Loss of LZAP inactivates p53 and regulates sensitivity of cells to DNA damage in a p53-dependent manner.

Chemotherapy and radiation, the two most common cancer therapies, exert their anticancer effects by causing damage to cellular DNA. However, systemic treatment damages DNA not only in cancer, but also in healthy cells, resulting in the progression of serious side effects and limiting efficacy of the treatment. Interestingly, in response to DNA damage, p53 seems to play an opposite role in normal and in the majority of cancer cells-wild-type p53 mediates apoptosis in healthy tissues, attributing to the side effects, whereas mutant p53 often is responsible for acquired cancer resistance to the treatment. Here, we show that leucine zipper-containing ARF-binding protein (LZAP) binds and stabilizes p53. LZAP depletion eliminates p53 protein independently of its mutation status, subsequently protecting wild-type p53 cells from DNA damage-induced cell death, while rendering cells expressing mutant p53 more sensitive to the treatment. In human non-small-cell lung cancer, LZAP levels correlated with p53 levels, suggesting that loss of LZAP may represent a novel mechanism of p53 inactivation in human cancer. Our studies establish LZAP as a p53 regulator and p53-dependent determinative of cell fate in response to DNA damaging treatment.

Cellular oxidative stress response mediates radiosensitivity in Fus1-deficient mice.

Mechanism of radiosensitivity of normal tissues, a key factor in determining the toxic side effects of cancer radiotherapy, is not fully understood. We recently demonstrated that deficiency of mitochondrial tumor suppressor, Fus1, increases radiosensitivity at the organismal, tissue and cellular levels. Since Fus1-deficient mice and cells exhibit high levels of oxidative stress, we hypothesized that dysregulation of cellular antioxidant defenses may contribute to the increased radiosensitivity. To address this potential mechanism, we treated the Fus1 KO mice with an inhibitor of pathogenic oxidative reactions, pyridoxamine (PM). Treatment with PM ameliorated IR-induced damage to GI epithelium of Fus1 KO mice and significantly increased the survival of irradiated mice. In cultured Fus1 KO epithelial cells, IR-induced oxidative stress was enhanced because of inadequate cellular antioxidant defenses, such as low levels and/or activities of cytochrome C, Sod 2 and STAT3. This resulted in dysregulation of IR-induced DNA-damage response and DNA synthesis. Treatment of Fus1 KO cells with PM or Sod 2 mimetic Tempol normalized the oxidative stress response, thus compensating to a significant degree for inadequate antioxidant response. Our findings using Fus1 KO radiosensitive mice suggest that radiosensitivity is mediated via dysregulation of antioxidant response and defective redox homeostasis.

PPM1A is a RelA phosphatase with tumor suppressor-like activity.

Nuclear factor-κB (NF-κB) signaling contributes to human disease processes, notably inflammatory diseases and cancer. NF-κB has a role in tumorigenesis and tumor growth, as well as promotion of metastases. Mechanisms responsible for abnormal NF-κB activation are not fully elucidated; however, RelA phosphorylation, particularly at serine residues S536 and S276, is critical for RelA function. Kinases that phosphorylate RelA promote oncogenic behaviors, suggesting that phosphatases targeting RelA could have tumor-inhibiting activities; however, few RelA phosphatases have been identified. Here, we identified tumor inhibitory and RelA phosphatase activities of the protein phosphatase 2C (PP2C) phosphatase family member, PPM1A. We show that PPM1A directly dephosphorylated RelA at residues S536 and S276 and selectively inhibited NF-κB transcriptional activity, resulting in decreased expression of monocyte chemotactic protein-1/chemokine (C-C motif) ligand 2 and interleukin-6, cytokines implicated in cancer metastasis. PPM1A depletion enhanced NF-κB-dependent cell invasion, whereas PPM1A expression inhibited invasion. Analyses of human expression data revealed that metastatic prostate cancer deposits had lower PPM1A expression compared with primary tumors without distant metastases. A hematogenous metastasis mouse model revealed that PPM1A expression inhibited bony metastases of prostate cancer cells after vascular injection. In summary, our findings suggest that PPM1A is a RelA phosphatase that regulates NF-κB activity and that PPM1A has tumor suppressor-like activity. Our analyses also suggest that PPM1A inhibits prostate cancer metastases and as neither gene deletions nor inactivating mutations of PPM1A have been described, increasing PPM1A activity in tumors represents a potential therapeutic strategy to inhibit NF-κB signaling or bony metastases in human cancer.

