Preclinical immunotherapy with Cytokine-Induced Killer lymphocytes against epithelial ovarian cancer.

Despite improvements in surgery and medical treatments, epithelial ovarian cancer (EOC) remains the most lethal gynaecological malignancy. Aim of this study is to investigate the preclinical immunotherapy activity of cytokine-induced killer lymphocytes (CIK) against epithelial ovarian cancers, focusing on platinum-resistant settings. We generated CIK ex vivo starting from human peripheral blood samples (PBMCs) collected from EOC patients. Their antitumor activity was tested in vitro and in vivo against platinum-resistant patient-derived ovarian cancer cells (pdOVCs) and a Patient Derived Xenograft (PDX), respectively. CIK were efficiently generated (48 fold median ex vivo expansion) from EOC patients; pdOVCs lines (n = 9) were successfully generated from metastatic ascites; the expression of CIK target molecules by pdOVC confirmed pre and post treatment in vitro with carboplatin. The results indicate that patient-derived CIK effectively killed autologous pdOVCs in vitro. Such intense activity was maintained against a subset of pdOVC that survived in vitro treatment with carboplatin. Moreover, CIK antitumor activity and tumor homing was confirmed in vivo within an EOC PDX model. Our preliminary data suggest that CIK are active in platinum resistant ovarian cancer models and should be therefore further investigated as a new therapeutic option in this extremely challenging setting.

TOP2A gene copy gain predicts response of epithelial ovarian cancers to pegylated liposomal doxorubicin: TOP2A as marker of response to PLD in ovarian cancer.

OBJECTIVE: The treatment of platinum resistant/refractory epithelial ovarian cancer (EOC) is a challenge for oncologists. One of the most utilized drugs in these patients is pegylated liposomal doxorubicin (PLD). As PLD is active only in a small subset of patients and causes side effects, selection of responsive patients is an unmet need and might be guided by the status of the DNA topoisomerase II alpha (TOP2A) that is poisoned by the drug. METHODS: From 176 ovarian cancers treated in three institutions, we selected 38 patients treated with PLD monotherapy as second/third line of treatment. TOP2A gene copies were measured using Fluorescent In Situ Hybridization (FISH) and expression evaluated using immunohistochemistry. Patients' derived xenografts (PDXs) of ovarian cancers were used to assess the correlation between TOP2A protein expression and response to PLD. RESULTS: Clinical data showed that TOP2A gene gain that is paralleled by increased expression of the protein, was associated with a higher probability of clinical benefit from PLD. Treatment of PDXs demonstrated that only xenografts showing a high percentage of TOP2A expressing cells underwent tumor shrinkage when treated with PLD. CONCLUSIONS: These data show that TOP2A gene gain and protein over-expression might predict activity of PLD in platinum resistant/refractory EOC.

A positive feedback loop between hepatocyte growth factor receptor and beta-catenin sustains colorectal cancer cell invasive growth.

Overexpressed or activated hepatocyte growth factor receptor, encoded by the MET proto-oncogene, was found in the majority of colorectal carcinomas (CRCs), whose stepwise progression to malignancy requires transcriptional activation of beta-catenin. We here demonstrate that a functional crosstalk between Met and beta-catenin signaling sustains and increases CRC cell invasive properties. Hepatocyte growth factor (HGF) stimulation prompts beta-catenin tyrosine phosphorylation and dissociation from Met, and upregulates beta-catenin expression via the phosphatidylinositol 3-kinase pathway in conditions that mimic those found by the invading and metastasizing cells. Additionally, a transcriptionally active form of beta-catenin, known to be oncogenic, enhances Met expression. Furthermore, HGF treatment increases the activity of the beta-catenin-regulated T-cell factor transcription factor in cells expressing the wild-type or the oncogenic beta-catenin. In the mirror experiments, either Met or beta-catenin knocking down also reduces their protein level. In biological assays, beta-catenin knocking down abrogates the HGF-induced motile phenotype, whereas active beta-catenin fosters ligand-independent cell scattering. Met and beta-catenin also cooperate in promoting entry into the cell cycle and in protecting cells from apoptosis. In conclusion, Met and beta-catenin pathways are mutually activated in CRC cells. This might generate a self-amplifying positive feedback loop resulting in the upregulation of the invasive growth properties of CRC cells.

