Histopathologic Features of Mucosal Head and Neck Cancer Cachexia.

Objective: Determine the histopathologic features that correlate with head and neck cancer (HNC) cachexia. Methods: A single-institution, retrospective study was performed on adults with HPV-negative, mucosal squamous cell carcinoma of the aerodigestive tract undergoing resection and free flap reconstruction from 2014 to 2019. Patients with distant metastases were excluded. Demographics, comorbidities, preoperative nutrition, and surgical pathology reports were collected. Comparisons of histopathologic features and cachexia severity were made. Results: The study included 222 predominantly male (64.9%) patients aged 61.3 ± 11.8 years. Cachexia was identified in 57.2% patients, and 18.5% were severe (≥15% weight loss). No differences in demographics were identified between the groups. Compared to control, patients with severe cachexia had lower serum hemoglobin (p=0.048) and albumin (p < 0.001), larger tumor diameter (p < 0.001), greater depth of invasion (p < 0.001), and elevated proportions of pT4 disease (p < 0.001), pN2-N3 disease (p=0.001), lymphovascular invasion (p=0.009), and extranodal extension (p=0.014). Multivariate logistic regression identified tumor size (OR [95% CI] = 1.36 [1.08-1.73]), oral cavity tumor (OR [95% CI] = 0.30 [0.11-0.84]), and nodal burden (OR [95% CI] = 1.16 [0.98-1.38]) as significant histopathologic contributors of cancer cachexia. Conclusions: Larger, more invasive tumors with nodal metastases and aggressive histologic features are associated with greater cachexia severity in mucosal HNC.

Masseter muscle thickness is predictive of cancer cachexia in patients with head and neck cancer.

BACKGROUND: Cancer cachexia is prevalent in head and neck cancer patients. The L3 skeletal muscle index (SMI) is often used to assess sarcopenia and cachexia but is infrequently able to be measured in this population. Masseter muscle thickness (MT) may serve as an alternative predictor of cachexia. METHODS: SMI and MT were calculated from 20 trauma (CTRL) and 40 cachectic (CA-CX) and non-cachectic (CA-NCX) head and neck cancer patients. Area Under the Curve of the Receiver Operating Characteristics (AUC-ROC) analysis was performed for SMI and MT. RESULTS: Both SMI and MT were significantly decreased in CA-CX patients (vs. CA-NCX mean difference -19.5 cm2/m2 and -2.06 mm, respectively) and significant predictors of CA-CX (AUC = 0.985 and 0.805, respectively). When analyzed by sex, the same findings were observed for MT in males and trended toward significance in females. CONCLUSIONS: Compared with SMI, MT is a good alternative prognostic biomarker to determine CA-CX status in HNC patients.

Tri-Vector Gracilis Microneurovascular Free Tissue Transfer with Periocular Component to Achieve a Duchenne Smile in Patients with Facial Paralysis.

Importance: Traditional techniques of facial reanimation using gracilis free tissue transfer do not address the lower eyelid or provide contraction at the site of orbicularis oculi, which is necessary to create a natural appearing Duchenne smile. In this report, we describe a novel technique to achieve this element of a true mimetic smile using a tri-vector gracilis muscle flap. Objective: To describe a novel gracilis free flap technique for facial reanimation to provide contraction of the inferior and lateral orbicularis oculi and achieve a Duchenne smile. Design, Setting, and Participants: This was a surgical pearls-description of a novel surgical technique at Academic Tertiary Medical Center. Three patients underwent the operation.

Postoperative consequences of cancer cachexia after head and neck free flap reconstruction.

BACKGROUND: Cachexia is detrimental for patients with head and neck cancer (HNC). However, postoperative consequences of HNC cachexia remain unknown. METHODS: A 2014-2019 retrospective review was performed of adults undergoing aerodigestive HNC resection with free tissue reconstruction. Propensity score matching using inverse probability of treatment weighting (IPTW) of cachectic and control groups was employed to adjust for covariate imbalances followed by binary logistic regression on postoperative outcomes. RESULTS: Out of 252 total patients, 135 (53.6%) had cancer cachexia. The cohort was predominantly white (94.4%) males (65.1%) aged 61.5 ± 11.5 years with stage III-IV (84.1%) malignancy of the oral cavity (66.3%). After matching cohort pre- and intra-operative covariates using IPTW, cancer cachexia remained a strong, significant predictor of serious National Surgical Quality Improvement Program (NSQIP) complications (OR [95%CI] = 3.84 [1.80-8.21]) and major Clavien-Dindo complications (OR [95%CI] = 3.00 [1.18-7.60]). CONCLUSIONS: Cancer cachexia is associated with worse HNC free flap reconstruction outcomes.

