Epigenetic inactivation implies independent functions for insulin-like growth factor binding protein (IGFBP)-related protein 1 and the related IGFBPL1 in inhibiting breast cancer phenotypes

PURPOSE

To analyze epigenetic regulation of two related genes, insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) and IGFBPL1, and its significance as a determinant of clinical phenotypes in human breast cancer.

EXPERIMENTAL DESIGN

We have investigated the expression and epigenetic regulation of IGFBP-rP1 and IGFBPL1 in human breast cancer cell lines and primary and metastatic carcinomas.

RESULTS

Expression of IGFBP-rP1 and IGFBPL1 is down-regulated in breast cancer cell lines. Aberrant methylation in the CpG islands of each gene correlates well with loss of expression at the mRNA level. Analysis of methylation in DNA isolated from human primary breast tumors showed that methylation in either gene was associated with a worse overall survival (OS; P=0.008) and disease-free survival (DFS) following surgery (P=0.04) and worse DFS following adjuvant chemotherapy (P=0.01). Methylation of IGFBP-rP1 alone was associated with a trend toward decreased OS (P=0.10) and decreased DFS (P=0.25). Methylation in IGFBPL1 was clearly associated with worse OS (P=0.001) and DFS (P<0.0001). Methylation in either IGFBP-rP1 or IGFBPL1 was significantly associated with nodal disease (P<0.001).

CONCLUSIONS

Expression of IGFBP-rP1 and IGFBPL1 is regulated by aberrant hypermethylation in breast cancer, implying that inactivation of these genes is involved in the pathogenesis of this malignancy. Analysis of methylation of these genes may have utility in prediction of clinical phenotypes, such as nodal disease and response to chemotherapy.

Dose-response effect of Red Maca (Lepidium meyenii) on benign prostatic hyperplasia induced by testosterone enanthate

The main goal of this study was to determine the effect of a freeze-dried aqueous extract of the red variety of Lepidium meyenii (Red Maca) on testosterone-induced benign prostatic hyperplasia (BPH) in adult rats of the Holtzman strain. Rats were treated with freeze-dried aqueous extract of Red Maca at doses of 0, 0.01, 0.05, 0.1, and 0.5 g/kg body wt. A positive control group received Finasteride (0.6 mg/kg body wt.). After treatment, the animals were sacrificed, and the ventral prostate was extracted, and weighed. HPLC was used to determine the presence of glucosinolates in Red Maca. The prostate weight diminished in a dose-dependent fashion in rats treated with Red Maca. The effect of Red Maca was better than that observed with Finasteride. Finasteride, but not Red Maca, reduced seminal vesicles weight. Analysis of the HPLC indicated the presence of benzyl glucosinolate (Glucotropaeolin) with a content of 0.639%. Serum testosterone levels were not affected by Red Maca. Moreover, serum testosterone levels were not related to prostate or seminal vesicles weight in rats treated with vehicle and Red Maca. In conclusion, Red Maca administered orally in rats seems to exert an inhibitory effect at a level post DHT conversion, on the BPH-induced experimentally, although a direct measure of reductase action would still be required.

Effect of chronic treatment with three varieties of Lepidium meyenii (Maca) on reproductive parameters and DNA quantification in adult male rats

The aim of this study was to evaluate the chronic effect of different varieties of Lepidium meyenii (Red Maca, Yellow Maca and Black Maca). Male rats were treated by gavage with aqueous extract of each variety of maca equivalent to 1 g hypocotyl kg(-1) body weight (BW) for 84 days. At the end of the treatment, daily sperm production (DSP), epididymal sperm count (ESC) and sperm count in vas deferens (SCVD) were assessed. In addition, testis DNA quantification was also determined. Any toxic effect was assessed in liver and spleen by histological studies. The results indicate that Yellow Maca and Black Maca improved ESC and that three varieties of maca increased the SCVD without affecting DSP. Moreover, testis DNA levels were not affected by treatment with any of the three varieties of maca. Histological picture of the liver in animals treated with the three varieties of maca was similar to that observed in controls. In conclusion, Yellow and Black Maca increased epididymal sperm count after 84 days of treatment without affecting DSP. Maca seems to act as a modulator of sperm count at the reproductive tract level.