Diagnostic SOX10 gene signatures in salivary adenoid cystic and breast basal-like carcinomas.

BACKGROUND: Salivary adenoid cystic carcinoma (ACC) is an insidious slow-growing cancer with the propensity to recur and metastasise to distant sites. Basal-like breast carcinoma (BBC) is a molecular subtype that constitutes 15-20% of breast cancers, shares histological similarities and basal cell markers with ACC, lacks expression of ER (oestrogen receptor), PR (progesterone receptor), and HER2 (human epidermal growth factor receptor 2), and, similar to ACC, metastasises predominantly to the lung and brain. Both cancers lack targeted therapies owing to poor understanding of their molecular drivers. METHODS: Gene expression profiling, immunohistochemical staining, western blot, RT-PCR, and in silico analysis of massive cancer data sets were used to identify novel markers and potential therapeutic targets for ACC and BBC. For the detection and comparison of gene signatures, we performed co-expression analysis using a recently developed web-based multi-experiment matrix tool for visualisation and rank aggregation. RESULTS: In ACC and BBC we identified characteristic and overlapping SOX10 gene signatures that contained a large set of novel potential molecular markers. SOX10 was validated as a sensitive diagnostic marker for both cancers and its expression was linked to normal and malignant myoepithelial/basal cells. In ACC, BBC, and melanoma (MEL), SOX10 expression strongly co-segregated with the expression of ROPN1B, GPM6B, COL9A3, and MIA. In ACC and breast cancers, SOX10 expression negatively correlated with FOXA1, a cell identity marker and major regulator of the luminal breast subtype. Diagnostic significance of several conserved elements of the SOX10 signature (MIA, TRIM2, ROPN1, and ROPN1B) was validated on BBC cell lines. CONCLUSION: SOX10 expression in ACC and BBC appears to be a part of a highly coordinated transcriptional programme characteristic for cancers with basal/myoepithelial features. Comparison between ACC/BBC and other cancers, such as neuroblastomaand MEL, reveals potential molecular markers specific for these cancers that are likely linked to their cell identity. SOX10 as a novel diagnostic marker for ACC and BBC provides important molecular insight into their molecular aetiology and cell origin. Given that SOX10 was recently described as a principal driver of MEL, identification of conserved elements of the SOX10 signatures may help in better understanding of SOX10-related signalling and development of novel diagnostic and therapeutic tools.

A novel radioprotective function for the mitochondrial tumor suppressor protein Fus1.

FUS1/TUSC2 is a mitochondrial tumor suppressor with activity to regulate cellular oxidative stress by maintaining balanced ROS production and mitochondrial homeostasis. Fus1 expression is inhibited by ROS, suggesting that individuals with a high level of ROS may have lower Fus1 in normal tissues and, thus, may be more prone to oxidative stress-induced side effects of cancer treatment, including radiotherapy. As the role of Fus1 in the modulation of cellular radiosensitivity is unknown, we set out to determine molecular mechanisms of Fus1 involvement in the IR response in normal tissues. Mouse whole-body irradiation methodology was employed to determine the role for Fus1 in the radiation response and explore underlying molecular mechanisms. Fus1(-/-) mice were more susceptible to radiation compared with Fus1(+/+) mice, exhibiting increased mortality and accelerated apoptosis of the GI crypt epithelial cells. Following untimely reentrance into the cell cycle, the Fus1(-/-) GI crypt cells died at accelerated rate via mitotic catastrophe that resulted in diminished and/or delayed crypt regeneration after irradiation. At the molecular level, dysregulated dynamics of activation of main IR response proteins (p53, NFκB, and GSK-3ß), as well as key signaling pathways involved in oxidative stress response (SOD2, PRDX1, and cytochrome c), apoptosis (BAX and PARP1), cell cycle (Cyclins B1 and D1), and DNA repair (γH2AX) were found in Fus1(-/-) cells after irradiation. Increased radiosensitivity of other tissues, such as immune cells and hair follicles was also detected in Fus1(-/-) mice. Our findings demonstrate a previously unknown radioprotective function of the mitochondrial tumor suppressor Fus1 in normal tissues and suggest new individualized therapeutic approaches based on Fus1 expression.