Sarcopenia is associated with blood transfusions in head and neck cancer free flap surgery.

OBJECTIVE: To determine if sarcopenia is a predictor of blood transfusion requirements in head and neck cancer free flap reconstruction (HNCFFR). METHODS: A single-institution, retrospective review was performed of HNCFFR patients with preoperative abdominal imaging from 2014 to 2019. Demographics, comorbidities (modified Charlson Comorbidity Index [mCCI]), skeletal muscle index (cm2/m2), oncologic history, intraoperative data, and 30-day postoperative complications (Clavien-Dindo score [CD]) were collected. Binary logistic regression was performed to determine predictors of transfusion. RESULTS: Eighty (33.5%), 66 (27.6%), and 110 (46.0%) of n = 239 total patients received an intraoperative, postoperative, or any perioperative blood transfusion, respectively. Sixty-two (25.9%) patients had sarcopenia. Patients receiving intraoperative transfusions had older age (P = .035), more frequent alcoholism (P = .028) and sarcopenia (P < .001), greater mCCI (P < .001), lower preoperative hemoglobin (P < .001), reconstruction with flaps other than forearm (P = .003), and greater operative times (P = .001), intravenous fluids (P < .001), and estimated blood loss (EBL, P < .001). Postoperative transfusions were associated with major complications (CD ≥ 3; P < .001). Multivariate regression determined sarcopenia (P = .023), mCCI (P = .013), preoperative hemoglobin (P = .002), operative time (P = .036), and EBL (P < .001) as independent predictors of intraoperative transfusion requirements. Postoperative transfusions were predicted by preoperative hemoglobin (P = .007), osseous flap (P = .036), and CD ≥ 3 (P < .001). A perioperative transfusion was predicted by sarcopenia (P = .021), preoperative hemoglobin (P < .001), operative time (P = .008), and CD ≥ 3 (P = .018). CONCLUSION: Sarcopenia is associated with increased blood transfusions in HNCFFR. Patients should be counseled preoperatively on the associated risks, and the increased blood product requirement should be accounted in resource-limited scenarios. LEVEL OF EVIDENCE: 4.

Metastatic Disease of the Temporal Bone: A Contemporary Review.

OBJECTIVES: To identify the frequency and primary site of metastatic pathologies to the temporal bone and characterize the associated symptomatology. METHODS: The MEDLINE, Embase, and Web of Science databases were systematically reviewed according to the PRISMA guidelines to identify all cases of pathologically confirmed distant temporal bone metastases published with English translation until October 2019. Descriptive statistics were performed. RESULTS: Out of 576 full-length articles included for review, 109 met final criteria for data extraction providing 255 individual cases of distant temporal bone metastases. There was a male predominance (54.9%) with median age of 59.0 years (range 2-90). The most common locations of primary malignancy included the breasts (19.6%), lungs (16.1%), and prostate (8.6%). Most tumors were carcinomas of epithelial origin (75.3%) and predominantly adenocarcinoma (49.4%). The commonest metastatic sites encountered within the temporal bone were the petrous (72.0%) and mastoid (49.0%) portions. Bilateral temporal bone metastases occurred in 39.8% of patients. Patients were asymptomatic in 32.0% of cases. Symptomatic patients primarily reported hearing loss (44.3%), facial palsy (31.2%), and otalgia (16.6%) for a median duration of 1 month. Petrous lesions were associated with asymptomatic cases (P = .001) while mastoid lesions more often exhibited facial palsy (P = .026), otalgia (P < .001), and otorrhea (P < .001). Non-carcinomatous tumors were associated with petrosal metastasis (P = .025) and asymptomatic cases (P = .109). Carcinomatous metastases more often presented with otalgia (P = .003). CONCLUSIONS: Temporal bone metastasis is uncommon but should be considered in patients with subacute otologic symptoms or facial palsy and history of distant malignancy. Laryngoscope, 131:1101-1109, 2021.

Skeletal Muscle Index's Impact on Discharge Disposition After Head and Neck Cancer Free Flap Reconstruction.