A phase I-II preoperative biomarker trial of fenretinide in ascitic ovarian cancer

PURPOSE

To evaluate study feasibility, toxicity, drug concentrations, and activity of escalating doses of the synthetic retinoid fenretinide [N-(4-hydroxyphenyl)retinamide (4-HPR)] in ovarian cancer by measuring serum CA125 and cytomorphometric biomarkers in cancer cells collected from ascitic fluid before and after treatment.

METHODS

Twenty-two naive patients with ascitic ovarian cancer were treated with escalating doses of 4-HPR at 0, 400, 600, and 800 mg/d for 1 to 4 weeks before surgery. Changes in the proportion of proliferating cells expressed by Ki67 and computer-assisted cytomorphometric variables (nuclear area, DNA index, and chromatin texture) were determined in ascitic cells. Drug levels were measured by high-performance liquid chromatography.

RESULTS

Doses up to 800 mg/d were well tolerated, and no adverse reactions occurred. There was no effect of 4-HPR on changes in serum CA125, Ki67 expression, which were assessed in 75% of subjects, and cytomorphometric variables, which were assessed in 80% of subjects. Plasma retinol levels were significantly lower in affected women than healthy donors. 4-HPR plasma concentrations increased slightly with increasing doses and attained a 1.4 micromol/L concentration with 800 mg/d. Drug levels in malignant ascitic cells and tumor tissue were higher than in plasma but were 50 and 5 times lower, respectively, than in carcinoma cells treated in vitro with 1 micromol/L 4-HPR.

CONCLUSIONS

Cell biomarkers can be measured in ascitic cells to assess drug activity. Under our experimental conditions, 4-HPR did not show activity in advanced ovarian cancer cells. However, clinical evidence supports further investigation of fenretinide for ovarian cancer prevention.

Gemcitabine and cisplatin in a concomitant alternating chemoradiotherapy program for locally advanced head-and-neck cancer: a pharmacology-guided schedule

PURPOSE

Administration of gemcitabine together with cisplatin at cytotoxic doses in a chemoradiotherapy regimen is hampered by a high degree of local toxicity. Using the pharmacologic properties of the drug we designed a modified schedule aimed at reducing toxicity while preserving activity.

METHODS AND MATERIALS

Patients with squamous cell carcinomas of the oral cavity, pharynx and larynx, bulky T4, and/or N2 to N3 were eligible. Gemcitabine was administered at a dose of 800 mg/m2 on Days 1 and 12 and cisplatin at a dose of 20 mg/m2 on Days 2 to 5, every 21 days for 3 courses. Radiotherapy, delivered with standard fractionation, was given on Days 8 to 12 and 15 to 19 and was repeated 3 times up to a total dose of > or = 60 Gy.

RESULTS

A total of 28 patients were selected. Grade 3 to 4 stomatitis was recorded in 25 patients (89%). Thirteen patients (46%) experienced Grade 3 to 4 neutropenia. Febrile neutropenia occurred in 8 patients (29%) and in 2 was complicated by infection and death. The overall complete response rate was 79%. At a median follow up of 71 months, 11 patients had a locoregional relapse (3-year locoregional control, 64%); 6 patients had distant metastases, among whom only 2 were without locoregional recurrence. The 3-year progression-free survival is 39% and 3-year overall survival has been 43%.

CONCLUSION

The schedule modification did not attenuate local toxicity. Moreover, infections and especially pneumonia, were a major problem. The high activity of gemcitabine when combined with radiotherapy would most likely be better exploited in the context of modified radiation schemes.

