Edward N. Hughes

Medulloblastoma at the joint center for radiation therapy between 1968 and 1984. The influence of radiation dose on the patterns of failure and survival

In order to assess the efficacy of high‐dose irradiation to the posterior fossa and low‐dose irradiation to the spinal axis, we reviewed the results of 60 patients with biopsy‐proven medulloblastoma treated at the Joint Center for Radiation Therapy (JCRT) between 1968 and 1984. The 5‐ and 10‐year actuarial survival rates for all patients were 68% and 44%, respectively. The median time to recurrence was 19 months. Extent of surgery, age, and radiation dose to the posterior fossa all were of prognostic value. Complete or subtotal gross resection appeared to be a favorable prognostic indicator compared with biopsy only (P < 0.05), with a 69% versus 40% actuarial survival rate at 5 years, respectively. Infants 2 years of age or less had a diminished 5‐year actuarial survival rate of 48% (P < 0.05) compared with older age groups. The posterior fossa was the predominant site of recurrence and accounted for 78% of all failures. Local control in the posterior fossa was dose dependent. Seventy‐nine percent of the tumors that received 5000 cGy or greater were controlled versus only 33% of the tumors that received less than 5000 cGy (P < 0.02). There were no supratentorial failures, and there was only one isolated spinal cord failure. There were no solitary spinal failures in 24 patients who received a median dose of only 2400 cGy to the spinal axis. We concluded that low‐dose irradiation to the spine and whole brain may be indicated with maintenance of a posterior fossa dose of greater than 5000 cGy.

Characterization of high mobility group protein binding to cisplatin-damaged DNA.

cis-Diamminedichloroplatinum (II) (cisplatin, CDDP) is a widely used chemotherapeutic agent. While many tumors are highly responsive to CDDP, certain tumors are resistant to this drug, limiting its efficacy. The anti-tumor activity of CDDP is believed to result from its coordination bonding to chromosomal DNA. Alterations in tumor cell sensitivity to CDDP may result from the presence or absence of protein(s) which specifically recognize CDDP-damaged DNA. We have developed a damaged-DNA affinity precipitation assay that allows the direct identification of cellular proteins that bind to CDDP-damaged DNA. Using this procedure, we have identified several proteins which specifically bind to CDDP-damaged DNA. Two of these proteins have been identified as high mobility group proteins (HMG) 1 and 2 in the current report, we have characterized the binding of these proteins to CDDP-DNA. The calculated Kd of binding to CDDP-damaged DNA was 3.27 x 10(-10) for HMG1 and 1.87 x 10(-10) for HMG2. Using highly specific chemical modifying reagents, we have determined that Cys residues play an important role in protein binding. We also observed that HMG2 will bind to DNA modified with carboplatin and iproplatin although to a lesser extent than to DNA damaged with CDDP. Thus, our results indicate that HMG 2 binds with high affinity to DNA modified with therapeutically active platinum compounds. In addition, our findings suggest that thiol groups play an essential role in the binding of HMG1 and HMG2 to CDDP-DNA.

Comparison of outcome between clinically staged, unresected superior sulcus tumors and other stage III non-small cell lung carcinomas treated with radiation therapy alone

Several studies suggest that patients with non‐small cell lung carcinoma (NSCLC) of the superior sulcus fare better after radiation therapy than hose patients with comparable tumors at other thoracic sites. There is limited data on stage‐by‐stagc; comparisons between patients with superior sulcus tumors (SST) and non‐SST (NSST). Thirty patients had SST among 656 patients with American Joint Committee on Cancer clinically staged IIIA (n = 389) and IIB (n ‐= 267) primary NSCLC who received definitive once‐daily radiation therapy. The median patient age, sex ratio, histologic findings, grade, weight loss, and performance status were similar for SST and NSST. Minimum follow‐up was 24 months, with 88% of patients followed until death.

