High expression of vascular endothelial growth factor is associated with liver metastasis and a poor prognosis for patients with ductal pancreatic adenocarcinoma

Recent advances in targeted therapy for pancreatic adenocarcinoma

Pancreatic adenocarcinoma (PDAC) is a fatal disease with a 5-year survival rate of 8% and a median survival of 6 mo. In PDAC, several mutations in the genes are involved, with Kirsten rat sarcoma oncogene (90%), cyclin-dependent kinase inhibitor 2A (90%), and tumor suppressor 53 (75%–90%) being the most common. Mothers against decapentaplegic homolog 4 represents 50%. In addition, the self-preserving cancer stem cells, dense tumor microenvironment (fibrous accounting for 90% of the tumor volume), and suppressive and relatively depleted immune niche of PDAC are also constitutive and relevant elements of PDAC. Molecular targeted therapy is widely utilized and effective in several solid tumors. In PDAC, targeted therapy has been extensively evaluated; however, survival improvement of this aggressive disease using a targeted strategy has been minimal. There is currently only one United States Food and Drug Administration-approved targeted therapy for PDAC – erlotinib, but the absolute benefit of erlotinib in combination with gemcitabine is also minimal (2 wk). In this review, we summarize current targeted therapies and clinical trials targeting dysregulated signaling pathways and components of the PDAC oncogenic process, analyze possible reasons for the lack of positive results in clinical trials, and suggest ways to improve them. We also discuss emerging trends in targeted therapies for PDAC: combining targeted inhibitors of multiple pathways. The PubMed database and National Center for Biotechnology Information clinical trial website (www.clinicaltrials.gov) were queried to identify completed and published (PubMed) and ongoing (clinicaltrials.gov) clinical trials (from 2003-2022) using the keywords pancreatic cancer and targeted therapy. The PubMed database was also queried to search for information about the pathogenesis and molecular pathways of pancreatic cancer using the keywords pancreatic cancer and molecular pathways.

Evaluation of biomarkers, genetic mutations, and epigenetic modifications in early diagnosis of pancreatic cancer

BACKGROUND

Pancreatic cancer (PC) is one of the deadliest malignancies with an alarming mortality rate. Despite significant advancement in diagnostics and therapeutics, early diagnosis remains elusive causing poor prognosis, marred by mutations and epigenetic modifications in key genes which contribute to disease progression.

AIM

To evaluate the various biological tumor markers collectively for early diagnosis which could act as prognostic biomarkers and helps in future therapeutics of PC in Kashmir valley.

METHODS

A total of 50 confirmed PC cases were included in the study to evaluate the levels of carbohydrate antigen 19-9 (CA 19-9), tissue polypeptide specific antigen (TPS), carcinoembryonic antigen (CEA), vascular endothelial growth factor-A (VEGF-A), and epidermal growth factor receptor (EGFR). Mutational analysis was performed to evaluate the mutations in Kirsten rat sarcoma (KRAS), Breast cancer type 2 (BRCA-2), and deleted in pancreatic cancer-4 (DPC-4) genes. However, epigenetic modifications (methylation of CpG islands) were performed in the promoter regions of cyclin-dependent kinase inhibitor 2A (p16; CDKN2A), MutL homolog 1 (hMLH1), and Ras association domain-containing protein 1(RASSF1A) genes.

RESULTS

We found significantly elevated levels of biological markers CA 19-9 (P ≤ 0.05), TPS (P ≤ 0.05), CEA (P ≤ 0.001), and VEGF (P ≤ 0.001). Molecular genetic analysis revealed that KRAS gene mutation is predominant in codon 12 (16 subjects, P ≤ 0.05), and 13 (12 subjects, P ≤ 0.05). However, we did not find a mutation in DPC-4 (1203G > T) and BRCA-2 (617delT) genes. Furthermore, epigenetic modification revealed that CpG methylation in 21 (P ≤ 0.05) and 4 subjects in the promoter regions of the p16 and hMLH1 gene, respectively.

CONCLUSION

In conclusion, CA 19-9, TPS, CEA, and VEGF levels were significantly elevated and collectively have potential as diagnostic and prognostic markers in PC. Global data of mutation in the KRAS gene commonly in codon 12 and rare in codon 13 could augment the predisposition towards PC. Additionally, methylation of the p16 gene could also modulate transcription of genes thereby increasing the predisposition and susceptibility towards PC.