Effect of Black maca (Lepidium meyenii) on one spermatogenic cycle in rats

Lepidium meyenii (Maca) grows exclusively between 4000 and 4500 m above sea level in the Peruvian central Andes. The hypocotyls of this plant are traditionally used in the Andean region for their supposed fertility-enhancing properties. The hypocotyls have different colours. Of these, Black maca has better effects on spermatogenesis. The present study aimed to test the hypothesis that Black maca has early effects during a spermatogenic cycle (12 days) of male rats. For this, testicular spermatid, epididymal sperm and vas deferens sperm counts were measured after 1, 3, 5, 7 and 12 days of treatment with Black maca. Aqueous extract of Black maca was given orally by daily gavage at a dose of 2 g kg(-1). In a spermatogenic cycle, compared with day 1, daily sperm production (DSP) was lower at day 7 (control), whereas with Black maca, the difference was observed at day 12. Epididymal sperm count was higher in rats treated with Black maca at days 1, 3 and 7, but similar to controls at days 5 and 12; similarly sperm counts in vas deferens was higher in rats treated with Black maca in days 3, 5 and 7, but similar to controls at days 1 and 12. From this, it is suggested that first action of Black maca was at epididymal level increasing sperm count after 1 day of treatment, whereas an increase in sperm count was observed in vas deferens at day 3 of treatment. Finally, an increase in DSP was observed after 7 days of treatment with Black maca. Testicular testosterone was not affected after 7 days treatment with Black maca. In conclusion, Black maca affects sperm count as early as 1 day after beginning of treatment.

iASPP preferentially binds p53 proline-rich region and modulates apoptotic function of codon 72-polymorphic p53

iASPP is one of the most evolutionarily conserved inhibitors of p53, whereas ASPP1 and ASPP2 are activators of p53. We show here that, in addition to the DNA-binding domain, the ASPP family members also bind to the proline-rich region of p53, which contains the most common p53 polymorphism at codon 72. Furthermore, the ASPP family members, particularly iASPP, bind to and regulate the activity of p53Pro72 more efficiently than that of p53Arg72. Hence, escape from negative regulation by iASPP is a newly identified mechanism by which p53Arg72 activates apoptosis more efficiently than p53Pro72.

DRAM, a p53-induced modulator of autophagy, is critical for apoptosis

Inactivation of cell death is a major step in tumor development, and p53, a tumor suppressor frequently mutated in cancer, is a critical mediator of cell death. While a role for p53 in apoptosis is well established, direct links to other pathways controlling cell death are unknown. Here we describe DRAM (damage-regulated autophagy modulator), a p53 target gene encoding a lysosomal protein that induces macroautophagy, as an effector of p53-mediated death. We show that p53 induces autophagy in a DRAM-dependent manner and, while overexpression of DRAM alone causes minimal cell death, DRAM is essential for p53-mediated apoptosis. Moreover, analysis of DRAM in primary tumors revealed frequent decreased expression often accompanied by retention of wild-type p53. Collectively therefore, these studies not only report a stress-induced regulator of autophagy but also highlight the relationship of DRAM and autophagy to p53 function and damage-induced programmed cell death.

AlteRCC phase I-II trial: Alternating radiotherapy and chemotherapy plus cetuximab in advanced head and neck cancer (HNC)

15515

Background: Pfister (ASCO 2003) added Cetuximab (C) to CT/RT to evaluate toxicity and activity of this combination in advanced HNC. The trial was early stopped due to an excess of toxicity including on treatment deaths. However, the treated pts achieved an excellent long term. Results: 76% of them were alive and disease free at 24 months. Therefore, a new, less toxic scheduling of CT/RT and C is highly attractive. Alternating CT/RT (ACR) may be less toxic than concurrent CT/RT (Haffty 2000; Merlano 2003). Therefore we designed a phase I-II trial, scheduling finding, combining ACR and C. Methods: The ACR regimen consists of cisplatin 20 mg/m2 and 5FU 200 mg/m2 days 1 to 5, weeks 1, 4 and 7; and RT, 2 Gy/day, days 1 to 5, weeks 2–3, 5–6, 8–10 to a total dose of 66 Gy. ACR remains unchanged during both phase I and phase II part of the study, whereas C is given to the first 6 pts (phase I, step I) weekly only in the weeks when RT is delivered. If no limiting toxicity is observed, C is combined also with CT, in a second group of six pts (phase I step II). If again no limiting toxicity is recorded, the trial will be continued as a phase II study (optimal two-stage design, 21+24 pts, Simon 1989). Results: At the time of the present report, the phase I step I is completed and 3 pts in phase I step II are on-going. All the pts had HNC stage IVa (8 pts) or stage III (1 pt). Two pts had disease recurrence after prior surgery, while the others had previously untreated cancers. All the tumors over-expressed EGFr (+++), but the percentage of cells expressing EGFr ranges between 10 to 100% (median 70%), One episode of neutropenic fever occurred in one pt enrolled in phase I step II. All the pts developed chemoradiation expected toxicities, including stomatitis and dysphagia requiring TPN. The only unexpected toxicity was a moist desquamation occurring within the irradiated field which was observed in all but one pts at a cumulative RT dose of 50–66 Gy. This toxicity did not interfere with ACR treatment but C was stopped until recovery. Recovery occurred in 5–7 days. Four pts out of the 6 evaluable for response, reached a complete response; the two remaining achieved a PR. One of them underwent surgical removal of a residual nodal mass without complications. Conclusions: The update of the AlteRCC trial will be presented.