TrkC signaling is activated in adenoid cystic carcinoma and requires NT-3 to stimulate invasive behavior.

Treatment options for adenoid cystic carcinoma (ACC) of the salivary gland, a slowly growing tumor with propensity for neuroinvasion and late recurrence, are limited to surgery and radiotherapy. Based on expression analysis performed on clinical specimens of salivary cancers, we identified in ACC expression of the neurotrophin-3 receptor TrkC/NTRK3, neural crest marker SOX10, and other neurologic genes. Here, we characterize TrkC as a novel ACC marker, which was highly expressed in 17 out of 18 ACC primary-tumor specimens, but not in mucoepidermoid salivary carcinomas or head and neck squamous cell carcinoma. Expression of the TrkC ligand NT-3 and Tyr-phosphorylation of TrkC detected in our study suggested the existence of an autocrine signaling loop in ACC with potential therapeutic significance. NT-3 stimulation of U2OS cells with ectopic TrkC expression triggered TrkC phosphorylation and resulted in Ras, Erk 1/2 and Akt activation, as well as VEGFR1 phosphorylation. Without NT-3, TrkC remained unphosphorylated, stimulated accumulation of phospho-p53 and had opposite effects on p-Akt and p-Erk 1/2. NT-3 promoted motility, migration, invasion, soft-agar colony growth and cytoskeleton restructuring in TrkC-expressing U2OS cells. Immunohistochemical analysis demonstrated that TrkC-positive ACC specimens also show high expression of Bcl2, a Trk target regulated via Erk 1/2, in agreement with activation of the TrkC pathway in real tumors. In normal salivary gland tissue, both TrkC and Bcl2 were expressed in myoepithelial cells, suggesting a principal role for this cell lineage in the ACC origin and progression. Sub-micromolar concentrations of a novel potent Trk inhibitor AZD7451 completely blocked TrkC activation and associated tumorigenic behaviors. Pre-clinical studies on ACC tumors engrafted in mice showed efficacy and low toxicity of AZD7451, validating our in vitro data and stimulating more research into its clinical application. In summary, we describe in ACC a previously unrecognized pro-survival neurotrophin signaling pathway and link it with cancer progression.

Nuclear factor-kappa B pathway and response in a phase II trial of bortezomib and docetaxel in patients with recurrent and/or metastatic head and neck squamous cell carcinoma.

BACKGROUND: Our previous study has shown that nuclear factor-kappa B (NF-kappaB)-signaling pathway was associated with a higher rate of recurrence in head and neck squamous cell carcinoma (HNSCC). The combination of bortezomib, an NF-kappaB inhibitor by inhibition of proteasomes, plus docetaxel was assessed for efficacy and toxicity. MATERIALS AND METHODS: Patients with recurrent and/or metastatic HNSCC were enrolled on a phase II bortezomib/docetaxel trial (bortezomib 1.6 mg/m(2) and docetaxel 40 mg/m(2) on days 1 and 8 of a 21-day cycle). Response was assessed using RECIST. Tissue specimens were evaluated for the presence of human papillomavirus (HPV) and expression of NF-kappaB-associated genes. RESULTS: Twenty-one of 25 enrolled patients were assessable for response; one partial response (PR, 5%), 10 stable disease (SD, 48%) and 10 progressive disease (PD, 48%). Patients with PR/SD had significantly longer survival compared with patients with PD and the regimen was well tolerated. Only one of 20 tumors was positive for HPV. Patients with PD had higher expression of NF-kappaB and epidermal growth factor receptor-associated genes in their tumors by gene expression analysis. CONCLUSION: Further understanding of treatment resistance and interactions between bortezomib and docetaxel may provide novel approaches in managing HNSCC.