Clinical significance of serum leptin, vascular endothelial growth factor and alpha-fetoprotein expression in hepatocelluar carcinoma

AIM: To explore the expression of serum leptin (Lep), vascular endothelial growth factor (VEGF) and alpha-fetoprotein (AFP) and their clinical significances in hepatocelluar carcinoma (HCC).

METHODS: Enzyme-linked immunosorbent assay (ELISA) was used to detect serum Lep, VEGF and AFP levels in 146 patients with HCC, 31 patients with liver cirrhosis and 30 healthy controls. The correlations Lep, VEGF, and AFP expression with clinical indexes were analyzed.

RESULTS: The serum Lep level was correlated with body mass index (BMI) in HCC patients (r = 0.64, P < 0.01), and significantly lower than that in cirrhotic patients and healthy controls (19 μg/L vs 35, 27 μg/L, P < 0.05). The serum Lep level in HCC patients was significantly decreased with upgrade of TNM stages, metastasis and recurrence (P < 0.05). In comparison with that in cirrhotic patients and healthy controls, the serum VEGF level in HCC patients was significantly increased (398 ng/Lvs 179, 167 ng/L, P < 0.01). There was no correlation between VEGF and AFP expression. The sensitivity and specificity of VEGF were 71.2% and 80.6%, and those of AFP were 73.3% and 83.9%, respectively, in the diagnosis of HCC. However, the sensitivity was increased to 91.8%, while the accuracy reached 90.4% after the combined detection of VEGF and AFP was used. There was a relationship beween the level of serum VEGF and tumor size (<3 cm: 237 ± 96 ng/L, >3 cm: 398 ± 124 ng/L, P < 0.01). As compared with that of TNMⅠ, Ⅱ stage, the serum VEGF of TNM Ⅲ, Ⅳstage was obviously higher (346 ± 131, 401 ± 152 ng/L vs 228 ± 89, 259 ± 102 ng/L, P < 0.01), and it also showed a significant elevation in the patients with metastasis and recurrent HCC (P < 0.01).

CONCLUSION: Nutrition status and prognosis of patients with HCC can be judged by serum Lep level, and the combined detection of serum VEGF and AFP may provide a significant marker for HCC diagnosis and prognosis.

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Expression of CD44v6 and vascular endothelial growth factor in hepatocellular carcinoma after transcatheter hepatic arterial chemoembolization

AIM: To investigate the role of vascular endothelial growth factor (VEGF) and CD44v6 in the recurrence and metastasis of hepatocellular carcinoma (HCC) after transcatheter hepatic arterial chemoembolization (TACE).

METHODS: The expression of CD44v6 and VEGF in 29 HCC samples obtained from the patients underwent secondary hepatectomy after TACE was examined by immunohistochemical staining and morphometric analysis. HCC samples (n = 30) obtained from the patients without TACE were used as the control group.

RESULTS: The value of VEGF absorbance in the TACE group was 0.149 ± 0.021, significantly higher than that in the controls (0.134 ± 0.018, P < 0.05). The positive rate of CD44v6 expression was 82.8% and 66.7% in the TACE group and control group, respectively, without significant difference between them (P > 0.05). The numbers of CD44v6 positive cells were also not markedly different between the two groups (112.4 ± 22.3 vs 102.4 ± 21.2, P > 0.05).

CONCLUSION: VEGF may take part in the recurrence and metastasis of HCC after TACE, while CD44v6 may not.

Angiostatin inhibits pancreatic cancer cell proliferation and growth in nude mice

AIM: To observe the biologic behavior of pancreatic cancer cells in vitro and in vivo, and to explore the potential value of angiostatin gene therapy for pancreatic cancer.

METHODS: The recombinant vector pcDNA3.1(+)-angiostatin was transfected into human pancreatic cancer cells PC-3 with Lipofectamine 2000, and paralleled with the vector and mock control. Angiostatin transcription and protein expression were determined by immunofluorescence and Western blot. The stable cell line was selected by G418. The supernatant was collected to treat endothelial cells. Cell proliferation and growth in vitro were observed under microscope. Cell growth curves were plotted. The troms-fected or untroms-fected cells overexpressing angiostatin vector were implanted subcutaneously into nude mice. The size of tumors was measured, and microvessel density count (MVD) in tumor tissues was assessed by immunohistochemistry with primary anti-CD34 antibody.