MET receptor is overexpressed but not mutated in oral squamous cell carcinomas.

Oral squamous cell carcinoma (SCC) is a neoplasm characterized by a high degree of local invasion and an elevated rate of metastasis to cervical lymph nodes. It has been shown that the Hepatocyte Growth Factor/Scatter Factor Receptor Met is constitutively activated in many human tumors of epithelial origin and that it plays a critical role to confer invasive properties to neoplastic cells. Most frequently, Met activation is due to receptor overexpression, but also point mutations in the tyrosine kinase domain can lead to deregulated activation. Here we show that in all the primary tumors examined this receptor is overexpressed. Direct sequencing of Met mRNAs failed to find any activating mutation in its intracellular domain. Moreover, in cell lines derived from squamous cell carcinomas, HGF-induced activation of Met resulted in the acquisition of invasive properties. All together these data suggest that the MET oncogene is involved in progression of squamous cell carcinoma toward an invasive-metastatic behavior.

Staging of head and neck squamous cell carcinoma using the MET oncogene product as marker of tumor cells in lymph node metastases.

In head and neck squamous cell carcinomas (HNSCC), metastasis to cervical lymph nodes is a major determinant of patient outcome. To detect metastases, we used the MET oncogene as marker, which encodes the receptor for hepatocyte growth factor/scatter factor, mediating epithelial cell motility and invasiveness. The MET gene is expressed in epithelia and over-expressed in carcinomas of specific histotypes, but not in lymphatic tissue. A total of 151 lymph nodes from 20 squamous cell carcinomas were studied with both in-depth histology and end-point and real-time quantitative RT-PCR. MET-encoded sequences were found in 61 of 151 nodes (40%), of which 24 (16%) were found metastatic by in-depth histopathology. Parallel routine histopathologic analysis of 654 lymph nodes from the same cases identified 36 metastases (5%). Real-time quantitative RT-PCR was used to measure MET gene-specific mRNA in normal tissues, primary tumors and lymphatic metastases and showed a 2-8-fold increased expression in tumor cells which metastasize. RT-PCR for 3 cytokeratins expressed in HNSCC (K4, K10 and K13) proved to be less sensitive in detecting occult lymphatic metastases. Western blot analysis demonstrated the presence of the full-size MET receptor in primary tumors and lymph node metastases; immunohistochemistry showed receptor localization in tumor cells. Altogether, these data demonstrate that the MET gene product is a valuable marker with which to detect occult tumor cells in lymph nodes, thanks to its high expression in metastatic cells. After RT-PCR analysis we were able to attribute a more advanced stage to 10 out of 20 HNSCC cases, including 5 cases classified as tumor-free after routine histopathology.

Somatic mutations of the MET oncogene are selected during metastatic spread of human HNSC carcinomas.

A metastatic cancer develops by accumulation of mutations in genes that control growth, survival and spreading. The latter genes have not yet been identified. In lymph node metastases of head and neck squamous cell carcinomas (HNSCC), we found mutations in the MET oncogene, which encodes the tyrosine kinase receptor for Scatter Factor, a cytokine that stimulates epithelial cell motility and invasiveness during embryogenesis and tissue remodeling. We identified two somatic mutations: the Y1230C, known as a MET germline mutation which predisposes to hereditary renal cell carcinoma, and the Y1235D that is novel and changes a critical tyrosine, known to regulate MET kinase activity. The mutated MET receptors are constitutively active and confer an invasive phenotype to transfected cells. Interestingly, cells carrying the MET mutations are selected during metastatic spread: transcripts of the mutant alleles are highly represented in metastases, but barely detectable in primary tumors. These data indicate that cells expressing mutant MET undergo clonal expansion during HNSCC progression and suggest that MET might be one of the long sought oncogenes controlling progression of primary cancers to metastasis.

