Expression of p21 and mutant p53 gene products in residual prostatic tumor cells after radical radiotherapy

Molecular and cellular consequences of mitochondrial DNA double-stranded breaks

Mitochondria are subcellular organelles essential for life. Beyond their role in producing energy, mitochondria govern various physiological mechanisms, encompassing energy generation, metabolic processes, apoptotic events, and immune responses. Mitochondria also contain genetic material that is susceptible to various forms of damage. Mitochondrial double-stranded breaks (DSB) are toxic lesions that the nucleus repairs promptly. Nevertheless, the significance of DSB repair in mammalian mitochondria is controversial. This review presents an updated view of the available research on the consequences of mitochondrial DNA DSB from the molecular to the cellular level. We discuss the crucial function of mitochondrial DNA damage in regulating processes such as senescence, integrated stress response, and innate immunity. Lastly, we discuss the potential role of mitochondrial DNA DSB in mediating the cellular consequences of ionizing radiations, the standard of care in treating solid tumors.

Curative radiation therapy in prostate cancer

Radiotherapy has experienced an extremely rapid development in recent years. Important improvements such as the introduction of multileaf collimators and computed tomography (CT)-based treatment planning software have enabled three dimensional conformal external beam radiation therapy (3DCRT). The development of treatment planning systems and technology for brachytherapy has been very rapid as well. Development of accelerators with integrated on-board imaging equipment and technology, for example image-guided radiation therapy (IGRT) has further improved the precision with reduced margins to adjacent normal tissues. This has, in turn, led to the possibility to administer even higher doses to the prostate than previously. Although radiotherapy and radical prostatectomy have been used for the last decades as curative treatment modalities, still there are no randomized trials published comparing these two options. Outcome data show that the two treatment modalities are highly comparable when used for low- and intermediate-risk prostate cancer.

Impact of differential cyclin D1 expression and localisation in prostate cancer

Cyclin D1 is a critical regulator of androgen-dependent transcription and cell cycle progression in prostate cancer cells. Despite the influence of D-type cyclins on prostate cancer proliferation, few studies have examined the expression of cyclin D1 in localised tumours or challenged its relevance to disease progression. Cyclin D1 status was characterised using immunohistochemistry in 38 non-neoplastic prostate samples, 138 primary human prostate carcinomas, and three lymph node metastatic specimens. Relevance of cyclin D1 to preoperative prostate-specific antigen (PSA) levels, Ki-67 index, and p21^Cip1 status was also examined. Cyclin D1-positive phenotype was increased in primary carcinoma compared to non-neoplastic tissue, and was evident in all lymph node metastases cases. Interestingly, at least three distinct localisation patterns were observed in the cyclin D1-positive cohort, wherein cytoplasmic localisation was identified in a large fraction, and this pattern was predominant in lower grade tumours. Relevance of altered cyclin D1 status was observed, wherein cyclin D1-positive tumours were associated with low preoperative PSA levels, consistent with in vitro reports that cyclin D1 may alter the expression of this tumour marker. Moreover, tumours with predominantly cytoplasmic cyclin D1 showed the lowest Ki-67 index, whereas nuclear cyclin D1 was associated with higher grade, elevated Ki-67, and increased nuclear p21^Cip1. These data demonstrate that differential cyclin D1 status may influence clinicopathological parameters, and reveal new insight as to the regulation and potential consequence of cyclin D1 expression in prostate cancer.

Relationship of p21(WAF-I) protein expression with prognosis in advanced prostate cancer treated by androgen ablation

OBJECTIVES

The objectives of our study were (1) to characterize the expression of p21 and p53 proteins in advanced stage prostate cancer, (2) to determine the relationship between p53 and p21 protein expressions, and (3) to relate p53 and p21 expression to clinical outcome after androgen ablation.

METHODS

Seventy-five patients with advanced prostate cancer (clinical stage C: 11, stage D1: 8, stage D2: 56), who all underwent androgen ablation, had tissue specimens obtained prior to hormonal therapy and studied immunohistochemicaly for p53 (Mab D07) and p21 (Mab EA10) expression. Clinical outcome was analyzed using the Kaplan-Meier method and log-rank tests. Cox proportional hazard model was used to determine the independence of multiple variables.