Aggressiveness of HNSCC tumors depends on expression levels of cortactin, a gene in the 11q13 amplicon.

11q13 amplification is a late-stage event in several cancers that is often associated with poor prognosis. Among 11q13-amplified genes, the actin assembly protein cortactin/CTTN is considered a likely candidate for direct involvement in tumor progression because of its cell motility-enhancing functions. We modulated cortactin expression in head and neck squamous cell carcinoma (HNSCC) cell lines. Cortactin expression levels directly correlated with tumor size, vascularization and cell proliferation in an orthotopic HNSCC in vivo model. In contrast, under normal in vitro culture conditions, cortactin expression levels had no effect on cell proliferation. However, cell lines in which cortactin expression was reduced by knockdown (KD) grew poorly in vitro under harsh conditions of growth factor deprivation, anchorage independence and space constraint. In contrast, overexpression of cortactin enhanced in vitro growth under the same harsh conditions. Surprisingly, defects in growth factor-independent proliferation of cortactin-KD cells were rescued by coculture with cortactin-expressing cells. As the cocultured cells are separated by permeable filters, cortactin-expressing cells must secrete growth-supporting autocrine factors to rescue the cortactin-KD cells. Overall, cortactin expression modulates multiple cellular traits that may allow survival in a tumor environment, suggesting that the frequent overexpression of cortactin in tumors is not an epiphenomenon but rather promotes tumor aggressiveness.

Microsatellite mutations in buccal cells are associated with aging and head and neck carcinoma.

Carcinogen exposure from tobacco smoking is the major cause of upper aerodigestive tract cancer, yet heavy smokers only have about a 10% life-time risk of developing one of these cancers. Current technologies allow only limited prediction of cancer risk and there are no approved screening methods applicable to the general population. We developed a method to assess somatic mutational load using small-pool PCR (SP-PCR) and analysed mutations in DNA isolated from cells obtained by mouth rinse. Mutation levels in the hypermutable tetranucleotide marker D7S1482 were analysed in specimens from 25 head and neck squamous carcinoma (HNSCC) cases and 31 controls and tested for associations with age, smoking history and cancer status. We found a significant association between mutation frequency and age (P=0.021, Generalized Linear Model (GLM), N=56), but no influence of smoking history. Cases had higher mutation frequencies than controls when corrected for the effects of age, a difference that was statistically significant in the subgroup of 10 HNSCC patients who were treated with surgery only (P=0.017, GLM, N=41). We also present evidence that cancer status is linked to levels of nonunique, and presumably clonally derived, mutations in D7S1482. Insertion mutations were observed in 833 (79%) of 1058 alleles, of which 457 (43%) could be explained by insertion of a single repeat unit; deletion mutations were found in 225 (21%) of tested alleles. In conclusion, we demonstrate that the sensitive detection of single molecule mutations in clinical specimens is feasible by SP-PCR. Our study confirms an earlier report that microsatellite mutations increase with age and is the first to provide evidence that these mutations may be associated with cancer status in individual subjects.

Chemoradiation for locally advanced squamous cell carcinoma of the head and neck for organ preservation and palliation.