Novel mutation in the ATP-binding site of the MET oncogene tyrosine kinase in a HPRCC family.

Germline mutations in the tyrosine-kinase domain of the MET proto-oncogene were found in patients suffering from the hereditary predisposition to develop multiple papillary renal-cell carcinomas (hereditary PRCC, HPRCC). PRCCs are often multiple and bilateral even in patients without a family history. We analyzed the germline of patients carrying multiple or single papillary tumors with and without family history. One patient had a familial cancer and carried a novel (V1110I) germline MET mutation, located in MET gene exon 16. This mis-sense mutation was found in affected members of this patient's family. Interestingly, the V1110I mutation is located in the ATP-binding site of the MET kinase and is homologous to the V157I mutation that triggers the sarcomagenic potential of the v-erbB oncogene. The V1110I mutated MET receptor is an active kinase and transforms NIH-3T3 fibroblasts in the in vitro assays. Patients without familiality did not show germline mutations in the MET kinase domain, showing that multiple and bilateral papillary kidney tumors develop in the absence of these mutations. In conclusion, we describe a new mutation in the MET oncogene kinase domain, associated to HPRCC, affecting an amino-acid residue critical for kinase activation in different oncogenes.

[Evaluation of Ron and Met proto-oncogene expression in epithelial ovarian tumors]. / Valutazione dell'espressione dei proto-oncogeni Ron e Met nei tumori epiteliali ovarici.

BACKGROUND: Epithelial ovarian cancer is the most lethal gynecologic neoplasia. Up to date, little is known about its biology, and this makes even more difficult the definition of new therapies and the finding of early diagnostic methods. In this study, the expression of two oncogenes, Ron and Met, whose role in cancer progression has already been shown, and the possible clinical implication of their presence in the neoplastic tissue have been evaluated. METHODS: Forty-eight ovarian cancer specimens, 5 borderline lesions, 4 benign ovarian tumors and 2 normal ovaries were analyzed; from frozen tissue, Rna was extracted and cDna obtained by a RT-PCR (Retrotranscriptase-Polymerase Chain Reaction). Finally, the cDna was assayed for the presence of the Ron and the Met gene by another PCR. The results were correlated with clinicopathological parameters, and patient survival. RESULTS: Ron expression was shown in 56% of malignant lesions, and in 60% of borderline ones, while Met expression was detected in 54 and 60%, respectively. No statistically significant correlation was found between Ron and Met expression and clinicopathological features, such as histotype, grading, staging, residual tumor after debulking surgery, and response to chemotherapy, while a strong correlation (p = 0.001) was observed between overexpression of one of the oncogenes and the concomitant expression of the other. CONCLUSIONS: Even if residual tumor after debulking surgery was the most relevant prognostic factor, this study showed new data about the concomitant expression of Ron and Met oncogenes, which may suggest their cooperative role in ovarian cancer progression.

Overexpression of the RON gene in human breast carcinoma.

Constitutive activation of the RON gene, known to code for the tyrosine-kinase receptor for Macrophage Stimulating Protein (also known as Scatter Factor 2), has been shown to induce invasive-metastatic phenotype in vitro. As yet, nothing is known about the expression of this novel member of the MET-oncogene family in spontaneously occurring human cancers. Here we report that Ron is expressed at abnormally high levels in about 50% primary breast carcinomas (35/74 patients). Among these, the expression is increased more than 20-fold in 12 cases and the overexpressed protein is constitutively phosphorylated on tyrosine residues. Notably, Ron is only barely detectable in epithelial cells of the mammary gland, and its expression remains unchanged in benign breast lesions (including adenomas and papillomas). Overexpression was observed in different histotypic variants of carcinomas; it is associated with the disease at any stage and correlates with the post-menopausal status. In breast carcinoma cells grown in vitro, activation of the Ron receptor resulted in proliferation, migration and invasion through reconstituted basement membranes. Altogether, these data suggest a role for the RON gene in progression of human breast carcinomas to the invasive-metastatic phenotype.

Negative/low expression of the Met/hepatocyte growth factor receptor identifies papillary thyroid carcinomas with high risk of distant metastases.