OBJECTIVE: To determine the role of skeletal muscle index (SMI) in the assessment of frailty and determination of discharge to post-acute care facilities (PACF) after head and neck cancer free flap reconstruction (HNCFFR). STUDY DESIGN: Retrospective cohort. SETTING: Single-institution, academic tertiary referral center. METHODS: Adult patients undergoing HNCFFR from 2014 to 2019 with preoperative abdominal computed tomography imaging were retrospectively analyzed. Patient demographics, 5-factor modified frailty index (5-mFI), body mass index (BMI), SMI at the third lumbar vertebra, oncologic history, perioperative data, and Clavien-Dindo (CD) complications were collected. Binary logistic regression was used to identify independent predictors of discharge disposition. RESULTS: The cohort consisted of 206 patients, 62 (30.1%) of whom were discharged to PACF. Patients discharged to PACF were of older age (65.4 vs 57.1 years, P < .0001) and had a lower SMI (38.8 vs 46.8 cm2/m2, P < .0001), higher 5-mFI (≥3; 25.8% vs 4.2%, P < .0001), and greater incidence of stage IV (80.6% vs 64.1%, P = .0211) aerodigestive cancer (80.6% vs 66.7%, P = .0462). Patients discharged to PACF experienced more blood transfusions (74.2% vs 35.4%, P < .0001), major postoperative complications (CD ≥3, 40.3% vs 12.9%, P < .0001), and delirium (33.9% vs 4.2%, P < .0001). After adjusting for pre- and postoperative factors, multivariate binary logistic regression identified age (P = .0255), 5-mFI (P < .0042), SMI (P = .0199), stage IV cancer (P = .0250), aerodigestive tumor (P = .0366), delirium (P < .0001), and perioperative blood transfusion (P = .0144) as independent predictors of discharge to PACF. CONCLUSIONS: SMI and 5-mFI are independently associated with discharge to PACF after HNCFFR and should be considered in preoperative planning and assessment of frailty.

ACVR2B antagonism as a countermeasure to multi-organ perturbations in metastatic colorectal cancer cachexia.

BACKGROUND: Advanced colorectal cancer (CRC) is often accompanied by the development of liver metastases, as well as cachexia, a multi-organ co-morbidity primarily affecting skeletal (SKM) and cardiac muscles. Activin receptor type 2B (ACVR2B) signalling is known to cause SKM wasting, and its inhibition restores SKM mass and prolongs survival in cancer. Using a recently generated mouse model, here we tested whether ACVR2B blockade could preserve multiple organs, including skeletal and cardiac muscle, in the presence of metastatic CRC. METHODS: NSG male mice (8 weeks old) were injected intrasplenically with HCT116 human CRC cells (mHCT116), while sham-operated animals received saline (n = 5-10 per group). Sham and tumour-bearing mice received weekly injections of ACVR2B/Fc, a synthetic peptide inhibitor of ACVR2B. RESULTS: mHCT116 hosts displayed losses in fat mass ( - 79%, P < 0.0001), bone mass ( - 39%, P < 0.05), and SKM mass (quadriceps: - 22%, P < 0.001), in line with reduced muscle cross-sectional area ( - 24%, P < 0.01) and plantarflexion force ( - 28%, P < 0.05). Further, despite only moderately affected heart size, cardiac function was significantly impaired (ejection fraction %: - 16%, P < 0.0001; fractional shortening %: - 25%, P < 0.0001) in the mHCT116 hosts. Conversely, ACVR2B/Fc preserved fat mass ( + 238%, P < 0.001), bone mass ( + 124%, P < 0.0001), SKM mass (quadriceps: + 31%, P < 0.0001), size (cross-sectional area: + 43%, P < 0.0001) and plantarflexion force ( + 28%, P < 0.05) in tumour hosts. Cardiac function was also completely preserved in tumour hosts receiving ACVR2B/Fc (ejection fraction %: + 19%, P < 0.0001), despite no effect on heart size. RNA sequencing analysis of heart muscle revealed rescue of genes related to cardiac development and contraction in tumour hosts treated with ACVR2B/Fc. CONCLUSIONS: Our metastatic CRC model recapitulates the multi-systemic derangements of cachexia by displaying loss of fat, bone, and SKM along with decreased muscle strength in mHCT116 hosts. Additionally, with evidence of severe cardiac dysfunction, our data support the development of cardiac cachexia in the occurrence of metastatic CRC. Notably, ACVR2B antagonism preserved adipose tissue, bone, and SKM, whereas muscle and cardiac functions were completely maintained upon treatment. Altogether, our observations implicate ACVR2B signalling in the development of multi-organ perturbations in metastatic CRC and further dictate that ACVR2B represents a promising therapeutic target to preserve body composition and functionality in cancer cachexia.