[Table: see text]

A multi-gene algorithm as predictor of response to chemo-radiotherapy in head and neck cancer

10086

Background: Chemo-radiotherapy results in clinical cure for stage III/IV head and neck cancer in approximately 40% of cases, with significant treatment-associated morbidity and mortality. Molecular genetic factors predictive of treatment outcome would clearly be of value in selection of patients with highest probability of response. We have analysed the structure and epigenetic regulation of specific genes as possible predictors of outcome to chemo-radiotherapy. The genes analyzed were: p53 (single nucleotide polymorphism (SNP) and mutation), MDM2 (SNP), Chfr (methylation), CRABP1 (methylation). Methods: 84 patients with locally advanced head and neck cancer receiving cisplatin-based chemo-radiotherapy were studied. SNP genotypes were determined by direct sequencing of DNA from normal tissue. Acquired mutations in p53 and aberrant methylation in the CpG islands of specific genes were analyzed by direct sequencing and methylation-specific PCR. Results: There were 6 treatment-related deaths in 84 patients, all occurring in cases with germ-line haplotype p53 72 Arg/Arg, MDM2 309T/T. At the time of analysis, 39/84 (46%) patients had progressed or died, with median time to progression or death = 17.3 months. Complete response was more common in patients whose genetic/epigenetic profile was p53 72 Arg/Arg wild type, MDM2 309 G/G, Chfr methylated, CRABP1 methylated, compared to the profile p53 72 Arg/Arg mutant, MDM2 309 T/T, Chfr unmethylated, CRABP1 unmethylated (91% vs 46%, log rank p = 0.002). Progression-free survival was significantly longer for patients with the profile p53 72 Arg/Arg wild type, MDM2 309 G/G, Chfr methylated, CRABP1 methylated, compared to those with p53 72 Arg/Arg mutant, MDM2 309 T/T, Chfr unmethylated, CRABP1 unmethylated (% surviving progression-free at 2 years = 74% vs 36%, p = 0.001). Overall survival was significantly longer in patients with the profile p53 72 Arg/Arg wild type, MDM2 309 G/G, Chfr methylated, CRABP1 methylated compared to those with p53 72 Arg/Arg mutant, MDM2 309 T/T, Chfr unmethylated, CRABP1 unmethylated (% surviving at 2 years = 88% vs 40%, p = 0.0004). Conclusions: Genetic and epigenetic parameters influence the toxicity and clinical outcome of chemo-radiotherapy in head and neck cancer.

No significant financial relationships to disclose.

SERMs in chemoprevention of breast cancer

Selective estrogen receptor modulators (SERMs) play a key role in breast cancer chemoprevention. Tamoxifen has been shown to reduce breast cancer incidence by 30-40% in at-risk subjects in large phase III trials. However, toxicity may be a limiting factor. Thus, different strategies are being pursued to improve the risk: benefit ratio of using these compounds in chemoprevention. Firstly, the second generation SERM raloxifene is currently undergoing evaluation in comparison with tamoxifen in a large phase III trial. Also, lower doses of tamoxifen are being assessed in phase II-III trials. In addition, the combination of hormone replacement therapy (HRT) or aromatase inhibitors and tamoxifen at low doses may reduce the risks while retaining the benefits of either agents. Finally, new agents that interfere with the onset of ER-negative breast cancer are being sought for combination chemoprevention since almost a third of breast cancers will not be sensitive to hormonal modulation.