OBJECTIVES: To measure the efficacy and toxic effects of our chemoradiotherapy regimen by means of response and survival in patients with advanced squamous cell carcinoma of the head and neck (HNSCC) for organ preservation in resectable disease or palliation in unresectable disease. DESIGN: All patients underwent evaluation by the multidisciplinary head and neck cancer team, with pathological diagnosis and staging. All patients underwent assessment for response to therapy using results of physical examination and radiologic imaging. Patients were followed up at 3-month intervals for a planned period of 5 years. SETTING: Academic center. PATIENTS: Thirty-eight previously untreated patients with newly diagnosed HNSCC were treated from June 1, 1996, through December 31, 1998, of whom 20 had resectable and 18 had unresectable tumors. INTERVENTION: Patients received intravenous cisplatin, 100 mg/m(2) for 1 hour on days 1 and 29; a 24-hour continuous infusion of fluorouracil, 1000 mg/m(2) on days 1 through 4 and 29 through 32; and radiation therapy, 150 rad twice daily for 12 days. The patients were given a 7- to 10-day break, and radiation therapy was restarted on day 29 for 12 additional days (total dose, 7200 rad). MAIN OUTCOME MEASURES: Complete, partial, and total response rates; disease-free survival; overall survival; and toxic effects. RESULTS: Toxic effects of treatment were moderately severe, including grades III to IV mucositis (89%), neutropenia (71%), and renal toxic effects (8%). In the 18 patients in the unresectable group, complete response in the 17 primary tumors and 15 cervical nodal metastases was achieved in 12 (71%) and 9 (60%), respectively; in the 20 patients undergoing organ preservation, complete response rates were 100% in the 23 primary tumors and 15 cervical nodal metastases. Complete response for all 38 patients was achieved in 31 (82%). In the unresectable group, the Kaplan-Meier relapse-free survival estimate is 56%, with follow-up from 29 to 45 months. In the organ preservation group, 75% of patients are alive without disease, and 8 have been followed up for 36 to 48 months. Of the 5 patients who have died, only 2 died of disease, with recurrences at 13.0 and 16.5 months. CONCLUSIONS: Chemoradiotherapy consisting of cisplatin, fluorouracil, and twice-daily external beam radiation is highly effective in achieving durable complete responses in patients with resectable HNSCC undergoing organ preservation and patients with unresectable HNSCC undergoing palliation. Toxic effects of this regimen were moderate to severe.

Different p16INK4a and p14ARF expression patterns in acute myeloid leukaemia and normal blood leukocytes.

The p16INK4a gene is often disrupted or transcriptionally silenced by CpG island methylation in human cancers. However, in acute myeloid leukaemia (AML) alterations of the INK4a-ARF tumour suppressor locus are rarely found despite the noted variable p16INK4a mRNA and protein levels. The p14ARF, an alternative reading frame protein encoded from the same INK4a-ARF locus, is a potent tumour suppressor functionally linked to p53. There is little known regarding the role of p14ARF in primary human tumours. Therefore, we analysed the expression patterns of these two tumour suppressors in 37 cases of AML. The relative expression of p16INK4a and p14ARF mRNA in AML blasts, measured by a specific p16INK4a/p14ARF multiplex RT-PCR, was significantly shifted towards p14ARF whereas relatively lower levels of p16INK4a were detected. Quantitative RT-PCR revealed significantly higher expression of both transcripts in AML blasts when compared to normal differentiated myeloid cells or CD34+ progenitor cells. Furthermore, a good correlation between p16INK4a protein and mRNA was observed, whereas no correlation was found with p14ARF. Our results suggest: a) increased levels of both p16INK4a and p14ARF may participate in the pathogenesis of AML, b) that high p14ARF mRNA expression might influence p16INK4a transcription and c) that post-transcriptional regulatory mechanisms are important for p14ARF expression.

Radiofrequency tissue volume reduction: multilesion vs single-lesion treatments for snoring.