Formation of colorectal liver metastases induces musculoskeletal and metabolic abnormalities consistent with exacerbated cachexia.

Advanced colorectal cancer (CRC) is often accompanied by development of liver metastases (LMs) and skeletal muscle wasting (i.e., cachexia). Despite plaguing the majority of CRC patients, cachexia remains unresolved. By using mice injected with Colon-26 mouse tumors, either subcutaneously (s.c.; C26) or intrasplenically to mimic hepatic dissemination of cancer cells (mC26), here we aimed to further characterize functional, molecular, and metabolic effects on skeletal muscle and examine whether LMs exacerbate CRC-induced cachexia. C26-derived LMs were associated with progressive loss of body weight, as well as with significant reductions in skeletal muscle size and strength, in line with reduced phosphorylation of markers of protein anabolism and enhanced protein catabolism. mC26 hosts showed prevalence of fibers with glycolytic metabolism and enhanced lipid accumulation, consistent with abnormalities of mitochondrial homeostasis and energy metabolism. In a comparison with mice bearing s.c. C26, cachexia appeared exacerbated in the mC26 hosts, as also supported by differentially expressed pathways within skeletal muscle. Overall, our model recapitulates the cachectic phenotype of metastatic CRC and reveals that formation of LMs resulting from CRC exacerbate cancer-induced skeletal muscle wasting by promoting differential gene expression signatures.

Impact of Sarcopenia on Outcomes of Autologous Head and Neck Free Tissue Reconstruction.

BACKGROUND: Sarcopenia has been implicated as a positive predictor of postsurgical complications. Its role in head and neck (H&N) free flap reconstruction has yet to be examined. Our study aimed to determine the clinical impact of sarcopenia on postoperative outcomes in patients receiving autologous free tissue reconstruction for H&N cancer (HNC). METHODS: A retrospective case-control study was conducted at our tertiary referral center. Patients with HNC who received oncologic resection followed by autologous free tissue reconstruction were included. Preoperative abdominal computed tomography (CT) imaging was analyzed at the third lumbar vertebra (L3) to calculate skeletal muscle cross-sectional area (CSA, cm2). Skeletal muscle index (SMI, cm2/m2) was calculated by normalizing CSA to patient height. Sarcopenia at L3 was defined as SMI ≤ 41.6 cm2/m2 for males and ≤ 32.0 cm2/m2 for females. Data analyses were performed to compare postoperative outcomes. RESULTS: Of the 168 patients who met inclusion criteria, 47 patients (28.0%) were determined to have preoperative sarcopenia. The sarcopenic group was older (63 vs. 58 years, p = 0.017), had lower body mass index (BMI; 21.2 vs. 27.2, p < 0.001), had greater incidence of alcohol abuse (55.3 vs. 23.1%, OR = 4.11, p < 0.001). Intraoperatively, sarcopenic patients were found to have greater rates of blood transfusions (63.8 vs. 29.8%, p < 0.001). Postoperatively, sarcopenic patients had higher rates of pneumonia (p < 0.01), venous thromboembolism (p < 0.01), prolonged ventilation (p < 0.01), delirium (p < 0.01), fistula (p < 0.05), wound disruption (p < 0.05), and longer intensive care unit stays (p < 0.05). Sarcopenic patients were ultimately found to have higher overall rates of general postoperative complications (p < 0.001) and flap-specific complications (p < 0.01). CONCLUSION: Sarcopenia was found to be a predictor of postoperative complications in H&N free flap reconstruction, signifying its value as a negative prognostic factor in surgical outcomes. This study reflects level of evidence IV.

HCT116 colorectal liver metastases exacerbate muscle wasting in a mouse model for the study of colorectal cancer cachexia.

