Targeting EGFR pathway in metastatic colorectal cancer- tumour heterogeniety and convergent evolution

Establishment of a stable hepatic metastasis mouse model of murine colorectal cancer by microsurgical orthotopic implantation

BACKGROUND

Liver metastasis is a common cause of death from colorectal cancer (CRC). In this paper we developed a liver metastasis mouse model by microsurgical orthotopic implantation (MSOI) to illuminate the CRC progression with an eye toward developing effective drug treatment.

METHODS

Murine colon carcinoma CT-26 cells were cultured and then injected to male BALB/c athymic nude mice right flank to generate subcutaneous implantation tumor with 2×107 CT-26 cell suspension in DMEM. Tumor tissue at an average size of 1 cm3 was injected into another nude mice right flank with 20-gauge inoculating needle. Between fourth and sixth generations, tumor tissue sewn into the cecal surface establishes orthotopic transplanted CRC model by MSOI. Then on the 7th, 14th, 21st and 35th day, body weight, abdomen circumference, volume of ascites and local tumor weight were observed and weighed. On the 21st day and 35th day, local tumor rate was calculated, and metastatic tumors of other organs were observed. Tumor tissue was stained by HE for pathologic analysis.

RESULTS

On the 35th day, body weight and abdomen circumference of the model group were significantly higher than the control group (P<0.01). Local tumor weight increased rapidly from the 21st d to the 35th d (P<0.01), and take rate was high (100%). Metastatic tumor appeared only in liver on the 21st day and then invaded to liver, stomach, retroperitoneal lymph node and abdominal wall on the 35th day. The metastatic rate of liver tumor respectively was 83.3% and 100% on the 21st day and 35th day, but liver function remained normal. Pathologic analysis showed that colorectal tumor invaded the normal tissue of liver, abdominal wall and stomach.

CONCLUSIONS

A stable hepatic metastasis mouse model of murine CRC was established by MSOI.

The inhibitory effect of ECG and EGCG dimeric procyanidins on colorectal cancer cells growth is associated with their actions at lipid rafts and the inhibition of the epidermal growth factor receptor signaling

Colorectal cancer (CRC) is one of the most common cancers worldwide. Epidemiological studies indicate that consumption of fruits and vegetables containing procyanidins is associated with lower CRC risk. This study investigated the capacity of two dimeric procyanidins composed of epicatechin gallate (ECG) or epigallocatechin gallate (EGCG) isolated from persimmons, to inhibit CRC cell growth and promote apoptosis, characterizing the underlying mechanisms. ECG and EGCG dimers reduced the growth of five human CRC cell lines in a concentration (10-60 μM)- and time (24-72 h)-dependent manner, with a 72 h-IC50 value in Caco-2 cells of 10 and 30 μM, respectively. ECG and EGCG dimers inhibited Caco-2 cell proliferation by arresting the cell cycle in G2/M phase and by inducing apoptosis via the mitochondrial pathway. In addition, ECG and EGCG dimers inhibited cell migration, invasion, and adhesion, decreasing the activity of matrix metalloproteinases (MMP-2/9). Mechanistically, ECG and EGCG dimers inhibited the activation of lipid raft-associated epidermal growth factor (EGF) receptor (EGFR), without affecting its localization at lipid rafts. In particular, ECG and EGCG dimers reduced EGFR phosphorylation at Tyr1068 residue, prevented EGFR dimerization and activation upon stimulation, and induced EGFR internalization both in the absence and presence of EGF. Furthermore, ECG and EGCG dimers increased EGFR phosphorylation at Tyr1045 residue, providing a docking site for ubiquitin ligase c-Cbl and induced EGFR degradation by the proteasome. Downstream of EGFR, ECG and EGCG dimers inhibited the activation of the MEK/ERK1/2 and PI3K/AKT signaling pathways, downregulating proteins involved in the modulation of cell survival. In conclusion, ECG and EGCG dimers reduced CRC cell growth by inhibiting EGFR activation at multiple steps, including the disruption of lipid rafts integrity and promoting EGFR degradation. These results shed light on a potential molecular mechanism on how procyanidins-rich diets may lower CRC risk.

Nephrotoxicity in cancer treatment: An overview

Anticancer drug nephrotoxicity is an important and increasing adverse drug event that limits the efficacy of cancer treatment. The kidney is an important elimination pathway for many antineoplastic drugs and their metabolites, which occurs by glomerular filtration and tubular secretion. Chemotherapeutic agents, both conventional cytotoxic agents and molecularly targeted agents, can affect any segment of the nephron including its microvasculature, leading to many clinical manifestations such as proteinuria, hypertension, electrolyte disturbances, glomerulopathy, acute and chronic interstitial nephritis, acute kidney injury and at times chronic kidney disease. The clinician should be alert to recognize several factors that may maximize renal dysfunction and contribute to the increased incidence of nephrotoxicity associated with these drugs, such as intravascular volume depletion, the associated use of nonchemotherapeutic nephrotoxic drugs (analgesics, antibiotics, proton pump inhibitors, and bone-targeted therapies), radiographic ionic contrast media or radiation therapy, urinary tract obstruction, and intrinsic renal disease. Identification of patients at higher risk for nephrotoxicity may allow the prevention or at least reduction in the development and severity of this adverse effect. Therefore, the aim of this brief review is to provide currently available evidences on oncologic drug-related nephrotoxicity.

RAS and BRAF in the foreground for non-small cell lung cancer and colorectal cancer: Similarities and main differences for prognosis and therapies

Lung and colorectal cancer are included in the most tremendously threatening diseases in terms of incidence and death. Although they are located in completely different organs and differ in various characteristics they do share some common features, especially regarding their molecular mutational profile. Among several commonly mutated genes KRAS and BRAF are spotted to be highly associated with patient's poor disease outcome and resistance to targeted therapies mostly in liaison with other mutant activated genes. Many studies have shed light in these mechanisms for disease progression and numerous preclinical models, clinical trials and meta-analysis reports investigate the impact of specific treatments or combination of therapies. The present review is an effort to compare the mutational imprint of these genes between the two diseases and their impact in prognosis, current therapy, mechanisms of therapy resistance and future therapeutic plans and provide a spherical perspective regarding the systemic molecular profile of cancer.