OBJECTIVE: To compare the safety and efficacy of single-lesion and multilesion radiofrequency tissue reduction (RFTR) of the soft palate for the treatment of snoring. DESIGN: Prospective, nonrandomized clinical trial. SETTING: University hospital outpatient clinic. PATIENTS: Nonrandomized patients undergoing RFTR to treat socially unacceptable snoring. Of 47 patients, 16 received single-lesion treatments and 31 received multilesion treatments. INTERVENTION: Soft-palate RFTR was performed using a radiofrequency generator. Patients required 1 to 3 treatments based on improvement or withdrawal from the study, and each received 1, 3, or 4 lesions per treatment. Patients who received single-lesion therapy did not cross over into the multilesion group; however, 5 patients in the multilesion group received 4-lesion therapy after a treatment with 3 lesions. MAIN OUTCOME MEASURES: Outcome measures were determined using visual analog scale questionnaires assessing level of snoring (snoring index) and level of pain (pain index) associated with the procedure. Adverse events and complications during treatment were cataloged. Data were collected before the procedure, 6 weeks after each treatment, and an average of 16 months after the last procedure. RESULTS: Single-lesion and multilesion groups showed significant improvement in snoring after RFTR treatments (P<.01 for both). However, compared with the single-lesion group, the multilesion group required fewer treatments (1.94 vs 2.38; P =.05) and was more than twice as likely to be cured after 2 treatments (61% vs 25%; P =.02). A trend toward improved clinical outcomes with increased number of lesions and total energy per treatment was observed when patients treated with 1, 3, or 4 lesions were compared. The 4-lesion group had the most pronounced improvement in snoring index score per treatment, the lowest number of treatments required for cure, and the greatest percentage of patients cured after 2 treatment sessions. Follow-up demonstrated minimal relapse of snoring in the multilesion group at a mean of 16 months. Although there was a statistically significant increase in pain in the multilesion group vs the single-lesion group, this increase did not increase narcotic use or time off work and was considered minimal by reporting patients. CONCLUSION: Multilesion RFTR using higher energy levels per treatment is safe and has increased efficacy without increased complications relative to single-lesion therapy.

Efficiency of adenovirus-mediated gene transfer to oropharyngeal epithelial cells correlates with cellular differentiation and human coxsackie and adenovirus receptor expression.

Adenovirus-mediated gene transfer is a novel treatment strategy for head and neck squamous cell carcinoma (HNSCC) that may improve the unacceptable morbidity and mortality associated with conventional treatment. Efficient adenoviral (AdV) infection largely depends on cellular expression of the human coxsackie and adenovirus receptor (hCAR); however, the relatively recent identification of this receptor precludes a comprehensive description of its tissue distribution. We have created tissue culture model systems that approximate the differentiation and three-dimensional structure of stratified squamous epithelium characteristic of head and neck mucosa. Using these systems, we have found that expression of hCAR in native and modeled normal oropharyngeal epithelium decreased as cells differentiated with the most superficial and differentiated cells expressing no detectable hCAR. In contrast, modeled stratified HNSCC cells, which did not differentiate morphologically and did not express cytokeratin markers of differentiation, had equivalent expression of hCAR in superficial and basal layers. The expression of hCAR in our models correlated not only with the undifferentiated state, but also with efficiency of AdV infection. Despite expression of hCAR in underlying basal and suprabasal cells, topical application of AdV to normal modeled epithelium resulted in inefficient transduction of the most superficial cell layer without any infection of underlying cells. These data suggest that in normal epithelium the overlying squamous cells act as a barrier preventing infection of underlying cells that would otherwise be easily infected. In modeled stratified HNSCC, transduction was much more efficient and occurred up to four cell layers deep, suggesting that unlike normal superficial epithelial cells, the superficial cells of stratified HNSCC do not act as an effective barrier to adenoviral infection. The distribution of hCAR in native tissue and the enhanced susceptibility of undifferentiated oropharyngeal epithelial cells, including undifferentiated cancer cells, to AdV infection has important implications for the development of AdV-based targeting strategies for the treatment of head and neck cancer or premalignancies.

Delayed-onset sensorineural hearing loss in a 3-year-old survivor of persistent pulmonary hypertension of the newborn.

Persistent pulmonary hypertension of the newborn (PPHN) and its conventional medical treatment are associated with sensorineural hearing loss, yet current recommendations for regular audiological evaluations of PPHN survivors are lacking. We report a case of delayed-onset, progressive sensorineural hearing loss in a 3-year-old patient with a history of PPHN and a normal auditory brainstem evoked response at 6 weeks of age. The relatively late detection of significant sensorineural hearing loss in this otherwise healthy 3-year-old illustrates the need for audiological evaluation at regular intervals in patients with a history of PPHN.