Colorectal cancer (CRC) is often accompanied by formation of liver metastases (LM) and skeletal muscle wasting, i.e. cachexia. Despite affecting the majority of CRC patients, cachexia remains underserved, understudied and uncured. Animal models for the study of CRC-induced cachexia, in particular models containing LM, are sparse; therefore, we aimed to characterize two new models of CRC cachexia. Male NSG mice were injected subcutaneously (HCT116) or intrasplenically (mHCT116) with human HCT116 CRC tumor cells to disseminate LM, whereas experimental controls received saline (n=5-8/group). Tumor growth was accompanied by loss of skeletal muscle mass (HCT116: -20%; mHCT116: -31%; quadriceps muscle) and strength (HCT116: -20%; mHCT116: -27%), with worsened loss of skeletal muscle mass in mHCT116 compared with HCT116 (gastrocnemius: -19%; tibialis anterior: -22%; quadriceps: -21%). Molecular analyses revealed elevated protein ubiquitination in HCT116, whereas mHCT116 also displayed elevated Murf1 and atrogin-1 expression, along with reduced mitochondrial proteins PGC1α, OPA1, mitofusin 2 and cytochrome C. Further, elevated IL6 levels were found in the blood of mHCT116 hosts, which was associated with higher phosphorylation of STAT3 in skeletal muscle. To clarify whether STAT3 was a main player in muscle wasting in this model, HCT116 cells were co-cultured with C2C12 myotubes. Marked myotube atrophy (-53%) was observed, along with elevated phospho-STAT3 levels (+149%). Conversely, inhibition of STAT3 signaling by means of a JAK/STAT3 inhibitor was sufficient to rescue myotube atrophy induced by HCT116 cells (+55%). Overall, our results indicate that the formation of LM exacerbates cachectic phenotype and associated skeletal muscle molecular alterations in HCT116 tumor hosts.

PDK4 drives metabolic alterations and muscle atrophy in cancer cachexia.

Cachexia is frequently accompanied by severe metabolic derangements, although the mechanisms responsible for this debilitating condition remain unclear. Pyruvate dehydrogenase kinase (PDK)4, a critical regulator of cellular energetic metabolism, was found elevated in experimental models of cancer, starvation, diabetes, and sepsis. Here we aimed to investigate the link between PDK4 and the changes in muscle size in cancer cachexia. High PDK4 and abnormal energetic metabolism were found in the skeletal muscle of colon-26 tumor hosts, as well as in mice fed a diet enriched in Pirinixic acid, previously shown to increase PDK4 levels. Viral-mediated PDK4 overexpression in myotube cultures was sufficient to promote myofiber shrinkage, consistent with enhanced protein catabolism and mitochondrial abnormalities. On the contrary, blockade of PDK4 was sufficient to restore myotube size in C2C12 cultures exposed to tumor media. Our data support, for the first time, a direct role for PDK4 in promoting cancer-associated muscle metabolic alterations and skeletal muscle atrophy.-Pin, F., Novinger, L. J., Huot, J. R., Harris, R. A., Couch, M. E., O'Connell, T. M., Bonetto, A. PDK4 drives metabolic alterations and muscle atrophy in cancer cachexia.

Growth of ovarian cancer xenografts causes loss of muscle and bone mass: a new model for the study of cancer cachexia.

BACKGROUND: Cachexia frequently occurs in women with advanced ovarian cancer (OC), along with enhanced inflammation. Despite being responsible for one third of all cancer deaths, cachexia is generally under-studied in OC due to a limited number of pre-clinical animal models. We aimed to address this gap by characterizing the cachectic phenotype in a mouse model of OC. METHODS: Nod SCID gamma mice (n = 6-10) were injected intraperitoneally with 1 × 107 ES-2 human OC cells to mimic disseminated abdominal disease. Muscle size and strength, as well as bone morphometry, were assessed. Tumour-derived effects on muscle fibres were investigated in C2C12 myotube cultures. IL-6 levels were detected in serum and ascites from tumour hosts, as well as in tumour sections. RESULTS: In about 2 weeks, ES-2 cells developed abdominal tumours infiltrating omentum, mesentery, and adjacent organs. The ES-2 tumours caused severe cachexia with marked loss of body weight (-12%, P < 0.01) and ascites accumulation in the peritoneal cavity (4.7 ± 1.5 mL). Skeletal muscles appeared markedly smaller in the tumour-bearing mice (approximately -35%, P < 0.001). Muscle loss was accompanied by fibre atrophy, consistent with reduced muscle cross-sectional area (-34%, P < 0.01) and muscle weakness (-50%, P < 0.001). Body composition assessment by dual-energy X-ray absorptiometry revealed decreased bone mineral density (-8%, P < 0.01) and bone mineral content (-19%, P < 0.01), also consistent with reduced trabecular bone in both femurs and vertebrae, as suggested by micro-CT imaging of bone morphometry. In the ES-2 mouse model, cachexia was also associated with high tumour-derived IL-6 levels in plasma and ascites (26.3 and 279.6 pg/mL, respectively) and with elevated phospho-STAT3 (+274%, P < 0.001), reduced phospho-AKT (-44%, P < 0.001) and decreased mitochondrial proteins, as well as with increased protein ubiquitination (+42%, P < 0.001) and expression of ubiquitin ligases in the skeletal muscle of tumour hosts. Similarly, ES-2 conditioned medium directly induced fibre atrophy in C2C12 mouse myotubes (-16%, P < 0.001), consistent with elevated phospho-STAT3 (+1.4-fold, P < 0.001) and altered mitochondrial homoeostasis and metabolism, while inhibition of the IL-6/STAT3 signalling by means of INCB018424 was sufficient to restore the myotubes size. CONCLUSIONS: Our results suggest that the development of ES-2 OC promotes muscle atrophy in both in vivo and in vitro conditions, accompanied by loss of bone mass, enhanced muscle protein catabolism, abnormal mitochondrial homoeostasis, and elevated IL-6 levels. Therefore, this represents an appropriate model for the study of OC cachexia. Our model will aid in identifying molecular mediators that could be effectively targeted in order to improve muscle wasting associated with OC.