Paclitaxel, cisplatin, 5-fluorouracil and radiotherapy in the management of advanced squamous cell carcinoma of the head and neck. A phase II trial

Aim of the present study was to test, activity and toxicity of a rapidly alternating chemoradiation (paclitaxel based) in 31 patients with unresectable, locally advanced or recurrent after surgery, head and neck cancer. Three-year overall survival and progression-free survival were 61.4 and 73.7%, respectively. Main side effects remain a major problem.

Carboplatin and weekly paclitaxel in non-small cell lung cancer patients unfit for or pretreated with chemotherapy

BACKGROUND

Carboplatin-Paclitaxel is one of the most active regimens in non-small cell lung cancer (NSCLC). We assessed the administration of weekly Paclitaxel as second-line chemotherapy, or as first-line chemotherapy in unfit patients.

PATIENTS AND METHODS

Forty-eight patients received Carboplatin at the dose of 6 x area under the concentration-time curve (AUC) on day 1 and Paclitaxel 100 mg/m2 on days 1, 8, 15 every 28. Thirty-two had received a prior platinum-based treatment, while 16 were chemotherapy-naive, unfit patients.

RESULTS

Grade 3-4 neutropenia occurred in 16 patients (33%); grade 3-4 thrombocytopenia in 7 (15%); grade 1-3 peripheral sensory neuropathy in 35 (73%). Nineteen patients (39.6%; 95% C.I.: 25.8% - 53.4%) achieved an objective response without any difference between the first-line and second-line group. One-year survival was 39.5% (95% CI: 25.4% - 53.6%).

CONCLUSION

The impressive activity of this regimen makes it suitable for further investigation in the second-line setting. Toxicity seen in the unfit population mandates some modification of the regimen.

Prospective evaluation of major vascular events in patients with nonsmall cell lung carcinoma treated with cisplatin and gemcitabine

BACKGROUND

Cancer and cisplatin-based chemotherapy both are well recognized risk factors for coagulation disorders and thrombosis. However, vascular events (VEs) seldom are considered adverse effects of treatment and may not even be taken into account in reports of chemotherapy trials.

METHODS

VEs were recorded prospectively in a population of patients with nonsmall-cell lung carcinoma (NSCLC) who were treated consecutively with cisplatin and gemcitabine using a diagnostic flow chart based on a thorough clinical examination, hematologic and coagulative parameters, and imaging assessments when appropriate.

RESULTS

From January, 2000 to January 2003, 108 patients with Stage III-IV NSCLC underwent chemotherapy and were evaluated. Overall, 22 VEs occurred in 19 patients (17.6%; 95% confidence interval [95% CI], 10.3-24.8%), including 10 arterial VEs (2 myocardial infarctions, 7 lower limb arterial thrombosis, and 1 ischemic stroke) and 12 venous VEs (3 catheter-related upper limb VEs, 6 venous thrombosis of the lower limb, and 3 pulmonary embolisms). The cumulative proportion of VEs at 1 year after the start of chemotherapy was 22.0% (95% CI, 12.7-31.3%). Four patients died due to the VE (overall mortality, 3.7%), and 3 patients needed surgical revascularization. In the other patients, conservative medical treatment was effective. Baseline patient-related and disease-related characteristics of the patients with VEs did not differ significantly from the characteristics of patients without VE; liver and brain metastases were more frequent in patients with VE, although the difference did not reach statistical significance. Response rates were similar in the two groups. A double VE was detected in three patients who were given further chemotherapy after resolution of the first event.

CONCLUSIONS

VEs were a common finding in chemotherapy-treated NSCLC patients. Chemotherapy itself seem to be a powerful risk factor for VE. Strategies to predict the occurrence of VEs should be developed to spare this life-threatening toxicity.

Effect of high altitude exposure on spermatogenesis and epididymal sperm count in male rats

The present study was designed to determine the effect of exposure to high altitude on spermatogenesis using transillumination technique and sperm count in male rats. In addition, the effect of oral intubation for intragastric administration of vehicle on testicular parameters in adult male rats in a schedule of 42 days was assessed. Male rats were exposed to Cerro de Pasco (Peru) at 4340 m for 3, 7, 14, 21, 28, 35 and 42 days resulting in a modification of the pattern of the seminiferous tubule stages. At day 3, stages I, IV-V, VI, VII and IX-XI were relatively shorter at high altitude than at sea level. At day 7, stages VIII, IX-XI, XII and XIII-XIV were reduced. At day 14, stages VII, VIII and IX-XI were reduced. At day 21 and 28, stages VIII, XII and XIII-XIV were significantly increased at high altitude. At day 35 an increase in stage XIII-XIV was observed. At day 42, stages II-III, IX-XI and XII were significantly increased at high altitude. Epididymal sperm count was significantly reduced at day 7 of exposure to high altitude and maintained low levels with respect to sea level up to 42 days. In conclusion, high altitude exposure affects spermatogenesis, particularly onset of mitosis and spermiation. This in turn affects epididymal sperm count.

