemination by blood and lymph vessels.

Haptoglobin Genotype Determines Myocardial Infarct Size in Diabetic Mice

OBJECTIVES

We sought to understand the importance of oxidative stress in explaining why the haptoglobin (Hp) genotype determines myocardial infarction (MI) size in diabetes mellitus (DM).

BACKGROUND

Two common alleles (1 and 2) exist at the Hp locus in humans. The Hp 2 allele is associated with increased MI size in individuals with DM. In vitro, the Hp 2 protein is associated with increased generation of oxidatively active iron, whereas the Hp 1 protein is associated with increased production of the antioxidant cytokine interleukin (IL)-10.

METHODS

Myocardial infarction was produced by myocardial ischemia-reperfusion (IR) in DM C57BL/6 mice carrying the Hp 1 or Hp 2 allele. Myocardial oxidative stress after IR was assessed using electrospray ionization mass spectrometry. Redox active iron and IL-10 were measured in the serum after IR.

RESULTS

Myocardial infarction size was significantly larger in Hp 2 mice as compared with Hp 1 mice (44.3 +/- 9.3% vs. 21.0 +/- 4.0%, p = 0.03), and these larger infarctions were associated with a significant increase in a panel of hydroxyl-eicosatetraenoic acids. Redox active iron was greater in Hp 2 mice (0.45 +/- 0.11 micromol/l vs. 0.14 +/- 0.05 micromol/l, p = 0.02), whereas IL-10 was greater in Hp 1 mice (85.8 +/- 12.9 pg/microl vs. 46.7 +/- 10.8 pg/microl, p = 0.04) after IR. Administration of an antioxidant (BXT-51072) to Hp 2 mice reduced myocardial injury after IR by more than 80% (p = 0.003), but no myocardial protection was provided by the antioxidant to Hp 1 mice.

CONCLUSIONS

The increased MI size in DM Hp 2 mice occurring after IR may be due to increased oxidative stress.

Calcitroic acid is a major catabolic metabolite in the metabolism of 1 alpha-dihydroxyvitamin D(2)

Calcitroic acid (1 alpha-hydroxy-23 carboxy-24,25,26,27-tetranorvitamin D(3)) is known to be the major water-soluble metabolite produced during the deactivation of 1 alpha,25-dihydroxyvitamin D(3). This deactivation process involves a series of oxidation reactions at C(24) and C(23) leading to side-chain cleavage and, ultimately, formation of the calcitroic acid. Like 1 alpha,25-dihydroxyvitamin D(3), 1 alpha,25-dihydroxyvitamin D(2) is also known to undergo side-chain oxidation; however, to date there has been no evidence suggesting that 1 alpha,25-dihydroxyvitamin D(2) undergoes side-chain cleavage. To investigate this possibility, we studied 1 alpha,25-dihydroxyvitamin D(2) metabolism in HPK1A-ras cells as well as the well characterized perfused rat kidney system. Lipid and aqueous-soluble metabolites were prepared for characterization. Aqueous-soluble metabolites were subjected to reverse-phase HPLC analysis. The major aqueous-soluble metabolite from both the kidney and cell incubations comigrated with authentic calcitroic acid on two reverse-phase HPLC columns of different chemistry. The putative calcitroic acid from the cell and kidney incubations was methylated and found to comigrate with methylated authentic standard on straight-phase and reverse-phase HPLC columns. The identity of the methylated metabolite from cell incubations was also confirmed by mass spectral analysis. These data show, for the first time, that calcitroic acid is a major terminal product for the deactivation of 1 alpha,25-dihydroxyvitamin D(2). Intermediates leading to the formation of the calcitroic acid in the 1 alpha,25-dihydroxyvitamin D(2) metabolism pathway are currently being studied.

The unique tryptophan residue of the vitamin D receptor is critical for ligand binding and transcriptional activation

The human vitamin D receptor (hVDR) is a member of the nuclear receptor superfamily of transcriptional regulators. Here we show that tryptophan 286 of the hVDR is critical for ligand binding and transactivation of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] target genes. Two mutants of the hVDR were produced, W286A and W286F, in which the tryptophan was replaced with an alanine or a phenylalanine, respectively. The W286A mutant did not bind 1,25(OH)2D3, interact with steroid receptor coactivator 1 (SRC-1) in vitro, or activate transcription. Moreover, the W286A receptor did not heterodimerize in a ligand-dependent manner with the human retinoid X receptor alpha (hRXRalpha). Although the W286F receptor heterodimerized with hRXRalpha, interacted with SRC-1, and bound 1,25(OH)2D3, its capacity to transactivate was attenuated severely. Thus, tryptophan 286 of hVDR plays an important role in specific 1,25(OH)2D3 ligand interaction and subsequently in hVDR/RXR interaction, SRC-1 binding, and ligand-dependent transactivation of 1,25(OH)2D3 target genes. These results identify the first amino acid that is absolutely required for ligand binding in the VDR and further define the structure-function relationship of 1,25(OH)2D3 interaction with its receptor.