RESULTS: After transfected into PC-3 with Lipofectamine 2000 and selected by G418, macroscopic resistant cell clones were formed in the experimental group transfected with pcDNA 3.1(+)-angiostatin and vector control. But untreated cells died in the mock control. Angiostatin protein expression was detected in the experimental group by immunofluorescence and Western-blot. Cell proliferation and growth in vitro in the three groups were observed respectively under microscope. After treatment with supernatant, significant differences were observed in endothelial cell (ECV-304) growth in vitro. The cell proliferation and growth were inhibited. In nude mice model, markedly inhibited tumorigenesis and slowed tumor expansion were observed in the experimental group as compared to controls, which was parallel to the decreased microvessel density in and around tumor tissue.

CONCLUSION: Angiostatin does not directly inhibit human pancreatic cancer cell proliferation and growth in vitro, but it inhibits endothelial cell growth in vitro. It exerts the anti-tumor functions through antiangiogenesis in a paracrine way in vivo.

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Inhibition of growth and metastasis of human gastric cancer implanted in nude mice by d-limonene

AIM: To investigate the effects and mechanism of d-limonene on the growth and metastasis of gastric cancer in vivo.

METHODS: Metastatic model simulating human gastric cancer was established by orthotopic implantation of histologically intact human tumor tissue into gastric wall of nude mice. One percent d-limonene was orally administered at dose of 15 ml/kg every other day for seven weeks. Eight weeks after implantation, tumor weight, inhibition rate, apoptotic index (AI), microvessel density (MVD), vascular endothelial growth factor (VEGF), variation of ultrastructure, and the presence of metastasis were evaluated, respectively, after the mice were sacrificed.

RESULTS: The tumor weight was significantly reduced in 5-FU group (2.55 ± 0.28 g), d-limonene group (1.49 ± 0.09 g) and combined treatment group (1.48 ± 0.21 g) compared with the control group(2.73 ± 0.23 g, P < 0.05). In 5-FU group, d-limonene group, combined treatment group, the inhibition rates were 2.60%, 47.58% and 46.84% and 0, respectively; AI was (3.31 ± 0.33)%, (8.26 ± 1.21)%, (20.99 ± 1.84)% and (19.34 ± 2.19)%, respectively; MVD was (8.64 ± 2.81), (16.77 ± 1.39), (5.32 ± 4.26) and (5.86 ± 2.27), respectively; VEGF expression was (45.77 ± 4.79), (41.34 ± 5.41), (29.71 ± 8.92) and (28.24 ± 8.55), respectively. The incidences of peritoneal metastasis also decreased significantly in 5-FU group(77.8%), d-limonene group (20.0%) and combined group (22.2%) compared with control group (100%) versus 62.5%, 30% and 22.2%) (P < 0.05). Liver metastasis was also inhibited and the incidences decreased significantly in 5-FU group, d-limonene group and combined group than that in control group (87.5% vs 55.5%, 20.0% and 22.2% respectively) (P < 0.05). The incidence of ascites in control group, 5-FU group, d-limonene group and combined group was 25.0%, 22.2%, 0, 0, respectively and 12.5%, 11.1% 0, 0, with respect to the metastasis rate to other organs.

CONCLUSION: d-limonene has antiangiogenic and proapoptotic effects on gastric cancer, thereby inhibits tumor growth and metastasis. Combination of d-limonene with cytotoxic agents may be more effective.

Antiangiogenic effect of somatostatin receptor subtype 2 on pancreatic cancer cell line: Inhibition of vascular endothelial growth factor and matrix metalloproteinase-2 expression in vitro

AIM: To investigate the anti-angiogenic effect of somatostatin receptor subtype 2 (SSTR2) gene transfer into pancreatic cancer cell line PC-3, and the mechanisms involved in this effect.