Polymorphism in wild-type p53 modulates response to chemotherapy in vitro and in vivo

A single-nucleotide polymorphism (SNP) in exon 4 results in expression of either arginine (72R) or proline (72P) at codon 72 of p53. We demonstrate that the in vitro response of cells exposed to anticancer agents is strongly influenced by this SNP in wild-type p53. In inducible systems and in cells expressing the endogenous protein, expression of 72P wild-type p53 results in a predominant G1 arrest, with only a minor apoptosis, at drug concentrations causing extensive apoptosis in cells expressing the 72R wild-type variant. The superior apoptosis-inducing activity of the 72R form correlates with more efficient induction of specific apoptosis-associated genes, and is maximal in the presence of serine 46 (S46). In vivo, the outcome of chemo-radiotherapy of squamous carcinomas is more favourable in cancers retaining a wild-type 72R allele, such cases having higher response rates and longer survival than those with wild-type 72P. Together, these results reveal that this SNP is an important determinant of response to anticancer agents in cells expressing wild-type p53. Analysis of complete p53 genotype (mutation and SNP) merits detailed investigation as a simple means for prediction of treatment response and survival in clinical oncology.

Functional regulation of p73 and p63: development and cancer

The transcription factor and tumour suppressor p53 and its two homologues p63 and p73 form a family of proteins. p63 and p73 show much greater molecular complexity than p53 because they are expressed both as multiple alternatively spliced C-terminal isoforms, and as N-terminally deleted, dominant-negative proteins that show reciprocal functional regulation. In addition, several other factors, such as post-translational modifications and specific and common family regulatory proteins, result overall in subtle modulation of their biological effects. Although all p53, p63 and p73 family members are regulators of the cell cycle and apoptosis, the developmental abnormalities of p73- and p63-null mice do not show enhanced tumour susceptibility of p53 knockouts, suggesting that complex regulatory processes modulate the functional effects of this family of proteins.

Effect of Lepidium meyenii (Maca) on spermatogenesis in male rats acutely exposed to high altitude (4340 m)

Lepidium meyenii (Maca) is a Peruvian hypocotyl that grows exclusively between 4000 and 4500 m in the central Andes. Maca is traditionally employed in the Andean region for its supposed fertility-enhancing properties. The aim of this study was to test the hypothesis that Maca can prevent high altitude-induced testicular disturbances. Adult male rats were exposed for 21 days to an altitude of 4340 m and treated with vehicle or aqueous extract of Maca (666.6 mg/day). The lengths of the stages of the seminiferous epithelium and epididymal sperm counts were obtained at 0, 7, 14 and 21 days of exposure. The stages of the seminiferous tubules were assessed by transillumination. A dose-response study was also performed at sea level to determine the effect of Maca given to male rats at doses of 0, 6.6, 66.6 and 666.6 mg/day for 7 days on body weight, seminiferous tubule stages and epididymal sperm count. The length of stage VIII and the epididymal sperm count were increased in a dose-dependent manner in Maca-treated rats but treatment reduced the length of stage I. At the highest dose, sperm count increased 1.58 times, the length of stage VIII increased 2.4 times and the length of stage I was reduced 0.48 times compared with the value at dose 0. Exposure to high altitude resulted in a reduction in epididymal sperm count after 7 days and lower values were maintained up to 21 days. Altitude reduced spermiation (stage VIII) to half and the onset of spermatogenesis (stages IX-XI) to a quarter on days 7 and 14 but treatment with Maca (666.6 mg/day) prevented these changes. Data on transillumination and epididymal sperm count in the Maca-treated group exposed to high altitude were similar to those obtained at sea level. Maca increased the sperm count on day 21 of exposure to high altitude to values similar (1095.25 +/- 20.41x10(6) sperm, means +/- S.E.M.) to those obtained in the Maca-treated group at sea level (1132.30 +/- 172.95x10(6) sperm). Furthermore, in the Maca-treated group exposed for 21 days to high altitude, epididymal sperm count was higher than in the non-treated group at sea level (690.49 +/- 43.67x10(6) sperm). In conclusion, treatment of rats with Maca at high altitude prevented high altitude-induced spermatogenic disruption.