To investigate the clinical impact of Met/hepatocyte growth factor receptor (HGF-R) expression in thyroid cancer we studied 163 thyroid carcinomas (129 papillary, 21 follicular, and 13 anaplastic) from patients followed-up for 25-147 months postthyroidectomy. Forty-nine thyroid adenomas were also studied. Met/HGF-R expression was evaluated by semiquantitative immunohistochemistry, measuring both the proportion (scale of 0-5) and the intensity (scale, 0-5) of stained cells and calculating a total score (scale of 0-10). Met/HGF-R was absent in the normal thyroid tissue, absent or focally expressed in follicular and anaplastic tumors, and expressed at various levels in most papillary carcinomas, including microcarcinomas. Papillary carcinomas were thus categorized as having negative/low Met/HGF-R (n = 50; total score, < or = 5) or high Met/HGF-R expression (n = 70; total score, > 5). High Met/HGF-R was inversely associated with vascular invasion (P = 0.0308), but not with other prognostic factors. Negative/low Met/HGF-R expression was the most effective predictor by multivariate Cox analysis of distant metastases (hazard ratio = 9.71; P = 0.0036), higher than extrathyroid invasion (hazard ratio = 4.25; P = 0.0181), age (< or = 45 vs. > 45 yr; hazard ratio = 3.99; P = 0.0099), and vascular invasion (hazard ratio = 3.19; P = 0.0358). These findings suggest a role for Met/HGF-R in papillary thyroid cancer and its clinical use to select patients with a high risk of distant metastases.

Detection of MET oncogene/hepatocyte growth factor receptor in lymph node metastases from head and neck squamous cell carcinomas.

The c-MET oncogene encodes the receptor for hepatocyte growth factor/scatter factor (HGF/SF), which is known to stimulate the invasive growth of epithelial cells cultured in vitro. The Met/HGF receptor is a heterodimeric transmembrane tyrosine kinase, which is a prototype for a new family of growth factor receptors. The c-MET oncogene is expressed in several types of epithelial tissue including keratinocytes and is over-expressed in a number of human carcinomas. Studies on various carcinoma cell lines have shown that over-expression and structural alteration of the receptor result in its activation and confer tumorigenesis. We have studied Met/HGF receptor expression in tissue specimens from 34 patients with head and neck squamous cell carcinomas (HNSCC) and in 17 regional lymph node metastases. Western blot analysis was employed, using monoclonal antibodies directed against either the intracellular or extracellular domain of the receptor. Each sample was compared to its normal counterpart. The receptor did not show any major structural alterations in HNSCC tissues, but its expression was increased from 2- to 50-fold in about 70% of tumors. Immunohistochemistry then showed that the same antibodies stained only a few cells in the basal layer of normal squamous epithelium but intensely marked tumor cells. In the lymph node metastases of Met-positive tumors, receptor expression was maintained and sometimes increased with respect to primary tumors. Immunohistochemical analysis of the metastatic lymph nodes showed that cells were negative in the normal lymphatic tissue and strongly stained in tumor cells. Over-expression of the Met/HGF receptor was found at all tumor stages but was more significant in those associated with enlarged or multiple (N2-N3) lymph node metastases. These data show that expression of the Met/HGF receptor may be involved in the progression of HNSCC towards a metastatic phenotype and may be a useful marker of head and neck tumor cell spread to regional lymph nodes.

Overexpression and activation of hepatocyte growth factor/scatter factor in human non-small-cell lung carcinomas.