METHODS: The full length human SSTR2 cDNA was introduced into pancreatic cancer cell line PC-3 by lipofectamine-mediated transfection. Positive clones were screened by G418 and stable expression of SSTR2 was detected by immunohistochemistry SABC methods and RT-PCR. Enzyme-linked immunosorbent assay (ELISA) was used to detect vascular endothelial growth factor (VEGF) levels in the cell culture supernatants of SSTR2-expressing cells, vector control and mock control cells. Furthermore, the expressions of VEGF and matrix metalloproteinase-2 (MMP-2) were detected by immunohistochemistry SABC methods and RT-PCR in these cells.

RESULTS: VEGF levels in the cell culture supernatants were significantly reduced in the SSTR2-expressing cells (first week, 172.63 ± 21.2 ng/L and after two months, 198.85 ± 26.44 ng/L) compared with the vector control (first week, 790.39 ± 86.52 ng/L and after two months, 795.69 ± 72.35 ng/L) and mock control (first week, 786.42 ± 90.62 ng/L and after two months, 805.32 ± 84.36 ng/L) (P < 0.05). The immunohistochemical assay showed a significant reduction of the integral optical density of VEGF and MMP-2 in the SSTR2-expressing cells (42.25 ± 8.6 and 70.5 ± 6.25, respectively) compared with the vector control (85.75 ± 12.9 and 110.52 ± 13.5, respectively) and mock control (82.6 ± 9.28 and 113.56 ± 9.62, respectively) (P < 0.05). Conversely, the average gray value of VEGF and MMP-2 was significantly increased in the SSTR2-expressing cells (121.56 ± 8.43 and 134.46 ± 19.95, respectively) compared with the vector control (55.72 ± 5.6 and 62.26 ± 12.68, respectively) and mock control cells (58.48 ± 6.2 and 65.49 ± 9.16, respectively) (P < 0.05). Moreover, the expressions of VEGF mRNA and MMP-2 mRNA were significantly reduced in the SSTR2-expressing cells (0.1384 ± 0.017 and 0.2343 ± 0.070, respectively) compared with the vector control (1.024 ± 0.117 and 0.806 ± 0.119, respectively) and mock control (1.085 ± 0.105 and 0.714 ± 0.079, respectively) (P < 0.05).

CONCLUSION: The expression of reintroduced human SSTR2 gene exerts its antiangiogenic effects by down-regulating the expressions of the factors involved in tumor angiogenesis and metastasis, suggesting SSTR2 gene transfer as a new strategy of gene therapy for pancreatic cancer.

Correlation of CT enhancement, tumor angiogenesis and pathologic grading of pancreatic carcinoma

AIM: To study the correlation between pancreatic phase CT enhancement, intratumor microvessel density (MVD) and pathologic grading of pancreatic carcinoma and to evaluate the relationship between the degrees of CT enhancement and malignancy of pancreatic carcinoma.

METHODS: Thirty four patients with pancreatic carcinoma underwent CT scanning before resection. The enhancement degrees and forms of tumor were observed in pancreatic phase. The operative sample was stained with HE and CD34 marked by immunohistochemistry. MVD and histopathological grades of pancreatic carcinoma were examined. CT enhancement of the tumor, MVD counting in hot spot areas of neoplastic parenchymal cells and pathological grades of pancreatic carcinoma were comparatively analyzed.

RESULTS: Highly differentiated pancreatic adenocarcinoma was identified in 16 patients, moderately-differentiated tumor in 7 and poorly-differentiated in 11. Isodensity CT enhancement was demonstrated in 13 cases, slightly low density enhancement in 9, slightly low density enhancement with small cystic lesions in 9 and slightly low density enhancement with large cystic lesions in 3. The counting of MVD with CD34 marked by immunohistochemistry in hot spot areas of neoplastic parenchyma cells was small in 10 cases, medium in 16 and large in 8. The pathological grades correlated well with CT enhancement of the tumor (r = 0.7857, P < 0.001) and with MVD counting of tumor (r = 0.3613, P < 0.05). The CT enhancement of tumor correlated with MVD(r = 0.6768, P < 0.001).

CONCLUSION: There is an obvious and significant correlation between CT enhancement, pathological grades and MVD number in the hot spot areas of tumor. The extent of CT enhancement is inversely proportional to the malignant degree of pancreatic carcinoma, and to the MVD number in the hot spot areas of neoplastic parenchyma. The MVD in the hot spot areas of neoplastic parenchyma cells can also reflect the prognosis of the patients, and is directly proportional to the malignant degree of pancreatic carcinoma.