p53 family members and chemoresistance in cancer: what we know and what we need to know

Resistance to chemotherapy remains a major obstacle to the successful management of many human cancers. Numerous genetic and epigenetic changes in the cancer cell may contribute to drug resistance. However, with the recognition of important roles for both p53 and its more recently described paralog p73 in mediating the activity of anti-cancer drugs, there has been increasing recognition that cellular resistance to such agents can and does arise through failure of p53 family member signalling. Abrogation of function in p53 occurs through point mutations which abolish DNA binding or by dominant negative inhibition by variants of p73 lacking the N-terminal transactivation domain. Conversely, the function of full-length transactivation-competent (TA)p73 variants expressing the transactivation domain is itself subject to trans-dominant inhibition by certain p53 mutants and, in some cancers, by transcriptional silencing. The specificity of target gene activation by p53 and TAp73 is modulated by transcriptional co-activators which thereby act as response modifiers. Changes in the activity/expression of co-activators may therefore cause an altered cellular response to p53/p73 activation. Despite these advances in understanding how cells respond to DNA damage in vitro, and how this is affected by molecular genetic changes which affect p53 family member signalling, the contribution of these to in vivo drug resistance has not been definitively established. Our major task now is to determine how these changes operate individually and collectively in vivo to produce the phenotype of clinical drug resistance, and how we can translate this knowledge into clinically useful strategies to improve the outcome of chemotherapy.

Distinct genetic and epigenetic changes in medullary breast cancer

Genetic instability resulting in chromosome aneuploidy or mismatch repair deficiency characterizes cancer. Medullary carcinoma (MC) of the breast is a specific form of breast cancer with unique clinical, epidemiologic, and prognostic features, suggesting distinctive tumorigenic pathways. To investigate the nature of the genetic changes associated with MC we analyzed a series of 22 tumors. Chromosomal imbalances were assessed by comparative genomic hybridization (CGH) and mismatch repair (MMR) deficiency tested for through assessment of microsatellite instability (MSI) and expression of MLH1 and MSH2 genes. MMR deficiency was detected in only a small proportion of cases. The chromosomal copy number changes showed some similarities to BRCA1-associated tumors. A high level of BRCA1 promoter hypermethylation was detected, suggesting a possible role of this gene in MC development.

The p53 network in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and, despite advances in treatment, still represents a clinical challenge. Inactivation of one or more components of the p53 network is an extremely common event in human neoplasia. In HNSCC, disabling of p53 occurs in a high proportion of cases by mutation in the p53 gene, but other mechanisms of inactivation, such as the presence of human papillomavirus (HPV) and molecular abnormalities in other components of the pathway, are also recognised. The frequent changes occurring in the p53 pathway in HNSCC imply that molecular genetic and immunocytochemical analysis of this critical tumour suppressor network may be of diagnostic and prognostic utility in the clinical management of HNSCC. Further, these changes also provide targets for the development of novel therapeutic approaches to this increasingly common cancer, in which clinical cure for advanced disease remains an elusive goal.

p53 polymorphism influences response in cancer chemotherapy via modulation of p73-dependent apoptosis

Intact p73 function is shown to be an important determinant of cellular sensitivity to anticancer agents. Inhibition of p73 function by dominant-negative proteins or by mutant p53 abrogates apoptosis and cytotoxicity induced by these agents. A polymorphism encoding either arginine (72R) or proline (72P) at codon 72 of p53 influences inhibition of p73 by a range of p53 mutants identified in squamous cancers. Clinical response following cisplatin-based chemo-radiotherapy for advanced head and neck cancer is influenced by this polymorphism, cancers expressing 72R mutants having lower response rates than those expressing 72P mutants. Polymorphism in p53 may influence individual responsiveness to cancer therapy.