Induction of apoptosis in human esophageal cancer cells by sequential transfer of the wild-type p53 and E2F-1 genes: involvement of p53 accumulation via ARF-mediated MDM2 down-regulation.

Transcriptional factor E2F-1 as well as tumor suppressor p53 have been shown to cause apoptosis independently in some types of human cancer cells when overexpressed. Here we report that sequential transfer of the wild-type p53 and E2F-1 genes efficiently induces apoptosis in human esophageal cancer cells and that E2F-1 overexpression directly, activates expression of p14 (ARF), which inhibits MDM2-mediated p53 degradation, resulting in the stabilization of p53. Infection of human esophageal cancer cell lines T.Tn and TE8 with adenovirus vector-expressing E2F-1 (Ad-E2F-1) enhanced mRNA and protein expression of ARF and decreased MDM2 protein expression. Transfection of ARF plasmid decreased MDM2 protein expression, which in turn increased p53 protein expression. Infection of T.Tn and TE8 cells first with adenovirus-expressing wild-type p53 (Ad-p53) and then with Ad-E2F-1 resulted in rapid induction of apoptosis; in contrast, simultaneous infection with Ad-E2F-1 and Ad-p53 had no significant antitumor effect. As shown by Western blot analysis, infection with suboptimal concentrations of Ad-E2F-1 induced the accumulation of exogenous p53 transduced by suboptimal concentrations of Ad-p53. Moreover, Ad-E2F-1-mediated ARF expression inhibited the up-regulation of MDM2 by overexpressed p53 in TE8 cells. Thus, overexpression of ectopic E2F-1 protein may stabilize endogenous as well as ectopic p53 protein via the E2F-1/ARF/MDM2/p53 regulatory pathway and, in this way, render cells more sensitive to apoptosis, an outcome that has important implications for the treatment of human esophageal cancers.

Nodal volume reduction after concurrent chemo- and radiotherapy: correlation between initial CT and histopathologic findings.

BACKGROUND AND PURPOSE: The role of concurrent chemoradiation for treatment of head and neck squamous cell carcinoma is expanding. We sought to evaluate the CT appearance of diseased and normal cervical lymph nodes before and after concurrent chemoradiation and to correlate lymph node volume reduction as revealed by CT with histopathologic findings of resected nodes. METHODS: Using concurrent chemoradiation, we treated seven patients with locally advanced head and neck squamous cell carcinoma. Our chemotherapeutic regimen consisted of cisplatin (100 mg/m2 body surface area administered on days 1 through 4 and 29 through 32) and 5-fluorouracil (1000 mg/m2 body surface area, administered on days 1 through 4 and 29 through 32). Radiotherapy was administered twice per day on dosing days 1 through 42 to a total dose of 7200 cGy to the primary tumor and 6000 cGy to the involved lymph nodes. Pre- and post-treatment CT scans were used to calculate lymph node volumes for all CT-positive (size criteria or extracapsular spread or both) diseased nodes (n = 19) and one normal node per patient (n = 7). Volume reduction was determined by CT results and correlated with the histopathologic findings of resected nodes. RESULTS: Average volume reduction (+/- standard error of the mean) for the 19 diseased nodes was 91%+/-4% and for the seven normal nodes was 55%+/-21% (P < .02, two-sided t test). Fifteen of 19 of the diseased lymph nodes showed extracapsular spread before treatment and none of 19 after treatment. The histopathologic findings of resected nodes included persistent tumor in one of the 19 diseased lymph nodes. Six of seven patients remained alive and disease-free, with an average follow-up duration of 24 months. CONCLUSION: Nodal volume reduction of greater than 90% was associated with eradication of tumor as assessed by histopathologic analysis of resected nodes. Serial CT scans obtained both before and after concurrent chemoradiation may be useful for predicting which patients will benefit from adjuvant surgical therapy.

Sinogenic subdural empyema and Streptococcus anginosus.