RESULTS

About 33.3% of cases expressed p53 and 33.3% expressed p21 positive immunoreactivity. No statistically significant correlation between p21 and p53 expression either in the entire study group (N = 75) or in stage D2 cases (N = 56) was observed (P = 0.38 and P = 0.68, respectively). Disease-specific survival was significantly related to p21 expression (P = 0.0006 for entire study group and P = 0.01 for D2 cases). There was no statistically significant differences in disease-specific survival between p53 positive or negative cases (P = 0.38 overall, P = 0.7 stage D2 only). p21 expression and the number of bone lesions were independently associated with shorter survival (multivariate P = 0.001, P = 0.005, respectively).

CONCLUSIONS

The data suggests that p21 expression is a strong and independent poor prognostic factor in patients with advanced stage prostate cancer treated by androgen ablation.

Repeated biopsies in evaluation of therapeutic effects in prostate carcinoma

BACKGROUND

Apoptosis is one of the major events following total androgen blockade (TAB). The aim of this study was to determine the predictive value of some histological parameters including apoptosis and gene products which influence apoptosis, based on repeated biopsies taken from the same patients.

METHODS

At the time of diagnosis by needle biopsy TNM stage, serum PSA, Gleason's grade, apoptotic and mitotic index, Ki67, p53, and bcl(2) expression were investigated in 60 prostate carcinoma patients. Antiandrogen therapy supplemented with surgical or chemical castration was administered. Serum PSA-test and needle biopsy were repeated 13-14 weeks after starting the therapy, simultaneously with determination of the apoptotic and mitotic index, Ki67, p53, and bcl(2) expression.

RESULTS

Forty-seven patients were alive at the end of the study, 13 patients died. Decrease in mitotic, increase in apoptotic index predicted favourable long-term response to antiandrogen therapy. Lower Ki67 and (mutant) p53 expression in the first and also in the second biopsy pointed to favourable effect of antiandrogen treatment. Since the ratio between Ki67 and apoptotic index strongly decreased in the survivors upon therapy, changes in Ki67/apoptosis ratio is recommended as a histologically detectable predictive factor. bcl(2) expression did not show significant correlation with the outcome of the disease.

CONCLUSIONS

Histological evaluation of mitotic and apoptotic index, Ki67, and p53 expression in repeated biopsies contributes to predicting the value of the actual treatment and may be useful to institute alterations in therapy.

The time course of histologic remission after treatment of patients with nasopharyngeal carcinoma

BACKGROUND

The objective of this study was to define the time course of histologic remission and to evaluate the prognostic significance of delayed histologic remission of patients with nasopharyngeal carcinoma (NPC).

METHODS

Between 1986-1994, 803 patients underwent serial postradiotherapy nasopharyngeal biopsies. Patients with positive histology underwent repeated biopsies every 2 weeks until the biopsies were found to be negative or, if remission did not occur by the 12th week after radiotherapy, treatment was initiated for persistent disease. Patients with positive histology found after the fifth week but who achieved spontaneous remission before the twelfth week were considered to have delayed histologic remission. Negative histology by the sixth week was considered early histologic remission. The outcome of patients with delayed histologic remission, early histologic remission, and persistent disease were compared.

RESULTS

Six hundred and seventeen patients (76.8%) had negative histology within 12 weeks of the completion of radiotherapy and 55 (6.9%) had persistent disease at Week 12. In 131 patients (16.3%) spontaneous remission was observed in repeat biopsies after initial positive histology. With increasing time after radiotherapy, the incidence of positive histology decreased but more patients were found to have persistent disease. Patients with early and delayed histologic remission had 5-year NPC control rates of 82.4% and 76.8%, respectively (P = 0.35) versus a 40% NPC control rate among patients with persistent disease (P < 0.001). The 5-year survival rates were 75.3%, 79.4%, and 54.2%, respectively, for the 3 groups (P < 0.001).

CONCLUSIONS

A high proportion of early positive histology remitted spontaneously. Delayed histologic remission in NPC patients is not a poor prognostic factor and additional treatment is not necessary. A confirmatory biopsy at 10 weeks is recommended before the initiation of salvage treatment.