Vitamin D resistance in RAS-transformed keratinocytes: mechanism and reversal strategies

Human retinoid X receptor alpha (hRXRalpha) plays a critical role in DNA binding and transcriptional activity through its heterodimeric association with several members of the nuclear receptor superfamily, including the vitamin D receptor (VDR). Several cancer cell lines derived from different tissues have been shown to be resistant to the growth-inhibitory action of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], the biologically active metabolite of vitamin D(3). Here we show that in RAS-transformed keratinocytes, Ser260 of hRXRalpha is phosphorylated through the RAS-RAF-MAP kinase cascade. This phosphorylation event results in the inhibition of vitamin D signaling via VDR/hRXRalpha heterodimers. Strategies to reverse this resistance include the use of the MAP kinase inhibitor, PD098059, and a non-phosphorylatable hRXRalpha mutant, Ala260, which completely abolishes RXR phosphorylation and restores the function of both 1,25(OH)(2)D(3) and a specific RXR ligand, LG1069 (4-[1-(5,6,7,8-tetrahydro-3,5,5,8,8-pentamethyl-2-naphtalenyl)ethenyl]-benzoic acid). In addition, we show that a vitamin D analog with low calcemic activity (EB1089) is more potent than 1,25(OH)(2)D(3) in inhibiting cancer cell growth in this system. Targeted therapy with selective analogs such as EB1089, in combination with the inhibition of phosphorylation of the RXR, could play a critical role in the development of strategies for cancer treatment.

Studies of the effects of 1,25-dihydroxyvitamin D on skeletal and calcium homeostasis and on inhibition of tumor cell growth

Vitamin D, parathyroid hormone (PTH), and parathyroid hormone-related peptide (PTHrP) are major regulators of calcium metabolism and vitamin D can also reduce the growth of normal cells and tumor cells. PTHrP and PTH act via a common membrane receptor (PTHR). The mouse PTHR is regulated by a kidney-selective upstream promoter P(1) and ubiquitous downstream promoter P(2). In vitro and in vivo 1,25(OH)(2)D can inhibit PTHR expression in bone but not cartilage by downregulating transcription via P(2). Gene transcription of PTHrP per se can also be downregulated by 1,25(OH)(2)D and by low calcemic vitamin D analogs. This inhibitory effect may reduce the hypercalcemia caused by overproduction of PTHrP by tumor cells. In a malignant keratinoctye cell line, phosphorylation of the retinoid X receptor alpha occurs through the activated Ras-MAP kinase pathway and results in attenuated trans-activation by the vitamin D receptor, its heterodimeric partner. This decreases the growth-inhibitory efficacy of 1,25(OH)(2)D. Studies of the capacity of vitamin D to alter PTHrP production and action and of its anti-proliferative effects can, therefore, shed important light on basic mechanisms controlling these events, and may also have major implications for clinical medicine and therapeutics.

Expression and regulation of parathyroid hormone-related peptide in normal and malignant melanocytes

We examined parathyroid hormone-related peptide (PTHrP) production and regulation in both normal human melanocytes and in a human amelanotic melanoma cell line (A375). Northern blot and immunocytochemical analysis demonstrated that both cultured A375 cells and normal human melanocytes express PTHrP, but A375 cells expressed much higher levels of the peptide. PTHrP secretory rate increased at least 10-fold after treatment with 10% fetal bovine serum (100.2 +/- 2.8 pmol/10(6) cells vs. basal <15 pmol/10(6) cells) in proliferating A375 cells but only twofold in confluent cells. Treatment of A375 cells with increasing concentrations of 1, 25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] or its low-calcemic analog EB-1089 revealed that EB-1089 was 10-fold more potent than 1, 25-(OH)(2)D(3) on inhibition of both cell proliferation and PTHrP expression. Furthermore, inoculation of A375 cells into the mammary fat pad of female severe combined immunodeficiency mice resulted in the development of hypercalcemia and elevated concentrations of plasma immunoreactive PTHrP in the absence of detectable skeletal metastases. Our study, therefore, demonstrates a stepwise increase in PTHrP expression when cells progress from normal to malignant phenotype and suggests that EB-1089 should be further evaluated as a therapeutic agent in human melanoma.