Subdural empyema (SDE) is most commonly caused by sinusitis and, without early diagnosis and neurosurgical intervention, is associated with high mortality. In a patient with sinusitis who presents with mental status changes, the diagnosis of SDE should be suspected on clinical grounds, even in the absence of significant computed tomographic findings. Computed tomography with contrast is a useful aid in the diagnosis of SDE, but findings may be subtle, and contrasted magnetic resonance imaging is superior. The association of Streptococcus anginosus sinusitis and related intracranial sequelae is important owing to the potentially catastrophic complications and should be recognized by otolaryngologists. In view of the rapidly progressing nature of sinogenic SDE, physicians should strongly consider early institution of aggressive therapy consisting of craniotomy with concurrent sinus drainage in patients in whom sinogenic SDE is suspected on clinical grounds, particularly in the presence of S. anginosus-positive sinus cultures.

Biologic and biochemical analyses of p16(INK4a) mutations from primary tumors.

BACKGROUND: Point mutations in the tumor suppressor gene p16(INK4a) (also known as p16, CDKN2, MTS1, and INK4a) are found in many tumor types. Because the function of the products of these naturally occurring mutants has not been fully explored, we investigated the functional activities of a wide range of naturally occurring p16 mutant proteins. METHODS: Sixteen cancer-associated p16 mutant proteins, resulting from missense mutations, were characterized for their ability to bind and inhibit the cyclin-dependent kinases (CDK4 and CDK6) and to induce cell cycle arrest in G(1) phase. RESULTS/CONCLUSIONS: Among 16 mutants analyzed, nine had detectable functional defects. Three mutants (D84V, D84G, and R87P) had defects in CDK binding, kinase inhibition, and cell cycle arrest. The corresponding mutations are located in the third ankyrin repeat in a highly conserved region believed to form the CDK binding cleft. Three mutants (P48L, D74N, and R87L) had defects in kinase inhibition and cell cycle arrest. Among the 10 mutants with normal CDK binding and inhibitory activity, three mutants (N71S, R80L, and H83Y) had defects only in their ability to induce cell cycle arrest. Thus, p16 mutant proteins that retain CDK4 and CDK6 binding may have more subtle functional defects. All nine mutations leading to functional impairments mapped to the central portion of the p16 protein. Ankyrin repeats II and III appear more critical to p16 function, and mutations in ankyrin repeats I and IV are less likely to disrupt p16 function.

Expression of p16INK4a/p16alpha and p19ARF/p16beta is frequently altered in non-small cell lung cancer and correlates with p53 overexpression.

The CDKN2 locus expresses two different mRNA transcripts, designated alpha and beta. The protein product of the alpha transcript is the cell cycle inhibitor and tumour suppressor p16INK4a. The beta transcript is translated in an alternate reading frame (ARF) and in humans encodes a 15 kDa protein (p19ARF). Immunohistochemical and Western analysis of p16INK4a has shown that the protein is downregulated in a significant number of tumours, but less is known on the expression of the p19ARF. We have examined the expression of p16INK4a and p19ARF in resectable non-small cell lung cancer (NSCLC) by immunostaining (n=49) and multiplex RT-PCR (n=28). In order to investigate the mechanism responsible for p16INK4a downregulation, exon 1alpha methylation was analysed in a PCR-based assay. Of 49 tumours examined by immunostaining, 24 and 20 tumours expressed p16INK4a and p19ARF at nil to low levels, respectively. p19ARF was localized primarily to the nuclei of tumour cells, but was also seen to varying degrees in nuclei of lymphocytes, chondrocytes, fibroblasts, and epithelial cells. No tumour with normal p16INK4a had decreased p19ARF expression. Among 16 tumours with nil to low p16INK4a expression, 11 tumours exhibited full methylation of at least one site within exon 1alpha and these tumours showed normal p19ARF expression. In contrast, no methylation of exon 1alpha was observed in five tumours which also lacked p19ARF. In normal lung, p16INK4a and p19ARF were not expressed at detectable levels, the multiplex RT-PCR results were balanced, and sites within exon 1alpha were strongly methylated. In tumours, imbalanced multiplex RT-PCR data (p16INK4a