Gregory S. Buzard

Alteration of the Tumor Suppressor Gene p53 in a High Fraction of Hormone Refractory Prostate Cancer

PURPOSEnWe studied the role of p53 tumor suppressor gene alteration in prostate cancer progression by demonstrating a difference in abnormal p53 findings between early and hormone refractory disease.nnnMATERIALS AND METHODSnThe study included p53 immunohistochemistry of 26 archival transurethral resection specimens from patients with radiation recurrent and hormone refractory disease, 27 untreated primary tumors and 8 untreated metastatic lesions. p53 mutation analysis of tumor deoxyribonucleic acid (DNA) from microdissected specimens was done by cold single strand conformational polymorphism and DNA sequencing.nnnRESULTSnElevated p53 protein was present in 16 of 17 hormone refractory specimens (94%), 4 of 8 untreated metastatic tumors (50%) and 6 of 27 primary untreated tumors (22%). DNA analysis of representative specimens with elevated p53 confirmed p53 gene alterations in 9 of 11 cases (82%).nnnCONCLUSIONSnOur study revealed a clear progression of increased p53 alteration from untreated primary to hormone refractory disease (p < 0.00005).

K-ras activation and ras p21 expression in latent prostatic carcinoma in Japanese men.

Twenty‐three clinically silent prostatic carcinomas discovered in Japanese men at autopsy were surveyed for ras proto‐oncogene mutations by mutation‐specific oligonucleotide probe hybridization after polymerase chain reaction (PCR) amplification from a section of formalin‐fixed, paraffin‐embedded tissue. Six of the 22 that were satisfactorily amplified contained activating point mutations in codon 12 of K‐ras, a significantly higher frequency than has been reported in patients with clinically advanced disease in the United States. Of the six cases with activating point mutations in codon 12 of K‐ras, one had a GGT → GAT transition, four had GGT → GTT trans‐versions, and one had both GGT → GAT and GGT → GTT mutations. Sections from the same tissues were immunohistochemically stained with an anti‐ras p21 antibody. Carcinoma cells stained for ras p21 to some degree in 13 cases. Immunohistochemically detectable expression of p21 was always focal and was not necessarily associated with K‐ras mutation. K‐ras oncogene activation in prostatic carcinoma appears to merit additional study as a significant event in the pathogenesis of this neoplasm.

Overexpression of LAMP3/TSC403/DC-LAMP Promotes Metastasis in Uterine Cervical Cancer

LAMP3 (DC-LAMP, TSC403, CD208) was originally isolated as a gene specifically expressed in lung tissues. LAMP3 is located on a chromosome 3q segment that is frequently amplified in some human cancers, including uterine cervical cancer. Because two other members of the LAMP family of lysosomal membrane glycoproteins, LAMP1 and LAMP2, were previously implicated in potentially modulating the interaction of vascular endothelial and cancer cells, we hypothesized that LAMP3 might also play an important part in metastasis. To clarify the metastatic potential of LAMP3 in cervical cancers, we transfected a LAMP3 expression vector into a human uterine cervical cancer cell line, TCS. In an in vitro invasion assay, the migration of LAMP3-overexpressing TCS cells was significantly higher than in control TCS cells. In an in vivo metastasis assay, distant metastasis was detected in 9 of 11 LAMP3-overexpressing TCS cell-injected mice and in only 1 of 11 control mice. Histologic study showed that LAMP3-overexpressing cells readily invaded into the lymph-vascular space. In clinical samples, quantitative real-time reverse transcription-PCR (RT-PCR) analyses showed that LAMP3 mRNA was significantly up-regulated in 47 of 47 (100%) cervical cancers and in 2 of 15 (13%) cervical intraepithelial neoplasias, compared with a low level of LAMP3 mRNA expressed in normal uterine cervixes. Interestingly, high LAMP3 expression was significantly correlated with the overall survival of patients with stage I/II cervical cancers. These findings indicate that LAMP3 overexpression is associated with an enhanced metastatic potential and may be a prognostic factor for cervical cancer.

Increased p53 Protein Does Not Correlate to p53 Gene Mutations in Microdissected Human Testicular Germ Cell Tumors

PURPOSEnTo determine if primary testicular germ cell tumors that overexpress p53 tumor suppressor gene protein have p53 gene mutations.nnnMATERIALS AND METHODSnWe examined 30 primary testicular tissues from 26 patients representing two groups. Group one consisted of eleven cases (6 nonseminomatous germ cell tumors and 5 seminomas) in which tissue samples for DNA analysis were microdissected from paraffin block regions with elevated immunohistochemical staining for p53 protein. Group two consisted of 19 testis tumor tissues which had been fresh frozen and were chosen to correspond to archival tissue specimens exhibiting elevated levels of p53 protein. The DNA was extracted from these tissues and subjected to exon specific amplification by polymerase chain reaction (PCR) and cold single-strand conformation polymorphism (Cold SSCP) analysis.nnnRESULTSnIn these cases with elevated p53 protein, no p53 gene exon 5-8 mutations were detected except 1 seminoma with a codon 140 silent mutation (no protein alteration).nnnCONCLUSIONSnTesticular tumors appear to exhibit elevated levels of wild-type p53 protein, the significance of which is yet to be elucidated.