Hepatocyte growth factor/scatter factor (HGF/SF) stimulates the invasive growth of epithelial cells via the c-MET oncogene-encoded receptor. In normal lung, both the receptor and the ligand are detected, and the latter is known to be a mitogenic and a motogenic factor for both cultured bronchial epithelial cells and non-small-cell carcinoma lines. Here, ligand and receptor expression was examined in 42 samples of primary human non-small-cell lung carcinoma of different histotype. Each carcinoma sample was compared with adjacent normal lung tissue. The Met/HGF receptor was found to be 2 to 10-fold increased in 25% of carcinoma samples (P = 0.0113). The ligand, HGF/SF, was found to be 10 to 100-fold overexpressed in carcinoma samples (P < 0.0001). Notably, while HGF/SF was occasionally detectable and found exclusively as a single-chain inactive precursor in normal tissues, it was constantly in the biologically-active heterodimeric form in carcinomas. Immunohistochemical staining showed homogeneous expression of both the receptor and the ligand in carcinoma samples, whereas staining was barely detectable in their normal counterparts. These data show that HGF/SF is overexpressed and consistently activated in non-small-cell lung carcinomas and may contribute to the invasive growth of lung cancer.

Expression of Met/hepatocyte growth factor receptor gene and malignant behavior of musculoskeletal tumors.

Overexpression of the hepatocyte growth factor receptor (Met/HGF receptor), a transmembrane tyrosine kinase encoded by the met proto-oncogene, has been associated with tumor progression in different human carcinomas. More recently, the Met/HGF receptor has also been described in tumor cell lines of mesenchymal origin, suggesting the existence of an autocrine loop that may contribute to the pathogenesis of sarcomas. In this study, we analyzed the expression of Met/HGF receptor by Western blotting and immunohistochemistry in frozen samples of 87 primary tumors of bone and soft tissues. Among benign tumors, overexpression was consistently found only in giant-cell tumor, a locally aggressive lesion that may also, although rarely, spread to the lung. Among malignant lesions, the presence of the Met/HGF receptor was detected in a relevant percentage of primaries and in almost all of the recurrences. The highest levels of Met/HGF receptor were found in osteosarcoma, a highly aggressive tumor that typically permeates the host bone and rapidly expands to the soft tissues. On the contrary, only low levels of Met/HGF receptor were found in chondrosarcoma, a slowly growing tumor that usually expands without massive destruction of the surrounding structures. These data indicate an association of Met/HGF expression with local aggressiveness in human mesenchymal tumors. The finding of Met/HGF receptor overexpression in all of the osteosarcomas suggests a role for the met proto-oncogene in the pathogenesis of this tumor.

Overexpression of the met/HGF receptor in renal cell carcinomas.

The c-met oncogene encodes the receptor for hepatocyte growth factor/scatter factor (HGF/SF), a multifunctional cytokine able to mediate morphogenesis as well as mitogenesis, motogenesis and invasiveness of epithelial cells. HGF/SF has been implicated in branching tubulogenesis of the developing kidney and in regeneration after renal injury and nephrectomy. We have examined the expression of the met/HGF receptor in normal human kidney and tissues of the genito-urinary tract, and in 50 kidney neoplasms of different histotypes, using monoclonal antibodies (MAbs) against the met/HGF receptor and immunohistochemistry. In normal kidneys, weak staining restricted to the distal tubules was observed. Transitional cell carcinomas were consistently negative, whereas increased expression at various levels was found in 87% of renal cell carcinomas with different cytological features and histological patterns. Western blot analysis of samples showed that the met/HGF receptor found in the malignant cells exhibits features of the normal receptor. The met/HGF receptor is also overexpressed in a renal cell carcinoma cell line, whose motility is triggered by HGF/SF. Our data suggest that expression of the met/HGF receptor may be involved in the onset and progression of renal cell carcinomas.

Retrogenic expression of the MET proto-oncogene correlates with the invasive phenotype of human rhabdomyosarcomas.

The MET oncogene encodes the receptor for HGF/Scatter Factor, known to control cell motility and invasion in epithelial cells. We report that the Met/HGF receptor, absent in differentiated adult skeletal muscles, is aberrantly expressed in clinical samples and in established cell lines of human rhadbomyosarcomas. In both the embryonal and alveolar histotypes the oncogene is overexpressed and, in some cases, amplified. The Met receptor is exposed at the cell surface and is functionally active in response to HGF/Scatter Factor. Accordingly, rhabdomyosarcoma cells exhibit an invasive phenotype in vitro in response to exogenous HGF/Scatter factor. As the factor is known to be produced by connective tissues, a paracrine stimulation of rhabdomyosarcoma invasiveness in vivo is hypothesized. Two alveolar rhabdomyosarcomas were found in co-express the ¿two-kringle' alternatively-spliced HGF/Scatter Factor variant, which has been previously shown to stimulate cell motility and matrix invasion in vitro. These cells displayed the invasive phenotype in the absence of exogenous HGF/Scatter Factor, suggesting an autocrine mechanism in vivo. These data indicate that aberrant expression of the MET proto-oncogene provides rhabdomyosarcoma cells with the same property as embryonal myoblasts to migrate into the surrounding connective tissues.

