HPV ctDNA detection of high-risk HPV types during chemoradiotherapy for locally advanced cervical cancer.

BACKGROUND: Chemoradiotherapy (CRT) is the standard of care for patients diagnosed with locally advanced cervical cancer (LACC), a human papillomavirus (HPV)-related cancer that relapses in 30%-60% of patients. This study aimed to (i) design HPV droplet digital PCR (ddPCR) assays for blood detection (including rare genotypes) and (ii) monitor blood HPV circulating tumor DNA (HPV ctDNA) levels during CRT in patients with LACC. METHODS: We analyzed blood and tumor samples from 55 patients with HPV-positive LACC treated by CRT in a retrospective cohort (n = 41) and a prospective cohort (n = 14). HPV-ctDNA detection was carried out by genotype-specific ddPCR. RESULTS: HPV ctDNA was successfully detected in 69% of patients (n = 38/55) before CRT for LACC, including nine patients with a rare genotype. HPV-ctDNA level was correlated with HPV copy number in the tumor (r = 0.41, P < 0.001). HPV-ctDNA positivity for HPV18 (20%, n = 2/10) was significantly lower than for HPV16 (77%, n = 27/35) or other types (90%, n = 9/10, P = 0.002). HPV-ctDNA detection (positive versus negative) before CRT was associated with tumor stage (P = 0.037) and lymph node status (P = 0.02). Taking into account all samples from the end of CRT and during follow-up in the prospective cohort, positive HPV-ctDNA detection was associated with lower disease-free survival (DFS) (P = 0.048) and overall survival (OS) (P = 0.0013). CONCLUSION: This is one of the largest studies to report HPV-ctDNA detection before CRT and showed clearance of HPV ctDNA at the end of treatment in most patients. Residual HPV ctDNA at the end of CRT or during follow-up could help to identify patients more likely to experience subsequent relapse.

Region-specific expression of cell cycle inhibitors in the adult brain.

In the adult brain, neural proliferation is almost absent and neurons are generally not renewed. By contrast, in the olfactory organ, olfactory neurons are produced continuously throughout life. To investigate whether specific cell cycle inhibitors are involved in the control of neural quiescence in adulthood, we compared their expression either in different regions of the adult brain weakly or non neurogenic or, for comparison, in the olfactory mucosa. We show that numerous cell cycle inhibitors are expressed in the adult brain either in an ubiquitous fashion (as p19Ink4d) or in specific brain regions (p15Ink4b in the forebrain, p27Kip1 and p21Cip1 in the cerebellum). By contrast p18Ink4c was expressed detectably only in the highly neurogenic olfactory epithelium. The present data suggest that various CDK inhibitors may be involved in a region-specific fashion in the maintenance of nerve cell quiescence in adults.

Potentiation of antitumour activity of docetaxel by combination with trastuzumab in a human prostate cancer xenograft model and underlying mechanisms.

Antitumour activity of docetaxel (Taxotere) in hormone-dependent (HD) and hormone-independent (HID) prostate cancer PAC120 xenograft model was previously reported, and its level was associated with HER2 protein expression. In the present study, we evaluate the antitumour effects of docetaxel combined with trastuzumab (Herceptin), an anti-HER2 antibody. Although trastuzumab alone had no effect on tumour growth, it potentiated the antitumour activity of docetaxel in HD tumours and more strongly in HID variants. Using the HID28 variant, we show that docetaxel treatment of tumour-bearing mice induces an increased HER2 mRNA expression of the tyrosine kinase receptor of 25-fold 24 h after docetaxel treatment, while HER2 protein and p-AKT decreased. This was followed by an increase of HER2 protein 3 days (two-fold) after docetaxel treatment and by a strong HER2 release in the serum of treated mice; expression of phospho-ERK, p27, BCL2 and HSP70 concomitantly increased. Similar molecular alterations were induced by docetaxel plus trastuzumab combination, except for that there was a transient and complete disappearance of AR and HSP90 proteins 24 h after treatment. We show that in addition to its known effects on tubulin and mitotic spindles, docetaxel induces complex signalisation pathway mechanisms in surviving cells, including HER2, which can be pharmacologically targeted. This study suggests that the docetaxel/trastuzumab combination may prove an effective therapeutic approach for HER2-expressing hormone-refractory prostate cancer.

Cell cycle regulation during mouse olfactory neurogenesis.

The development of the nervous system requires a strict control of cell cycle entry and withdrawal. The olfactory epithelium (OE) is noticeable by its ability to yield new neurons not only during development but also continuously during adulthood. The aim of our study was to investigate, by biochemical and immunohistochemical methods, which cell cycle regulators are involved in the control of neuron production during OE development and maturity. At birth, olfactory neural progenitors, the basal cells, exhibited a high mitogenic and neurogenic activity, decreasing in the following weeks together with the drop in expression of several cell cycle regulators. p27Kip1 and p18Ink4c, at birth, were expressed in the whole basal cell layer, whereas p16Ink4a, p19Ink4d, and p21Cip1 were rather located in differentiating or mature neurons. CDK inhibitors may thus act sequentially during this developmental neurogenic process. By comparison, in the adult OE, in which most neural precursors were quiescent, these cells still exhibited p18Ink4c expression but only occasionally p27Kip1 expression. It suggests that p18Ink4c may contribute to maintain basal cells in a quiescent state, whereas p27Kip1 expression in these cells may be rather linked to their neurogenic activity, which declines with age. In keeping with this hypothesis, transgenic mice that lacked p27Kip1 expression displayed a higher rate of cell proliferation versus differentiation in their OE. In these mice, a down-regulation of positive cell cycle regulators was observed that may contribute to compensate for the absence of p27Kip1. Taken together, the present data suggest distinct functions for CDK inhibitors, either in the control of cell cycle exit and differentiation during neurogenesis (respectively, p27Kip1 and p19Ink4d) or in the maintenance of a quiescent state in neural progenitors (p18Ink4c) or neurons (p21Cip1) in adults.