Effect of caffeine on the expression of a major X-ray-induced protein in human tumor cells

We have examined the effect of caffeine on the concomitant processes of the repair of potentially lethal damage (PLD) and the synthesis of X-ray-induced proteins in the human malignant melanoma cell line, Ul-Mel. Caffeine administered at a dose of 5mM after X radiation not only inhibited PLD repair but also markedly reduced the level of XIP269, a major X-ray-induced protein whose expression has been shown to correlate with the capacity to repair PLD. The expression of the vast majority of other cellular proteins, including seven other X-ray-induced proteins, remained unchanged following caffeine treatment. A possible role for XIP269 in cell cycle delay following DNA damage by X irradiation is discussed.

Adverse influence of younger age on outcome in patients with non-small cell lung carcinoma (nsclc) treated with radiation therapy (rt) alone

Treatment outcome of 63 patients younger than 50 years of age initiated on a course of once-daily definitive radiation therapy without concurrent or preirradiation chemotherapy for clinical Stages I-III unresected non-small cell lung carcinoma from 1978 to 1988 was compared to the outcome of 695 patients over the age of 50. Follow-up ranged from 24-110 months with follow-up until death in 88% of patients. The actuarial overall survival rate for all patients was 22% at 2 years with a median survival time of 11.5 months. Patients less than 50 and greater than or equal to 50 years old were similar in male:female ratio, distribution of histologic subtype, performance status, and extent of weight loss. Poorly differentiated histologic grade was more prevalent among the younger patients (59% vs 41%, p = .005). Ninety-four percent of younger patients and 86% of older patients had clinical stage III disease (p = NS). Survival was significantly worse for patients who were younger than 50 years old (p = .05), with a median survival time of 7.8 months. Median survival time for those patients 50 years of age or older was 12.4 months. Poorer survival outcome among young patients was most pronounced among patients with unfavorable characteristics of poor performance status (greater than or equal to 2) or weight loss (greater than 5%) (p = .002). Distant failure (p = .029) and brain failure (p = .003) as initial site of relapse was more common among younger patients. Among young patients, poor histologic grade was associated with both distant failure (p = .003) and brain metastasis (p = .002). The difference in distribution of histologic grade, incidence of distant failure, particularly in the brain, and poorer survival outcome among patients less than 50 may be indicative of more aggressive tumor behavior in the younger patients. These results indicate that patients less than 50 may require alternate treatment strategies. Age should be considered a stratification variable in non-operative randomized trials of non-small cell lung carcinoma which include patients with non-favorable characteristics.

Proteins binding to cisplatin-damaged DNA in human cell lines.

Cisplatin (CDDP) is a highly effective, frequently used cancer chemotherapeutic drug employed in the treatment of several human malignancies including ovarian, testicular, and bladder cancers. A common problem encountered with cisplatin therapy is intrinsic or acquired resistance to this drug. While the mechanisms of resistance to cisplatin, and other chemotherapeutic agents, are not fully understood, one factor affecting the cellular response to CDDP may result from differences in the level of specific proteins that recognize CDDP-damaged DNA. We have developed a damaged DNA affinity precipitation technique that allows the direct visualization and characterization of cellular proteins that bind to cisplatin-damaged DNA. In the present study we have utilized this method to analyze proteins present in several mammalian cell lines that bind to cisplatin-damaged DNA. We demonstrate that HeLa cells, resistant to CDDP cytotoxicity, contain high levels of high-mobility-group proteins 1 and 2, which bind to CDDP-DNA. We also show that xeroderma pigmentosum cells of different genetic complementation groups contain variable levels of a 45-kDa protein that binds to CDDP-DNA. Thus, our results indicate that different human cell lines demonstrate qualitative and quantitative differences in the expression of cisplatin-damaged DNA binding proteins.

Role of HMG and Other Proteins in Recognition of Cisplatin DNA Damage

Numerous biochemical processes are mobilized in cells in response to DNA damage. A key early event in this process requires detection, or recognition, of DNA damage. Presumably, damage recognition is mediated by specific damage-recognition proteins (DRPs), which recognize particular types of DNA lesions and/or specific DNA conformations resulting from adduct formation, such as that following binding of cis-diaminedichloroplatinum (II) (cisplatin or CDDP) to DNA. Once bound to DNA, DRPs are likely to have a major influence on the subsequent processing of specific types of DNA damage. For example, DRPs may influence the kinetics of repair of particular DNA abducts and, hence, determine the physiological response of cells to specific DNA-damaging agents.