Expression of the Met/hepatocyte growth factor receptor in human pancreatic cancer.

The c-MET oncogene encodes the receptor for hepatocyte growth factor (HGF) scatter factor, a multifunctional cytokine able to mediate morphogenesis as well as invasive growth of epithelial cells. The c-MET-encoded receptor is detectable only at low levels in the normal human exocrine pancreas, but it is up-regulated in the majority of pancreatic ductal adenocarcinomas. The c-MET-encoded HGF receptor is also overexpressed in a proportion of the panel of 31 human pancreatic cancer cell lines examined, which have a range of different growth properties and degrees of differentiation. In most cases the HGF receptor found in the malignant cells has features of the normal receptor. When added to pancreatic cancer cell lines, HGF triggers receptor phosphorylation and stimulates cells to move and proliferate. In overexpressing cell lines, the Met/HGF receptor is phosphorylated in the absence of endogenously produced or exogenously added ligand. These data suggest that the Met/HGF receptor may be involved in the growth and behavior of pancreatic cancer and may contribute to the ductal phenotype of these tumors.

The Met/HGF receptor is over-expressed in human osteosarcomas and is activated by either a paracrine or an autocrine circuit.

The c-MET oncogene encodes the receptor for the Hepatocyte Growth Factor/Scatter Factor (HGF), a cytokine that stimulates the invasive growth of normal and neoplastic cells. The Met/HGF receptor is expressed by epithelial cells and its ligand by cells of mesenchymal origin. Receptor-ligand interaction occurs via a paracrine circuit. We studied the expression of the Met/HGF receptor and of its ligand in mesenchymal human tumours by examining 39 clinical samples of bone tumours. The Met/HGF receptor was not detectable in the majority of bone tumours, as expected from their mesenchymal origin. Notably, the receptor was overexpressed in 60% of the osteosarcomas examined. In 12 osteosarcoma cell lines the Met/HGF receptor was overexpressed, phosphorylated by HGF stimulation and fully functional. HGF was detected in two out of seven clinical specimens of osteosarcoma. The ligand and the receptor are co-expressed in two clonal osteosarcoma cell lines. In these lines the Met/HGF receptor was constitutively phosphorylated; phosphorylation was suppressed by suramin treatment, a known blocker of autocrine loops. These data suggest that activation of the Met/HGF receptor by a paracrine or an autocrine mechanism might play a role in the particularly aggressive behaviour of osteosarcomas.

Overexpression and amplification of the met/HGF receptor gene during the progression of colorectal cancer.

The c-met oncogene encodes the receptor for hepatocyte growth factor/scatter factor, a potent mitogen for epithelial cells that also promotes cell motility and invasiveness. We have studied the changes of c-met gene expression that occur during the progression of colorectal tumors. Sixteen adenomas, 123 primitive carcinomas, and 25 liver metastases were examined. In several instances it was possible to compare same-patient samples of normal colon mucosa against primary tumor and primary carcinoma against synchronous metastasis. The expression of the c-met gene was increased from 5- to 50-fold in about 50% of tumors, at any stage of progression, and in 70% of liver metastases. Overexpression was associated with amplification of the c-met gene in only 10% of carcinomas, but in 8 of 9 metastases examined. These data suggest that overexpression of the c-met oncogene contributes a selective growth advantage to neoplastic colorectal cells at any stage of tumor progression. Moreover, amplification appears to give a further selective advantage for the acquisition of metastatic potential.