Mucinous differentiation features associated with hormonal escape in a human prostate cancer xenograft.

Many theories mention hypersensitive, promiscuous, outlaw or bypass signalling pathways to explain the acquisition of hormone independence in prostate cancer. Hormonal escape of prostate tumours is marked by many biological changes, including mucinous and neuroendocrine differentiation. Since expression of several mucins has been linked to carcinoma tumour progression, we have characterised the expression of mucins at both RNA and protein levels in an in vivo model of prostate cancer in hormonal escape. Using PAC120, a xenograft of a human hormone-dependent prostate tumour, and its hormone-independent variants, we analysed the expression of mucins (MUC1, MUC2, MUC4, MUC5AC, MUC5B, MUC6) by immunohistochemistry or reverse transcriptase (RT)-PCR. While the parental PAC120 tumour was a compact poorly-differentiated tumour of Gleason score 9 (5+4), hormone-independent variants displayed mucinous, neuroendocrine-like or mixed histological changes; these changes were stable through serial transplantations or after testosterone supply. MUC1 mRNA was expressed in both PAC120 and the hormone-independent variants, although at variable levels. All tumours displayed a high and constant expression of MUC2 and no expression of MUC4 mRNA. While MUC1 was expressed in all xenografts whatever their hormone dependence status, MUC2, MUC5B and MUC6 were preferentially expressed in hormone-independent variants. The loss of hormone dependence in this prostate cancer xenograft model is therefore marked by irreversible histological alterations, mucinous or neuro-endocrine, associated with an expression of secretory MUC2, MUC5B and MUC6, independent of the histological differentiation subtype. These data point to mucinous differentiation as an important step in the acquisition of hormone independence in this cancer, and suggest that secretory mucins might participate in an unknown pathway of hormonal escape in prostate cancer.

[A new model of human prostate cancer, the PAC120 xenograft]. / Un nouveau modèle de cancer humain de prostate, PAC120.

Prostate cancer is the second cause of cancer death in men. Often, initialy hormono-independent, escape from anti-androgen therapy is a key event of tumoral progression showing an hormone-independent phenotype. To study morphological, genetic and molecular bases associated with the hormono-dependence escape, a new model of human adenocarcinoma prostate xenograft, PAC120, was established with its hormono-dependent and independent variants. Its growth was strongly inhibited by surgical castration or by administration of the new gonadotrophin-releasing hormone antagonist, FE 200486 (Ferring, San Diego, CA). Evolution to hormono-independence was frequently associated with a mucoid differentiation or a neuroendocrine-like pattern, with the apparition of new chromosomic alterations and variations of human gene expressions. PAC120 xenograft is a new model of hormone-dependent prostate cancer, opening the opportunity to study the hormone dependence escape mechanism and to evaluate the efficacity of new therapeutics.

Clinical and experimental progression of a new model of human prostate cancer and therapeutic approach.

We report the clinical evolution of a prostate cancer, metastasizing to lungs and bones, recurring locally, and escaping from anti-androgen therapy. Key event of biological progression of the patient's tumor was the coincidence of allelic imbalance accumulation and of bone metastases occurrence. The recurrent tumor was established as the transplantable xenograft PAC120 in nude mice, where it grew locally. PAC120 displayed the same immunophenotype of the original tumor (positive for keratin, vimentin, prostatic acid phosphatase, and Leu-7) and expressed human HOXB9, HOXA4, HER-2/neu, and prostate-specific antigen genes, as detected by reverse transcriptase-polymerase chain reaction. It formed lung micrometastases detected by mRNA expression of human genes. Cytogenetic analysis demonstrated numerous alterations reflecting the tumor evolution. PAC120 was still hormone-dependent; its growth was strongly inhibited by the new gonadotropin-releasing hormone antagonist FE 200486 but weakly by gonadotropin-releasing hormone superagonist D-Trp(6)-luteinizing-hormone releasing hormone (decapeptyl). Tumor growth inhibition induced by anti-hormone therapy was linked to the hormone deprivation degree, more important and more stable with FE 200486 than with D-Trp(6)-luteinizing-hormone releasing hormone. Surgical castration of mice led to tumor regressions but did not prevent late recurrences. Transition to hormone-independent tumors was frequently associated with a mucoid differentiation or with a neuroendocrine-like pattern. Independent variations of mRNA expression of HER-2/neu and prostate-specific antigen were observed in hormone-independent tumors whereas HOXB9 gene expression was constant. In conclusion, PAC120 xenograft, a new model of hormone-dependent prostate cancer retained the progression potential of the original tumor, opening the opportunity to study the hormone dependence escape mechanism.