Identification of tumor-binding scFv derived from clonally related B cells in tumor and lymph node of a patient with breast cancer.

The purpose of this study was to determine the clonal relationship between B cells within a breast cancer and the B cells in the tumor-draining lymph node (TDLN). We also determined the binding capacity of antibodies derived from these sources to autologous cancer and autologous noncancer breast tissue. Antibody clonality of B cells derived from tumor and lymph node was determined by analyzing heavy and light chain immunoglobulin sequences. The number of shared clonal groups observed between tumor and lymph node antibodies was significant for both heavy (p = 0.004) and light chain (p = 0.012) populations. Panning with phage-displayed single-chain variable fragment libraries derived from the tumor and lymph node B cells resulted in multiple antibodies that bound autologous tumor. Sequence analysis of enriched antibodies recovered after the third round of panning the tumor and TDLN libraries against autologous tumor lysates had a genetic relationship. These results indicate that B cells infiltrating a patient's breast cancer and B cells present in the tumor-draining lymph node are clonally and functionally related.

Selenium modifies the osteoblast inflammatory stress response to bone metastatic breast cancer.

Breast cancer frequently metastasizes to the skeleton resulting in bone degradation due to osteoclast activation. Metastases also downregulate differentiation and the bone-rebuilding function of osteoblasts. Moreover, cancer cells trigger osteoblast inflammatory stress responses. Pro-inflammatory mediators such as interleukin (IL)-6, monocyte chemoattractant protein-1 (MCP-1), cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), expressed by osteoblasts (MC3T3-E1) stimulated with human breast cancer cell (MDA-MB-231) conditioned medium, are pivotal to osteoclast activation and metastasis. Given that these genes are regulated by nuclear factor-kappaB (NF-kappaB), a redox-sensitive transcription factor, we hypothesized that selenium (Se) could abrogate the inflammatory response to metastatic breast cancer cells by modulating NF-kappaB. Caffeic acid phenethyl ester and parthenolide inhibited NF-kappaB activation, as seen by gel shift assays and immunoblotting for p65 in nuclear fractions, as well as decreased production of IL-6 and MCP-1. Supplementation of MC3T3-E1 with methylseleninic acid (MSA) (0.5 microM to 4 microM) reduced the activation of NF-kappaB leading to a decrease in IL-6, MCP-1, COX-2 and iNOS in response to MDA-MB-231 conditioned medium. Addition of MSA to osteoblasts for as little as 15 min suppressed activation of NF-kappaB suggesting that short-lived active metabolites might be involved. However, brief exposure to MSA also brought about an increase in selenoprotein glutathione peroxidase 1. In summary, our data indicate that the osteoblast response to metastatic breast cancer cells is regulated by NF-kappaB activation, which can be effectively suppressed by MSA either through short-lived active metabolites and/or selenoproteins. Thus, Se supplementation may prevent the osteoblast inflammatory response or dampen the vicious cycle established when breast cancer cells, osteoblasts and osteoclasts interact.